markdown syntax highlighting in text editor

viewport/src/editor.rs

@@ -365,7 +365,7 @@ impl EditorState {
                     settings,
                     |highlight, _theme| Format {
                         color: Some(syntax::highlight_color(highlight.kind)),
-                        font: None,
+                        font: syntax::highlight_font(highlight.kind),
                     },
                 )
                 .into();

viewport/src/syntax.rs

@@ -1,13 +1,32 @@
 use std::ops::Range;
 
 use iced_wgpu::core::text::highlighter;
-use iced_wgpu::core::Color;
+use iced_wgpu::core::{Color, Font};
+use iced_wgpu::core::font::{Weight, Style as FontStyle};
 use acord_core::highlight::{highlight_source, HighlightSpan};
+use acord_core::doc::{classify_document, LineKind};
 use crate::editor::{RESULT_PREFIX, ERROR_PREFIX};
 
 pub const EVAL_RESULT_KIND: u8 = 24;
 pub const EVAL_ERROR_KIND: u8 = 25;
 
+const MD_HEADING_MARKER: u8 = 26;
+const MD_H1: u8 = 27;
+const MD_H2: u8 = 28;
+const MD_H3: u8 = 29;
+const MD_BOLD: u8 = 30;
+const MD_ITALIC: u8 = 31;
+const MD_INLINE_CODE: u8 = 32;
+const MD_FORMAT_MARKER: u8 = 33;
+const MD_LINK_TEXT: u8 = 34;
+const MD_LINK_URL: u8 = 35;
+const MD_BLOCKQUOTE_MARKER: u8 = 36;
+const MD_BLOCKQUOTE: u8 = 37;
+const MD_LIST_MARKER: u8 = 38;
+const MD_FENCE_MARKER: u8 = 39;
+const MD_CODE_BLOCK: u8 = 40;
+const MD_HR: u8 = 41;
+
 #[derive(Clone, PartialEq)]
 pub struct SyntaxSettings {
     pub lang: String,
@@ -23,6 +42,8 @@ pub struct SyntaxHighlighter {
     lang: String,
     spans: Vec<HighlightSpan>,
     line_offsets: Vec<usize>,
+    line_kinds: Vec<LineKind>,
+    in_fenced_code: bool,
     current_line: usize,
 }
 
