Struct Text 

pub struct Text(pub String);

The top-level UI text component.

Adding Text to an entity will pull in required components for setting up a UI text node.

The string in this component is the first ‘text span’ in a hierarchy of text spans that are collected into a ComputedTextBlock. See TextSpan for the component used by children of entities with Text.

Note that Transform on this entity is managed automatically by the UI layout system.

// Basic usage.
world.spawn(Text::new("hello world!"));

// With non-default style.
world.spawn((
    Text::new("hello world!"),
    TextFont {
        font: font_handle.clone().into(),
        font_size: FontSize::Px(60.0),
        ..Default::default()
    },
    TextColor(BLUE.into()),
));

// With text justification.
world.spawn((
    Text::new("hello world\nand bevy!"),
    TextLayout::justify(Justify::Center)
));

// With spans
world.spawn(Text::new("hello ")).with_children(|parent| {
    parent.spawn(TextSpan::new("world"));
    parent.spawn((TextSpan::new("!"), TextColor(BLUE.into())));
});

Tuple Fields

0: String

Implementations

impl Text

pub fn new(text: impl Into<String>) -> Text

Makes a new text component.

Examples found in repository

examples/3d/../helpers/widgets.rs (line 156)

pub fn ui_text(label: &str, color: Color) -> impl Bundle + use<> {
    (
        Text::new(label),
        TextFont {
            font_size: FontSize::Px(18.0),
            ..default()
        },
        TextColor(color),
    )
}

examples/3d/occlusion_culling.rs (line 378)

fn spawn_help_text(commands: &mut Commands) {
    commands.spawn((
        Text::new(""),
        Node {
            position_type: PositionType::Absolute,
            top: px(12),
            left: px(12),
            ..default()
        },
    ));
}

examples/animation/animation_graph.rs (line 260)

fn setup_help_text(commands: &mut Commands) {
    commands.spawn((
        Text::new(HELP_TEXT),
        Node {
            position_type: PositionType::Absolute,
            top: px(12),
            left: px(12),
            ..default()
        },
    ));
}

/// Initializes the node UI widgets.
fn setup_node_rects(commands: &mut Commands) {
    for (node_rect, node_type) in NODE_RECTS.iter().zip(NODE_TYPES.iter()) {
        let node_string = match *node_type {
            NodeType::Clip(ref clip) => clip.text,
            NodeType::Blend(text) => text,
        };

        let text = commands
            .spawn((
                Text::new(node_string),
                TextFont {
                    font_size: FontSize::Px(16.0),
                    ..default()
                },
                TextColor(ANTIQUE_WHITE.into()),
                TextLayout::justify(Justify::Center),
            ))
            .id();

        let container = {
            let mut container = commands.spawn((
                Node {
                    position_type: PositionType::Absolute,
                    bottom: px(node_rect.bottom),
                    left: px(node_rect.left),
                    height: px(node_rect.height),
                    width: px(node_rect.width),
                    align_items: AlignItems::Center,
                    justify_items: JustifyItems::Center,
                    align_content: AlignContent::Center,
                    justify_content: JustifyContent::Center,
                    ..default()
                },
                BorderColor::all(WHITE),
                Outline::new(px(1), Val::ZERO, Color::WHITE),
            ));

            if let NodeType::Clip(clip) = node_type {
                container.insert((
                    Interaction::None,
                    RelativeCursorPosition::default(),
                    (*clip).clone(),
                ));
            }

            container.id()
        };

        // Create the background color.
        if let NodeType::Clip(_) = node_type {
            let background = commands
                .spawn((
                    Node {
                        position_type: PositionType::Absolute,
                        top: px(0),
                        left: px(0),
                        height: px(node_rect.height),
                        width: px(node_rect.width),
                        ..default()
                    },
                    BackgroundColor(DARK_GREEN.into()),
                ))
                .id();

            commands.entity(container).add_child(background);
        }

        commands.entity(container).add_child(text);
    }
}

examples/3d/specular_tint.rs (line 171)

    fn create_text(&self) -> Text {
        let tint_map_help_text = match self.tint_type {
            TintType::Solid => SWITCH_TO_MAP_HELP_TEXT,
            TintType::Map => SWITCH_TO_SOLID_TINT_HELP_TEXT,
        };

        Text::new(tint_map_help_text)
    }

examples/3d/light_probe_blending.rs (line 379)

fn spawn_help_text(commands: &mut Commands) {
    commands.spawn((
        Text::new(""),
        Node {
            position_type: PositionType::Absolute,
            top: px(12),
            left: px(12),
            ..default()
        },
        HelpText,
    ));
}

/// Moves the sphere a bit every frame.
fn move_sphere(mut spheres: Query<&mut Transform, With<ReflectiveSphere>>, time: Res<Time>) {
    let Some(t) = SmoothStepCurve
        .ping_pong()
        .unwrap()
        .forever()
        .unwrap()
        .sample(time.elapsed_secs() * SPHERE_MOVEMENT_SPEED)
    else {
        return;
    };
    for mut sphere_transform in &mut spheres {
        sphere_transform.translation.z = -ROOM_SEPARATION * t;
    }
}

/// Processes requests from the user to move the camera.
fn orbit_camera(
    mut cameras: Query<(&mut Transform, &mut OrbitCamera)>,
    spheres: Query<&Transform, (With<ReflectiveSphere>, Without<OrbitCamera>)>,
    mouse_buttons: Res<ButtonInput<MouseButton>>,
    mouse_motion: Res<AccumulatedMouseMotion>,
    mouse_scroll: Res<AccumulatedMouseScroll>,
) {
    // Grab the sphere transform.
    let Some(sphere_transform) = spheres.iter().next() else {
        return;
    };

    for (mut camera_transform, mut orbit_camera) in &mut cameras {
        // Only pan if the left mouse button is pressed.
        if mouse_buttons.pressed(MouseButton::Left) {
            let delta = mouse_motion.delta;
            orbit_camera.azimuth -= delta.x * CAMERA_ORBIT_SPEED_AZIMUTH;
            orbit_camera.inclination += delta.y * CAMERA_ORBIT_SPEED_INCLINATION;
        }

        // Zooming doesn't require a mouse button press, as it uses the mouse
        // wheel.
        orbit_camera.radius =
            (orbit_camera.radius - CAMERA_ZOOM_SPEED * mouse_scroll.delta.y).max(0.01);

        // Calculate the new translation using the [spherical coordinates
        // formula].
        //
        // [spherical coordinates formula]:
        // https://en.wikipedia.org/wiki/Spherical_coordinate_system#Cartesian_coordinates
        let new_translation = orbit_camera.radius
            * vec3(
                sin(orbit_camera.inclination) * cos(orbit_camera.azimuth),
                cos(orbit_camera.inclination),
                sin(orbit_camera.inclination) * sin(orbit_camera.azimuth),
            );

        // Write in the new transform.
        *camera_transform =
            Transform::from_translation(new_translation + sphere_transform.translation)
                .looking_at(sphere_transform.translation, Vec3::Y);
    }
}

/// A system that toggles gizmos on or off when the user clicks on one of the
/// corresponding radio buttons.
fn handle_gizmos_enabled_change(
    mut help_text_query: Query<&mut Text, With<HelpText>>,
    mut app_status: ResMut<AppStatus>,
    mut messages: MessageReader<WidgetClickEvent<GizmosEnabled>>,
) {
    let mut any_changes = false;
    for message in messages.read() {
        app_status.gizmos_enabled = **message;
        any_changes = true;
    }

    if any_changes {
        set_help_text(&app_status, &mut help_text_query);
    }
}

/// A system that toggles object visibility when the user clicks on one of the
/// corresponding radio buttons.
fn handle_object_to_show_change(
    mut spheres_query: Query<&mut Visibility, (With<ReflectiveSphere>, Without<ReflectivePrism>)>,
    mut prisms_query: Query<&mut Visibility, (With<ReflectivePrism>, Without<ReflectiveSphere>)>,
    mut app_status: ResMut<AppStatus>,
    mut messages: MessageReader<WidgetClickEvent<ObjectToShow>>,
) {
    for message in messages.read() {
        app_status.object_to_show = **message;

        for mut sphere_visibility in &mut spheres_query {
            *sphere_visibility = match **message {
                ObjectToShow::Sphere => Visibility::Inherited,
                ObjectToShow::Prism => Visibility::Hidden,
            }
        }
        for mut prism_visibility in &mut prisms_query {
            *prism_visibility = match **message {
                ObjectToShow::Sphere => Visibility::Hidden,
                ObjectToShow::Prism => Visibility::Inherited,
            }
        }
    }
}

/// A system that toggles the camera mode when the user clicks on one of the
/// corresponding radio buttons.
fn handle_camera_mode_change(
    mut commands: Commands,
    cameras_query: Query<(Entity, &Transform), With<Camera3d>>,
    sphere_query: Query<&Transform, (With<ReflectiveSphere>, Without<Camera3d>)>,
    mut help_text_query: Query<&mut Text, With<HelpText>>,
    mut windows_query: Query<&mut CursorOptions>,
    mut app_status: ResMut<AppStatus>,
    mut messages: MessageReader<WidgetClickEvent<CameraMode>>,
) {
    let Some(sphere_transform) = sphere_query.iter().next() else {
        return;
    };

    let mut any_changes = false;
    for message in messages.read() {
        app_status.camera_mode = **message;

        match **message {
            CameraMode::Orbit => {
                for (camera_entity, camera_transform) in &cameras_query {
                    // Convert from Cartesian coordinates back to spherical
                    // coordinates.
                    let relative_camera_position =
                        camera_transform.translation - sphere_transform.translation;
                    let radius = relative_camera_position.length();
                    let inclination = atan2(
                        relative_camera_position.xz().length() / radius,
                        relative_camera_position.y / radius,
                    );
                    let azimuth = atan2(
                        relative_camera_position.z * relative_camera_position.xz().length_recip(),
                        relative_camera_position.x * relative_camera_position.xz().length_recip(),
                    );

                    commands
                        .entity(camera_entity)
                        .remove::<FreeCamera>()
                        .insert(OrbitCamera {
                            radius,
                            inclination,
                            azimuth,
                        });
                }
            }

            CameraMode::Free => {
                for (camera_entity, _) in &cameras_query {
                    commands
                        .entity(camera_entity)
                        .remove::<OrbitCamera>()
                        .insert(FreeCamera::default());
                }
            }
        }

        any_changes = true;
    }

    if any_changes {
        set_help_text(&app_status, &mut help_text_query);

        // Reset the cursor grab mode, because the free camera controller may
        // have enabled it, and we don't want the cursor to disappear.
        for mut cursor_options in &mut windows_query {
            cursor_options.grab_mode = CursorGrabMode::None;
            cursor_options.visible = true;
        }
    }
}

/// A system that updates the radio buttons at the bottom of the screen to
/// reflect whether gizmos are enabled or not.
fn update_radio_buttons(
    mut widgets_query: Query<(
        Entity,
        Option<&mut BackgroundColor>,
        Has<Text>,
        AnyOf<(
            &WidgetClickSender<GizmosEnabled>,
            &WidgetClickSender<ObjectToShow>,
            &WidgetClickSender<CameraMode>,
        )>,
    )>,
    app_status: Res<AppStatus>,
    mut text_ui_writer: TextUiWriter,
) {
    for (
        entity,
        maybe_bg_color,
        has_text,
        (maybe_gizmos_enabled, maybe_object_to_show, maybe_camera_mode),
    ) in &mut widgets_query
    {
        let selected = if let Some(sender) = maybe_gizmos_enabled {
            app_status.gizmos_enabled == **sender
        } else if let Some(sender) = maybe_object_to_show {
            app_status.object_to_show == **sender
        } else if let Some(sender) = maybe_camera_mode {
            app_status.camera_mode == **sender
        } else {
            continue;
        };

        if let Some(mut bg_color) = maybe_bg_color {
            widgets::update_ui_radio_button(&mut bg_color, selected);
        }
        if has_text {
            widgets::update_ui_radio_button_text(entity, &mut text_ui_writer, selected);
        }
    }
}

/// Draws gizmos that show the boundaries of the various boxes associated with
/// the light probes in the scene.
fn draw_gizmos(
    light_probes: Query<(&LightProbe, &ParallaxCorrection, &Transform)>,
    app_status: Res<AppStatus>,
    mut gizmos: Gizmos,
) {
    // If the user has gizmos disabled, bail.
    if matches!(app_status.gizmos_enabled, GizmosEnabled::Off) {
        return;
    }

    for (light_probe, parallax_correction, transform) in &light_probes {
        // Draw light probe bounds.
        gizmos.cube(*transform, TAN);

        // Draw light probe falloff.
        gizmos.cube(
            Transform {
                scale: transform.scale * (Vec3::ONE - light_probe.falloff),
                ..*transform
            },
            CRIMSON,
        );

        // Draw light probe parallax correction bounds.
        if let ParallaxCorrection::Custom(parallax_correction_bounds) = *parallax_correction {
            gizmos.cube(
                Transform {
                    scale: transform.scale * parallax_correction_bounds,
                    ..*transform
                },
                CORNFLOWER_BLUE,
            );
        }
    }
}

/// Updates the help text at the top of the screen to reflect a change in camera
/// or gizmo application settings.
fn set_help_text(app_status: &AppStatus, help_text_query: &mut Query<&mut Text, With<HelpText>>) {
    for mut ui_text in help_text_query {
        let mut help_text = String::new();
        match app_status.camera_mode {
            CameraMode::Orbit => {
                help_text.push_str(
                    "Click and drag to orbit the camera\nUse the mouse wheel to zoom the camera\n",
                );
            }
            CameraMode::Free => {
                help_text.push_str(
                    "Click and drag to rotate the camera\nUse WASDEQ to move the camera\n",
                );
            }
        }

        help_text.push('\n');

        if matches!(app_status.gizmos_enabled, GizmosEnabled::On) {
            help_text.push_str(
                "\
Gizmos:
Tan: Light probe bounds
Red: Light probe falloff bounds
Blue: Parallax correction bounds",
            );
        }

        *ui_text = Text::new(help_text);
    }
}

examples/3d/clearcoat.rs (line 331)

    fn create_help_text(&self) -> Text {
        let help_text = match *self {
            LightMode::Point => "Press Space to switch to a directional light",
            LightMode::Directional => "Press Space to switch to a point light",
        };

        Text::new(help_text)
    }

Additional examples can be found in:

• examples/app/logs.rs
• examples/ui/layout/ghost_nodes.rs
• examples/shader_advanced/render_depth_to_texture.rs
• examples/3d/clustered_decals.rs
• examples/3d/light_textures.rs
• examples/3d/mirror.rs
• examples/camera/pan_camera_controller.rs
• examples/scene/world_serialization.rs
• examples/camera/2d_top_down_camera.rs
• examples/camera/2d_screen_shake.rs
• examples/asset/multi_asset_sync.rs
• examples/audio/play_sound_effect.rs
• examples/3d/atmospheric_fog.rs
• examples/camera/camera_orbit.rs
• examples/camera/projection_zoom.rs
• examples/asset/alter_mesh.rs
• examples/asset/alter_sprite.rs
• examples/window/window_resizing.rs
• examples/camera/first_person_view_model.rs
• examples/usage/context_menu.rs
• examples/3d/color_grading.rs
• examples/window/custom_cursor_image.rs
• examples/ecs/state_scoped.rs
• examples/ui/layout/flex_layout.rs
• examples/movement/physics_in_fixed_timestep.rs
• examples/dev_tools/fps_overlay.rs
• examples/gizmos/2d_gizmos.rs
• examples/ui/scroll_and_overflow/scrollbars.rs
• examples/ui/window_fallthrough.rs
• examples/showcase/stepping.rs
• examples/audio/audio_control.rs
• examples/showcase/contributors.rs
• examples/ui/layout/anchor_layout.rs
• examples/showcase/loading_screen.rs
• examples/ecs/entity_disabling.rs
• examples/shader_advanced/fullscreen_material.rs
• examples/window/scale_factor_override.rs
• examples/3d/mixed_lighting.rs
• examples/app/settings.rs
• examples/ui/text/font_atlas_debug.rs
• examples/window/screenshot.rs
• examples/3d/tonemapping.rs
• examples/camera/free_camera_controller.rs
• examples/ui/widgets/standard_widgets_observers.rs
• examples/state/custom_transitions.rs
• examples/state/states.rs
• examples/ui/widgets/button.rs
• examples/state/sub_states.rs
• examples/3d/generate_custom_mesh.rs
• examples/audio/spatial_audio_2d.rs
• examples/picking/simple_picking.rs
• examples/ui/relative_cursor_position.rs
• examples/animation/animated_mesh_control.rs
• tests/window/desktop_request_redraw.rs
• examples/ui/text/font_weights.rs
• examples/picking/debug_picking.rs
• examples/remote/app_under_test.rs
• examples/window/multiple_windows.rs
• examples/ui/ui_scaling.rs
• examples/2d/2d_viewport_to_world.rs
• examples/usage/cooldown.rs
• examples/ui/widgets/standard_widgets.rs
• examples/ui/images/ui_texture_atlas.rs
• examples/ui/text/font_variations.rs
• examples/ecs/observers.rs
• examples/animation/animated_ui.rs
• examples/ui/scroll_and_overflow/overflow_debug.rs
• examples/app/render_recovery.rs
• examples/audio/spatial_audio_3d.rs
• examples/ui/text/text_input.rs
• examples/2d/rotation.rs
• examples/3d/rect_light.rs
• examples/ui/images/ui_texture_slice.rs
• examples/2d/sprite_animation.rs
• examples/math/cubic_splines.rs
• examples/ui/text/ime_support.rs
• examples/animation/animation_masks.rs
• tests/3d/test_invalid_skinned_mesh.rs
• examples/time/virtual_time.rs
• examples/ui/layout/size_constraints.rs
• examples/ui/text/generic_font_families.rs
• examples/gizmos/3d_gizmos.rs
• examples/picking/dragdrop_picking.rs
• examples/transforms/align.rs
• examples/ui/styling/transparency_ui.rs
• examples/math/random_sampling.rs
• examples/ui/images/ui_texture_atlas_slice.rs
• examples/state/computed_states.rs
• examples/showcase/alien_cake_addict.rs
• examples/gizmos/transform_gizmo.rs
• examples/3d/spotlight.rs
• examples/showcase/game_menu.rs
• examples/ui/text/system_fonts.rs
• examples/3d/pbr.rs
• examples/ui/ui_target_camera.rs
• examples/math/custom_primitives.rs
• examples/3d/auto_exposure.rs
• examples/window/multi_window_text.rs
• examples/ui/scroll_and_overflow/overflow.rs
• examples/gizmos/light_gizmos.rs
• examples/diagnostics/log_diagnostics.rs
• examples/ui/widgets/vertical_slider.rs
• examples/ui/layout/display_and_visibility.rs
• examples/ui/widgets/tab_navigation.rs
• examples/3d/split_screen.rs
• examples/2d/2d_shapes.rs
• examples/showcase/breakout.rs
• examples/ui/scroll_and_overflow/scroll.rs
• examples/picking/mesh_picking.rs
• examples/ui/render_ui_to_texture.rs
• examples/ui/images/image_node_resizing.rs
• examples/ui/text/strikethrough_and_underline.rs
• examples/ui/navigation/directional_navigation.rs
• examples/stress_tests/many_text.rs
• examples/ui/text/multiple_text_inputs.rs
• examples/ui/ui_drag_and_drop.rs
• examples/ui/styling/box_shadow.rs
• examples/3d/contact_shadows.rs
• examples/ui/text/text.rs
• examples/3d/3d_shapes.rs
• examples/usage/debug_frustum_culling.rs
• examples/3d/blend_modes.rs
• examples/ui/styling/borders.rs
• examples/ui/text/letter_spacing.rs
• examples/ui/navigation/directional_navigation_overrides.rs
• examples/ui/text/text_debug.rs
• examples/ui/layout/grid.rs
• examples/ui/ui_transform.rs
• examples/ui/text/font_query.rs
• examples/ui/text/multiline_text_input.rs
• examples/ui/styling/gradients.rs
• examples/testbed/full_ui.rs
• examples/testbed/ui.rs

Methods from Deref<Target = String>

pub fn as_str(&self) -> &str

Extracts a string slice containing the entire String.

