Add site syntax highlighting

site/decodal-site/src/lib/docs.js

@@ -1,4 +1,5 @@
 import { marked } from 'marked';
+import { escapeAttribute, escapeHtml, highlightCode } from './highlight.js';
 
 const modules = import.meta.glob('../../../../doc/manual/souce/**/*.md', {
   query: '?raw',
@@ -79,7 +80,17 @@ export const nav = [
   { title: 'Open Issues', slug: 'open-issues' },
 ];
 
-marked.setOptions({ gfm: true });
+const renderer = new marked.Renderer();
+
+renderer.code = (code, language = '') => {
+  const normalizedLanguage = language.split(/\s+/)[0] ?? '';
+  const className = normalizedLanguage ? ` class="language-${escapeAttribute(normalizedLanguage)}"` : '';
+  return `<pre class="code-block"><code${className}>${highlightCode(code, normalizedLanguage)}</code></pre>`;
+};
+
+renderer.codespan = (code) => `<code>${escapeHtml(code)}</code>`;
+
+marked.setOptions({ gfm: true, renderer });
 
 export function allDocSlugs() {
   return Object.keys(docs).filter((slug) => slug !== 'index');

site/decodal-site/src/lib/highlight.js

@@ -0,0 +1,196 @@
+const DECODAL_KEYWORDS = new Set(['let', 'in', 'fn', 'match', 'import', 'default']);
+const DECODAL_TYPES = new Set(['String', 'Int', 'Float', 'Bool']);
+const DECODAL_LITERALS = new Set(['true', 'false']);
+
+const HTML_ESCAPE = {
+  '&': '&',
+  '<': '&lt;',
+  '>': '&gt;',
+  '"': '&quot;',
+  "'": '&#39;',
+};
+
+export function escapeHtml(value) {
+  return String(value).replace(/[&<>"']/g, (char) => HTML_ESCAPE[char]);
+}
+
+export function escapeAttribute(value) {
+  return escapeHtml(value).replace(/`/g, '&#96;');
+}
+
+export function highlightCode(code, language = '') {
+  const normalized = language.toLowerCase();
+  if (normalized === 'dcdl' || normalized === 'decodal') return highlightDecodal(code);
+  if (normalized === 'sh' || normalized === 'bash' || normalized === 'shell') return highlightShell(code);
+  return escapeHtml(code);
+}
+
+export function highlightDecodal(source) {
+  let html = '';
+  let index = 0;
+
+  while (index < source.length) {
+    const char = source[index];
+    const next = source[index + 1];
+
+    if (char === '/' && next === '/') {
+      const end = readUntilLineEnd(source, index);
+      html += token('comment', source.slice(index, end));
+      index = end;
+      continue;
+    }
+
+    if (char === '"') {
+      const end = readString(source, index);
+      html += token('string', source.slice(index, end));
+      index = end;
+      continue;
+    }
+
+    if (char === '/' && next && next !== '/') {
+      const end = readRegex(source, index);
+      html += token('regex', source.slice(index, end));
+      index = end;
+      continue;
+    }
+
+    if (isNumberStart(source, index)) {
+      const end = readNumber(source, index);
+      html += token('number', source.slice(index, end));
+      index = end;
+      continue;
+    }
+
+    if (isIdentifierStart(char)) {
+      const end = readIdentifier(source, index);
+      const ident = source.slice(index, end);
+      if (DECODAL_KEYWORDS.has(ident)) html += token('keyword', ident);
+      else if (DECODAL_TYPES.has(ident)) html += token('type', ident);
+      else if (DECODAL_LITERALS.has(ident)) html += token('literal', ident);
+      else html += escapeHtml(ident);
+      index = end;
+      continue;
+    }
+
+    if (isOperatorStart(char)) {
+      const end = readOperator(source, index);
+      html += token('operator', source.slice(index, end));
+      index = end;
+      continue;
+    }
+
+    html += escapeHtml(char);
+    index += 1;
+  }
+
+  return html;
+}
+
+function highlightShell(source) {
+  return source
+    .split(/(\n)/)
+    .map((line) => {
+      if (line === '\n') return line;
+      const commentIndex = line.indexOf('#');
+      const code = commentIndex >= 0 ? line.slice(0, commentIndex) : line;
+      const comment = commentIndex >= 0 ? line.slice(commentIndex) : '';
+      return `${highlightShellCode(code)}${comment ? token('comment', comment) : ''}`;
+    })
+    .join('');
+}
+
+function highlightShellCode(source) {
+  const escaped = escapeHtml(source);
+  return escaped
+    .replace(/(&quot;[^&]*(?:&(?!quot;)[^&]*)*&quot;|'[^']*')/g, '<span class="tok-string">$1</span>')
+    .replace(/(^|\s)(--?[A-Za-z0-9][A-Za-z0-9-]*)/g, '$1<span class="tok-operator">$2</span>');
+}
+
+function token(kind, value) {
+  return `<span class="tok-${kind}">${escapeHtml(value)}</span>`;
+}
+
+function readUntilLineEnd(source, start) {
+  const end = source.indexOf('\n', start);
+  return end < 0 ? source.length : end;
+}
+
+function readString(source, start) {
+  let index = start + 1;
+  while (index < source.length) {
+    if (source[index] === '\\') {
+      index += 2;
+      continue;
+    }
+    if (source[index] === '"') return index + 1;
+    index += 1;
+  }
+  return source.length;
+}
+
+function readRegex(source, start) {
+  let index = start + 1;
+  let inClass = false;
+  while (index < source.length) {
+    const char = source[index];
+    if (char === '\\') {
+      index += 2;
+      continue;
+    }
+    if (char === '[') inClass = true;
+    else if (char === ']') inClass = false;
+    else if (char === '/' && !inClass) {
+      index += 1;
+      while (/[A-Za-z]/.test(source[index] ?? '')) index += 1;
+      return index;
+    }
+    if (char === '\n') return index;
+    index += 1;
+  }
+  return source.length;
+}
+
+function isNumberStart(source, index) {
+  const char = source[index];
+  const next = source[index + 1];
+  const prev = source[index - 1];
+  if (/[0-9]/.test(char)) return true;
+  return char === '-' && /[0-9]/.test(next ?? '') && !isIdentifierPart(prev ?? '');
+}
+
+function readNumber(source, start) {
+  let index = start;
+  if (source[index] === '-') index += 1;
+  while (/[0-9]/.test(source[index] ?? '')) index += 1;
+  if (source[index] === '.' && /[0-9]/.test(source[index + 1] ?? '')) {
+    index += 1;
+    while (/[0-9]/.test(source[index] ?? '')) index += 1;
+  }
+  return index;
+}
+
+function isIdentifierStart(char) {
+  return /[A-Za-z_]/.test(char ?? '');
+}
+
+function isIdentifierPart(char) {
+  return /[A-Za-z0-9_-]/.test(char ?? '');
+}
+
+function readIdentifier(source, start) {
+  let index = start + 1;
+  while (isIdentifierPart(source[index])) index += 1;
+  return index;
+}
+
+function isOperatorStart(char) {
+  return /[&=<>!|:;,.{}()[\]]/.test(char ?? '');
+}
+
+function readOperator(source, start) {
+  let index = start + 1;
+  if ((source[start] === '<' || source[start] === '>' || source[start] === '=' || source[start] === '!') && source[index] === '=') {
+    index += 1;
+  }
+  return index;
+}

