Files
ratatui/src/text/span.rs

815 lines
27 KiB
Rust

use std::{borrow::Cow, fmt};
use unicode_segmentation::UnicodeSegmentation;
use unicode_width::UnicodeWidthStr;
use crate::{prelude::*, style::Styled, text::StyledGrapheme};
/// Represents a part of a line that is contiguous and where all characters share the same style.
///
/// A `Span` is the smallest unit of text that can be styled. It is usually combined in the [`Line`]
/// type to represent a line of text where each `Span` may have a different style.
///
/// # Constructor Methods
///
/// - [`Span::default`] creates an span with empty content and the default style.
/// - [`Span::raw`] creates an span with the specified content and the default style.
/// - [`Span::styled`] creates an span with the specified content and style.
///
/// # Setter Methods
///
/// These methods are fluent setters. They return a new `Span` with the specified property set.
///
/// - [`Span::content`] sets the content of the span.
/// - [`Span::style`] sets the style of the span.
///
/// # Other Methods
///
/// - [`Span::patch_style`] patches the style of the span, adding modifiers from the given style.
/// - [`Span::reset_style`] resets the style of the span.
/// - [`Span::width`] returns the unicode width of the content held by this span.
/// - [`Span::styled_graphemes`] returns an iterator over the graphemes held by this span.
///
/// # Examples
///
/// A `Span` with `style` set to [`Style::default()`] can be created from a `&str`, a `String`, or
/// any type convertible to [`Cow<str>`].
///
/// ```rust
/// use ratatui::prelude::*;
///
/// let span = Span::raw("test content");
/// let span = Span::raw(String::from("test content"));
/// let span = Span::from("test content");
/// let span = Span::from(String::from("test content"));
/// let span: Span = "test content".into();
/// let span: Span = String::from("test content").into();
/// ```
///
/// Styled spans can be created using [`Span::styled`] or by converting strings using methods from
/// the [`Stylize`] trait.
///
/// ```rust
/// use ratatui::prelude::*;
///
/// let span = Span::styled("test content", Style::new().green());
/// let span = Span::styled(String::from("test content"), Style::new().green());
///
/// // using Stylize trait shortcuts
/// let span = "test content".green();
/// let span = String::from("test content").green();
/// ```
///
/// `Span` implements the [`Styled`] trait, which allows it to be styled using the shortcut methods
/// defined in the [`Stylize`] trait.
///
/// ```rust
/// use ratatui::prelude::*;
///
/// let span = Span::raw("test content").green().on_yellow().italic();
/// let span = Span::raw(String::from("test content"))
/// .green()
/// .on_yellow()
/// .italic();
/// ```
///
/// `Span` implements the [`Widget`] trait, which allows it to be rendered to a [`Buffer`]. Usually
/// apps will use the [`Paragraph`] widget instead of rendering `Span` directly, as it handles text
/// wrapping and alignment for you.
///
/// ```rust
/// use ratatui::prelude::*;
///
/// # fn render_frame(frame: &mut Frame) {
/// frame.render_widget("test content".green().on_yellow().italic(), frame.size());
/// # }
/// ```
/// [`Line`]: crate::text::Line
/// [`Paragraph`]: crate::widgets::Paragraph
/// [`Stylize`]: crate::style::Stylize
/// [`Cow<str>`]: std::borrow::Cow
#[derive(Debug, Default, Clone, Eq, PartialEq, Hash)]
pub struct Span<'a> {
/// The content of the span as a Clone-on-write string.
pub content: Cow<'a, str>,
/// The style of the span.
pub style: Style,
}
impl<'a> Span<'a> {
/// Create a span with the default style.
///
/// # Examples
///
/// ```rust
/// # use ratatui::prelude::*;
/// Span::raw("test content");
/// Span::raw(String::from("test content"));
/// ```
pub fn raw<T>(content: T) -> Self
where
T: Into<Cow<'a, str>>,
{
Self {
content: content.into(),
style: Style::default(),
}
}
/// Create a span with the specified style.
///
/// `content` accepts any type that is convertible to [`Cow<str>`] (e.g. `&str`, `String`,
/// `&String`, etc.).
