tui/syntax_highlighting/
syntax_highlighter.rs

1use super::syntect_bridge::{find_syntax_for_hint, syntect_to_wisp_style};
2use crate::line::Line;
3use crate::span::Span;
4use crate::style::Style;
5use crate::theme::Theme;
6use std::collections::HashMap;
7use std::sync::{LazyLock, Mutex};
8use syntect::easy::HighlightLines;
9use syntect::parsing::SyntaxSet;
10
11/// Unified syntax-highlighting facade.
12///
13/// Results are cached by `(lang, code)` so repeated re-renders
14/// (e.g. during streaming) skip the expensive syntect pass.
15///
16/// The cache uses interior mutability (`Mutex`) so `highlight`
17/// works through shared references (`&self`).
18pub struct SyntaxHighlighter {
19    cache: Mutex<HashMap<String, HashMap<String, Vec<Line>>>>,
20}
21
22impl Default for SyntaxHighlighter {
23    fn default() -> Self {
24        Self::new()
25    }
26}
27
28impl SyntaxHighlighter {
29    pub fn new() -> Self {
30        Self { cache: Mutex::new(HashMap::new()) }
31    }
32
33    /// Syntax-highlights `code`, caching the result by `(lang, code)`.
34    pub fn highlight(&self, code: &str, lang: &str, theme: &Theme) -> Vec<Line> {
35        if let Some(cached) = self.cache.lock().unwrap().get(lang).and_then(|m| m.get(code)) {
36            return cached.clone();
37        }
38
39        let lines = render_highlighted_lines(code, lang, theme);
40        self.cache.lock().unwrap().entry(lang.to_string()).or_default().insert(code.to_string(), lines.clone());
41
42        lines
43    }
44}
45
46static SYNTAX_SET: LazyLock<SyntaxSet> = LazyLock::new(two_face::syntax::extra_newlines);
47
48fn render_highlighted_lines(code: &str, lang: &str, theme: &Theme) -> Vec<Line> {
49    let Some(syntax) = find_syntax_for_hint(&SYNTAX_SET, lang) else {
50        return plain_code_lines(code, theme);
51    };
52
53    let syntect_theme = theme.syntect_theme();
54    let mut h = HighlightLines::new(syntax, syntect_theme);
55    let mut lines = Vec::new();
56
57    for source_line in code.lines() {
58        let Ok(ranges) = h.highlight_line(source_line, &SYNTAX_SET) else {
59            lines.push(Line::with_style(source_line, Style::fg(theme.code_fg())));
60            continue;
61        };
62
63        let mut line = Line::default();
64        for (syntect_style, text) in ranges {
65            line.push_span(Span::with_style(text, syntect_to_wisp_style(syntect_style)));
66        }
67        lines.push(line);
68    }
69
70    lines
71}
72
73fn plain_code_lines(code: &str, theme: &Theme) -> Vec<Line> {
74    let style = Style::fg(theme.code_fg());
75    code.lines().map(|line| Line::with_style(line, style)).collect()
76}
tui/syntax_highlighting/syntax_highlighter.rs

tui/syntax_highlighting/
syntax_highlighter.rs