Examples

let s = String::from("foo");

assert_eq!("foo", s.as_str());

Examples found in repository

examples/time/time.rs (line 44)

fn runner(mut app: App) -> AppExit {
    banner();
    help();
    let stdin = io::stdin();
    for line in stdin.lock().lines() {
        if let Err(err) = line {
            println!("read err: {err:#}");
            break;
        }
        match line.unwrap().as_str() {
            "" => {
                app.update();
            }
            "f" => {
                println!("FAST: setting relative speed to 2x");
                app.world_mut()
                    .resource_mut::<Time<Virtual>>()
                    .set_relative_speed(2.0);
            }
            "n" => {
                println!("NORMAL: setting relative speed to 1x");
                app.world_mut()
                    .resource_mut::<Time<Virtual>>()
                    .set_relative_speed(1.0);
            }
            "s" => {
                println!("SLOW: setting relative speed to 0.5x");
                app.world_mut()
                    .resource_mut::<Time<Virtual>>()
                    .set_relative_speed(0.5);
            }
            "p" => {
                println!("PAUSE: pausing virtual clock");
                app.world_mut().resource_mut::<Time<Virtual>>().pause();
            }
            "u" => {
                println!("UNPAUSE: resuming virtual clock");
                app.world_mut().resource_mut::<Time<Virtual>>().unpause();
            }
            "q" => {
                println!("QUITTING!");
                break;
            }
            _ => {
                help();
            }
        }
    }

    AppExit::Success
}

examples/gltf/edit_material_on_gltf.rs (line 83)

fn change_material(
    scene_ready: On<WorldInstanceReady>,
    mut commands: Commands,
    children: Query<&Children>,
    color_override: Query<&ColorOverride>,
    mesh_materials: Query<(&MeshMaterial3d<StandardMaterial>, &GltfMaterialName)>,
    mut asset_materials: ResMut<Assets<StandardMaterial>>,
) {
    info!("processing Scene Entity: {}", scene_ready.entity);

    // Get the `ColorOverride` of the entity, if it does not have a color override, return
    let Ok(color_override) = color_override.get(scene_ready.entity) else {
        info!("{} does not have a color override", scene_ready.entity);
        return;
    };

    // Iterate over all children recursively
    for descendant in children.iter_descendants(scene_ready.entity) {
        // Get the material id and name which were created from the glTF file information
        let Ok((id, material_name)) = mesh_materials.get(descendant) else {
            continue;
        };
        // Get the material of the descendant
        let Some(material) = asset_materials.get(id.id()) else {
            continue;
        };

        // match on the material name, modifying the materials as necessary
        match material_name.0.as_str() {
            "LeatherPartsMat" => {
                info!("editing LeatherPartsMat to use ColorOverride tint");
                // Create a copy of the material and override base color
                // If you intend on creating multiple models with the same tint, it
                // is best to cache the handle somewhere, as having multiple materials
                // that are identical is expensive
                let mut new_material = material.clone();
                new_material.base_color = color_override.0;

                // Override `MeshMaterial3d` with new material
                commands
                    .entity(descendant)
                    .insert(MeshMaterial3d(asset_materials.add(new_material)));
            }
            name => {
                info!("not replacing: {name}");
            }
        }
    }
}

examples/3d/solari.rs (line 424)

fn add_raytracing_meshes_on_scene_load(
    scene_ready: On<WorldInstanceReady>,
    children: Query<&Children>,
    mesh_query: Query<(
        &Mesh3d,
        &MeshMaterial3d<StandardMaterial>,
        Option<&GltfMaterialName>,
    )>,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
    mut commands: Commands,
    args: Res<Args>,
) {
    for descendant in children.iter_descendants(scene_ready.entity) {
        if let Ok((Mesh3d(mesh_handle), MeshMaterial3d(material_handle), material_name)) =
            mesh_query.get(descendant)
        {
            // Add raytracing mesh component
            commands
                .entity(descendant)
                .insert(RaytracingMesh3d(mesh_handle.clone()));

            // Ensure meshes are Solari compatible
            let mut mesh = meshes.get_mut(mesh_handle).unwrap();
            if !mesh.contains_attribute(Mesh::ATTRIBUTE_UV_0) {
                let vertex_count = mesh.count_vertices();
                mesh.insert_attribute(Mesh::ATTRIBUTE_UV_0, vec![[0.0, 0.0]; vertex_count]);
                mesh.insert_attribute(
                    Mesh::ATTRIBUTE_TANGENT,
                    vec![[0.0, 0.0, 0.0, 0.0]; vertex_count],
                );
            }
            if !mesh.contains_attribute(Mesh::ATTRIBUTE_TANGENT) {
                mesh.generate_tangents().unwrap();
            }
            if mesh.contains_attribute(Mesh::ATTRIBUTE_UV_1) {
                mesh.remove_attribute(Mesh::ATTRIBUTE_UV_1);
            }
            if let Some(indices) = mesh.indices_mut()
                && let Indices::U16(_) = indices
            {
                *indices = Indices::U32(indices.iter().map(|i| i as u32).collect());
            }

            // Prevent rasterization if using pathtracer
            if args.pathtracer == Some(true) {
                commands.entity(descendant).remove::<Mesh3d>();
            }

            // Adjust scene materials to better demo Solari features
            if material_name.map(|s| s.0.as_str()) == Some("material") {
                let mut material = materials.get_mut(material_handle).unwrap();
                material.emissive = LinearRgba::BLACK;
            }
            if material_name.map(|s| s.0.as_str()) == Some("Lights") {
                let mut material = materials.get_mut(material_handle).unwrap();
                material.emissive =
                    LinearRgba::from(Color::srgb(0.941, 0.714, 0.043)) * 1_000_000.0;
                material.alpha_mode = AlphaMode::Opaque;
                material.specular_transmission = 0.0;

                commands.insert_resource(RobotLightMaterial(material_handle.clone()));
            }
            if material_name.map(|s| s.0.as_str()) == Some("Glass_Dark_01") {
                let mut material = materials.get_mut(material_handle).unwrap();
                material.alpha_mode = AlphaMode::Opaque;
                material.specular_transmission = 0.0;
            }
        }
    }
}

examples/3d/tonemapping.rs (line 541)

fn update_ui(
    mut text_query: Single<&mut Text, Without<SceneNumber>>,
    settings: Single<(&Tonemapping, &ColorGrading)>,
    current_scene: Res<CurrentScene>,
    selected_parameter: Res<SelectedParameter>,
    mut hide_ui: Local<bool>,
    keys: Res<ButtonInput<KeyCode>>,
) {
    if keys.just_pressed(KeyCode::KeyH) {
        *hide_ui = !*hide_ui;
    }

    if *hide_ui {
        if !text_query.is_empty() {
            // single_mut() always triggers change detection,
            // so only access if text actually needs changing
            text_query.clear();
        }
        return;
    }

    let (tonemapping, color_grading) = *settings;
    let tonemapping = *tonemapping;

    let mut text = String::with_capacity(text_query.len());

    let scn = current_scene.0;
    text.push_str("(H) Hide UI\n\n");
    text.push_str("Test Scene: \n");
    text.push_str(&format!(
        "(Q) {} Basic Scene\n",
        if scn == 1 { ">" } else { "" }
    ));
    text.push_str(&format!(
        "(W) {} Color Sweep\n",
        if scn == 2 { ">" } else { "" }
    ));
    text.push_str(&format!(
        "(E) {} Image Viewer\n",
        if scn == 3 { ">" } else { "" }
    ));

    text.push_str("\n\nTonemapping Method:\n");
    text.push_str(&format!(
        "(1) {} Disabled\n",
        if tonemapping == Tonemapping::None {
            ">"
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(2) {} Reinhard\n",
        if tonemapping == Tonemapping::Reinhard {
            "> "
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(3) {} Reinhard Luminance\n",
        if tonemapping == Tonemapping::ReinhardLuminance {
            ">"
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(4) {} ACES Fitted\n",
        if tonemapping == Tonemapping::AcesFitted {
            ">"
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(5) {} AgX\n",
        if tonemapping == Tonemapping::AgX {
            ">"
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(6) {} SomewhatBoringDisplayTransform\n",
        if tonemapping == Tonemapping::SomewhatBoringDisplayTransform {
            ">"
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(7) {} TonyMcMapface\n",
        if tonemapping == Tonemapping::TonyMcMapface {
            ">"
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(8) {} Blender Filmic\n",
        if tonemapping == Tonemapping::BlenderFilmic {
            ">"
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(9) {} Khronos PBR Neutral\n",
        if tonemapping == Tonemapping::KhronosPbrNeutral {
            ">"
        } else {
            ""
        }
    ));

    text.push_str("\n\nColor Grading:\n");
    text.push_str("(arrow keys)\n");
    if selected_parameter.value == 0 {
        text.push_str("> ");
    }
    text.push_str(&format!("Exposure: {:.2}\n", color_grading.global.exposure));
    if selected_parameter.value == 1 {
        text.push_str("> ");
    }
    text.push_str(&format!("Gamma: {:.2}\n", color_grading.shadows.gamma));
    if selected_parameter.value == 2 {
        text.push_str("> ");
    }
    text.push_str(&format!(
        "PreSaturation: {:.2}\n",
        color_grading.shadows.saturation
    ));
    if selected_parameter.value == 3 {
        text.push_str("> ");
    }
    text.push_str(&format!(
        "PostSaturation: {:.2}\n",
        color_grading.global.post_saturation
    ));
    text.push_str("(Space) Reset all to default\n");

    if current_scene.0 == 1 {
        text.push_str("(Enter) Reset all to scene recommendation\n");
    }

    if text != text_query.as_str() {
        // single_mut() always triggers change detection,
        // so only access if text actually changed
        text_query.0 = text;
    }
}

pub fn as_mut_str(&mut self) -> &mut str

Converts a String into a mutable string slice.

Examples

let mut s = String::from("foobar");
let s_mut_str = s.as_mut_str();

s_mut_str.make_ascii_uppercase();

assert_eq!("FOOBAR", s_mut_str);

pub fn push_str(&mut self, string: &str)

Available on non-no_global_oom_handling only.

Appends a given string slice onto the end of this String.

Panics

Panics if the new capacity exceeds isize::MAX bytes.

Examples

let mut s = String::from("foo");

s.push_str("bar");

assert_eq!("foobar", s);

Examples found in repository

examples/stress_tests/many_text.rs (line 213)

fn update_lorem_text(mut lorem_text_query: Query<(&mut Text, &mut Lorem)>) {
    for (mut text, mut lorem) in &mut lorem_text_query {
        if lorem.0 {
            text.0.clear();
            text.0.push_str(LOREM_TEXT_1);
        } else {
            text.0.clear();
            text.0.push_str(LOREM_TEXT_2);
        }

        lorem.0 = !lorem.0;
    }
}

examples/math/bounding_2d.rs (line 82)

fn update_text(mut text: Single<&mut Text>, cur_state: Res<State<Test>>) {
    if !cur_state.is_changed() {
        return;
    }

    text.clear();

    text.push_str("Intersection test:\n");
    use Test::*;
    for &test in &[AabbSweep, CircleSweep, RayCast, AabbCast, CircleCast] {
        let s = if **cur_state == test { "*" } else { " " };
        text.push_str(&format!(" {s} {test:?} {s}\n"));
    }
    text.push_str("\nPress space to cycle");
}

examples/shader_advanced/fullscreen_material.rs (line 105)

fn toggle_effect(
    mut text: Single<&mut Text>,
    keys: Res<ButtonInput<KeyCode>>,
    camera: Single<(Entity, Option<&FullscreenEffect>), With<Camera3d>>,
    mut commands: Commands,
) {
    if keys.just_pressed(KeyCode::KeyT) {
        let (entity, effect) = *camera;

        if effect.is_some() {
            commands.entity(entity).remove::<FullscreenEffect>();
            text.clear();
            text.push_str("(T) FullscreenEffect: Off");
        } else {
            commands.entity(entity).insert(FullscreenEffect::new(0.0));
            text.clear();
            text.push_str("(T) FullscreenEffect: On");
        }
    }
}

examples/ecs/entity_disabling.rs (line 68)

fn list_all_named_entities(
    query: Query<&Name>,
    mut name_text_query: Query<&mut Text, With<EntityNameText>>,
    mut commands: Commands,
) {
    let mut text_string = String::from("Named entities found:\n");
    // Query iteration order is not guaranteed, so we sort the names
    // to ensure the output is consistent.
    for name in query.iter().sort::<&Name>() {
        text_string.push_str(&format!("{name:?}\n"));
    }

    if let Ok(mut text) = name_text_query.single_mut() {
        *text = Text::new(text_string);
    } else {
        commands.spawn((
            EntityNameText,
            Text::default(),
            Node {
                position_type: PositionType::Absolute,
                top: px(12),
                right: px(12),
                ..default()
            },
        ));
    }
}

examples/ui/images/image_node_resizing.rs (lines 229-232)

fn update_text(
    event: On<TextUpdate>,
    mut textmeta: Single<&mut TextData>,
    mut text: Single<&mut Text>,
) {
    let mut new_text = Text::new(TEXT_PREFIX);
    match event.direction {
        Direction::Height => {
            textmeta.height = (textmeta.height + event.change)
                .clamp(IMAGE_GROUP_BOX_MIN_HEIGHT, IMAGE_GROUP_BOX_MAX_HEIGHT);
            new_text.push_str(&format!(
                "height : {}%, width : {}%",
                textmeta.height, textmeta.width
            ));
        }
        Direction::Width => {
            textmeta.width = (textmeta.width + event.change)
                .clamp(IMAGE_GROUP_BOX_MIN_WIDTH, IMAGE_GROUP_BOX_MAX_WIDTH);
            new_text.push_str(&format!(
                "height : {}%, width : {}%",
                textmeta.height, textmeta.width
            ));
        }
    }
    text.0 = new_text.0;
}

examples/3d/light_probe_blending.rs (lines 654-656)

fn set_help_text(app_status: &AppStatus, help_text_query: &mut Query<&mut Text, With<HelpText>>) {
    for mut ui_text in help_text_query {
        let mut help_text = String::new();
        match app_status.camera_mode {
            CameraMode::Orbit => {
                help_text.push_str(
                    "Click and drag to orbit the camera\nUse the mouse wheel to zoom the camera\n",
                );
            }
            CameraMode::Free => {
                help_text.push_str(
                    "Click and drag to rotate the camera\nUse WASDEQ to move the camera\n",
                );
            }
        }

        help_text.push('\n');

        if matches!(app_status.gizmos_enabled, GizmosEnabled::On) {
            help_text.push_str(
                "\
Gizmos:
Tan: Light probe bounds
Red: Light probe falloff bounds
Blue: Parallax correction bounds",
            );
        }

        *ui_text = Text::new(help_text);
    }
}

Additional examples can be found in:

• examples/ui/text/multiple_text_inputs.rs
• examples/asset/processing/asset_processing.rs
• examples/ecs/relationships.rs
• examples/3d/post_processing.rs
• examples/3d/solari.rs
• examples/3d/occlusion_culling.rs
• examples/3d/deferred_rendering.rs
• examples/math/custom_primitives.rs
• examples/3d/ssao.rs
• examples/2d/2d_shapes.rs
• examples/3d/tonemapping.rs
• examples/3d/bloom_3d.rs
• examples/3d/fog.rs
• examples/2d/bloom_2d.rs
• examples/3d/anti_aliasing.rs
• examples/3d/3d_shapes.rs
• examples/ui/text/multiline_text_input.rs

pub fn extend_from_within<R>(&mut self, src: R)

where R: RangeBounds<usize>,

Available on non-no_global_oom_handling only.

Copies elements from src range to the end of the string.

Panics

Panics if the range has start_bound > end_bound, if the range is bounded on either end and does not lie on a char boundary, or if the new capacity exceeds isize::MAX bytes.

Examples

let mut string = String::from("abcde");

string.extend_from_within(2..);
assert_eq!(string, "abcdecde");

string.extend_from_within(..2);
assert_eq!(string, "abcdecdeab");

string.extend_from_within(4..8);
assert_eq!(string, "abcdecdeabecde");

pub fn capacity(&self) -> usize

Returns this String’s capacity, in bytes.

Examples

let s = String::with_capacity(10);

assert!(s.capacity() >= 10);

pub fn reserve(&mut self, additional: usize)

Available on non-no_global_oom_handling only.

Reserves capacity for at least additional bytes more than the current length. The allocator may reserve more space to speculatively avoid frequent allocations. After calling reserve, capacity will be greater than or equal to self.len() + additional. Does nothing if capacity is already sufficient.

Panics

Panics if the new capacity exceeds isize::MAX bytes.

Examples

Basic usage:

let mut s = String::new();

s.reserve(10);

assert!(s.capacity() >= 10);

This might not actually increase the capacity:

let mut s = String::with_capacity(10);
s.push('a');
s.push('b');

// s now has a length of 2 and a capacity of at least 10
let capacity = s.capacity();
assert_eq!(2, s.len());
assert!(capacity >= 10);

// Since we already have at least an extra 8 capacity, calling this...
s.reserve(8);

// ... doesn't actually increase.
assert_eq!(capacity, s.capacity());

Examples found in repository

examples/ui/text/multiple_text_inputs.rs (line 192)

fn synchronize_output_text(
    changed_inputs: Query<(&EditableText, &TextInputRow), Changed<EditableText>>,
    mut outputs: Query<(&mut Text, &TextInputRow), With<TextOutput>>,
) {
    for (editable_text, input_row) in &changed_inputs {
        for (mut text, output_row) in &mut outputs {
            if output_row.0 == input_row.0 {
                // `EditableText::value()` returns a `SplitString` because Parley may keep IME preedit text
                // in a contiguous range of the editor’s internal `String` buffer during composition.
                // The returned `SplitString` omits that preedit range, exposing only the text before and after it.
                //
                // To avoid allocating a new `String`, we reserve the total length of the `SplitString`'s slices,
                // then append them to the output `Text`.
                text.0.clear();
                text.0
                    .reserve(editable_text.value().into_iter().map(str::len).sum());
                for sub_str in editable_text.value() {
                    text.0.push_str(sub_str);
                }
            }
        }
    }
}

// Submit the focused input's text when Enter is pressed.
fn submit_text(
    mut input_focus: ResMut<InputFocus>,
    keyboard_input: Res<ButtonInput<Key>>,
    mut text_input: Query<(&mut EditableText, &TextInputRow)>,
    mut text_output: Query<(&mut Text, &TextInputRow), With<SubmitOutput>>,
    tab_navigation: TabNavigation,
) {
    if keyboard_input.just_pressed(Key::Enter)
        && let Some(focused_entity) = input_focus.get()
        && let Ok((mut editable_text, input_row)) = text_input.get_mut(focused_entity)
    {
        for (mut text, output_row) in &mut text_output {
            if input_row.0 == output_row.0 {
                text.0.clear();
                text.0
                    .reserve(editable_text.value().into_iter().map(str::len).sum());
                for sub_str in editable_text.value() {
                    text.0.push_str(sub_str);
                }
                break;
            }
        }
        editable_text.clear();

        if let Ok(next) = tab_navigation.navigate(&input_focus, NavAction::Next) {
            input_focus.set(next, FocusCause::Navigated);
        }
    }
}

examples/ui/text/multiline_text_input.rs (line 99)

fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
    commands.spawn(Camera2d);

    commands
        .spawn(Node {
            width: percent(100.),
            height: percent(100.),
            justify_content: JustifyContent::Center,
            align_items: AlignItems::Center,
            ..default()
        })
        .with_children(|parent| {
            parent
                .spawn((
                    Node {
                        flex_direction: FlexDirection::Column,
                        align_items: AlignItems::End,
                        row_gap: px(10.),
                        ..default()
                    },
                    TabGroup::default(),
                ))
                .with_children(|parent| {
                    parent
                        .spawn((
                            Node {
                                width: px(450.),
                                border: px(2.).all(),
                                padding: px(8.).all(),
                                ..default()
                            },
                            EditableText {
                                visible_lines: Some(8.),
                                allow_newlines: true,
                                ..default()
                            },
                            TextLayout {
                                linebreak: LineBreak::WordOrCharacter,
                                ..default()
                            },
                            TextCursorStyle {
                                color: Color::WHITE,
                                selected_text_color: Some(Color::BLACK),
                                ..default()
                            },
                            TextFont {
                                font: asset_server.load("fonts/FiraMono-Medium.ttf").into(),
                                font_size: FontSize::Px(30.),
                                ..default()
                            },
                            BackgroundColor(DARK_SLATE_GRAY.into()),
                            BorderColor::all(SLATE_300),
                            MultilineInput,
                            TabIndex(0),
                            AutoFocus,
                        ))
                        .observe(
                            |on: On<FocusedInput<KeyboardInput>>,
                             keys: Res<ButtonInput<Key>>,
                             input_query: Query<&EditableText, With<MultilineInput>>| {
                                if !(on.input.state.is_pressed()
                                    && on.input.logical_key == Key::Enter
                                    && keys.pressed(Key::Control))
                                {
                                    return;
                                }
                                let Ok(input) = input_query.get(on.focused_entity) else {
                                    return;
                                };

                                let mut output = String::new();
                                output.reserve(input.value().into_iter().map(str::len).sum());
                                for sub_str in input.value() {
                                    output.push_str(sub_str);
                                }