///
/// `style` accepts any type that is convertible to [`Style`] (e.g. [`Style`], [`Color`], or
/// your own type that implements [`Into<Style>`]).
///
/// # Examples
///
/// ```rust
/// # use ratatui::prelude::*;
/// let style = Style::new().yellow().on_green().italic();
/// Span::styled("test content", style);
/// Span::styled(String::from("test content"), style);
/// ```
pub fn styled<T, S>(content: T, style: S) -> Self
where
T: Into<Cow<'a, str>>,
S: Into<Style>,
{
Self {
content: content.into(),
style: style.into(),
}
}
/// Sets the content of the span.
///
/// This is a fluent setter method which must be chained or used as it consumes self
///
/// Accepts any type that can be converted to [`Cow<str>`] (e.g. `&str`, `String`, `&String`,
/// etc.).
///
/// # Examples
///
/// ```rust
/// # use ratatui::prelude::*;
/// let mut span = Span::default().content("content");
/// ```
#[must_use = "method moves the value of self and returns the modified value"]
pub fn content<T>(mut self, content: T) -> Self
where
T: Into<Cow<'a, str>>,
{
self.content = content.into();
self
}
/// Sets the style of the span.
///
/// This is a fluent setter method which must be chained or used as it consumes self
///
/// In contrast to [`Span::patch_style`], this method replaces the style of the span instead of
/// patching it.
///
/// `style` accepts any type that is convertible to [`Style`] (e.g. [`Style`], [`Color`], or
/// your own type that implements [`Into<Style>`]).
///
/// # Examples
///
/// ```rust
/// # use ratatui::prelude::*;
/// let mut span = Span::default().style(Style::new().green());
/// ```
#[must_use = "method moves the value of self and returns the modified value"]
pub fn style<S: Into<Style>>(mut self, style: S) -> Self {
self.style = style.into();
self
}
/// Patches the style of the Span, adding modifiers from the given style.
///
/// `style` accepts any type that is convertible to [`Style`] (e.g. [`Style`], [`Color`], or
/// your own type that implements [`Into<Style>`]).
///
/// This is a fluent setter method which must be chained or used as it consumes self
///
/// # Example
///
/// ```rust
/// # use ratatui::prelude::*;
/// let span = Span::styled("test content", Style::new().green().italic())
/// .patch_style(Style::new().red().on_yellow().bold());
/// assert_eq!(span.style, Style::new().red().on_yellow().italic().bold());
/// ```
#[must_use = "method moves the value of self and returns the modified value"]
pub fn patch_style<S: Into<Style>>(mut self, style: S) -> Self {
self.style = self.style.patch(style);
self
}
/// Resets the style of the Span.
///
/// This is Equivalent to calling `patch_style(Style::reset())`.
///
/// This is a fluent setter method which must be chained or used as it consumes self
///
/// # Example
///
/// ```rust
/// # use ratatui::prelude::*;
/// let span = Span::styled(
/// "Test Content",
/// Style::new().dark_gray().on_yellow().italic(),
/// )
/// .reset_style();
/// assert_eq!(span.style, Style::reset());
/// ```
#[must_use = "method moves the value of self and returns the modified value"]
pub fn reset_style(self) -> Self {
self.patch_style(Style::reset())
}
/// Returns the unicode width of the content held by this span.
pub fn width(&self) -> usize {
self.content.width()
}
/// Returns an iterator over the graphemes held by this span.
///
/// `base_style` is the [`Style`] that will be patched with the `Span`'s `style` to get the
/// resulting [`Style`].
///
/// `base_style` accepts any type that is convertible to [`Style`] (e.g. [`Style`], [`Color`],
/// or your own type that implements [`Into<Style>`]).
