Struct Segment 

pub struct Segment<'a> {
    pub text: Cow<'a, str>,
    pub style: Option<Style>,
    pub control: Option<SmallVec<[ControlCode; 2]>>,
}

A segment of styled text.

Segments are the atomic units of text rendering. They can contain:

• Regular text with optional styling
• Control codes for non-textual actions

Text is stored as Cow<str> to allow zero-copy for static strings while still supporting owned data when needed.

Fields

text: Cow<'a, str>

The text content (may be empty for control-only segments).

style: Option<Style>

Optional style applied to this segment.

control: Option<SmallVec<[ControlCode; 2]>>

Optional control codes (stack-allocated for common cases).

Implementations

impl<'a> Segment<'a>

pub fn text(s: impl Into<Cow<'a, str>>) -> Self

Create a new text segment without styling.

pub fn styled(s: impl Into<Cow<'a, str>>, style: Style) -> Self

Create a new styled text segment.

pub fn control(code: ControlCode) -> Self

Create a control segment (no text, just control codes).

pub fn newline() -> Self

Create a newline segment.

pub const fn empty() -> Self

Create an empty segment.

pub fn as_str(&self) -> &str

Get the text as a string slice.

pub fn is_empty(&self) -> bool

Check if this segment is empty (no text and no control codes).

pub fn has_text(&self) -> bool

Check if this segment has text content.

pub fn is_control(&self) -> bool

Check if this is a control-only segment.

pub fn is_newline(&self) -> bool

Check if this segment contains a newline control code.

pub fn cell_length(&self) -> usize

Get the display width in terminal cells.

Control segments have zero width. Text width is calculated using Unicode width rules.

pub fn cell_length_with<F>(&self, width_fn: F) -> usize

where F: Fn(&str) -> usize,

Calculate cell length with a specific width function.

This allows custom width calculations (e.g., for testing or terminal-specific behavior).

pub fn split_at_cell(&self, cell_pos: usize) -> (Self, Self)

Split the segment at a cell position.

Returns (left, right) where:

• left contains content up to (but not exceeding) cell_pos cells
• right contains the remaining content

The split respects grapheme cluster boundaries to avoid breaking emoji, combining characters, or other complex graphemes.

Panics

Does not panic; if cell_pos is beyond the segment length, returns (self, empty).

pub fn with_style(self, style: Style) -> Self

Apply a style to this segment.

pub fn into_owned(self) -> Segment<'static>

Convert to an owned segment (no lifetime constraints).

pub fn with_control(self, code: ControlCode) -> Self

Add a control code to this segment.

Trait Implementations

impl<'a> Clone for Segment<'a>

fn clone(&self) -> Segment<'a>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<'a> Debug for Segment<'a>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'a> Default for Segment<'a>

fn default() -> Self

Returns the “default value” for a type.

impl<'a> From<&'a str> for Segment<'a>

fn from(s: &'a str) -> Self

Converts to this type from the input type.

impl<'a> From<Segment<'a>> for Span<'a>

fn from(seg: Segment<'a>) -> Self

Converts to this type from the input type.

impl From<String> for Segment<'static>

fn from(s: String) -> Self

Converts to this type from the input type.

impl<'a> PartialEq for Segment<'a>

fn eq(&self, other: &Segment<'a>) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<'a> Eq for Segment<'a>

impl<'a> StructuralPartialEq for Segment<'a>