                                info!("{output}"                                    );
                            },
                        );

                    parent
                        .spawn((
                            Node {
                                flex_direction: FlexDirection::Row,
                                column_gap: px(10.),
                                ..default()
                            },
                            children![
                                (
                                    Text::new("visible lines:"),
                                    TextFont {
                                        font: asset_server.load("fonts/FiraMono-Medium.ttf").into(),
                                        font_size: FontSize::Px(30.),
                                        ..default()
                                    },
                                ),
                                (
                                    Node {
                                        width: px(100.),
                                        border: px(2.).all(),
                                        ..default()
                                    },
                                    TextFont {
                                        font: asset_server.load("fonts/FiraMono-Medium.ttf").into(),
                                        font_size: FontSize::Px(30.),
                                        ..default()
                                    },
                                    TextLayout {
                                        justify: Justify::End,
                                        ..default()
                                    },
                                    BackgroundColor(DARK_SLATE_GRAY.into()),
                                    BorderColor::all(SLATE_300),
                                    EditableText::new("8"),
                                    EditableTextFilter::new(|c| c.is_ascii_digit() || c == '.'),
                                    TextCursorStyle {
                                        color: Color::WHITE,
                                        selected_text_color: Some(Color::BLACK),
                                        unfocused_selection_color: Color::NONE,
                                        ..default()
                                    },
                                    SelectAllOnFocus,
                                    VisibleLinesInput,
                                    TabIndex(1),
                                )
                            ],
                        ))
                        .observe(
                            |on: On<FocusedInput<KeyboardInput>>,
                             mut query_set: ParamSet<(
                                Query<&EditableText, With<VisibleLinesInput>>,
                                Query<&mut EditableText, With<MultilineInput>>,
                            )>| {
                                if !(on.input.state.is_pressed()
                                    && on.input.logical_key == Key::Enter)
                                {
                                    return;
                                }

                                let visible_lines_query = query_set.p0();
                                let Ok(input) = visible_lines_query.get(on.original_event_target())
                                else {
                                    return;
                                };

                                let mut output = String::new();
                                output.reserve(input.value().into_iter().map(str::len).sum());
                                for sub_str in input.value() {
                                    output.push_str(sub_str);
                                }

                                let Ok(lines) = output.parse::<f32>() else {
                                    return;
                                };

                                let mut multiline_query = query_set.p1();
                                let Ok(mut multiline_input) = multiline_query.single_mut() else {
                                    return;
                                };

                                multiline_input.visible_lines = Some(lines.clamp(1., 10.));
                            },
                        );

                    parent
                        .spawn((
                            Node {
                                flex_direction: FlexDirection::Row,
                                column_gap: px(10.),
                                ..default()
                            },
                            children![
                                (
                                    Text::new("font size:"),
                                    TextFont {
                                        font: asset_server.load("fonts/FiraMono-Medium.ttf").into(),
                                        font_size: FontSize::Px(30.),
                                        ..default()
                                    },
                                ),
                                (
                                    Node {
                                        width: px(100.),
                                        border: px(2.).all(),
                                        ..default()
                                    },
                                    TextFont {
                                        font: asset_server.load("fonts/FiraMono-Medium.ttf").into(),
                                        font_size: FontSize::Px(30.),
                                        ..default()
                                    },
                                    TextLayout {
                                        justify: Justify::End,
                                        ..default()
                                    },
                                    BackgroundColor(DARK_SLATE_GRAY.into()),
                                    BorderColor::all(SLATE_300),
                                    EditableText::new("30"),
                                    EditableTextFilter::new(|c| c.is_ascii_digit()),
                                    TextCursorStyle {
                                        color: Color::WHITE,
                                        selected_text_color: Some(Color::BLACK),
                                        unfocused_selection_color: Color::NONE,
                                        ..default()
                                    },
                                    SelectAllOnFocus,
                                    FontSizeInput,
                                    TabIndex(2),
                                )
                            ],
                        ))
                        .observe(
                            |on: On<FocusedInput<KeyboardInput>>,
                             font_size_input_query: Query<&EditableText, With<FontSizeInput>>,
                             mut multiline_input_font: Single<
                                &mut TextFont,
                                With<MultilineInput>,
                            >| {
                                if !(on.input.state.is_pressed()
                                    && on.input.logical_key == Key::Enter)
                                {
                                    return;
                                }

                                let Ok(input) =
                                    font_size_input_query.get(on.original_event_target())
                                else {
                                    return;
                                };

                                let mut output = String::new();
                                output.reserve(input.value().into_iter().map(str::len).sum());
                                for sub_str in input.value() {
                                    output.push_str(sub_str);
                                }

                                let Ok(font_size) = output.parse::<f32>() else {
                                    return;
                                };

                                multiline_input_font.font_size =
                                    FontSize::Px(font_size.clamp(5., 50.));
                            },
                        );
                });
        });
}

pub fn reserve_exact(&mut self, additional: usize)

Available on non-no_global_oom_handling only.

Reserves the minimum capacity for at least additional bytes more than the current length. Unlike reserve, this will not deliberately over-allocate to speculatively avoid frequent allocations. After calling reserve_exact, capacity will be greater than or equal to self.len() + additional. Does nothing if the capacity is already sufficient.

Panics

Panics if the new capacity exceeds isize::MAX bytes.

Examples

Basic usage:

let mut s = String::new();

s.reserve_exact(10);

assert!(s.capacity() >= 10);

This might not actually increase the capacity:

let mut s = String::with_capacity(10);
s.push('a');
s.push('b');

// s now has a length of 2 and a capacity of at least 10
let capacity = s.capacity();
assert_eq!(2, s.len());
assert!(capacity >= 10);

// Since we already have at least an extra 8 capacity, calling this...
s.reserve_exact(8);

// ... doesn't actually increase.
assert_eq!(capacity, s.capacity());

pub fn try_reserve(&mut self, additional: usize) -> Result<(), TryReserveError>

Tries to reserve capacity for at least additional bytes more than the current length. The allocator may reserve more space to speculatively avoid frequent allocations. After calling try_reserve, capacity will be greater than or equal to self.len() + additional if it returns Ok(()). Does nothing if capacity is already sufficient. This method preserves the contents even if an error occurs.

Errors

If the capacity overflows, or the allocator reports a failure, then an error is returned.

Examples

use std::collections::TryReserveError;

fn process_data(data: &str) -> Result<String, TryReserveError> {
    let mut output = String::new();

    // Pre-reserve the memory, exiting if we can't
    output.try_reserve(data.len())?;

    // Now we know this can't OOM in the middle of our complex work
    output.push_str(data);

    Ok(output)
}

pub fn try_reserve_exact( &mut self, additional: usize, ) -> Result<(), TryReserveError>

Tries to reserve the minimum capacity for at least additional bytes more than the current length. Unlike try_reserve, this will not deliberately over-allocate to speculatively avoid frequent allocations. After calling try_reserve_exact, capacity will be greater than or equal to self.len() + additional if it returns Ok(()). Does nothing if the capacity is already sufficient.

Note that the allocator may give the collection more space than it requests. Therefore, capacity can not be relied upon to be precisely minimal. Prefer try_reserve if future insertions are expected.

Errors

If the capacity overflows, or the allocator reports a failure, then an error is returned.

Examples

use std::collections::TryReserveError;

fn process_data(data: &str) -> Result<String, TryReserveError> {
    let mut output = String::new();

    // Pre-reserve the memory, exiting if we can't
    output.try_reserve_exact(data.len())?;

    // Now we know this can't OOM in the middle of our complex work
    output.push_str(data);

    Ok(output)
}

pub fn shrink_to_fit(&mut self)

Available on non-no_global_oom_handling only.

Shrinks the capacity of this String to match its length.

Examples

let mut s = String::from("foo");

s.reserve(100);
assert!(s.capacity() >= 100);

s.shrink_to_fit();
assert_eq!(3, s.capacity());

pub fn shrink_to(&mut self, min_capacity: usize)

Available on non-no_global_oom_handling only.

Shrinks the capacity of this String with a lower bound.

The capacity will remain at least as large as both the length and the supplied value.

If the current capacity is less than the lower limit, this is a no-op.

Examples

let mut s = String::from("foo");

s.reserve(100);
assert!(s.capacity() >= 100);

s.shrink_to(10);
assert!(s.capacity() >= 10);
s.shrink_to(0);
assert!(s.capacity() >= 3);

pub fn push(&mut self, ch: char)

Available on non-no_global_oom_handling only.

Appends the given char to the end of this String.

Panics

Panics if the new capacity exceeds isize::MAX bytes.

Examples

let mut s = String::from("abc");

s.push('1');
s.push('2');
s.push('3');

assert_eq!("abc123", s);

Examples found in repository

examples/ui/text/font_atlas_debug.rs (line 79)

fn text_update_system(
    mut state: ResMut<State>,
    time: Res<Time>,
    mut query: Query<&mut Text>,
    mut seeded_rng: ResMut<SeededRng>,
) {
    if !state.timer.tick(time.delta()).just_finished() {
        return;
    }

    for mut text in &mut query {
        let c = seeded_rng.random::<u8>() as char;
        let string = &mut **text;
        if !string.contains(c) {
            string.push(c);
        }
    }
}

examples/3d/light_probe_blending.rs (line 665)

fn set_help_text(app_status: &AppStatus, help_text_query: &mut Query<&mut Text, With<HelpText>>) {
    for mut ui_text in help_text_query {
        let mut help_text = String::new();
        match app_status.camera_mode {
            CameraMode::Orbit => {
                help_text.push_str(
                    "Click and drag to orbit the camera\nUse the mouse wheel to zoom the camera\n",
                );
            }
            CameraMode::Free => {
                help_text.push_str(
                    "Click and drag to rotate the camera\nUse WASDEQ to move the camera\n",
                );
            }
        }

        help_text.push('\n');

        if matches!(app_status.gizmos_enabled, GizmosEnabled::On) {
            help_text.push_str(
                "\
Gizmos:
Tan: Light probe bounds
Red: Light probe falloff bounds
Blue: Parallax correction bounds",
            );
        }

        *ui_text = Text::new(help_text);
    }
}

pub fn as_bytes(&self) -> &[u8]

Returns a byte slice of this String’s contents.

The inverse of this method is from_utf8.

Examples

let s = String::from("hello");

assert_eq!(&[104, 101, 108, 108, 111], s.as_bytes());

Examples found in repository

examples/asset/processing/asset_processing.rs (line 223)

    async fn save(
        &self,
        writer: &mut Writer,
        asset: SavedAsset<'_, '_, Self::Asset>,
        _settings: &Self::Settings,
        _asset_path: AssetPath<'_>,
    ) -> Result<TextSettings, Self::Error> {
        writer.write_all(asset.text.as_bytes()).await?;
        Ok(TextSettings::default())
    }

examples/asset/asset_saving_with_subassets.rs (line 191)

    async fn save(
        &self,
        writer: &mut Writer,
        asset: SavedAsset<'_, '_, Self::Asset>,
        _settings: &Self::Settings,
        _asset_path: AssetPath<'_>,
    ) -> Result<(), Self::Error> {
        let boxes = asset
            .boxes
            .iter()
            .map(|handle| {
                asset
                    .get_labeled_by_id::<OneBox>(handle)
                    .unwrap()
                    .get()
                    .clone()
            })
            .collect();

        // Note: serializing to string isn't ideal since we can't do a streaming write, but this is
        // fine for an example.
        let serialized = ron::to_string(&SerializableManyBoxes { boxes })?;
        writer.write_all(serialized.as_bytes()).await?;

        Ok(())
    }

examples/animation/animation_graph.rs (line 198)

fn setup_assets_programmatically(
    commands: &mut Commands,
    asset_server: &mut AssetServer,
    animation_graphs: &mut Assets<AnimationGraph>,
    _save: bool,
) {
    // Create the nodes.
    let mut animation_graph = AnimationGraph::new();
    let blend_node = animation_graph.add_blend(0.5, animation_graph.root);
    animation_graph.add_clip(
        asset_server.load(GltfAssetLabel::Animation(0).from_asset("models/animated/Fox.glb")),
        1.0,
        animation_graph.root,
    );
    animation_graph.add_clip(
        asset_server.load(GltfAssetLabel::Animation(1).from_asset("models/animated/Fox.glb")),
        1.0,
        blend_node,
    );
    animation_graph.add_clip(
        asset_server.load(GltfAssetLabel::Animation(2).from_asset("models/animated/Fox.glb")),
        1.0,
        blend_node,
    );

    // If asked to save, do so.
    #[cfg(not(target_arch = "wasm32"))]
    if _save {
        let animation_graph = animation_graph.clone();

        IoTaskPool::get()
            .spawn(async move {
                use std::io::Write;

                let animation_graph: SerializedAnimationGraph = animation_graph
                    .try_into()
                    .expect("The animation graph failed to convert to its serialized form");

                let serialized_graph =
                    ron::ser::to_string_pretty(&animation_graph, PrettyConfig::default())
                        .expect("Failed to serialize the animation graph");
                let mut animation_graph_writer = File::create(Path::join(
                    &FileAssetReader::get_base_path(),
                    Path::join(Path::new("assets"), Path::new(ANIMATION_GRAPH_PATH)),
                ))
                .expect("Failed to open the animation graph asset");
                animation_graph_writer
                    .write_all(serialized_graph.as_bytes())
                    .expect("Failed to write the animation graph");
            })
            .detach();
    }

    // Add the graph.
    let handle = animation_graphs.add(animation_graph);

    // Save the assets in a resource.
    commands.insert_resource(ExampleAnimationGraph(handle));
}

examples/scene/world_serialization.rs (line 211)

fn save_world_system(world: &mut World) {
    let asset_server = world.resource::<AssetServer>().clone();
    // The `TypeRegistry` resource contains information about all registered types (including components).
    // This is used to construct worlds, so we'll want to ensure that we use the registry from the
    // main world. To do this, we can simply clone the `AppTypeRegistry` resource.
    let type_registry = world.resource::<AppTypeRegistry>().clone();

    // Any ECS World can be serialized.
    // For demonstration purposes, we'll create a new one.
    let mut scene_world = World::new();

    let mut component_b = ComponentB::from_world(world);
    component_b.value = "hello".to_string();
    scene_world.spawn((
        component_b,
        ComponentA { x: 1.0, y: 2.0 },
        Transform::IDENTITY,
        Name::new("joe"),
        WorldAssetRoot(asset_server.load("models/FlightHelmet/FlightHelmet.gltf#Scene0")),
    ));
    scene_world.spawn(ComponentA { x: 3.0, y: 4.0 });
    scene_world.insert_resource(ResourceA { score: 1 });

    // With our sample world ready to go, we can now create a DynamicWorld from it.
    // For simplicity, we will create our scene using DynamicWorld directly, but if
    // you need more control, you can use DynamicWorldBuilder.
    let dynamic_world = DynamicWorld::from_world_with(&scene_world, &type_registry.read());

    // Dynamic Worlds can be serialized like this:
    let type_registry = world.resource::<AppTypeRegistry>();
    let type_registry = type_registry.read();
    let serialized_world = dynamic_world.serialize(&type_registry).unwrap();

    // Shows the serialized world in the console
    info!("{}", serialized_world);

    // Writing the world to a new file. Using a task to avoid calling the filesystem APIs in a system
    // as they are blocking.
    //
    // This can't work in Wasm as there is no filesystem access.
    #[cfg(not(target_arch = "wasm32"))]
    IoTaskPool::get()
        .spawn(async move {
            // Write the world RON data to file
            File::create(format!("assets/{NEW_WORLD_FILE_PATH}"))
                .and_then(|mut file| file.write(serialized_world.as_bytes()))
                .expect("Error while writing world to file");
        })
        .detach();
}

pub fn truncate(&mut self, new_len: usize)

Shortens this String to the specified length.

If new_len is greater than or equal to the string’s current length, this has no effect.

Note that this method has no effect on the allocated capacity of the string

Panics

Panics if new_len does not lie on a char boundary.

Examples

let mut s = String::from("hello");

s.truncate(2);

assert_eq!("he", s);

pub fn pop(&mut self) -> Option<char>

Removes the last character from the string buffer and returns it.

Returns None if this String is empty.

Examples

let mut s = String::from("abč");

assert_eq!(s.pop(), Some('č'));
assert_eq!(s.pop(), Some('b'));
assert_eq!(s.pop(), Some('a'));

assert_eq!(s.pop(), None);

pub fn remove(&mut self, idx: usize) -> char

Removes a char from this String at byte position idx and returns it.

Copies all bytes after the removed char to new positions.

Note that calling this in a loop can result in quadratic behavior.

Panics

Panics if idx is larger than or equal to the String’s length, or if it does not lie on a char boundary.

Examples

let mut s = String::from("abç");

assert_eq!(s.remove(0), 'a');
assert_eq!(s.remove(1), 'ç');
assert_eq!(s.remove(0), 'b');

pub fn remove_matches<P>(&mut self, pat: P)

where P: Pattern,

🔬This is a nightly-only experimental API. (string_remove_matches)

Available on non-no_global_oom_handling only.

Remove all matches of pattern pat in the String.

Examples

#![feature(string_remove_matches)]
let mut s = String::from("Trees are not green, the sky is not blue.");
s.remove_matches("not ");
assert_eq!("Trees are green, the sky is blue.", s);

Matches will be detected and removed iteratively, so in cases where patterns overlap, only the first pattern will be removed:

#![feature(string_remove_matches)]
let mut s = String::from("banana");
s.remove_matches("ana");
assert_eq!("bna", s);

pub fn retain<F>(&mut self, f: F)

where F: FnMut(char) -> bool,

Retains only the characters specified by the predicate.

In other words, remove all characters c such that f(c) returns false. This method operates in place, visiting each character exactly once in the original order, and preserves the order of the retained characters.

Examples

let mut s = String::from("f_o_ob_ar");

s.retain(|c| c != '_');

assert_eq!(s, "foobar");

Because the elements are visited exactly once in the original order, external state may be used to decide which elements to keep.

let mut s = String::from("abcde");
let keep = [false, true, true, false, true];
let mut iter = keep.iter();
s.retain(|_| *iter.next().unwrap());
assert_eq!(s, "bce");

pub fn insert(&mut self, idx: usize, ch: char)

Available on non-no_global_oom_handling only.

Inserts a character into this String at byte position idx.

Reallocates if self.capacity() is insufficient, which may involve copying all self.capacity() bytes. Makes space for the insertion by copying all bytes of &self[idx..] to new positions.

Note that calling this in a loop can result in quadratic behavior.

Panics

Panics if idx is larger than the String’s length, or if it does not lie on a char boundary.

Examples

let mut s = String::with_capacity(3);

s.insert(0, 'f');
s.insert(1, 'o');
s.insert(2, 'o');

assert_eq!("foo", s);

pub fn insert_str(&mut self, idx: usize, string: &str)

Available on non-no_global_oom_handling only.

Inserts a string slice into this String at byte position idx.

Reallocates if self.capacity() is insufficient, which may involve copying all self.capacity() bytes. Makes space for the insertion by copying all bytes of &self[idx..] to new positions.

Note that calling this in a loop can result in quadratic behavior.

Panics

Panics if idx is larger than the String’s length, or if it does not lie on a char boundary.

Examples

let mut s = String::from("bar");

s.insert_str(0, "foo");

assert_eq!("foobar", s);

pub unsafe fn as_mut_vec(&mut self) -> &mut Vec<u8>

Returns a mutable reference to the contents of this String.

Safety

This function is unsafe because the returned &mut Vec allows writing bytes which are not valid UTF-8. If this constraint is violated, using the original String after dropping the &mut Vec may violate memory safety, as the rest of the standard library assumes that Strings are valid UTF-8.

Examples

let mut s = String::from("hello");

unsafe {
    let vec = s.as_mut_vec();
    assert_eq!(&[104, 101, 108, 108, 111][..], &vec[..]);

    vec.reverse();
}
assert_eq!(s, "olleh");

pub fn len(&self) -> usize

Returns the length of this String, in bytes, not chars or graphemes. In other words, it might not be what a human considers the length of the string.