///
/// # Example
///
/// ```rust
/// use std::iter::Iterator;
///
/// use ratatui::{prelude::*, text::StyledGrapheme};
///
/// let span = Span::styled("Test", Style::new().green().italic());
/// let style = Style::new().red().on_yellow();
/// assert_eq!(
/// span.styled_graphemes(style)
/// .collect::<Vec<StyledGrapheme>>(),
/// vec![
/// StyledGrapheme::new("T", Style::new().green().on_yellow().italic()),
/// StyledGrapheme::new("e", Style::new().green().on_yellow().italic()),
/// StyledGrapheme::new("s", Style::new().green().on_yellow().italic()),
/// StyledGrapheme::new("t", Style::new().green().on_yellow().italic()),
/// ],
/// );
/// ```
pub fn styled_graphemes<S: Into<Style>>(
&'a self,
base_style: S,
) -> impl Iterator<Item = StyledGrapheme<'a>> {
let style = base_style.into().patch(self.style);
self.content
.as_ref()
.graphemes(true)
.filter(|g| *g != "\n")
.map(move |g| StyledGrapheme { symbol: g, style })
}
/// Converts this Span into a left-aligned [`Line`]
///
/// # Example
///
/// ```rust
/// # use ratatui::prelude::*;
/// let line = "Test Content".green().italic().into_left_aligned_line();
/// ```
#[must_use = "method moves the value of self and returns the modified value"]
pub fn into_left_aligned_line(self) -> Line<'a> {
Line::from(self).left_aligned()
}
#[allow(clippy::wrong_self_convention)]
#[deprecated = "use into_left_aligned_line"]
pub fn to_left_aligned_line(self) -> Line<'a> {
self.into_left_aligned_line()
}
/// Converts this Span into a center-aligned [`Line`]
///
/// # Example
///
/// ```rust
/// # use ratatui::prelude::*;
/// let line = "Test Content".green().italic().into_centered_line();
/// ```
#[must_use = "method moves the value of self and returns the modified value"]
pub fn into_centered_line(self) -> Line<'a> {
Line::from(self).centered()
}
#[allow(clippy::wrong_self_convention)]
#[deprecated = "use into_centered_line"]
pub fn to_centered_line(self) -> Line<'a> {
self.into_centered_line()
}
/// Converts this Span into a right-aligned [`Line`]
///
/// # Example
///
/// ```rust
/// # use ratatui::prelude::*;
/// let line = "Test Content".green().italic().into_right_aligned_line();
/// ```
#[must_use = "method moves the value of self and returns the modified value"]
pub fn into_right_aligned_line(self) -> Line<'a> {
Line::from(self).right_aligned()
}
#[allow(clippy::wrong_self_convention)]
#[deprecated = "use into_right_aligned_line"]
pub fn to_right_aligned_line(self) -> Line<'a> {
self.into_right_aligned_line()
}
}
impl<'a, T> From<T> for Span<'a>
where
T: Into<Cow<'a, str>>,
{
fn from(s: T) -> Self {
Span::raw(s.into())
}
}
impl<'a> std::ops::Add<Self> for Span<'a> {
type Output = Line<'a>;
fn add(self, rhs: Self) -> Self::Output {
Line::from_iter([self, rhs])
}
}
impl<'a> Styled for Span<'a> {
type Item = Self;
fn style(&self) -> Style {
self.style
}
fn set_style<S: Into<Style>>(self, style: S) -> Self::Item {
self.style(style)
}
}
impl Widget for Span<'_> {
fn render(self, area: Rect, buf: &mut Buffer) {
self.render_ref(area, buf);
}
}
impl WidgetRef for Span<'_> {
fn render_ref(&self, area: Rect, buf: &mut Buffer) {
let area = area.intersection(buf.area);
if area.is_empty() {
return;
}
let Rect { mut x, y, .. } = area;
for (i, grapheme) in self.styled_graphemes(Style::default()).enumerate() {
let symbol_width = grapheme.symbol.width();
let next_x = x.saturating_add(symbol_width as u16);
if next_x > area.right() {
break;
}
if i == 0 {
// the first grapheme is always set on the cell
buf.get_mut(x, y)
.set_symbol(grapheme.symbol)
.set_style(grapheme.style);
} else if x == area.x {
// there is one or more zero-width graphemes in the first cell, so the first cell
// must be appended to.
buf.get_mut(x, y)
.append_symbol(grapheme.symbol)
.set_style(grapheme.style);
} else if symbol_width == 0 {
// append zero-width graphemes to the previous cell
buf.get_mut(x - 1, y)
.append_symbol(grapheme.symbol)
.set_style(grapheme.style);
} else {
// just a normal grapheme (not first, not zero-width, not overflowing the area)
buf.get_mut(x, y)
.set_symbol(grapheme.symbol)
.set_style(grapheme.style);
}
// multi-width graphemes must clear the cells of characters that are hidden by the
// grapheme, otherwise the hidden characters will be re-rendered if the grapheme is
// overwritten.
for x_hidden in (x + 1)..next_x {
// it may seem odd that the style of the hidden cells are not set to the style of
// the grapheme, but this is how the existing buffer.set_span() method works.
buf.get_mut(x_hidden, y).reset();
}
x = next_x;
}
}
}
/// A trait for converting a value to a [`Span`].
