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|
//! Markdown rendering component using pulldown-cmark.
//!
//! More robust than eye-declare's built-in Markdown component:
//! uses a proper CommonMark parser rather than line-by-line regex.
use eye_declare::{Component, props};
use pulldown_cmark::{Event, Parser, Tag, TagEnd};
use ratatui_core::{
buffer::Buffer,
layout::Rect,
style::{Color, Modifier, Style},
text::{Line, Span, Text},
widgets::Widget,
};
use ratatui_widgets::paragraph::{Paragraph, Wrap};
/// A markdown rendering component backed by pulldown-cmark.
#[props]
pub struct Markdown {
pub source: String,
}
impl Markdown {
pub fn new(source: impl Into<String>) -> Self {
Self {
source: source.into(),
}
}
}
/// Style configuration for markdown rendering.
pub struct MarkdownStyles {
pub base: Style,
pub code_inline: Style,
pub code_block: Style,
pub bold: Style,
pub italic: Style,
pub heading: Style,
}
impl MarkdownStyles {
pub fn new() -> Self {
let base = Style::default();
Self {
base,
code_inline: Style::default().fg(Color::Yellow),
code_block: Style::default().fg(Color::Green),
bold: base.add_modifier(Modifier::BOLD),
italic: base.add_modifier(Modifier::ITALIC),
heading: Style::default()
.fg(Color::Cyan)
.add_modifier(Modifier::BOLD),
}
}
}
impl Default for MarkdownStyles {
fn default() -> Self {
Self::new()
}
}
impl Component for Markdown {
type State = MarkdownStyles;
fn render(&self, area: Rect, buf: &mut Buffer, state: &Self::State) {
if self.source.is_empty() || area.width == 0 || area.height == 0 {
return;
}
let text = parse_markdown(&self.source, state);
Paragraph::new(text)
.wrap(Wrap { trim: false })
.render(area, buf);
}
fn desired_height(&self, width: u16, state: &Self::State) -> Option<u16> {
if self.source.is_empty() || width == 0 {
return Some(0);
}
let text = parse_markdown(&self.source, state);
Some(
Paragraph::new(text)
.wrap(Wrap { trim: false })
.line_count(width) as u16,
)
}
fn initial_state(&self) -> Option<MarkdownStyles> {
Some(MarkdownStyles::new())
}
}
/// Parse markdown source into styled ratatui Text using pulldown-cmark.
fn parse_markdown<'a>(source: &'a str, styles: &'a MarkdownStyles) -> Text<'static> {
let parser = Parser::new(source);
let mut lines: Vec<Vec<Span<'static>>> = vec![Vec::new()];
let mut current_line = 0;
let mut style_stack: Vec<Style> = vec![styles.base];
let mut in_code_block = false;
for event in parser {
match event {
Event::Start(Tag::Strong) => {
let bold = style_stack
.last()
.copied()
.unwrap_or(styles.base)
.add_modifier(Modifier::BOLD);
style_stack.push(bold);
}
Event::End(TagEnd::Strong) => {
style_stack.pop();
}
Event::Start(Tag::Emphasis) => {
let italic = style_stack
.last()
.copied()
.unwrap_or(styles.base)
.add_modifier(Modifier::ITALIC);
style_stack.push(italic);
}
Event::End(TagEnd::Emphasis) => {
style_stack.pop();
}
Event::Start(Tag::CodeBlock(_)) => {
in_code_block = true;
if !lines[current_line].is_empty() {
current_line += 1;
lines.push(Vec::new());
current_line += 1;
lines.push(Vec::new());
}
}
Event::End(TagEnd::CodeBlock) => {
in_code_block = false;
if !lines[current_line].is_empty() {
current_line += 1;
lines.push(Vec::new());
}
}
Event::Code(code) => {
lines[current_line].push(Span::styled(format!("{}", code), styles.code_inline));
}
Event::Text(text) => {
let current_style = if in_code_block {
styles.code_block
} else {
style_stack.last().copied().unwrap_or(styles.base)
};
let prefix = if in_code_block { " " } else { "" };
let parts: Vec<&str> = text.split('\n').collect();
for (i, part) in parts.iter().enumerate() {
if i > 0 {
current_line += 1;
lines.push(Vec::new());
}
if !part.is_empty() {
lines[current_line]
.push(Span::styled(format!("{}{}", prefix, part), current_style));
}
}
}
Event::SoftBreak => {
let current_style = style_stack.last().copied().unwrap_or(styles.base);
lines[current_line].push(Span::styled(" ", current_style));
}
Event::HardBreak => {
current_line += 1;
lines.push(Vec::new());
}
Event::Start(Tag::Paragraph) => {
if current_line > 0 || !lines[0].is_empty() {
// Two line advances: one to end the current line, one for a blank separator.
current_line += 1;
lines.push(Vec::new());
current_line += 1;
lines.push(Vec::new());
}
}
Event::End(TagEnd::Paragraph) => {}
Event::Start(Tag::Heading { .. }) => {
if current_line > 0 || !lines[0].is_empty() {
current_line += 1;
lines.push(Vec::new());
current_line += 1;
lines.push(Vec::new());
}
style_stack.push(styles.heading);
}
Event::End(TagEnd::Heading(_)) => {
style_stack.pop();
}
Event::Start(Tag::Item) => {
if current_line > 0 || !lines[0].is_empty() {
current_line += 1;
lines.push(Vec::new());
}
lines[current_line].push(Span::styled("- ", Style::default().fg(Color::DarkGray)));
}
Event::End(TagEnd::Item) => {}
Event::Start(Tag::List(_)) => {
if current_line > 0 || !lines[0].is_empty() {
current_line += 1;
lines.push(Vec::new());
}
}
Event::End(TagEnd::List(_)) => {}
_ => {}
}
}
let text_lines: Vec<Line<'static>> = lines.into_iter().map(Line::from).collect();
Text::from(text_lines)
}
|