Examples

let a = String::from("foo");
assert_eq!(a.len(), 3);

let fancy_f = String::from("ƒoo");
assert_eq!(fancy_f.len(), 4);
assert_eq!(fancy_f.chars().count(), 3);

Examples found in repository

examples/3d/tonemapping.rs (line 419)

fn update_ui(
    mut text_query: Single<&mut Text, Without<SceneNumber>>,
    settings: Single<(&Tonemapping, &ColorGrading)>,
    current_scene: Res<CurrentScene>,
    selected_parameter: Res<SelectedParameter>,
    mut hide_ui: Local<bool>,
    keys: Res<ButtonInput<KeyCode>>,
) {
    if keys.just_pressed(KeyCode::KeyH) {
        *hide_ui = !*hide_ui;
    }

    if *hide_ui {
        if !text_query.is_empty() {
            // single_mut() always triggers change detection,
            // so only access if text actually needs changing
            text_query.clear();
        }
        return;
    }

    let (tonemapping, color_grading) = *settings;
    let tonemapping = *tonemapping;

    let mut text = String::with_capacity(text_query.len());

    let scn = current_scene.0;
    text.push_str("(H) Hide UI\n\n");
    text.push_str("Test Scene: \n");
    text.push_str(&format!(
        "(Q) {} Basic Scene\n",
        if scn == 1 { ">" } else { "" }
    ));
    text.push_str(&format!(
        "(W) {} Color Sweep\n",
        if scn == 2 { ">" } else { "" }
    ));
    text.push_str(&format!(
        "(E) {} Image Viewer\n",
        if scn == 3 { ">" } else { "" }
    ));

    text.push_str("\n\nTonemapping Method:\n");
    text.push_str(&format!(
        "(1) {} Disabled\n",
        if tonemapping == Tonemapping::None {
            ">"
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(2) {} Reinhard\n",
        if tonemapping == Tonemapping::Reinhard {
            "> "
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(3) {} Reinhard Luminance\n",
        if tonemapping == Tonemapping::ReinhardLuminance {
            ">"
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(4) {} ACES Fitted\n",
        if tonemapping == Tonemapping::AcesFitted {
            ">"
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(5) {} AgX\n",
        if tonemapping == Tonemapping::AgX {
            ">"
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(6) {} SomewhatBoringDisplayTransform\n",
        if tonemapping == Tonemapping::SomewhatBoringDisplayTransform {
            ">"
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(7) {} TonyMcMapface\n",
        if tonemapping == Tonemapping::TonyMcMapface {
            ">"
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(8) {} Blender Filmic\n",
        if tonemapping == Tonemapping::BlenderFilmic {
            ">"
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(9) {} Khronos PBR Neutral\n",
        if tonemapping == Tonemapping::KhronosPbrNeutral {
            ">"
        } else {
            ""
        }
    ));

    text.push_str("\n\nColor Grading:\n");
    text.push_str("(arrow keys)\n");
    if selected_parameter.value == 0 {
        text.push_str("> ");
    }
    text.push_str(&format!("Exposure: {:.2}\n", color_grading.global.exposure));
    if selected_parameter.value == 1 {
        text.push_str("> ");
    }
    text.push_str(&format!("Gamma: {:.2}\n", color_grading.shadows.gamma));
    if selected_parameter.value == 2 {
        text.push_str("> ");
    }
    text.push_str(&format!(
        "PreSaturation: {:.2}\n",
        color_grading.shadows.saturation
    ));
    if selected_parameter.value == 3 {
        text.push_str("> ");
    }
    text.push_str(&format!(
        "PostSaturation: {:.2}\n",
        color_grading.global.post_saturation
    ));
    text.push_str("(Space) Reset all to default\n");

    if current_scene.0 == 1 {
        text.push_str("(Enter) Reset all to scene recommendation\n");
    }

    if text != text_query.as_str() {
        // single_mut() always triggers change detection,
        // so only access if text actually changed
        text_query.0 = text;
    }
}

pub fn is_empty(&self) -> bool

Returns true if this String has a length of zero, and false otherwise.

Examples

let mut v = String::new();
assert!(v.is_empty());

v.push('a');
assert!(!v.is_empty());

Examples found in repository

examples/3d/tonemapping.rs (line 408)

fn update_ui(
    mut text_query: Single<&mut Text, Without<SceneNumber>>,
    settings: Single<(&Tonemapping, &ColorGrading)>,
    current_scene: Res<CurrentScene>,
    selected_parameter: Res<SelectedParameter>,
    mut hide_ui: Local<bool>,
    keys: Res<ButtonInput<KeyCode>>,
) {
    if keys.just_pressed(KeyCode::KeyH) {
        *hide_ui = !*hide_ui;
    }

    if *hide_ui {
        if !text_query.is_empty() {
            // single_mut() always triggers change detection,
            // so only access if text actually needs changing
            text_query.clear();
        }
        return;
    }

    let (tonemapping, color_grading) = *settings;
    let tonemapping = *tonemapping;

    let mut text = String::with_capacity(text_query.len());

    let scn = current_scene.0;
    text.push_str("(H) Hide UI\n\n");
    text.push_str("Test Scene: \n");
    text.push_str(&format!(
        "(Q) {} Basic Scene\n",
        if scn == 1 { ">" } else { "" }
    ));
    text.push_str(&format!(
        "(W) {} Color Sweep\n",
        if scn == 2 { ">" } else { "" }
    ));
    text.push_str(&format!(
        "(E) {} Image Viewer\n",
        if scn == 3 { ">" } else { "" }
    ));

    text.push_str("\n\nTonemapping Method:\n");
    text.push_str(&format!(
        "(1) {} Disabled\n",
        if tonemapping == Tonemapping::None {
            ">"
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(2) {} Reinhard\n",
        if tonemapping == Tonemapping::Reinhard {
            "> "
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(3) {} Reinhard Luminance\n",
        if tonemapping == Tonemapping::ReinhardLuminance {
            ">"
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(4) {} ACES Fitted\n",
        if tonemapping == Tonemapping::AcesFitted {
            ">"
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(5) {} AgX\n",
        if tonemapping == Tonemapping::AgX {
            ">"
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(6) {} SomewhatBoringDisplayTransform\n",
        if tonemapping == Tonemapping::SomewhatBoringDisplayTransform {
            ">"
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(7) {} TonyMcMapface\n",
        if tonemapping == Tonemapping::TonyMcMapface {
            ">"
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(8) {} Blender Filmic\n",
        if tonemapping == Tonemapping::BlenderFilmic {
            ">"
        } else {
            ""
        }
    ));
    text.push_str(&format!(
        "(9) {} Khronos PBR Neutral\n",
        if tonemapping == Tonemapping::KhronosPbrNeutral {
            ">"
        } else {
            ""
        }
    ));

    text.push_str("\n\nColor Grading:\n");
    text.push_str("(arrow keys)\n");
    if selected_parameter.value == 0 {
        text.push_str("> ");
    }
    text.push_str(&format!("Exposure: {:.2}\n", color_grading.global.exposure));
    if selected_parameter.value == 1 {
        text.push_str("> ");
    }
    text.push_str(&format!("Gamma: {:.2}\n", color_grading.shadows.gamma));
    if selected_parameter.value == 2 {
        text.push_str("> ");
    }
    text.push_str(&format!(
        "PreSaturation: {:.2}\n",
        color_grading.shadows.saturation
    ));
    if selected_parameter.value == 3 {
        text.push_str("> ");
    }
    text.push_str(&format!(
        "PostSaturation: {:.2}\n",
        color_grading.global.post_saturation
    ));
    text.push_str("(Space) Reset all to default\n");

    if current_scene.0 == 1 {
        text.push_str("(Enter) Reset all to scene recommendation\n");
    }

    if text != text_query.as_str() {
        // single_mut() always triggers change detection,
        // so only access if text actually changed
        text_query.0 = text;
    }
}

examples/ecs/dynamic.rs (line 84)

fn main() {
    let mut world = World::new();
    let mut lines = std::io::stdin().lines();
    let mut component_names = HashMap::<String, ComponentId>::new();
    let mut component_info = HashMap::<ComponentId, ComponentInfo>::new();
    let mut event_names = HashMap::<String, EventKey>::new();

    println!("{PROMPT}");
    loop {
        print!("\n> ");
        let _ = std::io::stdout().flush();
        let Some(Ok(line)) = lines.next() else {
            return;
        };

        if line.is_empty() {
            return;
        };

        let Some((first, rest)) = line.trim().split_once(|c: char| c.is_whitespace()) else {
            match &line.chars().next() {
                Some('c') => println!("{COMPONENT_PROMPT}"),
                Some('s') => println!("{ENTITY_PROMPT}"),
                Some('q') => println!("{QUERY_PROMPT}"),
                Some('e') => println!("{EVENT_PROMPT}"),
                Some('t') => println!("{EMIT_PROMPT}"),
                _ => println!("{PROMPT}"),
            }
            continue;
        };

        match &first[0..1] {
            "c" => {
                rest.split(',').for_each(|component| {
                    let mut component = component.split_whitespace();
                    let Some(name) = component.next() else {
                        return;
                    };
                    let size = match component.next().map(str::parse) {
                        Some(Ok(size)) => size,
                        _ => 0,
                    };
                    // Register our new component to the world with a layout specified by it's size
                    // SAFETY: [u64] is Send + Sync
                    let id = world.register_component_with_descriptor(unsafe {
                        ComponentDescriptor::new_with_layout(
                            name.to_string(),
                            StorageType::Table,
                            Layout::array::<u64>(size).unwrap(),
                            None,
                            true,
                            ComponentCloneBehavior::Default,
                            None,
                        )
                    });
                    let Some(info) = world.components().get_info(id) else {
                        return;
                    };
                    component_names.insert(name.to_string(), id);
                    component_info.insert(id, info.clone());
                    println!("Component {} created with id: {}", name, id.index());
                });
            }
            "s" => {
                let mut to_insert_ids = Vec::new();
                let mut to_insert_data = Vec::new();
                rest.split(',').for_each(|component| {
                    let mut component = component.split_whitespace();
                    let Some(name) = component.next() else {
                        return;
                    };

                    // Get the id for the component with the given name
                    let Some(&id) = component_names.get(name) else {
                        println!("Component {name} does not exist");
                        return;
                    };

                    // Calculate the length for the array based on the layout created for this component id
                    let info = world.components().get_info(id).unwrap();
                    let len = info.layout().size() / size_of::<u64>();
                    let mut values: Vec<u64> = component
                        .take(len)
                        .filter_map(|value| value.parse::<u64>().ok())
                        .collect();
                    values.resize(len, 0);

                    // Collect the id and array to be inserted onto our entity
                    to_insert_ids.push(id);
                    to_insert_data.push(values);
                });

                let mut entity = world.spawn_empty();

                // Construct an `OwningPtr` for each component in `to_insert_data`
                let to_insert_ptr = to_owning_ptrs(&mut to_insert_data);

                // SAFETY:
                // - Component ids have been taken from the same world
                // - Each array is created to the layout specified in the world
                unsafe {
                    entity.insert_by_ids(&to_insert_ids, to_insert_ptr.into_iter());
                }

                println!("Entity spawned with id: {}", entity.id());
            }
            "q" => {
                let mut builder = QueryBuilder::<FilteredEntityMut>::new(&mut world);
                parse_query(rest, &mut builder, &component_names);
                let mut query = builder.build();
                query.iter_mut(&mut world).for_each(|filtered_entity| {
                    let terms = filtered_entity
                        .access()
                        .try_iter_access()
                        .unwrap()
                        .map(|component_access| {
                            let id = *component_access.index();
                            let ptr = filtered_entity.get_by_id(id).unwrap();
                            let info = component_info.get(&id).unwrap();
                            let len = info.layout().size() / size_of::<u64>();

                            // SAFETY:
                            // - All components are created with layout [u64]
                            // - len is calculated from the component descriptor
                            let data = unsafe {
                                std::slice::from_raw_parts_mut(
                                    ptr.assert_unique().as_ptr().cast::<u64>(),
                                    len,
                                )
                            };

                            // If we have write access, increment each value once
                            if matches!(component_access, ComponentAccessKind::Exclusive(_)) {
                                data.iter_mut().for_each(|data| {
                                    *data += 1;
                                });
                            }

                            format!("{}: {:?}", info.name(), data[0..len].to_vec())
                        })
                        .collect::<Vec<_>>()
                        .join(", ");

                    println!("{}: {}", filtered_entity.id(), terms);
                });
            }
            "e" => {
                rest.split(',').for_each(|event| {
                    let name = event.trim();
                    if name.is_empty() {
                        return;
                    }

                    // Register a ComponentId for this event, no Rust type needed.
                    // SAFETY: ZST with no drop
                    let event_component_id = world.register_component_with_descriptor(unsafe {
                        ComponentDescriptor::new_with_layout(
                            format!("event:{name}"),
                            StorageType::Table,
                            Layout::new::<()>(),
                            None,
                            false,
                            ComponentCloneBehavior::Ignore,
                            None,
                        )
                    });
                    // SAFETY: event_component_id was just registered for this event
                    let event_key = unsafe { EventKey::new(event_component_id) };
                    event_names.insert(name.to_string(), event_key);

                    // Build a dynamic observer that prints when the event fires.
                    let runner: ObserverRunner = |mut world, _observer, ctx, _event, _trigger| {
                        println!("  Observer fired!");
                        if let Some(mut counts) = world.get_resource_mut::<EventFireCount>() {
                            *counts.0.entry(ctx.event_key).or_insert(0) += 1;
                        }
                    };

                    // SAFETY: event_key was just registered, runner ignores pointers
                    let observer =
                        unsafe { Observer::with_dynamic_runner(runner).with_event_key(event_key) };
                    world.spawn(observer);

                    println!(
                        "Event '{name}' registered (key: {}) with a dynamic observer",
                        event_component_id.index()
                    );
                });

                // Ensure the counter resource exists.
                world.init_resource::<EventFireCount>();
            }
            "t" => {
                let name = rest.trim();
                let Some(&event_key) = event_names.get(name) else {
                    println!(
                        "Event '{name}' does not exist. Register it first with 'event {name}'"
                    );
                    continue;
                };

                let mut event_data = ();
                let mut trigger_data = ();
                // SAFETY: event_key was registered in this world, both pointers are valid ZSTs
                unsafe {
                    world.trigger_dynamic(
                        event_key,
                        PtrMut::from(&mut event_data),
                        PtrMut::from(&mut trigger_data),
                    );
                }

                let count = world
                    .get_resource::<EventFireCount>()
                    .map_or(0, |c| c.0.get(&event_key).copied().unwrap_or(0));
                println!("Event '{name}' triggered ({count} fires)");
            }
            _ => continue,
        }
    }
}

pub fn split_off(&mut self, at: usize) -> String

Available on non-no_global_oom_handling only.

Splits the string into two at the given byte index.

Returns a newly allocated String. self contains bytes [0, at), and the returned String contains bytes [at, len). at must be on the boundary of a UTF-8 code point.

Note that the capacity of self does not change.

Panics

Panics if at is not on a UTF-8 code point boundary, or if it is beyond the last code point of the string.

Examples

let mut hello = String::from("Hello, World!");
let world = hello.split_off(7);
assert_eq!(hello, "Hello, ");
assert_eq!(world, "World!");

pub fn clear(&mut self)

Truncates this String, removing all contents.

While this means the String will have a length of zero, it does not touch its capacity.

Examples

let mut s = String::from("foo");

s.clear();

assert!(s.is_empty());
assert_eq!(0, s.len());
assert_eq!(3, s.capacity());

Examples found in repository

examples/stress_tests/many_text.rs (line 212)

fn update_lorem_text(mut lorem_text_query: Query<(&mut Text, &mut Lorem)>) {
    for (mut text, mut lorem) in &mut lorem_text_query {
        if lorem.0 {
            text.0.clear();
            text.0.push_str(LOREM_TEXT_1);
        } else {
            text.0.clear();
            text.0.push_str(LOREM_TEXT_2);
        }

        lorem.0 = !lorem.0;
    }
}

examples/math/bounding_2d.rs (line 80)

fn update_text(mut text: Single<&mut Text>, cur_state: Res<State<Test>>) {
    if !cur_state.is_changed() {
        return;
    }

    text.clear();

    text.push_str("Intersection test:\n");
    use Test::*;
    for &test in &[AabbSweep, CircleSweep, RayCast, AabbCast, CircleCast] {
        let s = if **cur_state == test { "*" } else { " " };
        text.push_str(&format!(" {s} {test:?} {s}\n"));
    }
    text.push_str("\nPress space to cycle");
}

examples/shader_advanced/fullscreen_material.rs (line 104)

fn toggle_effect(
    mut text: Single<&mut Text>,
    keys: Res<ButtonInput<KeyCode>>,
    camera: Single<(Entity, Option<&FullscreenEffect>), With<Camera3d>>,
    mut commands: Commands,
) {
    if keys.just_pressed(KeyCode::KeyT) {
        let (entity, effect) = *camera;

        if effect.is_some() {
            commands.entity(entity).remove::<FullscreenEffect>();
            text.clear();
            text.push_str("(T) FullscreenEffect: Off");
        } else {
            commands.entity(entity).insert(FullscreenEffect::new(0.0));
            text.clear();
            text.push_str("(T) FullscreenEffect: On");
        }
    }
}

examples/ui/text/multiple_text_inputs.rs (line 190)

fn synchronize_output_text(
    changed_inputs: Query<(&EditableText, &TextInputRow), Changed<EditableText>>,
    mut outputs: Query<(&mut Text, &TextInputRow), With<TextOutput>>,
) {
    for (editable_text, input_row) in &changed_inputs {
        for (mut text, output_row) in &mut outputs {
            if output_row.0 == input_row.0 {
                // `EditableText::value()` returns a `SplitString` because Parley may keep IME preedit text
                // in a contiguous range of the editor’s internal `String` buffer during composition.
                // The returned `SplitString` omits that preedit range, exposing only the text before and after it.
                //
                // To avoid allocating a new `String`, we reserve the total length of the `SplitString`'s slices,
                // then append them to the output `Text`.
                text.0.clear();
                text.0
                    .reserve(editable_text.value().into_iter().map(str::len).sum());
                for sub_str in editable_text.value() {
                    text.0.push_str(sub_str);
                }
            }
        }
    }
}

// Submit the focused input's text when Enter is pressed.
fn submit_text(
    mut input_focus: ResMut<InputFocus>,
    keyboard_input: Res<ButtonInput<Key>>,
    mut text_input: Query<(&mut EditableText, &TextInputRow)>,
    mut text_output: Query<(&mut Text, &TextInputRow), With<SubmitOutput>>,
    tab_navigation: TabNavigation,
) {
    if keyboard_input.just_pressed(Key::Enter)
        && let Some(focused_entity) = input_focus.get()
        && let Ok((mut editable_text, input_row)) = text_input.get_mut(focused_entity)
    {
        for (mut text, output_row) in &mut text_output {
            if input_row.0 == output_row.0 {
                text.0.clear();
                text.0
                    .reserve(editable_text.value().into_iter().map(str::len).sum());
                for sub_str in editable_text.value() {
                    text.0.push_str(sub_str);
                }
                break;
            }
        }
        editable_text.clear();

        if let Ok(next) = tab_navigation.navigate(&input_focus, NavAction::Next) {
            input_focus.set(next, FocusCause::Navigated);
        }
    }
}

examples/3d/post_processing.rs (line 271)

fn update_help_text(mut text: Single<&mut Text>, app_settings: Res<AppSettings>) {
    text.clear();
    let text_list = [
        format!(
            "Chromatic aberration intensity: {:.2}\n",
            app_settings.chromatic_aberration_intensity
        ),
        format!(
            "Vignette intensity: {:.2}\n",
            app_settings.vignette_intensity
        ),
        format!("Vignette radius: {:.2}\n", app_settings.vignette_radius),
        format!(
            "Vignette smoothness: {:.2}\n",
            app_settings.vignette_smoothness
        ),
        format!(
            "Vignette roundness: {:.2}\n",
            app_settings.vignette_roundness
        ),
        format!(
            "Vignette edge_compensation: {:.2}\n",
            app_settings.vignette_edge_compensation
        ),
        format!(
            "Lens Distortion intensity: {:.2}\n",
            app_settings.lens_distortion_intensity
        ),
        format!(
            "Lens Distortion multiplier x: {:.2}\n",
            app_settings.lens_distortion_multiplier_x
        ),
        format!(
            "Lens Distortion multiplier y: {:.2}\n",
            app_settings.lens_distortion_multiplier_y
        ),
    ];
    for (i, val) in text_list.iter().enumerate() {
        if i == app_settings.selected {
            text.push_str("> ");
        }
        text.push_str(val);
    }
    text.push_str("\n(Press Up or Down to select)\n(Press Left or Right to change)");
}

examples/3d/solari.rs (line 538)

fn update_control_text(
    mut text: Single<&mut Text, With<ControlText>>,
    robot_light_material: Option<Res<RobotLightMaterial>>,
    materials: Res<Assets<StandardMaterial>>,
    directional_light: Query<Entity, With<DirectionalLight>>,
    time: Res<Time<Virtual>>,
    #[cfg(all(feature = "dlss", not(feature = "force_disable_dlss")))] dlss_rr_supported: Option<
        Res<DlssRayReconstructionSupported>,
    >,
) {
    text.0.clear();

    if time.is_paused() {
        text.0.push_str("(Space): Resume");
    } else {
        text.0.push_str("(Space): Pause");
    }

    if directional_light.single().is_ok() {
        text.0.push_str("\n(1): Disable directional light");
    } else {
        text.0.push_str("\n(1): Enable directional light");
    }

    match robot_light_material.and_then(|m| materials.get(&m.0)) {
        Some(robot_light_material) if robot_light_material.emissive != LinearRgba::BLACK => {
            text.0.push_str("\n(2): Disable robot emissive light");
        }
        _ => {
            text.0.push_str("\n(2): Enable robot emissive light");
        }
    }

    #[cfg(all(feature = "dlss", not(feature = "force_disable_dlss")))]
    if dlss_rr_supported.is_some() {
        text.0
            .push_str("\nDenoising: DLSS Ray Reconstruction enabled");
    } else {
        text.0
            .push_str("\nDenoising: DLSS Ray Reconstruction not supported");
    }

    #[cfg(any(not(feature = "dlss"), feature = "force_disable_dlss"))]
    text.0
        .push_str("\nDenoising: App not compiled with DLSS support");
}

#[derive(Component)]
struct PerformanceText;

fn update_performance_text(
    mut text: Single<&mut Text, With<PerformanceText>>,
    diagnostics: Res<DiagnosticsStore>,
) {
    text.0.clear();

    let mut total = 0.0;
    let mut add_diagnostic = |name: &str, path: &'static str| {
        let path = DiagnosticPath::new(path);
        if let Some(value) = diagnostics.get(&path).and_then(Diagnostic::smoothed) {
            text.push_str(&format!("{name:17}  {value:.2} ms\n"));
            total += value;
        }
    };

    (add_diagnostic)(
        "Light tiles",
        "render/solari_lighting/presample_light_tiles/elapsed_gpu",
    );
    (add_diagnostic)(
        "World cache",
        "render/solari_lighting/world_cache/elapsed_gpu",
    );
    (add_diagnostic)(
        "Direct lighting",
        "render/solari_lighting/direct_lighting/elapsed_gpu",
    );
    (add_diagnostic)(
        "Diffuse indirect",
        "render/solari_lighting/diffuse_indirect_lighting/elapsed_gpu",
    );
    (add_diagnostic)(
        "Specular indirect",
        "render/solari_lighting/specular_indirect_lighting/elapsed_gpu",
    );
    (add_diagnostic)("DLSS-RR", "render/dlss_ray_reconstruction/elapsed_gpu");
    text.push_str(&format!("{:17}  {total:.2} ms\n", "Total"));

    if let Some(world_cache_active_cells_count) = diagnostics
        .get(&DiagnosticPath::new(
            "render/solari_lighting/world_cache_active_cells_count",
        ))
        .and_then(Diagnostic::smoothed)
    {
        text.push_str(&format!(
            "\nWorld cache cells {} ({:.0}%)",
            world_cache_active_cells_count as u32,
            (world_cache_active_cells_count * 100.0) / (2u64.pow(20) as f64)
        ));
    }
}

Additional examples can be found in:

• examples/3d/deferred_rendering.rs
• examples/3d/ssao.rs
• examples/3d/tonemapping.rs

pub fn drain<R>(&mut self, range: R) -> Drain<'_>

where R: RangeBounds<usize>,

Removes the specified range from the string in bulk, returning all removed characters as an iterator.