///
/// This trait is automatically implemented for any type that implements the [`Display`] trait. As
/// such, `ToSpan` shouln't be implemented directly: [`Display`] should be implemented instead, and
/// you get the `ToSpan` implementation for free.
///
/// [`Display`]: std::fmt::Display
pub trait ToSpan {
/// Converts the value to a [`Span`].
fn to_span(&self) -> Span<'_>;
}
/// # Panics
///
/// In this implementation, the `to_span` method panics if the `Display` implementation returns an
/// error. This indicates an incorrect `Display` implementation since `fmt::Write for String` never
/// returns an error itself.
impl<T: fmt::Display> ToSpan for T {
fn to_span(&self) -> Span<'_> {
Span::raw(self.to_string())
}
}
impl fmt::Display for Span<'_> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::Display::fmt(&self.content, f)
}
}
#[cfg(test)]
mod tests {
use buffer::Cell;
use rstest::fixture;
use super::*;
#[fixture]
fn small_buf() -> Buffer {
Buffer::empty(Rect::new(0, 0, 10, 1))
}
#[test]
fn default() {
let span = Span::default();
assert_eq!(span.content, Cow::Borrowed(""));
assert_eq!(span.style, Style::default());
}
#[test]
fn raw_str() {
let span = Span::raw("test content");
assert_eq!(span.content, Cow::Borrowed("test content"));
assert_eq!(span.style, Style::default());
}
#[test]
fn raw_string() {
let content = String::from("test content");
let span = Span::raw(content.clone());
assert_eq!(span.content, Cow::Owned::<str>(content));
assert_eq!(span.style, Style::default());
}
#[test]
fn styled_str() {
let style = Style::new().red();
let span = Span::styled("test content", style);
assert_eq!(span.content, Cow::Borrowed("test content"));
assert_eq!(span.style, Style::new().red());
}
#[test]
fn styled_string() {
let content = String::from("test content");
let style = Style::new().green();
let span = Span::styled(content.clone(), style);
assert_eq!(span.content, Cow::Owned::<str>(content));
assert_eq!(span.style, style);
}
#[test]
fn set_content() {
let span = Span::default().content("test content");
assert_eq!(span.content, Cow::Borrowed("test content"));
}
#[test]
fn set_style() {
let span = Span::default().style(Style::new().green());
assert_eq!(span.style, Style::new().green());
}
#[test]
fn from_ref_str_borrowed_cow() {
let content = "test content";
let span = Span::from(content);
assert_eq!(span.content, Cow::Borrowed(content));
assert_eq!(span.style, Style::default());
}
#[test]
fn from_string_ref_str_borrowed_cow() {
let content = String::from("test content");
let span = Span::from(content.as_str());
assert_eq!(span.content, Cow::Borrowed(content.as_str()));
assert_eq!(span.style, Style::default());
}
#[test]
fn from_string_owned_cow() {
let content = String::from("test content");
let span = Span::from(content.clone());
assert_eq!(span.content, Cow::Owned::<str>(content));
assert_eq!(span.style, Style::default());
}
#[test]
fn from_ref_string_borrowed_cow() {
let content = String::from("test content");
let span = Span::from(&content);
assert_eq!(span.content, Cow::Borrowed(content.as_str()));
assert_eq!(span.style, Style::default());
}
#[test]
fn to_span() {
assert_eq!(42.to_span(), Span::raw("42"));
assert_eq!("test".to_span(), Span::raw("test"));
}
#[test]
fn reset_style() {
let span = Span::styled("test content", Style::new().green()).reset_style();
assert_eq!(span.style, Style::reset());
}
#[test]
fn patch_style() {
let span = Span::styled("test content", Style::new().green().on_yellow())