@@ -35,8 +56,221 @@ impl SyntaxHighlighter {
             self.line_offsets.push(offset);
             offset += line.len() + 1;
         }
+        let classified = classify_document(source);
+        self.line_kinds = classified.into_iter().map(|cl| cl.kind).collect();
+        self.in_fenced_code = false;
         self.current_line = 0;
     }
+
+    fn highlight_markdown(&self, line: &str) -> Vec<(Range<usize>, SyntaxHighlight)> {
+        let trimmed = line.trim_start();
+        let leading = line.len() - trimmed.len();
+
+        if is_horizontal_rule(trimmed) {
+            return vec![(0..line.len(), SyntaxHighlight { kind: MD_HR })];
+        }
+
+        if let Some(level) = heading_level(trimmed) {
+            let marker_end = leading + level + 1;
+            let kind = match level {
+                1 => MD_H1,
+                2 => MD_H2,
+                _ => MD_H3,
+            };
+            let mut spans = vec![
+                (0..marker_end, SyntaxHighlight { kind: MD_HEADING_MARKER }),
+            ];
+            if marker_end < line.len() {
+                spans.push((marker_end..line.len(), SyntaxHighlight { kind }));
+            }
+            return spans;
+        }
+
+        if trimmed.starts_with("> ") || trimmed == ">" {
+            let marker_end = leading + if trimmed.len() > 1 { 2 } else { 1 };
+            let mut spans = vec![
+                (0..marker_end, SyntaxHighlight { kind: MD_BLOCKQUOTE_MARKER }),
+            ];
+            if marker_end < line.len() {
+                let content = &line[marker_end..];
+                let inner = parse_inline(content, marker_end);
+                if inner.is_empty() {
+                    spans.push((marker_end..line.len(), SyntaxHighlight { kind: MD_BLOCKQUOTE }));
+                } else {
+                    spans.extend(inner);
+                }
+            }
+            return spans;
+        }
+
+        if let Some(marker_len) = list_marker_len(trimmed) {
+            let marker_end = leading + marker_len;
+            let mut spans = vec![
+                (0..marker_end, SyntaxHighlight { kind: MD_LIST_MARKER }),
+            ];
+            if marker_end < line.len() {
+                let content = &line[marker_end..];
+                let inner = parse_inline(content, marker_end);
+                if inner.is_empty() {
+                    return spans;
+                }
+                spans.extend(inner);
+            }
+            return spans;
+        }
+
+        parse_inline(line, 0)
+    }
+}
+
+fn heading_level(trimmed: &str) -> Option<usize> {
+    let bytes = trimmed.as_bytes();
+    if bytes.is_empty() || bytes[0] != b'#' { return None; }
+    let mut level = 0;
+    while level < bytes.len() && bytes[level] == b'#' { level += 1; }
+    if level > 3 { return None; }
+    if level < bytes.len() && bytes[level] == b' ' {
+        Some(level)
+    } else {
+        None
+    }
+}
+
+fn is_horizontal_rule(trimmed: &str) -> bool {
+    if trimmed.len() < 3 { return false; }
+    let first = trimmed.as_bytes()[0];
+    if !matches!(first, b'-' | b'*' | b'_') { return false; }
+    trimmed.bytes().all(|b| b == first || b == b' ')
+}
+
+fn list_marker_len(trimmed: &str) -> Option<usize> {
+    let bytes = trimmed.as_bytes();
+    if bytes.is_empty() { return None; }
+
+    if matches!(bytes[0], b'-' | b'*' | b'+') && bytes.get(1) == Some(&b' ') {
+        if trimmed.starts_with("- [ ] ") || trimmed.starts_with("- [x] ") || trimmed.starts_with("- [X] ") {
+            return Some(6);
+        }
+        return Some(2);
+    }
+
+    let mut i = 0;
+    while i < bytes.len() && bytes[i].is_ascii_digit() { i += 1; }
+    if i > 0 && i < bytes.len() && matches!(bytes[i], b'.' | b')') {
+        if bytes.get(i + 1) == Some(&b' ') {
+            return Some(i + 2);
+        }
+    }
+    None
+}
+
+fn parse_inline(text: &str, base: usize) -> Vec<(Range<usize>, SyntaxHighlight)> {
+    let bytes = text.as_bytes();
+    let len = bytes.len();
+    let mut spans = Vec::new();
+    let mut i = 0;
+
+    while i < len {
+        if i + 1 < len && bytes[i] == b'*' && bytes[i + 1] == b'*' {
+            if let Some(end) = find_closing(bytes, i + 2, b'*', b'*') {
+                spans.push((base + i..base + i + 2, SyntaxHighlight { kind: MD_FORMAT_MARKER }));
+                if i + 2 < end {
+                    spans.push((base + i + 2..base + end, SyntaxHighlight { kind: MD_BOLD }));
+                }
+                spans.push((base + end..base + end + 2, SyntaxHighlight { kind: MD_FORMAT_MARKER }));
+                i = end + 2;
+                continue;
+            }
+        }
+
+        if bytes[i] == b'*' && (i + 1 >= len || bytes[i + 1] != b'*') {
+            if let Some(end) = find_single_closing(bytes, i + 1, b'*') {
+                spans.push((base + i..base + i + 1, SyntaxHighlight { kind: MD_FORMAT_MARKER }));
+                if i + 1 < end {
+                    spans.push((base + i + 1..base + end, SyntaxHighlight { kind: MD_ITALIC }));
+                }
+                spans.push((base + end..base + end + 1, SyntaxHighlight { kind: MD_FORMAT_MARKER }));
+                i = end + 1;
+                continue;
+            }
+        }
+
+        if bytes[i] == b'`' {
+            if let Some(end) = find_single_closing(bytes, i + 1, b'`') {
+                spans.push((base + i..base + i + 1, SyntaxHighlight { kind: MD_FORMAT_MARKER }));
+                if i + 1 < end {
+                    spans.push((base + i + 1..base + end, SyntaxHighlight { kind: MD_INLINE_CODE }));
+                }
+                spans.push((base + end..base + end + 1, SyntaxHighlight { kind: MD_FORMAT_MARKER }));
+                i = end + 1;
+                continue;
+            }
+        }
+
+        if bytes[i] == b'[' {
+            if let Some((text_end, url_end)) = find_link(bytes, i) {
+                spans.push((base + i..base + i + 1, SyntaxHighlight { kind: MD_FORMAT_MARKER }));
+                if i + 1 < text_end {
+                    spans.push((base + i + 1..base + text_end, SyntaxHighlight { kind: MD_LINK_TEXT }));
+                }
+                spans.push((base + text_end..base + text_end + 2, SyntaxHighlight { kind: MD_FORMAT_MARKER }));
+                if text_end + 2 < url_end {
+                    spans.push((base + text_end + 2..base + url_end, SyntaxHighlight { kind: MD_LINK_URL }));
+                }
+                spans.push((base + url_end..base + url_end + 1, SyntaxHighlight { kind: MD_FORMAT_MARKER }));
+                i = url_end + 1;
+                continue;
+            }
+        }
+
+        i += 1;
+    }
+
+    spans
+}
+
+fn find_closing(bytes: &[u8], start: usize, c1: u8, c2: u8) -> Option<usize> {
+    let mut i = start;
+    while i + 1 < bytes.len() {
+        if bytes[i] == c1 && bytes[i + 1] == c2 {
+            return Some(i);
+        }
+        i += 1;
+    }
+    None
+}
+
+fn find_single_closing(bytes: &[u8], start: usize, ch: u8) -> Option<usize> {
+    let mut i = start;
+    while i < bytes.len() {
+        if bytes[i] == ch {
+            return Some(i);
+        }
+        i += 1;
+    }
+    None
+}
+
+fn find_link(bytes: &[u8], open: usize) -> Option<(usize, usize)> {
+    let mut i = open + 1;
+    while i < bytes.len() {
+        if bytes[i] == b']' {
+            if i + 1 < bytes.len() && bytes[i + 1] == b'(' {
+                let text_end = i;
+                let mut j = i + 2;
+                while j < bytes.len() {
+                    if bytes[j] == b')' {
+                        return Some((text_end, j));
+                    }
+                    j += 1;
+                }
+            }
+            return None;
+        }
+        if bytes[i] == b'\n' { return None; }
+        i += 1;
+    }
+    None
 }
 