The returned iterator keeps a mutable borrow on the string to optimize its implementation.

Panics

Panics if the range has start_bound > end_bound, or, if the range is bounded on either end and does not lie on a char boundary.

Leaking

If the returned iterator goes out of scope without being dropped (due to core::mem::forget, for example), the string may still contain a copy of any drained characters, or may have lost characters arbitrarily, including characters outside the range.

Examples

let mut s = String::from("α is alpha, β is beta");
let beta_offset = s.find('β').unwrap_or(s.len());

// Remove the range up until the β from the string
let t: String = s.drain(..beta_offset).collect();
assert_eq!(t, "α is alpha, ");
assert_eq!(s, "β is beta");

// A full range clears the string, like `clear()` does
s.drain(..);
assert_eq!(s, "");

pub fn replace_range<R>(&mut self, range: R, replace_with: &str)

where R: RangeBounds<usize>,

Available on non-no_global_oom_handling only.

Removes the specified range in the string, and replaces it with the given string. The given string doesn’t need to be the same length as the range.

Panics

Panics if the range has start_bound > end_bound, or, if the range is bounded on either end and does not lie on a char boundary.

Examples

let mut s = String::from("α is alpha, β is beta");
let beta_offset = s.find('β').unwrap_or(s.len());

// Replace the range up until the β from the string
s.replace_range(..beta_offset, "Α is capital alpha; ");
assert_eq!(s, "Α is capital alpha; β is beta");

pub fn replace_first<P>(&mut self, from: P, to: &str)

where P: Pattern,

🔬This is a nightly-only experimental API. (string_replace_in_place)

Available on non-no_global_oom_handling only.

Replaces the leftmost occurrence of a pattern with another string, in-place.

This method can be preferred over string = string.replacen(..., 1);, as it can use the String’s existing capacity to prevent a reallocation if sufficient space is available.

Examples

Basic usage:

#![feature(string_replace_in_place)]

let mut s = String::from("Test Results: ❌❌❌");

// Replace the leftmost ❌ with a ✅
s.replace_first('❌', "✅");
assert_eq!(s, "Test Results: ✅❌❌");

pub fn replace_last<P>(&mut self, from: P, to: &str)

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

🔬This is a nightly-only experimental API. (string_replace_in_place)

Available on non-no_global_oom_handling only.

Replaces the rightmost occurrence of a pattern with another string, in-place.

Examples

Basic usage:

#![feature(string_replace_in_place)]

let mut s = String::from("Test Results: ❌❌❌");

// Replace the rightmost ❌ with a ✅
s.replace_last('❌', "✅");
assert_eq!(s, "Test Results: ❌❌✅");

Methods from Deref<Target = str>

pub fn len(&self) -> usize

Returns the length of self.

This length is in bytes, not chars or graphemes. In other words, it might not be what a human considers the length of the string.

Examples

let len = "foo".len();
assert_eq!(3, len);

assert_eq!("ƒoo".len(), 4); // fancy f!
assert_eq!("ƒoo".chars().count(), 3);

pub fn is_empty(&self) -> bool

Returns true if self has a length of zero bytes.

Examples

let s = "";
assert!(s.is_empty());

let s = "not empty";
assert!(!s.is_empty());

pub fn is_char_boundary(&self, index: usize) -> bool

Checks that index-th byte is the first byte in a UTF-8 code point sequence or the end of the string.

The start and end of the string (when index == self.len()) are considered to be boundaries.

Returns false if index is greater than self.len().

Examples

let s = "Löwe 老虎 Léopard";
assert!(s.is_char_boundary(0));
// start of `老`
assert!(s.is_char_boundary(6));
assert!(s.is_char_boundary(s.len()));

// second byte of `ö`
assert!(!s.is_char_boundary(2));

// third byte of `老`
assert!(!s.is_char_boundary(8));

pub fn floor_char_boundary(&self, index: usize) -> usize

Finds the closest x not exceeding index where is_char_boundary(x) is true.

This method can help you truncate a string so that it’s still valid UTF-8, but doesn’t exceed a given number of bytes. Note that this is done purely at the character level and can still visually split graphemes, even though the underlying characters aren’t split. For example, the emoji 🧑‍🔬 (scientist) could be split so that the string only includes 🧑 (person) instead.

Examples

let s = "❤️🧡💛💚💙💜";
assert_eq!(s.len(), 26);
assert!(!s.is_char_boundary(13));

let closest = s.floor_char_boundary(13);
assert_eq!(closest, 10);
assert_eq!(&s[..closest], "❤️🧡");

pub fn ceil_char_boundary(&self, index: usize) -> usize

Finds the closest x not below index where is_char_boundary(x) is true.

If index is greater than the length of the string, this returns the length of the string.

This method is the natural complement to floor_char_boundary. See that method for more details.

Examples

let s = "❤️🧡💛💚💙💜";
assert_eq!(s.len(), 26);
assert!(!s.is_char_boundary(13));

let closest = s.ceil_char_boundary(13);
assert_eq!(closest, 14);
assert_eq!(&s[..closest], "❤️🧡💛");

pub fn as_bytes(&self) -> &[u8]

Converts a string slice to a byte slice. To convert the byte slice back into a string slice, use the from_utf8 function.

Examples

let bytes = "bors".as_bytes();
assert_eq!(b"bors", bytes);

pub unsafe fn as_bytes_mut(&mut self) -> &mut [u8]

Converts a mutable string slice to a mutable byte slice.

Safety

The caller must ensure that the content of the slice is valid UTF-8 before the borrow ends and the underlying str is used.

Use of a str whose contents are not valid UTF-8 is undefined behavior.

Examples

Basic usage:

let mut s = String::from("Hello");
let bytes = unsafe { s.as_bytes_mut() };

assert_eq!(b"Hello", bytes);

Mutability:

let mut s = String::from("🗻∈🌏");

unsafe {
    let bytes = s.as_bytes_mut();

    bytes[0] = 0xF0;
    bytes[1] = 0x9F;
    bytes[2] = 0x8D;
    bytes[3] = 0x94;
}

assert_eq!("🍔∈🌏", s);

pub fn as_ptr(&self) -> *const u8

Converts a string slice to a raw pointer.

As string slices are a slice of bytes, the raw pointer points to a u8. This pointer will be pointing to the first byte of the string slice.

The caller must ensure that the returned pointer is never written to. If you need to mutate the contents of the string slice, use as_mut_ptr.

Examples

let s = "Hello";
let ptr = s.as_ptr();

pub fn as_mut_ptr(&mut self) -> *mut u8

Converts a mutable string slice to a raw pointer.

As string slices are a slice of bytes, the raw pointer points to a u8. This pointer will be pointing to the first byte of the string slice.

It is your responsibility to make sure that the string slice only gets modified in a way that it remains valid UTF-8.

pub fn get<I>(&self, i: I) -> Option<&<I as SliceIndex<str>>::Output>

where I: SliceIndex<str>,

Returns a subslice of str.

This is the non-panicking alternative to indexing the str. Returns None whenever equivalent indexing operation would panic.

Examples

let v = String::from("🗻∈🌏");

assert_eq!(Some("🗻"), v.get(0..4));

// indices not on UTF-8 sequence boundaries
assert!(v.get(1..).is_none());
assert!(v.get(..8).is_none());

// out of bounds
assert!(v.get(..42).is_none());

pub fn get_mut<I>( &mut self, i: I, ) -> Option<&mut <I as SliceIndex<str>>::Output>

where I: SliceIndex<str>,

Returns a mutable subslice of str.

This is the non-panicking alternative to indexing the str. Returns None whenever equivalent indexing operation would panic.

Examples

let mut v = String::from("hello");
// correct length
assert!(v.get_mut(0..5).is_some());
// out of bounds
assert!(v.get_mut(..42).is_none());
assert_eq!(Some("he"), v.get_mut(0..2).map(|v| &*v));

assert_eq!("hello", v);
{
    let s = v.get_mut(0..2);
    let s = s.map(|s| {
        s.make_ascii_uppercase();
        &*s
    });
    assert_eq!(Some("HE"), s);
}
assert_eq!("HEllo", v);

pub unsafe fn get_unchecked<I>(&self, i: I) -> &<I as SliceIndex<str>>::Output

where I: SliceIndex<str>,

Returns an unchecked subslice of str.

This is the unchecked alternative to indexing the str.

Safety

Callers of this function are responsible that these preconditions are satisfied:

• The starting index must not exceed the ending index;
• Indexes must be within bounds of the original slice;
• Indexes must lie on UTF-8 sequence boundaries.

Failing that, the returned string slice may reference invalid memory or violate the invariants communicated by the str type.

Examples

let v = "🗻∈🌏";
unsafe {
    assert_eq!("🗻", v.get_unchecked(0..4));
    assert_eq!("∈", v.get_unchecked(4..7));
    assert_eq!("🌏", v.get_unchecked(7..11));
}

pub unsafe fn get_unchecked_mut<I>( &mut self, i: I, ) -> &mut <I as SliceIndex<str>>::Output

where I: SliceIndex<str>,

Returns a mutable, unchecked subslice of str.

This is the unchecked alternative to indexing the str.

Safety

Callers of this function are responsible that these preconditions are satisfied:

• The starting index must not exceed the ending index;
• Indexes must be within bounds of the original slice;
• Indexes must lie on UTF-8 sequence boundaries.

Failing that, the returned string slice may reference invalid memory or violate the invariants communicated by the str type.

Examples

let mut v = String::from("🗻∈🌏");
unsafe {
    assert_eq!("🗻", v.get_unchecked_mut(0..4));
    assert_eq!("∈", v.get_unchecked_mut(4..7));
    assert_eq!("🌏", v.get_unchecked_mut(7..11));
}

pub unsafe fn slice_unchecked(&self, begin: usize, end: usize) -> &str

👎Deprecated since 1.29.0:

use get_unchecked(begin..end) instead

Creates a string slice from another string slice, bypassing safety checks.

This is generally not recommended, use with caution! For a safe alternative see str and Index.

This new slice goes from begin to end, including begin but excluding end.

To get a mutable string slice instead, see the slice_mut_unchecked method.

Safety

Callers of this function are responsible that three preconditions are satisfied:

• begin must not exceed end.
• begin and end must be byte positions within the string slice.
• begin and end must lie on UTF-8 sequence boundaries.

Examples

let s = "Löwe 老虎 Léopard";

unsafe {
    assert_eq!("Löwe 老虎 Léopard", s.slice_unchecked(0, 21));
}

let s = "Hello, world!";

unsafe {
    assert_eq!("world", s.slice_unchecked(7, 12));
}

pub unsafe fn slice_mut_unchecked( &mut self, begin: usize, end: usize, ) -> &mut str

👎Deprecated since 1.29.0:

use get_unchecked_mut(begin..end) instead

Creates a string slice from another string slice, bypassing safety checks.

This is generally not recommended, use with caution! For a safe alternative see str and IndexMut.

This new slice goes from begin to end, including begin but excluding end.

To get an immutable string slice instead, see the slice_unchecked method.

Safety

Callers of this function are responsible that three preconditions are satisfied:

• begin must not exceed end.
• begin and end must be byte positions within the string slice.
• begin and end must lie on UTF-8 sequence boundaries.

pub fn split_at(&self, mid: usize) -> (&str, &str)

Divides one string slice into two at an index.

The argument, mid, should be a byte offset from the start of the string. It must also be on the boundary of a UTF-8 code point.

The two slices returned go from the start of the string slice to mid, and from mid to the end of the string slice.

To get mutable string slices instead, see the split_at_mut method.

Panics

Panics if mid is not on a UTF-8 code point boundary, or if it is past the end of the last code point of the string slice. For a non-panicking alternative see split_at_checked.

Examples

let s = "Per Martin-Löf";

let (first, last) = s.split_at(3);

assert_eq!("Per", first);
assert_eq!(" Martin-Löf", last);

pub fn split_at_mut(&mut self, mid: usize) -> (&mut str, &mut str)

Divides one mutable string slice into two at an index.

The argument, mid, should be a byte offset from the start of the string. It must also be on the boundary of a UTF-8 code point.

The two slices returned go from the start of the string slice to mid, and from mid to the end of the string slice.

To get immutable string slices instead, see the split_at method.

Panics

Panics if mid is not on a UTF-8 code point boundary, or if it is past the end of the last code point of the string slice. For a non-panicking alternative see split_at_mut_checked.

Examples

let mut s = "Per Martin-Löf".to_string();
{
    let (first, last) = s.split_at_mut(3);
    first.make_ascii_uppercase();
    assert_eq!("PER", first);
    assert_eq!(" Martin-Löf", last);
}
assert_eq!("PER Martin-Löf", s);

pub fn split_at_checked(&self, mid: usize) -> Option<(&str, &str)>

Divides one string slice into two at an index.

The argument, mid, should be a valid byte offset from the start of the string. It must also be on the boundary of a UTF-8 code point. The method returns None if that’s not the case.

The two slices returned go from the start of the string slice to mid, and from mid to the end of the string slice.

To get mutable string slices instead, see the split_at_mut_checked method.

Examples

let s = "Per Martin-Löf";

let (first, last) = s.split_at_checked(3).unwrap();
assert_eq!("Per", first);
assert_eq!(" Martin-Löf", last);

assert_eq!(None, s.split_at_checked(13));  // Inside “ö”
assert_eq!(None, s.split_at_checked(16));  // Beyond the string length

pub fn split_at_mut_checked( &mut self, mid: usize, ) -> Option<(&mut str, &mut str)>

Divides one mutable string slice into two at an index.

The argument, mid, should be a valid byte offset from the start of the string. It must also be on the boundary of a UTF-8 code point. The method returns None if that’s not the case.

The two slices returned go from the start of the string slice to mid, and from mid to the end of the string slice.

To get immutable string slices instead, see the split_at_checked method.

Examples

let mut s = "Per Martin-Löf".to_string();
if let Some((first, last)) = s.split_at_mut_checked(3) {
    first.make_ascii_uppercase();
    assert_eq!("PER", first);
    assert_eq!(" Martin-Löf", last);
}
assert_eq!("PER Martin-Löf", s);

assert_eq!(None, s.split_at_mut_checked(13));  // Inside “ö”
assert_eq!(None, s.split_at_mut_checked(16));  // Beyond the string length

pub fn chars(&self) -> Chars<'_>

Returns an iterator over the chars of a string slice.

As a string slice consists of valid UTF-8, we can iterate through a string slice by char. This method returns such an iterator.

It’s important to remember that char represents a Unicode Scalar Value, and might not match your idea of what a ‘character’ is. Iteration over grapheme clusters may be what you actually want. This functionality is not provided by Rust’s standard library, check crates.io instead.

Examples

Basic usage:

let word = "goodbye";

let count = word.chars().count();
assert_eq!(7, count);

let mut chars = word.chars();

assert_eq!(Some('g'), chars.next());
assert_eq!(Some('o'), chars.next());
assert_eq!(Some('o'), chars.next());
assert_eq!(Some('d'), chars.next());
assert_eq!(Some('b'), chars.next());
assert_eq!(Some('y'), chars.next());
assert_eq!(Some('e'), chars.next());

assert_eq!(None, chars.next());

Remember, chars might not match your intuition about characters:

let y = "y̆";

let mut chars = y.chars();

assert_eq!(Some('y'), chars.next()); // not 'y̆'
assert_eq!(Some('\u{0306}'), chars.next());

assert_eq!(None, chars.next());

pub fn char_indices(&self) -> CharIndices<'_>

Returns an iterator over the chars of a string slice, and their positions.

As a string slice consists of valid UTF-8, we can iterate through a string slice by char. This method returns an iterator of both these chars, as well as their byte positions.

The iterator yields tuples. The position is first, the char is second.

Examples

Basic usage:

let word = "goodbye";

let count = word.char_indices().count();
assert_eq!(7, count);

let mut char_indices = word.char_indices();

assert_eq!(Some((0, 'g')), char_indices.next());
assert_eq!(Some((1, 'o')), char_indices.next());
assert_eq!(Some((2, 'o')), char_indices.next());
assert_eq!(Some((3, 'd')), char_indices.next());
assert_eq!(Some((4, 'b')), char_indices.next());
assert_eq!(Some((5, 'y')), char_indices.next());
assert_eq!(Some((6, 'e')), char_indices.next());

assert_eq!(None, char_indices.next());

Remember, chars might not match your intuition about characters:

let yes = "y̆es";

let mut char_indices = yes.char_indices();

assert_eq!(Some((0, 'y')), char_indices.next()); // not (0, 'y̆')
assert_eq!(Some((1, '\u{0306}')), char_indices.next());

// note the 3 here - the previous character took up two bytes
assert_eq!(Some((3, 'e')), char_indices.next());
assert_eq!(Some((4, 's')), char_indices.next());

assert_eq!(None, char_indices.next());

pub fn bytes(&self) -> Bytes<'_>

Returns an iterator over the bytes of a string slice.

As a string slice consists of a sequence of bytes, we can iterate through a string slice by byte. This method returns such an iterator.

Examples

let mut bytes = "bors".bytes();

assert_eq!(Some(b'b'), bytes.next());
assert_eq!(Some(b'o'), bytes.next());
assert_eq!(Some(b'r'), bytes.next());
assert_eq!(Some(b's'), bytes.next());

assert_eq!(None, bytes.next());

pub fn split_whitespace(&self) -> SplitWhitespace<'_>

Splits a string slice by whitespace.

The iterator returned will return string slices that are sub-slices of the original string slice, separated by any amount of whitespace.

‘Whitespace’ is defined according to the terms of the Unicode Derived Core Property White_Space. If you only want to split on ASCII whitespace instead, use split_ascii_whitespace.

Examples

Basic usage:

let mut iter = "A few words".split_whitespace();

assert_eq!(Some("A"), iter.next());
assert_eq!(Some("few"), iter.next());
assert_eq!(Some("words"), iter.next());

assert_eq!(None, iter.next());

All kinds of whitespace are considered:

let mut iter = " Mary   had\ta\u{2009}little  \n\t lamb".split_whitespace();
assert_eq!(Some("Mary"), iter.next());
assert_eq!(Some("had"), iter.next());
assert_eq!(Some("a"), iter.next());
assert_eq!(Some("little"), iter.next());
assert_eq!(Some("lamb"), iter.next());

assert_eq!(None, iter.next());

If the string is empty or all whitespace, the iterator yields no string slices:

assert_eq!("".split_whitespace().next(), None);
assert_eq!("   ".split_whitespace().next(), None);

pub fn split_ascii_whitespace(&self) -> SplitAsciiWhitespace<'_>

Splits a string slice by ASCII whitespace.

The iterator returned will return string slices that are sub-slices of the original string slice, separated by any amount of ASCII whitespace.

This uses the same definition as char::is_ascii_whitespace. To split by Unicode Whitespace instead, use split_whitespace. Note that because of this difference in definition, even if s.is_ascii() is true, s.split_ascii_whitespace() behavior will differ from s.split_whitespace() if s contains U+000B VERTICAL TAB.