.patch_style(Style::new().red().bold());
assert_eq!(span.style, Style::new().red().on_yellow().bold());
}
#[test]
fn width() {
assert_eq!(Span::raw("").width(), 0);
assert_eq!(Span::raw("test").width(), 4);
assert_eq!(Span::raw("test content").width(), 12);
}
#[test]
fn stylize() {
let span = Span::raw("test content").green();
assert_eq!(span.content, Cow::Borrowed("test content"));
assert_eq!(span.style, Style::new().green());
let span = Span::styled("test content", Style::new().green());
let stylized = span.on_yellow().bold();
assert_eq!(stylized.content, Cow::Borrowed("test content"));
assert_eq!(stylized.style, Style::new().green().on_yellow().bold());
}
#[test]
fn display_span() {
let span = Span::raw("test content");
assert_eq!(format!("{span}"), "test content");
assert_eq!(format!("{span:.4}"), "test");
}
#[test]
fn display_styled_span() {
let stylized_span = Span::styled("stylized test content", Style::new().green());
assert_eq!(format!("{stylized_span}"), "stylized test content");
assert_eq!(format!("{stylized_span:.8}"), "stylized");
}
#[test]
fn left_aligned() {
let span = Span::styled("Test Content", Style::new().green().italic());
let line = span.into_left_aligned_line();
assert_eq!(line.alignment, Some(Alignment::Left));
}
#[test]
fn centered() {
let span = Span::styled("Test Content", Style::new().green().italic());
let line = span.into_centered_line();
assert_eq!(line.alignment, Some(Alignment::Center));
}
#[test]
fn right_aligned() {
let span = Span::styled("Test Content", Style::new().green().italic());
let line = span.into_right_aligned_line();
assert_eq!(line.alignment, Some(Alignment::Right));
}
mod widget {
use rstest::rstest;
use super::*;
#[test]
fn render() {
let style = Style::new().green().on_yellow();
let span = Span::styled("test content", style);
let mut buf = Buffer::empty(Rect::new(0, 0, 15, 1));
span.render(buf.area, &mut buf);
let expected = Buffer::with_lines([Line::from(vec![
"test content".green().on_yellow(),
" ".into(),
])]);
assert_eq!(buf, expected);
}
#[rstest]
#[case::x(20, 0)]
#[case::y(0, 20)]
#[case::both(20, 20)]
fn render_out_of_bounds(mut small_buf: Buffer, #[case] x: u16, #[case] y: u16) {
let out_of_bounds = Rect::new(x, y, 10, 1);
Span::raw("Hello, World!").render(out_of_bounds, &mut small_buf);
assert_eq!(small_buf, Buffer::empty(small_buf.area));
}
/// When the content of the span is longer than the area passed to render, the content
/// should be truncated
#[test]
fn render_truncates_too_long_content() {
let style = Style::new().green().on_yellow();
let span = Span::styled("test content", style);
let mut buf = Buffer::empty(Rect::new(0, 0, 10, 1));
span.render(Rect::new(0, 0, 5, 1), &mut buf);
let expected = Buffer::with_lines([Line::from(vec![
"test ".green().on_yellow(),
" ".into(),
])]);
assert_eq!(buf, expected);
}
/// When there is already a style set on the buffer, the style of the span should be
/// patched with the existing style
#[test]
fn render_patches_existing_style() {
let style = Style::new().green().on_yellow();
let span = Span::styled("test content", style);
let mut buf = Buffer::empty(Rect::new(0, 0, 15, 1));
buf.set_style(buf.area, Style::new().italic());
span.render(buf.area, &mut buf);
let expected = Buffer::with_lines([Line::from(vec![
"test content".green().on_yellow().italic(),
" ".italic(),
])]);
assert_eq!(buf, expected);
}
/// When the span contains a multi-width grapheme, the grapheme will ensure that the cells
/// of the hidden characters are cleared.