 impl highlighter::Highlighter for SyntaxHighlighter {
@@ -49,6 +283,8 @@ impl highlighter::Highlighter for SyntaxHighlighter {
             lang: settings.lang.clone(),
             spans: Vec::new(),
             line_offsets: Vec::new(),
+            line_kinds: Vec::new(),
+            in_fenced_code: false,
             current_line: 0,
         };
         h.rebuild(&settings.source);
@@ -62,18 +298,42 @@ impl highlighter::Highlighter for SyntaxHighlighter {
 
     fn change_line(&mut self, line: usize) {
         self.current_line = self.current_line.min(line);
+        if line == 0 {
+            self.in_fenced_code = false;
+        }
     }
 
-    fn highlight_line(&mut self, _line: &str) -> Self::Iterator<'_> {
+    fn highlight_line(&mut self, line: &str) -> Self::Iterator<'_> {
         let ln = self.current_line;
         self.current_line += 1;
 
-        let trimmed = _line.trim_start();
+        let trimmed = line.trim_start();
         if trimmed.starts_with(RESULT_PREFIX) {
-            return vec![(0.._line.len(), SyntaxHighlight { kind: EVAL_RESULT_KIND })].into_iter();
+            return vec![(0..line.len(), SyntaxHighlight { kind: EVAL_RESULT_KIND })].into_iter();
         }
         if trimmed.starts_with(ERROR_PREFIX) {
-            return vec![(0.._line.len(), SyntaxHighlight { kind: EVAL_ERROR_KIND })].into_iter();
+            return vec![(0..line.len(), SyntaxHighlight { kind: EVAL_ERROR_KIND })].into_iter();
+        }
+
+        let is_markdown = ln < self.line_kinds.len()
+            && self.line_kinds[ln] == LineKind::Markdown;
+
+        if is_markdown {
+            if trimmed.starts_with("```") {
+                self.in_fenced_code = !self.in_fenced_code;
+                return vec![(0..line.len(), SyntaxHighlight { kind: MD_FENCE_MARKER })].into_iter();
+            }
+
+            if self.in_fenced_code {
+                return vec![(0..line.len(), SyntaxHighlight { kind: MD_CODE_BLOCK })].into_iter();
+            }
+
+            let md_spans = self.highlight_markdown(line);
+            if !md_spans.is_empty() {
+                return md_spans.into_iter();
+            }
+        } else if self.in_fenced_code {
+            self.in_fenced_code = false;
         }
 