Examples

Basic usage:

let mut iter = "A few words".split_ascii_whitespace();

assert_eq!(Some("A"), iter.next());
assert_eq!(Some("few"), iter.next());
assert_eq!(Some("words"), iter.next());

assert_eq!(None, iter.next());

Various kinds of ASCII whitespace are considered (see char::is_ascii_whitespace):

let mut iter = " Mary   had\ta little  \n\t lamb".split_ascii_whitespace();
assert_eq!(Some("Mary"), iter.next());
assert_eq!(Some("had"), iter.next());
assert_eq!(Some("a"), iter.next());
assert_eq!(Some("little"), iter.next());
assert_eq!(Some("lamb"), iter.next());

assert_eq!(None, iter.next());

If the string is empty or all ASCII whitespace, the iterator yields no string slices:

assert_eq!("".split_ascii_whitespace().next(), None);
assert_eq!("   ".split_ascii_whitespace().next(), None);

pub fn lines(&self) -> Lines<'_>

Returns an iterator over the lines of a string, as string slices.

Lines are split at line endings that are either newlines (\n) or sequences of a carriage return followed by a line feed (\r\n).

Line terminators are not included in the lines returned by the iterator.

Note that any carriage return (\r) not immediately followed by a line feed (\n) does not split a line. These carriage returns are thereby included in the produced lines.

The final line ending is optional. A string that ends with a final line ending will return the same lines as an otherwise identical string without a final line ending.

An empty string returns an empty iterator.

Examples

Basic usage:

let text = "foo\r\nbar\n\nbaz\r";
let mut lines = text.lines();

assert_eq!(Some("foo"), lines.next());
assert_eq!(Some("bar"), lines.next());
assert_eq!(Some(""), lines.next());
// Trailing carriage return is included in the last line
assert_eq!(Some("baz\r"), lines.next());

assert_eq!(None, lines.next());

The final line does not require any ending:

let text = "foo\nbar\n\r\nbaz";
let mut lines = text.lines();

assert_eq!(Some("foo"), lines.next());
assert_eq!(Some("bar"), lines.next());
assert_eq!(Some(""), lines.next());
assert_eq!(Some("baz"), lines.next());

assert_eq!(None, lines.next());

An empty string returns an empty iterator:

let text = "";
let mut lines = text.lines();

assert_eq!(lines.next(), None);

pub fn lines_any(&self) -> LinesAny<'_>

👎Deprecated since 1.4.0:

use lines() instead now

Returns an iterator over the lines of a string.

pub fn encode_utf16(&self) -> EncodeUtf16<'_>

Returns an iterator of u16 over the string encoded as native endian UTF-16 (without byte-order mark).

Examples

let text = "Zażółć gęślą jaźń";

let utf8_len = text.len();
let utf16_len = text.encode_utf16().count();

assert!(utf16_len <= utf8_len);

pub fn contains<P>(&self, pat: P) -> bool

where P: Pattern,

Returns true if the given pattern matches a sub-slice of this string slice.

Returns false if it does not.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Examples

let bananas = "bananas";

assert!(bananas.contains("nana"));
assert!(!bananas.contains("apples"));

pub fn starts_with<P>(&self, pat: P) -> bool

where P: Pattern,

Returns true if the given pattern matches a prefix of this string slice.

Returns false if it does not.

The pattern can be a &str, in which case this function will return true if the &str is a prefix of this string slice.

The pattern can also be a char, a slice of chars, or a function or closure that determines if a character matches. These will only be checked against the first character of this string slice. Look at the second example below regarding behavior for slices of chars.

Examples

let bananas = "bananas";

assert!(bananas.starts_with("bana"));
assert!(!bananas.starts_with("nana"));

let bananas = "bananas";

// Note that both of these assert successfully.
assert!(bananas.starts_with(&['b', 'a', 'n', 'a']));
assert!(bananas.starts_with(&['a', 'b', 'c', 'd']));

pub fn ends_with<P>(&self, pat: P) -> bool

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

Returns true if the given pattern matches a suffix of this string slice.

Returns false if it does not.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Examples

let bananas = "bananas";

assert!(bananas.ends_with("anas"));
assert!(!bananas.ends_with("nana"));

pub fn find<P>(&self, pat: P) -> Option<usize>

where P: Pattern,

Returns the byte index of the first character of this string slice that matches the pattern.

Returns None if the pattern doesn’t match.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Examples

Simple patterns:

let s = "Löwe 老虎 Léopard Gepardi";

assert_eq!(s.find('L'), Some(0));
assert_eq!(s.find('é'), Some(14));
assert_eq!(s.find("pard"), Some(17));

More complex patterns using point-free style and closures:

let s = "Löwe 老虎 Léopard";

assert_eq!(s.find(char::is_whitespace), Some(5));
assert_eq!(s.find(char::is_lowercase), Some(1));
assert_eq!(s.find(|c: char| c.is_whitespace() || c.is_lowercase()), Some(1));
assert_eq!(s.find(|c: char| (c < 'o') && (c > 'a')), Some(4));

Not finding the pattern:

let s = "Löwe 老虎 Léopard";
let x: &[_] = &['1', '2'];

assert_eq!(s.find(x), None);

pub fn rfind<P>(&self, pat: P) -> Option<usize>

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

Returns the byte index for the first character of the last match of the pattern in this string slice.

Returns None if the pattern doesn’t match.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Examples

Simple patterns:

let s = "Löwe 老虎 Léopard Gepardi";

assert_eq!(s.rfind('L'), Some(13));
assert_eq!(s.rfind('é'), Some(14));
assert_eq!(s.rfind("pard"), Some(24));

More complex patterns with closures:

let s = "Löwe 老虎 Léopard";

assert_eq!(s.rfind(char::is_whitespace), Some(12));
assert_eq!(s.rfind(char::is_lowercase), Some(20));

Not finding the pattern:

let s = "Löwe 老虎 Léopard";
let x: &[_] = &['1', '2'];

assert_eq!(s.rfind(x), None);

pub fn split<P>(&self, pat: P) -> Split<'_, P>

where P: Pattern,

Returns an iterator over substrings of this string slice, separated by characters matched by a pattern.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

If there are no matches the full string slice is returned as the only item in the iterator.

Iterator behavior

The returned iterator will be a DoubleEndedIterator if the pattern allows a reverse search and forward/reverse search yields the same elements. This is true for, e.g., char, but not for &str.

If the pattern allows a reverse search but its results might differ from a forward search, the rsplit method can be used.

Examples

Simple patterns:

let v: Vec<&str> = "Mary had a little lamb".split(' ').collect();
assert_eq!(v, ["Mary", "had", "a", "little", "lamb"]);

let v: Vec<&str> = "".split('X').collect();
assert_eq!(v, [""]);

let v: Vec<&str> = "lionXXtigerXleopard".split('X').collect();
assert_eq!(v, ["lion", "", "tiger", "leopard"]);

let v: Vec<&str> = "lion::tiger::leopard".split("::").collect();
assert_eq!(v, ["lion", "tiger", "leopard"]);

let v: Vec<&str> = "AABBCC".split("DD").collect();
assert_eq!(v, ["AABBCC"]);

let v: Vec<&str> = "abc1def2ghi".split(char::is_numeric).collect();
assert_eq!(v, ["abc", "def", "ghi"]);

let v: Vec<&str> = "lionXtigerXleopard".split(char::is_uppercase).collect();
assert_eq!(v, ["lion", "tiger", "leopard"]);

If the pattern is a slice of chars, split on each occurrence of any of the characters:

let v: Vec<&str> = "2020-11-03 23:59".split(&['-', ' ', ':', '@'][..]).collect();
assert_eq!(v, ["2020", "11", "03", "23", "59"]);

A more complex pattern, using a closure:

let v: Vec<&str> = "abc1defXghi".split(|c| c == '1' || c == 'X').collect();
assert_eq!(v, ["abc", "def", "ghi"]);

If a string contains multiple contiguous separators, you will end up with empty strings in the output:

let x = "||||a||b|c".to_string();
let d: Vec<_> = x.split('|').collect();

assert_eq!(d, &["", "", "", "", "a", "", "b", "c"]);

Contiguous separators are separated by the empty string.

let x = "(///)".to_string();
let d: Vec<_> = x.split('/').collect();

assert_eq!(d, &["(", "", "", ")"]);

Separators at the start or end of a string are neighbored by empty strings.

let d: Vec<_> = "010".split("0").collect();
assert_eq!(d, &["", "1", ""]);

When the empty string is used as a separator, it separates every character in the string, along with the beginning and end of the string.

let f: Vec<_> = "rust".split("").collect();
assert_eq!(f, &["", "r", "u", "s", "t", ""]);

Contiguous separators can lead to possibly surprising behavior when whitespace is used as the separator. This code is correct:

let x = "    a  b c".to_string();
let d: Vec<_> = x.split(' ').collect();

assert_eq!(d, &["", "", "", "", "a", "", "b", "c"]);

It does not give you:

assert_eq!(d, &["a", "b", "c"]);

Use split_whitespace for this behavior.

pub fn split_inclusive<P>(&self, pat: P) -> SplitInclusive<'_, P>

where P: Pattern,

Returns an iterator over substrings of this string slice, separated by characters matched by a pattern.

Differs from the iterator produced by split in that split_inclusive leaves the matched part as the terminator of the substring.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Examples

let v: Vec<&str> = "Mary had a little lamb\nlittle lamb\nlittle lamb."
    .split_inclusive('\n').collect();
assert_eq!(v, ["Mary had a little lamb\n", "little lamb\n", "little lamb."]);

If the last element of the string is matched, that element will be considered the terminator of the preceding substring. That substring will be the last item returned by the iterator.

let v: Vec<&str> = "Mary had a little lamb\nlittle lamb\nlittle lamb.\n"
    .split_inclusive('\n').collect();
assert_eq!(v, ["Mary had a little lamb\n", "little lamb\n", "little lamb.\n"]);

pub fn rsplit<P>(&self, pat: P) -> RSplit<'_, P>

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

Returns an iterator over substrings of the given string slice, separated by characters matched by a pattern and yielded in reverse order.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Iterator behavior

The returned iterator requires that the pattern supports a reverse search, and it will be a DoubleEndedIterator if a forward/reverse search yields the same elements.

For iterating from the front, the split method can be used.

Examples

Simple patterns:

let v: Vec<&str> = "Mary had a little lamb".rsplit(' ').collect();
assert_eq!(v, ["lamb", "little", "a", "had", "Mary"]);

let v: Vec<&str> = "".rsplit('X').collect();
assert_eq!(v, [""]);

let v: Vec<&str> = "lionXXtigerXleopard".rsplit('X').collect();
assert_eq!(v, ["leopard", "tiger", "", "lion"]);

let v: Vec<&str> = "lion::tiger::leopard".rsplit("::").collect();
assert_eq!(v, ["leopard", "tiger", "lion"]);

A more complex pattern, using a closure:

let v: Vec<&str> = "abc1defXghi".rsplit(|c| c == '1' || c == 'X').collect();
assert_eq!(v, ["ghi", "def", "abc"]);

pub fn split_terminator<P>(&self, pat: P) -> SplitTerminator<'_, P>

where P: Pattern,

Returns an iterator over substrings of the given string slice, separated by characters matched by a pattern.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Equivalent to split, except that the trailing substring is skipped if empty.

This method can be used for string data that is terminated, rather than separated by a pattern.

Iterator behavior

The returned iterator will be a DoubleEndedIterator if the pattern allows a reverse search and forward/reverse search yields the same elements. This is true for, e.g., char, but not for &str.

If the pattern allows a reverse search but its results might differ from a forward search, the rsplit_terminator method can be used.

Examples

let v: Vec<&str> = "A.B.".split_terminator('.').collect();
assert_eq!(v, ["A", "B"]);

let v: Vec<&str> = "A..B..".split_terminator(".").collect();
assert_eq!(v, ["A", "", "B", ""]);

let v: Vec<&str> = "A.B:C.D".split_terminator(&['.', ':'][..]).collect();
assert_eq!(v, ["A", "B", "C", "D"]);

pub fn rsplit_terminator<P>(&self, pat: P) -> RSplitTerminator<'_, P>

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

Returns an iterator over substrings of self, separated by characters matched by a pattern and yielded in reverse order.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Equivalent to split, except that the trailing substring is skipped if empty.

This method can be used for string data that is terminated, rather than separated by a pattern.

Iterator behavior

The returned iterator requires that the pattern supports a reverse search, and it will be double ended if a forward/reverse search yields the same elements.

For iterating from the front, the split_terminator method can be used.

Examples

let v: Vec<&str> = "A.B.".rsplit_terminator('.').collect();
assert_eq!(v, ["B", "A"]);

let v: Vec<&str> = "A..B..".rsplit_terminator(".").collect();
assert_eq!(v, ["", "B", "", "A"]);

let v: Vec<&str> = "A.B:C.D".rsplit_terminator(&['.', ':'][..]).collect();
assert_eq!(v, ["D", "C", "B", "A"]);

pub fn splitn<P>(&self, n: usize, pat: P) -> SplitN<'_, P>

where P: Pattern,

Returns an iterator over substrings of the given string slice, separated by a pattern, restricted to returning at most n items.

If n substrings are returned, the last substring (the nth substring) will contain the remainder of the string.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Iterator behavior

The returned iterator will not be double ended, because it is not efficient to support.

If the pattern allows a reverse search, the rsplitn method can be used.

Examples

Simple patterns:

let v: Vec<&str> = "Mary had a little lambda".splitn(3, ' ').collect();
assert_eq!(v, ["Mary", "had", "a little lambda"]);

let v: Vec<&str> = "lionXXtigerXleopard".splitn(3, "X").collect();
assert_eq!(v, ["lion", "", "tigerXleopard"]);

let v: Vec<&str> = "abcXdef".splitn(1, 'X').collect();
assert_eq!(v, ["abcXdef"]);

let v: Vec<&str> = "".splitn(1, 'X').collect();
assert_eq!(v, [""]);

A more complex pattern, using a closure:

let v: Vec<&str> = "abc1defXghi".splitn(2, |c| c == '1' || c == 'X').collect();
assert_eq!(v, ["abc", "defXghi"]);

pub fn rsplitn<P>(&self, n: usize, pat: P) -> RSplitN<'_, P>

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

Returns an iterator over substrings of this string slice, separated by a pattern, starting from the end of the string, restricted to returning at most n items.

If n substrings are returned, the last substring (the nth substring) will contain the remainder of the string.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Iterator behavior

The returned iterator will not be double ended, because it is not efficient to support.

For splitting from the front, the splitn method can be used.

Examples

Simple patterns:

let v: Vec<&str> = "Mary had a little lamb".rsplitn(3, ' ').collect();
assert_eq!(v, ["lamb", "little", "Mary had a"]);

let v: Vec<&str> = "lionXXtigerXleopard".rsplitn(3, 'X').collect();
assert_eq!(v, ["leopard", "tiger", "lionX"]);

let v: Vec<&str> = "lion::tiger::leopard".rsplitn(2, "::").collect();
assert_eq!(v, ["leopard", "lion::tiger"]);

A more complex pattern, using a closure:

let v: Vec<&str> = "abc1defXghi".rsplitn(2, |c| c == '1' || c == 'X').collect();
assert_eq!(v, ["ghi", "abc1def"]);

pub fn split_once<P>(&self, delimiter: P) -> Option<(&str, &str)>

where P: Pattern,

Splits the string on the first occurrence of the specified delimiter and returns prefix before delimiter and suffix after delimiter.

Examples

assert_eq!("cfg".split_once('='), None);
assert_eq!("cfg=".split_once('='), Some(("cfg", "")));
assert_eq!("cfg=foo".split_once('='), Some(("cfg", "foo")));
assert_eq!("cfg=foo=bar".split_once('='), Some(("cfg", "foo=bar")));

pub fn rsplit_once<P>(&self, delimiter: P) -> Option<(&str, &str)>

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

Splits the string on the last occurrence of the specified delimiter and returns prefix before delimiter and suffix after delimiter.

Examples

assert_eq!("cfg".rsplit_once('='), None);
assert_eq!("cfg=".rsplit_once('='), Some(("cfg", "")));
assert_eq!("cfg=foo".rsplit_once('='), Some(("cfg", "foo")));
assert_eq!("cfg=foo=bar".rsplit_once('='), Some(("cfg=foo", "bar")));

pub fn matches<P>(&self, pat: P) -> Matches<'_, P>

where P: Pattern,

Returns an iterator over the disjoint matches of a pattern within the given string slice.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Iterator behavior

The returned iterator will be a DoubleEndedIterator if the pattern allows a reverse search and forward/reverse search yields the same elements. This is true for, e.g., char, but not for &str.

If the pattern allows a reverse search but its results might differ from a forward search, the rmatches method can be used.

Examples

let v: Vec<&str> = "abcXXXabcYYYabc".matches("abc").collect();
assert_eq!(v, ["abc", "abc", "abc"]);

let v: Vec<&str> = "1abc2abc3".matches(char::is_numeric).collect();
assert_eq!(v, ["1", "2", "3"]);

pub fn rmatches<P>(&self, pat: P) -> RMatches<'_, P>

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

Returns an iterator over the disjoint matches of a pattern within this string slice, yielded in reverse order.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Iterator behavior

The returned iterator requires that the pattern supports a reverse search, and it will be a DoubleEndedIterator if a forward/reverse search yields the same elements.

For iterating from the front, the matches method can be used.

Examples

let v: Vec<&str> = "abcXXXabcYYYabc".rmatches("abc").collect();
assert_eq!(v, ["abc", "abc", "abc"]);

let v: Vec<&str> = "1abc2abc3".rmatches(char::is_numeric).collect();
assert_eq!(v, ["3", "2", "1"]);

pub fn match_indices<P>(&self, pat: P) -> MatchIndices<'_, P>

where P: Pattern,

Returns an iterator over the disjoint matches of a pattern within this string slice as well as the index that the match starts at.

For matches of pat within self that overlap, only the indices corresponding to the first match are returned.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Iterator behavior

The returned iterator will be a DoubleEndedIterator if the pattern allows a reverse search and forward/reverse search yields the same elements. This is true for, e.g., char, but not for &str.

If the pattern allows a reverse search but its results might differ from a forward search, the rmatch_indices method can be used.

Examples

let v: Vec<_> = "abcXXXabcYYYabc".match_indices("abc").collect();
assert_eq!(v, [(0, "abc"), (6, "abc"), (12, "abc")]);

let v: Vec<_> = "1abcabc2".match_indices("abc").collect();
assert_eq!(v, [(1, "abc"), (4, "abc")]);

let v: Vec<_> = "ababa".match_indices("aba").collect();
assert_eq!(v, [(0, "aba")]); // only the first `aba`

pub fn rmatch_indices<P>(&self, pat: P) -> RMatchIndices<'_, P>

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

Returns an iterator over the disjoint matches of a pattern within self, yielded in reverse order along with the index of the match.

For matches of pat within self that overlap, only the indices corresponding to the last match are returned.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Iterator behavior

The returned iterator requires that the pattern supports a reverse search, and it will be a DoubleEndedIterator if a forward/reverse search yields the same elements.

For iterating from the front, the match_indices method can be used.

Examples

let v: Vec<_> = "abcXXXabcYYYabc".rmatch_indices("abc").collect();
assert_eq!(v, [(12, "abc"), (6, "abc"), (0, "abc")]);

let v: Vec<_> = "1abcabc2".rmatch_indices("abc").collect();
assert_eq!(v, [(4, "abc"), (1, "abc")]);

let v: Vec<_> = "ababa".rmatch_indices("aba").collect();
assert_eq!(v, [(2, "aba")]); // only the last `aba`

pub fn trim(&self) -> &str

Returns a string slice with leading and trailing whitespace removed.

‘Whitespace’ is defined according to the terms of the Unicode Derived Core Property White_Space, which includes newlines.

Examples

let s = "\n Hello\tworld\t\n";

assert_eq!("Hello\tworld", s.trim());

pub fn trim_start(&self) -> &str

Returns a string slice with leading whitespace removed.

‘Whitespace’ is defined according to the terms of the Unicode Derived Core Property White_Space, which includes newlines.

Text directionality

A string is a sequence of bytes. start in this context means the first position of that byte string; for a left-to-right language like English or Russian, this will be left side, and for right-to-left languages like Arabic or Hebrew, this will be the right side.

Examples

Basic usage:

let s = "\n Hello\tworld\t\n";
assert_eq!("Hello\tworld\t\n", s.trim_start());

Directionality:

let s = "  English  ";
assert!(Some('E') == s.trim_start().chars().next());

let s = "  עברית  ";
assert!(Some('ע') == s.trim_start().chars().next());

pub fn trim_end(&self) -> &str

Returns a string slice with trailing whitespace removed.

‘Whitespace’ is defined according to the terms of the Unicode Derived Core Property White_Space, which includes newlines.

Text directionality

A string is a sequence of bytes. end in this context means the last position of that byte string; for a left-to-right language like English or Russian, this will be right side, and for right-to-left languages like Arabic or Hebrew, this will be the left side.