#[test]
fn render_multi_width_symbol() {
let style = Style::new().green().on_yellow();
let span = Span::styled("test 😃 content", style);
let mut buf = Buffer::empty(Rect::new(0, 0, 15, 1));
span.render(buf.area, &mut buf);
// The existing code in buffer.set_line() handles multi-width graphemes by clearing the
// cells of the hidden characters. This test ensures that the existing behavior is
// preserved.
let expected = Buffer::with_lines(["test 😃 content".green().on_yellow()]);
assert_eq!(buf, expected);
}
/// When the span contains a multi-width grapheme that does not fit in the area passed to
/// render, the entire grapheme will be truncated.
#[test]
fn render_multi_width_symbol_truncates_entire_symbol() {
// the 😃 emoji is 2 columns wide so it will be truncated
let style = Style::new().green().on_yellow();
let span = Span::styled("test 😃 content", style);
let mut buf = Buffer::empty(Rect::new(0, 0, 6, 1));
span.render(buf.area, &mut buf);
let expected =
Buffer::with_lines([Line::from(vec!["test ".green().on_yellow(), " ".into()])]);
assert_eq!(buf, expected);
}
/// When the area passed to render overflows the buffer, the content should be truncated
/// to fit the buffer.
#[test]
fn render_overflowing_area_truncates() {
let style = Style::new().green().on_yellow();
let span = Span::styled("test content", style);
let mut buf = Buffer::empty(Rect::new(0, 0, 15, 1));
span.render(Rect::new(10, 0, 20, 1), &mut buf);
let expected = Buffer::with_lines([Line::from(vec![
" ".into(),
"test ".green().on_yellow(),
])]);
assert_eq!(buf, expected);
}
#[test]
fn render_first_zero_width() {
let span = Span::raw("\u{200B}abc");
let mut buf = Buffer::empty(Rect::new(0, 0, 3, 1));
span.render(buf.area, &mut buf);
assert_eq!(
buf.content(),
[Cell::new("\u{200B}a"), Cell::new("b"), Cell::new("c"),]
);
}
#[test]
fn render_second_zero_width() {
let span = Span::raw("a\u{200B}bc");
let mut buf = Buffer::empty(Rect::new(0, 0, 3, 1));
span.render(buf.area, &mut buf);
assert_eq!(
buf.content(),
[Cell::new("a\u{200B}"), Cell::new("b"), Cell::new("c")]
);
}
#[test]
fn render_middle_zero_width() {
let span = Span::raw("ab\u{200B}c");
let mut buf = Buffer::empty(Rect::new(0, 0, 3, 1));
span.render(buf.area, &mut buf);
assert_eq!(
buf.content(),
[Cell::new("a"), Cell::new("b\u{200B}"), Cell::new("c")]
);
}
#[test]
fn render_last_zero_width() {
let span = Span::raw("abc\u{200B}");
let mut buf = Buffer::empty(Rect::new(0, 0, 3, 1));
span.render(buf.area, &mut buf);
assert_eq!(
buf.content(),
[Cell::new("a"), Cell::new("b"), Cell::new("c\u{200B}")]
);
}
}
/// Regression test for <https://github.com/ratatui-org/ratatui/issues/1160> One line contains
/// some Unicode Left-Right-Marks (U+200E)
///
/// The issue was that a zero-width character at the end of the buffer causes the buffer bounds
/// to be exceeded (due to a position + 1 calculation that fails to account for the possibility
/// that the next position might not be available).
#[test]
fn issue_1160() {
let span = Span::raw("Hello\u{200E}");
let mut buf = Buffer::empty(Rect::new(0, 0, 5, 1));
span.render(buf.area, &mut buf);
assert_eq!(
buf.content(),
[
Cell::new("H"),
Cell::new("e"),
Cell::new("l"),
Cell::new("l"),
Cell::new("o\u{200E}"),
]
);
}
#[test]
fn add() {
assert_eq!(
Span::default() + Span::default(),
Line::from(vec![Span::default(), Span::default()])
);
assert_eq!(
Span::default() + Span::raw("test"),
Line::from(vec![Span::default(), Span::raw("test")])
);
assert_eq!(
Span::raw("test") + Span::default(),
Line::from(vec![Span::raw("test"), Span::default()])
);
assert_eq!(
Span::raw("test") + Span::raw("content"),
Line::from(vec![Span::raw("test"), Span::raw("content")])
);
}
}