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use crate::format::{Color, Style};
use crate::layout::{PartLayout, SegmentLayout};
use crate::position::AbsolutePosition;
use crate::terminal::Terminal;
use crate::text::{TextParameters, TextParametersWithLayout};
use crate::Result;
use std::mem::swap;
use std::sync::atomic::{AtomicUsize, Ordering};
/// A unique segment identifier.
#[derive(Debug, Eq, PartialEq, Hash, Clone, Copy)]
pub struct SegmentId(usize);
/// The greatest provisioned segment identifier.
static ID_VALUE: AtomicUsize = AtomicUsize::new(0);
impl SegmentId {
/// Create a new, unique segment identifier.
fn new() -> Self {
Self(ID_VALUE.fetch_add(1, Ordering::Relaxed))
}
}
/// A segment of text which may have formatting. Accumulates changes until applied by its parent
/// `Line`. May be obtained from the `Line` API.
#[derive(Debug)]
pub struct Segment {
/// This segment's immutable, unique identifier.
identifier: SegmentId,
/// The currently-rendered state.
current: SegmentState,
/// If changed, the state with queued and unapplied changes.
alternate: Option<SegmentState>,
}
impl Segment {
/// Create a new segment with no content or formatting.
pub(crate) fn new() -> Segment {
Segment {
identifier: SegmentId::new(),
current: SegmentState::default(),
alternate: None,
}
}
/// Create an exact clone of this segment and its states.
pub(crate) fn clone(&self) -> Segment {
Segment {
identifier: self.identifier.clone(),
current: self.current.clone(),
alternate: self.alternate.clone(),
}
}
/// This segment's unique identifier.
pub fn identifier(&self) -> SegmentId {
self.identifier
}
/// This segment's text. Reflects the latest state, even if staged changes have not yet been
/// applied to the interface.
pub fn text(&self) -> Option<&String> {
let latest_state = self.get_latest_state();
latest_state.text.as_ref()
}
/// This segment's color. Reflects the latest state, even if staged changes have not yet been
/// applied to the interface.
pub fn color(&self) -> Option<&Color> {
let latest_state = self.get_latest_state();
latest_state.color.as_ref()
}
/// This segment's styles. Reflects the latest state, even if staged changes have not yet been
/// applied to the interface.
pub fn styles(&self) -> &Vec<Style> {
let latest_state = self.get_latest_state();
latest_state.styles.as_ref()
}
/// Update this segment's text. The new text will be staged until applied for this `Interface`.
pub fn set_text(&mut self, text: &str) {
let alternate = self.get_alternate_mut();
alternate.text = Some(String::from(text));
}
/// Update this segment's color. The new color is staged until applied for this `Interface`.
pub fn set_color(&mut self, color: Color) {
let alternate = self.get_alternate_mut();
alternate.color = Some(color);
}
/// Clear this segment's color. The reset is staged until applied for this `Interface`.
pub fn reset_color(&mut self) {
let alternate = self.get_alternate_mut();
alternate.color = None;
}
/// Update this segment's styles. The new styles are staged until applied for this `Interface`.
pub fn set_styles(&mut self, styles: Vec<Style>) {
let alternate = self.get_alternate_mut();
alternate.styles = styles;
}
/// Clear this segment's styles. The reset is staged until applied for this `Interface`.
pub fn reset_styles(&mut self) {
let alternate = self.get_alternate_mut();
alternate.styles = Vec::new();
}
/// Whether this segment has any staged changes.
pub fn has_changes(&self) -> bool {
self.alternate.is_some()
}
/// Render this segment at the specified `location`, including any staged changes. Assumes any
/// previous render is still valid and attempts to optimize updates. If `force_render`, the
/// segment will be rendered without any optimization.
pub(crate) fn update(
&mut self,
terminal: &mut Terminal,
location: AbsolutePosition,
force_render: bool,
) -> Result<SegmentLayout> {
let mut previous_state = None;
if self.alternate.is_some() {
previous_state = Some(self.swap_alternate());
}
if force_render {
previous_state = None;
}
let segment_layout = self.render(terminal, location, previous_state.as_ref())?;
self.current.layout = Some(segment_layout.parts().clone());
Ok(segment_layout)
}
/// Renders the specified state for this segment at `location`. If provided, renders the state
/// diff'd against the previous state to minimize the amount of text being written.
fn render(
&self,
terminal: &mut Terminal,
location: AbsolutePosition,
previous_state: Option<&SegmentState>,
) -> Result<SegmentLayout> {
Ok(if let Some(parameters) = self.get_current_parameters() {
let previous_parameters = self.get_previous_parameters(previous_state);
let layouts =
terminal.render_segment(location, parameters, previous_parameters.as_ref())?;
SegmentLayout::new(self.identifier, layouts)
} else {
SegmentLayout::default()
})
}
/// Retrieves parameters for the current state.
fn get_current_parameters(&self) -> Option<TextParameters> {
Some(TextParameters::new(
self.current.text.as_ref()?,
self.current.color,
self.current.styles.clone(),
))
}
/// Given an optional state, extracts as many parameters as possible.
fn get_previous_parameters<'a>(
&self,
previous_state: Option<&'a SegmentState>,
) -> Option<TextParametersWithLayout<'a>> {
Some(TextParametersWithLayout::new(
TextParameters::new(
previous_state?.text.as_ref()?,
previous_state?.color,
previous_state?.styles.clone(),
),
previous_state?.layout.as_ref()?.clone(),
))
}
/// Get a mutable reference to this segment's alternate state, creating it and dirtying the
/// segment if necessary.
fn get_alternate_mut(&mut self) -> &mut SegmentState {
if self.alternate.is_none() {
self.alternate = Some(self.current.clone());
}
self.alternate.as_mut().unwrap()
}
/// Get a reference to the most-recent state, whether current or staged alternate.
fn get_latest_state(&self) -> &SegmentState {
match self.alternate {
Some(ref state) => state,
None => &self.current,
}
}
/// Swaps this segment's alternate state out for its current and returns the previous-current
/// state. This segment must have an alternate for this to be called.
fn swap_alternate(&mut self) -> SegmentState {
let mut alternate = self.alternate.take().unwrap();
swap(&mut self.current, &mut alternate);
alternate
}
}
/// The segment's text and formatting.
#[derive(Clone, Debug)]
struct SegmentState {
/// This segment's text. If unspecified, the segment is not rendered.
text: Option<String>,
/// This segment's optional foreground color.
color: Option<Color>,
/// This segment's optional formats.
styles: Vec<Style>,
/// This segment's layout on screen, if it has been rendered.
layout: Option<Vec<PartLayout>>,
}
impl Default for SegmentState {
/// An empty state with no text, color, or styles.
fn default() -> Self {
Self {
text: None,
color: None,
styles: Vec::new(),
layout: None,
}
}
}