Examples

Basic usage:

let s = "\n Hello\tworld\t\n";
assert_eq!("\n Hello\tworld", s.trim_end());

Directionality:

let s = "  English  ";
assert!(Some('h') == s.trim_end().chars().rev().next());

let s = "  עברית  ";
assert!(Some('ת') == s.trim_end().chars().rev().next());

pub fn trim_left(&self) -> &str

👎Deprecated since 1.33.0:

superseded by trim_start

Returns a string slice with leading whitespace removed.

‘Whitespace’ is defined according to the terms of the Unicode Derived Core Property White_Space.

Text directionality

A string is a sequence of bytes. ‘Left’ in this context means the first position of that byte string; for a language like Arabic or Hebrew which are ‘right to left’ rather than ‘left to right’, this will be the right side, not the left.

Examples

Basic usage:

let s = " Hello\tworld\t";

assert_eq!("Hello\tworld\t", s.trim_left());

Directionality:

let s = "  English";
assert!(Some('E') == s.trim_left().chars().next());

let s = "  עברית";
assert!(Some('ע') == s.trim_left().chars().next());

pub fn trim_right(&self) -> &str

👎Deprecated since 1.33.0:

superseded by trim_end

Returns a string slice with trailing whitespace removed.

‘Whitespace’ is defined according to the terms of the Unicode Derived Core Property White_Space.

Text directionality

A string is a sequence of bytes. ‘Right’ in this context means the last position of that byte string; for a language like Arabic or Hebrew which are ‘right to left’ rather than ‘left to right’, this will be the left side, not the right.

Examples

Basic usage:

let s = " Hello\tworld\t";

assert_eq!(" Hello\tworld", s.trim_right());

Directionality:

let s = "English  ";
assert!(Some('h') == s.trim_right().chars().rev().next());

let s = "עברית  ";
assert!(Some('ת') == s.trim_right().chars().rev().next());

pub fn trim_matches<P>(&self, pat: P) -> &str

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> DoubleEndedSearcher<'a>,

Returns a string slice with all prefixes and suffixes that match a pattern repeatedly removed.

The pattern can be a char, a slice of chars, or a function or closure that determines if a character matches.

Examples

Simple patterns:

assert_eq!("11foo1bar11".trim_matches('1'), "foo1bar");
assert_eq!("123foo1bar123".trim_matches(char::is_numeric), "foo1bar");

let x: &[_] = &['1', '2'];
assert_eq!("12foo1bar12".trim_matches(x), "foo1bar");

A more complex pattern, using a closure:

assert_eq!("1foo1barXX".trim_matches(|c| c == '1' || c == 'X'), "foo1bar");

pub fn trim_start_matches<P>(&self, pat: P) -> &str

where P: Pattern,

Returns a string slice with all prefixes that match a pattern repeatedly removed.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Text directionality

A string is a sequence of bytes. start in this context means the first position of that byte string; for a left-to-right language like English or Russian, this will be left side, and for right-to-left languages like Arabic or Hebrew, this will be the right side.

Examples

assert_eq!("11foo1bar11".trim_start_matches('1'), "foo1bar11");
assert_eq!("123foo1bar123".trim_start_matches(char::is_numeric), "foo1bar123");

let x: &[_] = &['1', '2'];
assert_eq!("12foo1bar12".trim_start_matches(x), "foo1bar12");

pub fn strip_prefix<P>(&self, prefix: P) -> Option<&str>

where P: Pattern,

Returns a string slice with the prefix removed.

If the string starts with the pattern prefix, returns the substring after the prefix, wrapped in Some. Unlike trim_start_matches, this method removes the prefix exactly once.

If the string does not start with prefix, returns None.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Examples

assert_eq!("foo:bar".strip_prefix("foo:"), Some("bar"));
assert_eq!("foo:bar".strip_prefix("bar"), None);
assert_eq!("foofoo".strip_prefix("foo"), Some("foo"));

pub fn strip_suffix<P>(&self, suffix: P) -> Option<&str>

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

Returns a string slice with the suffix removed.

If the string ends with the pattern suffix, returns the substring before the suffix, wrapped in Some. Unlike trim_end_matches, this method removes the suffix exactly once.

If the string does not end with suffix, returns None.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Examples

assert_eq!("bar:foo".strip_suffix(":foo"), Some("bar"));
assert_eq!("bar:foo".strip_suffix("bar"), None);
assert_eq!("foofoo".strip_suffix("foo"), Some("foo"));

pub fn strip_circumfix<P, S>(&self, prefix: P, suffix: S) -> Option<&str>

where P: Pattern, S: Pattern, <S as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

Returns a string slice with the prefix and suffix removed.

If the string starts with the pattern prefix and ends with the pattern suffix, and the prefix and suffix don’t overlap, returns the substring after the prefix and before the suffix, wrapped in Some. Unlike trim_start_matches and trim_end_matches, this method removes both the prefix and suffix exactly once.

If the string does not start with prefix, does not end with suffix, or the prefix and suffix overlap in the string, returns None.

Each pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Examples

assert_eq!("bar:hello:foo".strip_circumfix("bar:", ":foo"), Some("hello"));
assert_eq!("bar:foo".strip_circumfix("foo", "foo"), None);
assert_eq!("foo:bar;".strip_circumfix("foo:", ';'), Some("bar"));
assert_eq!("foo:bar:baz".strip_circumfix("foo:bar:", ":bar:baz"), None);

pub fn trim_prefix<P>(&self, prefix: P) -> &str

where P: Pattern,

🔬This is a nightly-only experimental API. (trim_prefix_suffix)

Returns a string slice with the optional prefix removed.

If the string starts with the pattern prefix, returns the substring after the prefix. Unlike strip_prefix, this method always returns &str for easy method chaining, instead of returning Option<&str>.

If the string does not start with prefix, returns the original string unchanged.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Examples

#![feature(trim_prefix_suffix)]

// Prefix present - removes it
assert_eq!("foo:bar".trim_prefix("foo:"), "bar");
assert_eq!("foofoo".trim_prefix("foo"), "foo");

// Prefix absent - returns original string
assert_eq!("foo:bar".trim_prefix("bar"), "foo:bar");

// Method chaining example
assert_eq!("<https://example.com/>".trim_prefix('<').trim_suffix('>'), "https://example.com/");

pub fn trim_suffix<P>(&self, suffix: P) -> &str

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

🔬This is a nightly-only experimental API. (trim_prefix_suffix)

Returns a string slice with the optional suffix removed.

If the string ends with the pattern suffix, returns the substring before the suffix. Unlike strip_suffix, this method always returns &str for easy method chaining, instead of returning Option<&str>.

If the string does not end with suffix, returns the original string unchanged.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Examples

#![feature(trim_prefix_suffix)]

// Suffix present - removes it
assert_eq!("bar:foo".trim_suffix(":foo"), "bar");
assert_eq!("foofoo".trim_suffix("foo"), "foo");

// Suffix absent - returns original string
assert_eq!("bar:foo".trim_suffix("bar"), "bar:foo");

// Method chaining example
assert_eq!("<https://example.com/>".trim_prefix('<').trim_suffix('>'), "https://example.com/");

pub fn trim_end_matches<P>(&self, pat: P) -> &str

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

Returns a string slice with all suffixes that match a pattern repeatedly removed.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Text directionality

A string is a sequence of bytes. end in this context means the last position of that byte string; for a left-to-right language like English or Russian, this will be right side, and for right-to-left languages like Arabic or Hebrew, this will be the left side.

Examples

Simple patterns:

assert_eq!("11foo1bar11".trim_end_matches('1'), "11foo1bar");
assert_eq!("123foo1bar123".trim_end_matches(char::is_numeric), "123foo1bar");

let x: &[_] = &['1', '2'];
assert_eq!("12foo1bar12".trim_end_matches(x), "12foo1bar");

A more complex pattern, using a closure:

assert_eq!("1fooX".trim_end_matches(|c| c == '1' || c == 'X'), "1foo");

pub fn trim_left_matches<P>(&self, pat: P) -> &str

where P: Pattern,

👎Deprecated since 1.33.0:

superseded by trim_start_matches

Returns a string slice with all prefixes that match a pattern repeatedly removed.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Text directionality

A string is a sequence of bytes. ‘Left’ in this context means the first position of that byte string; for a language like Arabic or Hebrew which are ‘right to left’ rather than ‘left to right’, this will be the right side, not the left.

Examples

assert_eq!("11foo1bar11".trim_left_matches('1'), "foo1bar11");
assert_eq!("123foo1bar123".trim_left_matches(char::is_numeric), "foo1bar123");

let x: &[_] = &['1', '2'];
assert_eq!("12foo1bar12".trim_left_matches(x), "foo1bar12");

pub fn trim_right_matches<P>(&self, pat: P) -> &str

where P: Pattern, <P as Pattern>::Searcher<'a>: for<'a> ReverseSearcher<'a>,

👎Deprecated since 1.33.0:

superseded by trim_end_matches

Returns a string slice with all suffixes that match a pattern repeatedly removed.

The pattern can be a &str, char, a slice of chars, or a function or closure that determines if a character matches.

Text directionality

A string is a sequence of bytes. ‘Right’ in this context means the last position of that byte string; for a language like Arabic or Hebrew which are ‘right to left’ rather than ‘left to right’, this will be the left side, not the right.

Examples

Simple patterns:

assert_eq!("11foo1bar11".trim_right_matches('1'), "11foo1bar");
assert_eq!("123foo1bar123".trim_right_matches(char::is_numeric), "123foo1bar");

let x: &[_] = &['1', '2'];
assert_eq!("12foo1bar12".trim_right_matches(x), "12foo1bar");

A more complex pattern, using a closure:

assert_eq!("1fooX".trim_right_matches(|c| c == '1' || c == 'X'), "1foo");

pub fn parse<F>(&self) -> Result<F, <F as FromStr>::Err>

where F: FromStr,

Parses this string slice into another type.

Because parse is so general, it can cause problems with type inference. As such, parse is one of the few times you’ll see the syntax affectionately known as the ‘turbofish’: ::<>. This helps the inference algorithm understand specifically which type you’re trying to parse into.

parse can parse into any type that implements the FromStr trait.

Errors

Will return Err if it’s not possible to parse this string slice into the desired type.

Examples

Basic usage:

let four: u32 = "4".parse().unwrap();

assert_eq!(4, four);

Using the ‘turbofish’ instead of annotating four:

let four = "4".parse::<u32>();

assert_eq!(Ok(4), four);

Failing to parse:

let nope = "j".parse::<u32>();

assert!(nope.is_err());

pub fn is_ascii(&self) -> bool

Checks if all characters in this string are within the ASCII range.

An empty string returns true.

Examples

let ascii = "hello!\n";
let non_ascii = "Grüße, Jürgen ❤";

assert!(ascii.is_ascii());
assert!(!non_ascii.is_ascii());

pub fn as_ascii(&self) -> Option<&[AsciiChar]>

🔬This is a nightly-only experimental API. (ascii_char)

If this string slice is_ascii, returns it as a slice of ASCII characters, otherwise returns None.

pub unsafe fn as_ascii_unchecked(&self) -> &[AsciiChar]

🔬This is a nightly-only experimental API. (ascii_char)

Converts this string slice into a slice of ASCII characters, without checking whether they are valid.

Safety

Every character in this string must be ASCII, or else this is UB.

pub fn eq_ignore_ascii_case(&self, other: &str) -> bool

Checks that two strings are an ASCII case-insensitive match.

Same as to_ascii_lowercase(a) == to_ascii_lowercase(b), but without allocating and copying temporaries.

For Unicode-aware case-insensitive matching, consider str::eq_ignore_case_unnormalized.

Examples

assert!("Ferris".eq_ignore_ascii_case("FERRIS"));
assert!("Ferrös".eq_ignore_ascii_case("FERRöS"));
assert!(!"Ferrös".eq_ignore_ascii_case("FERRÖS"));

pub fn eq_ignore_case_unnormalized(&self, other: &str) -> bool

🔬This is a nightly-only experimental API. (casefold)

Checks that two strings are a caseless match, according to Definition 144 in Chapter 3 of the Unicode Standard.

Same as a.to_casefold_unnormalized() == b.to_casefold_unnormalized(), but without allocating. See that method’s documentation, as well as char::to_casefold_unnormalized(), for more information about case folding.

No normalization (e.g. NFC) is performed, so visually and semantically identical strings might still compare unequal. For example, "Å" (U+00C5 LATIN CAPITAL LETTER A WITH RING ABOVE) is considered distinct from "Å" (A followed by U+030A COMBINING RING ABOVE), even though Unicode considers them canonically equivalent.

In addition, this method is independent of language/locale, so the special behavior of I/ı/İ/i in Turkish and Azeri is not handled.

Examples

#![feature(casefold)]
assert!("Ferris".eq_ignore_case_unnormalized("FERRIS"));
assert!("Ferrös".eq_ignore_case_unnormalized("FERRÖS"));
assert!("ẞ".eq_ignore_case_unnormalized("ss"));

No NFC normalization is performed:

#![feature(casefold)]
// These two strings are visually and semantically identical...
let comp = "Å";
let decomp = "Å";

// ... but not codepoint-for-codepoint equal.
assert_eq!(comp, "\u{C5}");
assert_eq!(decomp, "A\u{030A}");

// Their case-foldings are likewise unequal:
assert!(!comp.eq_ignore_case_unnormalized(decomp));

pub fn make_ascii_uppercase(&mut self)

Converts this string to its ASCII upper case equivalent in-place.

ASCII letters ‘a’ to ‘z’ are mapped to ‘A’ to ‘Z’, but non-ASCII letters are unchanged.

To return a new uppercased value without modifying the existing one, use to_ascii_uppercase().

Examples

let mut s = String::from("Grüße, Jürgen ❤");

s.make_ascii_uppercase();

assert_eq!("GRüßE, JüRGEN ❤", s);

pub fn make_ascii_lowercase(&mut self)

Converts this string to its ASCII lower case equivalent in-place.

ASCII letters ‘A’ to ‘Z’ are mapped to ‘a’ to ‘z’, but non-ASCII letters are unchanged.

To return a new lowercased value without modifying the existing one, use to_ascii_lowercase().

Examples

let mut s = String::from("GRÜßE, JÜRGEN ❤");

s.make_ascii_lowercase();

assert_eq!("grÜße, jÜrgen ❤", s);

pub fn copy_from_str(&mut self, src: &str)

🔬This is a nightly-only experimental API. (str_copy_from_str)

Copies the string from src into self, using a memcpy.

The length of src must be the same as self.

Panics

This function will panic if the two strings have different lengths.

Examples

#![feature(str_copy_from_str)]
let src = "Saludos";
let mut dst = String::from("Grüße, Jürgen");

// Because the strings have to be the same length,
// we slice the destination slice from sixteen bytes
// to seven. It will panic if we don't do this.
dst[..7].copy_from_str(src);

assert_eq!(src, "Saludos");
assert_eq!(dst, "Saludos, Jürgen");

Rust enforces that there can only be one mutable reference with no immutable references to a particular piece of data in a particular scope. Because of this, attempting to use copy_from_str on a single string will result in a compile failure:

#![feature(str_copy_from_str)]
let mut string = String::from("Abcde");

string[..2].copy_from_str(&string[3..]); // compile fail!

To work around this, we can use split_at_mut to create two distinct sub-slices from a string:

#![feature(str_copy_from_str)]
let mut string = String::from("Abcde");

{
    let (left, right) = string.split_at_mut(2);
    left.copy_from_str(&right[1..]);
}

assert_eq!(string, "decde");

pub fn trim_ascii_start(&self) -> &str

Returns a string slice with leading ASCII whitespace removed.

‘Whitespace’ refers to the definition used by u8::is_ascii_whitespace. Importantly, this definition excludes the U+000B code point even though it has the Unicode White_Space property and is removed by str::trim_start.

Examples

assert_eq!(" \t \u{3000}hello world\n".trim_ascii_start(), "\u{3000}hello world\n");
assert_eq!("  ".trim_ascii_start(), "");
assert_eq!("".trim_ascii_start(), "");

pub fn trim_ascii_end(&self) -> &str

Returns a string slice with trailing ASCII whitespace removed.

‘Whitespace’ refers to the definition used by u8::is_ascii_whitespace. Importantly, this definition excludes the U+000B code point even though it has the Unicode White_Space property and is removed by str::trim_end.

Examples

assert_eq!("\r hello world\u{3000}\n ".trim_ascii_end(), "\r hello world\u{3000}");
assert_eq!("  ".trim_ascii_end(), "");
assert_eq!("".trim_ascii_end(), "");

pub fn trim_ascii(&self) -> &str

Returns a string slice with leading and trailing ASCII whitespace removed.

‘Whitespace’ refers to the definition used by u8::is_ascii_whitespace. Importantly, this definition excludes the U+000B code point even though it has the Unicode White_Space property and is removed by str::trim.

Examples

assert_eq!("\r hello world\n ".trim_ascii(), "hello world");
assert_eq!("  ".trim_ascii(), "");
assert_eq!("".trim_ascii(), "");

pub fn escape_debug(&self) -> EscapeDebug<'_>

Returns an iterator that escapes each char in self with char::escape_debug.

Note: only extended grapheme codepoints that begin the string will be escaped.

Examples

As an iterator:

for c in "❤\n!".escape_debug() {
    print!("{c}");
}
println!();

Using println! directly:

println!("{}", "❤\n!".escape_debug());

Both are equivalent to:

println!("❤\\n!");

Using to_string:

assert_eq!("❤\n!".escape_debug().to_string(), "❤\\n!");

pub fn escape_default(&self) -> EscapeDefault<'_>

Returns an iterator that escapes each char in self with char::escape_default.

Examples

As an iterator:

for c in "❤\n!".escape_default() {
    print!("{c}");
}
println!();

Using println! directly:

println!("{}", "❤\n!".escape_default());

Both are equivalent to:

println!("\\u{{2764}}\\n!");

Using to_string:

assert_eq!("❤\n!".escape_default().to_string(), "\\u{2764}\\n!");

pub fn escape_unicode(&self) -> EscapeUnicode<'_>

Returns an iterator that escapes each char in self with char::escape_unicode.

Examples

As an iterator:

for c in "❤\n!".escape_unicode() {
    print!("{c}");
}
println!();

Using println! directly:

println!("{}", "❤\n!".escape_unicode());

Both are equivalent to:

println!("\\u{{2764}}\\u{{a}}\\u{{21}}");

Using to_string:

assert_eq!("❤\n!".escape_unicode().to_string(), "\\u{2764}\\u{a}\\u{21}");

pub fn substr_range(&self, substr: &str) -> Option<Range<usize>>

Returns the range that a substring points to.

Returns None if substr does not point within self.

Unlike str::find, this does not search through the string. Instead, it uses pointer arithmetic to find where in the string substr is derived from.

This is useful for extending str::split and similar methods.

Note that this method may return false positives (typically either Some(0..0) or Some(self.len()..self.len())) if substr is a zero-length str that points at the beginning or end of another, independent, str.

Examples

use core::range::Range;

let data = "a, b, b, a";
let mut iter = data.split(", ").map(|s| data.substr_range(s).unwrap());

assert_eq!(iter.next(), Some(Range { start: 0, end: 1 }));
assert_eq!(iter.next(), Some(Range { start: 3, end: 4 }));
assert_eq!(iter.next(), Some(Range { start: 6, end: 7 }));
assert_eq!(iter.next(), Some(Range { start: 9, end: 10 }));

pub fn as_str(&self) -> &str

🔬This is a nightly-only experimental API. (str_as_str)

Returns the same string as a string slice &str.

This method is redundant when used directly on &str, but it helps dereferencing other string-like types to string slices, for example references to Box<str> or Arc<str>.

pub fn replace<P>(&self, from: P, to: &str) -> String

where P: Pattern,

Available on non-no_global_oom_handling only.

Replaces all matches of a pattern with another string.

replace creates a new String, and copies the data from this string slice into it. While doing so, it attempts to find matches of a pattern. If it finds any, it replaces them with the replacement string slice.

Examples

let s = "this is old";

assert_eq!("this is new", s.replace("old", "new"));
assert_eq!("than an old", s.replace("is", "an"));

When the pattern doesn’t match, it returns this string slice as String:

let s = "this is old";
assert_eq!(s, s.replace("cookie monster", "little lamb"));

pub fn replacen<P>(&self, pat: P, to: &str, count: usize) -> String

where P: Pattern,

Available on non-no_global_oom_handling only.

Replaces first N matches of a pattern with another string.

replacen creates a new String, and copies the data from this string slice into it. While doing so, it attempts to find matches of a pattern. If it finds any, it replaces them with the replacement string slice at most count times.

Examples

let s = "foo foo 123 foo";
assert_eq!("new new 123 foo", s.replacen("foo", "new", 2));
assert_eq!("faa fao 123 foo", s.replacen('o', "a", 3));
assert_eq!("foo foo new23 foo", s.replacen(char::is_numeric, "new", 1));

When the pattern doesn’t match, it returns this string slice as String:

let s = "this is old";
assert_eq!(s, s.replacen("cookie monster", "little lamb", 10));

pub fn to_lowercase(&self) -> String

Available on non-no_global_oom_handling only.