         if ln >= self.line_offsets.len() {
@@ -84,7 +344,7 @@ impl highlighter::Highlighter for SyntaxHighlighter {
         let line_end = if ln + 1 < self.line_offsets.len() {
             self.line_offsets[ln + 1] - 1
         } else {
-            line_start + _line.len()
+            line_start + line.len()
         };
 
         let mut result = Vec::new();
@@ -134,6 +394,37 @@ pub fn highlight_color(kind: u8) -> Color {
         23 => Color::from_rgb(0.804, 0.839, 0.957),  // embedded - text
         24 => Color::from_rgb(0.651, 0.890, 0.631),  // eval result - green
         25 => Color::from_rgb(0.890, 0.400, 0.400),  // eval error - muted red
-        _ => Color::from_rgb(0.804, 0.839, 0.957),   // default text
+        MD_HEADING_MARKER => Color::from_rgb(0.424, 0.443, 0.537),
+        MD_H1 => Color::from_rgb(0.961, 0.878, 0.863),
+        MD_H2 => Color::from_rgb(0.988, 0.702, 0.529),
+        MD_H3 => Color::from_rgb(0.976, 0.827, 0.522),
+        MD_BOLD => Color::from_rgb(0.988, 0.702, 0.529),
+        MD_ITALIC => Color::from_rgb(0.804, 0.569, 0.945),
+        MD_INLINE_CODE => Color::from_rgb(0.651, 0.890, 0.631),
+        MD_FORMAT_MARKER => Color::from_rgb(0.424, 0.443, 0.537),
+        MD_LINK_TEXT => Color::from_rgb(0.537, 0.706, 0.980),
+        MD_LINK_URL => Color::from_rgb(0.502, 0.525, 0.639),
+        MD_BLOCKQUOTE_MARKER => Color::from_rgb(0.424, 0.443, 0.537),
+        MD_BLOCKQUOTE => Color::from_rgb(0.604, 0.831, 0.898),
+        MD_LIST_MARKER => Color::from_rgb(0.604, 0.831, 0.898),
+        MD_FENCE_MARKER => Color::from_rgb(0.424, 0.443, 0.537),
+        MD_CODE_BLOCK => Color::from_rgb(0.804, 0.839, 0.957),
+        MD_HR => Color::from_rgb(0.502, 0.525, 0.639),
+        _ => Color::from_rgb(0.804, 0.839, 0.957),
+    }
+}
+
+pub fn highlight_font(kind: u8) -> Option<Font> {
+    match kind {
+        MD_HEADING_MARKER => Some(Font { weight: Weight::Bold, ..Font::MONOSPACE }),
+        MD_H1 | MD_H2 | MD_H3 => Some(Font { weight: Weight::Bold, ..Font::DEFAULT }),
+        MD_BOLD => Some(Font { weight: Weight::Bold, ..Font::DEFAULT }),
+        MD_ITALIC => Some(Font { style: FontStyle::Italic, ..Font::DEFAULT }),
+        MD_INLINE_CODE => Some(Font::MONOSPACE),
+        MD_FORMAT_MARKER => Some(Font::MONOSPACE),
+        MD_BLOCKQUOTE => Some(Font { style: FontStyle::Italic, ..Font::DEFAULT }),
+        MD_FENCE_MARKER => Some(Font::MONOSPACE),
+        MD_CODE_BLOCK => Some(Font::MONOSPACE),
+        _ => None,
     }
 }