Returns the lowercase equivalent of this string slice, as a new String.

‘Lowercase’ is defined according to the terms of Chapter 3 (Conformance) of the Unicode standard.

Since some characters can expand into multiple characters when changing the case, this function returns a String instead of modifying the parameter in-place.

Unlike char::to_lowercase(), this method fully handles the context-dependent casing of Greek sigma. However, like that method, it does not handle locale-specific casing, like Turkish and Azeri I/ı/İ/i. See its documentation for more information.

Examples

Basic usage:

let s = "HELLO WORLD";

assert_eq!("hello world", s.to_lowercase());

Tricky examples, with sigma:

let sigma = "Σ";

assert_eq!("σ", sigma.to_lowercase());

// but at the end of a word, it's ς, not σ:
let odysseus = "ὈΔΥΣΣΕΎΣ";

assert_eq!("ὀδυσσεύς", odysseus.to_lowercase());

let odysseus_king_of_ithaca = "Ο ΟΔΥΣΣΈΑΣ ΒΑΣΙΛΙΆΣ ΤΗΣ ΙΘΆΚΗΣ";

assert_eq!("ο οδυσσέας βασιλιάς της ιθάκης", odysseus_king_of_ithaca.to_lowercase());

Languages without case are not changed:

let new_year = "农历新年";

assert_eq!(new_year, new_year.to_lowercase());

Examples found in repository

examples/testbed/ui.rs (line 102)

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let mut isit = Self::default();
        while s.to_lowercase() != format!("{isit:?}").to_lowercase() {
            isit = isit.next();
            if isit == Self::default() {
                return Err(format!("Invalid Scene name: {s}"));
            }
        }
        Ok(isit)
    }

examples/testbed/2d.rs (line 71)

    fn from_str(s: &str) -> std::result::Result<Self, Self::Err> {
        let mut isit = Self::default();
        while s.to_lowercase() != format!("{isit:?}").to_lowercase() {
            isit = isit.next();
            if isit == Self::default() {
                return Err(format!("Invalid Scene name: {s}"));
            }
        }
        Ok(isit)
    }

examples/testbed/3d.rs (line 82)

    fn from_str(s: &str) -> std::result::Result<Self, Self::Err> {
        let mut isit = Self::default();
        while s.to_lowercase() != format!("{isit:?}").to_lowercase() {
            isit = isit.next();
            if isit == Self::default() {
                return Err(format!("Invalid Scene name: {s}"));
            }
        }
        Ok(isit)
    }

pub fn word_to_titlecase(&self) -> String

🔬This is a nightly-only experimental API. (titlecase)

Available on non-no_global_oom_handling only.

Returns the titlecase equivalent of this string slice, which is assumed to represent a single word, as a new String.

Essentially, this consists of uppercasing the first cased letter (with char::to_titlecase()), and lowercasing everything that follows.

‘Titlecase’ is defined according to the terms of Chapter 3 (Conformance) of the Unicode standard.

Since some characters can expand into multiple characters when changing the case, this function returns a String instead of modifying the parameter in-place.

Unlike char::to_lowercase(), this method fully handles the context-dependent casing of Greek sigma. However, like that method, it does not handle locale-specific casing, like Turkish and Azeri I/ı/İ/i. See its documentation for more information.

This method does not perform any kind of word segmentation.

Examples

Basic usage:

#![feature(titlecase)]
let s = "HELLO WORLD";

assert_eq!("Hello world", s.word_to_titlecase());

The first cased letter is uppercased:

#![feature(titlecase)]
let the_night_before_christmas = "'twas";

assert_eq!("'Twas", the_night_before_christmas.word_to_titlecase());

Languages without case are not changed:

#![feature(titlecase)]
let new_year = "农历新年";

assert_eq!(new_year, new_year.word_to_titlecase());

Georgian uppercase (“Mtavruli”) letters are not used in titlecase:

#![feature(titlecase)]
let georgian = "ერთობაშია";

assert_eq!(georgian, georgian.word_to_titlecase());

No word segmentation is performed, so only the first cased letter in the whole string gets uppercased:

#![feature(titlecase)]
let blazingly_fast = "ferris and I";

assert_eq!("Ferris and i", blazingly_fast.word_to_titlecase());

Tricky examples, with sigma:

#![feature(titlecase)]
let odysseus = "ὈΔΥΣΣΕΎΣ";

assert_eq!("Ὀδυσσεύς", odysseus.word_to_titlecase());

let odysseus_king_of_ithaca = "Ο ΟΔΥΣΣΈΑΣ ΒΑΣΙΛΙΆΣ ΤΗΣ ΙΘΆΚΗΣ";

assert_eq!("Ο οδυσσέας βασιλιάς της ιθάκης", odysseus_king_of_ithaca.word_to_titlecase());

pub fn to_uppercase(&self) -> String

Available on non-no_global_oom_handling only.

Returns the uppercase equivalent of this string slice, as a new String.

‘Uppercase’ is defined according to the terms of Chapter 3 (Conformance) of the Unicode standard.

Since some characters can expand into multiple characters when changing the case, this function returns a String instead of modifying the parameter in-place.

Like char::to_uppercase() this method does not handle language-specific casing, like Turkish and Azeri I/ı/İ/i. See that method’s documentation for more information.

Examples

Basic usage:

let s = "hello world";

assert_eq!("HELLO WORLD", s.to_uppercase());

Scripts without case are not changed:

let new_year = "农历新年";

assert_eq!(new_year, new_year.to_uppercase());

One character can become multiple:

let s = "tschüß";

assert_eq!("TSCHÜSS", s.to_uppercase());

pub fn to_casefold_unnormalized(&self) -> String

🔬This is a nightly-only experimental API. (casefold)

Available on non-no_global_oom_handling only.

Returns the case-folded equivalent of this string slice, as a new String.

Case folding is a transformation, mostly matching lowercase, that is meant to be used for case-insensitive string comparisons. Case-folded strings should not usually be exposed directly to users.

For the precise specification of case folding, see Chapter 3 (Conformance) of the Unicode standard.

Since some characters can expand into multiple characters when case folding, this function returns a String instead of modifying the parameter in-place.

No normalization (e.g. NFC) is performed, so visually and semantically identical strings might still casefold differently. For example, "Å" (U+00C5 LATIN CAPITAL LETTER A WITH RING ABOVE) is considered distinct from "Å" (A followed by U+030A COMBINING RING ABOVE), even though Unicode considers them canonically equivalent.

Like char::to_casefold_unnormalized() this method does not handle language-specific casing, like Turkish and Azeri I/ı/İ/i. See that method’s documentation for more information.

Examples

Basic usage:

#![feature(casefold)]
let s0 = "HELLO";
let s1 = "Hello";

assert_eq!(s0.to_casefold_unnormalized(), s1.to_casefold_unnormalized());
assert_eq!(s0.to_casefold_unnormalized(), "hello")

Scripts without case are not changed:

#![feature(casefold)]
let new_year = "农历新年";

assert_eq!(new_year, new_year.to_casefold_unnormalized());

One character can become multiple:

#![feature(casefold)]
let s0 = "TSCHÜẞ";
let s1 = "TSCHÜSS";
let s2 = "tschüß";

assert_eq!(s0.to_casefold_unnormalized(), s1.to_casefold_unnormalized());
assert_eq!(s0.to_casefold_unnormalized(), s2.to_casefold_unnormalized());
assert_eq!(s0.to_casefold_unnormalized(), "tschüss");

No NFC normalization is performed:

#![feature(casefold)]
// These two strings are visually and semantically identical...
let comp = "Å";
let decomp = "Å";

// ... but not codepoint-for-codepoint equal.
assert_eq!(comp, "\u{C5}");
assert_eq!(decomp, "A\u{030A}");

// Their case-foldings are likewise unequal:
assert_eq!(comp.to_casefold_unnormalized(), "\u{E5}");
assert_eq!(decomp.to_casefold_unnormalized(), "a\u{030A}");

pub fn repeat(&self, n: usize) -> String

Available on non-no_global_oom_handling only.

Creates a new String by repeating a string n times.

Panics

This function will panic if the capacity would overflow.

Examples

Basic usage:

assert_eq!("abc".repeat(4), String::from("abcabcabcabc"));

A panic upon overflow:

// this will panic at runtime
let huge = "0123456789abcdef".repeat(usize::MAX);

Examples found in repository

examples/stress_tests/many_glyphs.rs (line 68)

fn setup(mut commands: Commands, args: Res<Args>) {
    warn!(include_str!("warning_string.txt"));

    commands.spawn(Camera2d);
    let text_string = "0123456789".repeat(10_000);
    let text_font = TextFont {
        font_size: FontSize::Px(4.),
        ..Default::default()
    };
    let text_block = TextLayout {
        justify: Justify::Left,
        linebreak: LineBreak::AnyCharacter,
    };

    if !args.no_ui {
        commands
            .spawn(Node {
                width: percent(100),
                align_items: AlignItems::Center,
                justify_content: JustifyContent::Center,
                ..default()
            })
            .with_children(|commands| {
                commands
                    .spawn(Node {
                        width: px(1000),
                        ..Default::default()
                    })
                    .with_child((Text(text_string.clone()), text_font.clone(), text_block));
            });
    }

    if !args.no_text2d {
        commands.spawn((
            Text2d::new(text_string),
            text_font.clone(),
            TextColor(RED.into()),
            bevy::sprite::Anchor::CENTER,
            TextBounds::new_horizontal(1000.),
            text_block,
        ));
    }
}

examples/stress_tests/text_pipeline.rs (line 42)

fn spawn(mut commands: Commands, asset_server: Res<AssetServer>) {
    warn!(include_str!("warning_string.txt"));

    commands.spawn(Camera2d);

    let make_spans = |i| {
        [
            (
                TextSpan("text".repeat(i)),
                TextFont {
                    font: asset_server.load("fonts/FiraMono-Medium.ttf").into(),
                    font_size: FontSize::Px((4 + i % 10) as f32),
                    ..Default::default()
                },
                TextColor(BLUE.into()),
            ),
            (
                TextSpan("pipeline".repeat(i)),
                TextFont {
                    font: asset_server.load("fonts/FiraSans-Bold.ttf").into(),
                    font_size: FontSize::Px((4 + i % 11) as f32),
                    ..default()
                },
                TextColor(YELLOW.into()),
            ),
        ]
    };

    let spans = (1..50).flat_map(|i| make_spans(i).into_iter());

    commands
        .spawn((
            Text2d::default(),
            TextLayout {
                justify: Justify::Center,
                linebreak: LineBreak::AnyCharacter,
            },
            TextBounds::default(),
        ))
        .with_children(|p| {
            for span in spans {
                p.spawn(span);
            }
        });
}

pub fn to_ascii_uppercase(&self) -> String

Available on non-no_global_oom_handling only.

Returns a copy of this string where each character is mapped to its ASCII upper case equivalent.

ASCII letters ‘a’ to ‘z’ are mapped to ‘A’ to ‘Z’, but non-ASCII letters are unchanged.

To uppercase the value in-place, use make_ascii_uppercase.

To uppercase ASCII characters in addition to non-ASCII characters, use to_uppercase.

Examples

let s = "Grüße, Jürgen ❤";

assert_eq!("GRüßE, JüRGEN ❤", s.to_ascii_uppercase());

pub fn to_ascii_lowercase(&self) -> String

Available on non-no_global_oom_handling only.

Returns a copy of this string where each character is mapped to its ASCII lower case equivalent.

ASCII letters ‘A’ to ‘Z’ are mapped to ‘a’ to ‘z’, but non-ASCII letters are unchanged.

To lowercase the value in-place, use make_ascii_lowercase.

To lowercase ASCII characters in addition to non-ASCII characters, use to_lowercase.

Examples

let s = "Grüße, Jürgen ❤";

assert_eq!("grüße, jürgen ❤", s.to_ascii_lowercase());

Trait Implementations

impl Clone for Text

fn clone(&self) -> Text

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Component for Text

where Text: Send + Sync + 'static,

Required Components: Node, TextLayout, TextFont, TextColor, LineHeight, LetterSpacing, TextNodeFlags, ContentSize, FontHinting.

A component’s Required Components are inserted whenever it is inserted. Note that this will also insert the required components of the required components, recursively, in depth-first order.

const STORAGE_TYPE: StorageType = bevy_ecs::component::StorageType::Table

A constant indicating the storage type used for this component.

type Mutability = Mutable

A marker type to assist Bevy with determining if this component is mutable, or immutable. Mutable components will have Component<Mutability = Mutable>, while immutable components will instead have Component<Mutability = Immutable>.

fn register_required_components( _requiree: ComponentId, required_components: &mut RequiredComponentsRegistrator<'_, '_>, )

Registers required components.

fn clone_behavior() -> ComponentCloneBehavior

Called when registering this component, allowing to override clone function (or disable cloning altogether) for this component.

fn relationship_accessor() -> Option<ComponentRelationshipAccessor<Text>>

Returns ComponentRelationshipAccessor required for working with relationships in dynamic contexts.

fn on_add() -> Option<for<'w> fn(DeferredWorld<'w>, HookContext)>

Gets the on_add ComponentHook for this Component if one is defined.

fn on_insert() -> Option<for<'w> fn(DeferredWorld<'w>, HookContext)>

Gets the on_insert ComponentHook for this Component if one is defined.

fn on_discard() -> Option<for<'w> fn(DeferredWorld<'w>, HookContext)>

Gets the on_discard ComponentHook for this Component if one is defined.

fn on_remove() -> Option<for<'w> fn(DeferredWorld<'w>, HookContext)>

Gets the on_remove ComponentHook for this Component if one is defined.

fn on_despawn() -> Option<for<'w> fn(DeferredWorld<'w>, HookContext)>

Gets the on_despawn ComponentHook for this Component if one is defined.

fn map_entities<E>(_this: &mut Self, _mapper: &mut E)

where E: EntityMapper,

Maps the entities on this component using the given EntityMapper. This is used to remap entities in contexts like scenes and entity cloning. When deriving Component, this is populated by annotating fields containing entities with #[entities]

impl Debug for Text

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for Text

fn default() -> Text

Returns the “default value” for a type.

impl Deref for Text

type Target = String

The resulting type after dereferencing.

fn deref(&self) -> &<Text as Deref>::Target

Dereferences the value.

impl DerefMut for Text

fn deref_mut(&mut self) -> &mut <Text as Deref>::Target

Mutably dereferences the value.

impl From<&str> for Text

fn from(value: &str) -> Text

Converts to this type from the input type.

impl From<String> for Text

fn from(value: String) -> Text

Converts to this type from the input type.

impl FromArg for Text

type This<'from_arg> = Text

The type to convert into.

fn from_arg(arg: Arg<'_>) -> Result<<Text as FromArg>::This<'_>, ArgError>

Creates an item from an argument.

impl FromReflect for Text

fn from_reflect(reflect: &(dyn PartialReflect + 'static)) -> Option<Text>

Constructs a concrete instance of Self from a reflected value.

fn take_from_reflect( reflect: Box<dyn PartialReflect>, ) -> Result<Self, Box<dyn PartialReflect>>

Attempts to downcast the given value to Self using, constructing the value using from_reflect if that fails.

impl GetOwnership for Text

fn ownership() -> Ownership

Returns the ownership of Self.

impl GetTypeRegistration for Text

fn get_type_registration() -> TypeRegistration

Returns the default TypeRegistration for this type.

fn register_type_dependencies(registry: &mut TypeRegistry)

Registers other types needed by this type.

impl IntoReturn for Text

fn into_return<'into_return>(self) -> Return<'into_return>

where Text: 'into_return,

Converts Self into a Return value.

impl PartialEq for Text

fn eq(&self, other: &Text) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialReflect for Text

fn get_represented_type_info(&self) -> Option<&'static TypeInfo>

Returns the TypeInfo of the type represented by this value.

fn try_apply( &mut self, value: &(dyn PartialReflect + 'static), ) -> Result<(), ApplyError>

Tries to apply a reflected value to this value.

fn reflect_kind(&self) -> ReflectKind

Returns a zero-sized enumeration of “kinds” of type.

fn reflect_ref(&self) -> ReflectRef<'_>

Returns an immutable enumeration of “kinds” of type.

fn reflect_mut(&mut self) -> ReflectMut<'_>

Returns a mutable enumeration of “kinds” of type.

fn reflect_owned(self: Box<Text>) -> ReflectOwned

Returns an owned enumeration of “kinds” of type.

fn try_into_reflect( self: Box<Text>, ) -> Result<Box<dyn Reflect>, Box<dyn PartialReflect>>

Attempts to cast this type to a boxed, fully-reflected value.

fn try_as_reflect(&self) -> Option<&(dyn Reflect + 'static)>

Attempts to cast this type to a fully-reflected value.

fn try_as_reflect_mut(&mut self) -> Option<&mut (dyn Reflect + 'static)>

Attempts to cast this type to a mutable, fully-reflected value.

fn into_partial_reflect(self: Box<Text>) -> Box<dyn PartialReflect>

Casts this type to a boxed, reflected value.

fn as_partial_reflect(&self) -> &(dyn PartialReflect + 'static)

Casts this type to a reflected value.

fn as_partial_reflect_mut(&mut self) -> &mut (dyn PartialReflect + 'static)

Casts this type to a mutable, reflected value.

fn reflect_partial_eq( &self, value: &(dyn PartialReflect + 'static), ) -> Option<bool>

Returns a “partial equality” comparison result.

fn reflect_partial_cmp( &self, value: &(dyn PartialReflect + 'static), ) -> Option<Ordering>

Returns a “partial comparison” result.

fn debug(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Debug formatter for the value.

fn reflect_clone(&self) -> Result<Box<dyn Reflect>, ReflectCloneError>

Attempts to clone Self using reflection.

fn apply(&mut self, value: &(dyn PartialReflect + 'static))

Applies a reflected value to this value.

fn to_dynamic(&self) -> Box<dyn PartialReflect>

Converts this reflected value into its dynamic representation based on its kind.

fn reflect_clone_and_take<T>(&self) -> Result<T, ReflectCloneError>

where T: 'static, Self: Sized + TypePath,

For a type implementing PartialReflect, combines reflect_clone and take in a useful fashion, automatically constructing an appropriate ReflectCloneError if the downcast fails.

fn reflect_hash(&self) -> Option<u64>

Returns a hash of the value (which includes the type).

fn is_dynamic(&self) -> bool

Indicates whether or not this type is a dynamic type.

impl Reflect for Text

fn into_any(self: Box<Text>) -> Box<dyn Any>

Returns the value as a Box<dyn Any>.

fn as_any(&self) -> &(dyn Any + 'static)

Returns the value as a &dyn Any.

fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)

Returns the value as a &mut dyn Any.

fn into_reflect(self: Box<Text>) -> Box<dyn Reflect>

Casts this type to a boxed, fully-reflected value.

fn as_reflect(&self) -> &(dyn Reflect + 'static)

Casts this type to a fully-reflected value.

fn as_reflect_mut(&mut self) -> &mut (dyn Reflect + 'static)

Casts this type to a mutable, fully-reflected value.

fn set(&mut self, value: Box<dyn Reflect>) -> Result<(), Box<dyn Reflect>>

Performs a type-checked assignment of a reflected value to this value.

impl StructuralPartialEq for Text

impl TextSection for Text

fn get_text(&self) -> &str

Returns the text for this section.

fn get_text_mut(&mut self) -> &mut String

Returns a mutable reference to the text for this section.

impl TupleStruct for Text

fn field(&self, index: usize) -> Option<&(dyn PartialReflect + 'static)>

Returns a reference to the value of the field with index index as a &dyn Reflect.

fn field_mut( &mut self, index: usize, ) -> Option<&mut (dyn PartialReflect + 'static)>

Returns a mutable reference to the value of the field with index index as a &mut dyn Reflect.

fn field_len(&self) -> usize

Returns the number of fields in the tuple struct.

fn iter_fields(&self) -> TupleStructFieldIter<'_>

Returns an iterator over the values of the tuple struct’s fields.

fn to_dynamic_tuple_struct(&self) -> DynamicTupleStruct

Creates a new DynamicTupleStruct from this tuple struct.

fn get_represented_tuple_struct_info(&self) -> Option<&'static TupleStructInfo>

Will return None if TypeInfo is not available.

impl TypePath for Text

fn type_path() -> &'static str

Returns the fully qualified path of the underlying type.

fn short_type_path() -> &'static str

Returns a short, pretty-print enabled path to the type.

fn type_ident() -> Option<&'static str>

Returns the name of the type, or None if it is anonymous.

fn crate_name() -> Option<&'static str>

Returns the name of the crate the type is in, or None if it is anonymous.

fn module_path() -> Option<&'static str>

Returns the path to the module the type is in, or None if it is anonymous.

impl Typed for Text

fn type_info() -> &'static TypeInfo

Returns the compile-time info for the underlying type.