site/decodal-site/src/pages/playground.astro

@@ -12,9 +12,12 @@ import ManualLayout from '../layouts/ManualLayout.astro';
     </div>
     <p id="status" class="status">Loading WASM...</p>
     <div class="playground-grid">
-      <label class="pane">
+      <label class="pane input-pane">
         <span>Input</span>
-        <textarea id="source" spellcheck="false"></textarea>
+        <div class="editor-wrap">
+          <pre id="source-highlight" aria-hidden="true"></pre>
+          <textarea id="source" spellcheck="false"></textarea>
+        </div>
       </label>
       <section class="pane output-pane">
         <span>Output</span>
@@ -22,5 +25,7 @@ import ManualLayout from '../layouts/ManualLayout.astro';
       </section>
     </div>
   </section>
-  <script type="module" src="../scripts/playground.js"></script>
+  <script>
+    import '../scripts/playground.js';
+  </script>
 </ManualLayout>

site/decodal-site/src/scripts/playground.js

@@ -1,4 +1,5 @@
 import init, { evaluate } from '../wasm/decodal_wasm.js';
+import { highlightDecodal } from '../lib/highlight.js';
 
 const starter = `let
   Service = {
@@ -14,11 +15,22 @@ in
 `;
 
 const source = document.getElementById('source');
+const sourceHighlight = document.getElementById('source-highlight');
 const output = document.getElementById('output');
 const run = document.getElementById('run');
 const status = document.getElementById('status');
 
 source.value = starter;
+updateHighlight();
+
+function updateHighlight() {
+  sourceHighlight.innerHTML = `${highlightDecodal(source.value)}\n`;
+}
+
+function syncHighlightScroll() {
+  sourceHighlight.scrollTop = source.scrollTop;
+  sourceHighlight.scrollLeft = source.scrollLeft;
+}
 
 function execute() {
   const result = JSON.parse(evaluate(source.value));
@@ -36,6 +48,11 @@ try {
 }
 
 run.addEventListener('click', execute);
+source.addEventListener('input', () => {
+  updateHighlight();
+  syncHighlightScroll();
+});
+source.addEventListener('scroll', syncHighlightScroll);
 source.addEventListener('keydown', (event) => {
   if ((event.metaKey || event.ctrlKey) && event.key === 'Enter') execute();
 });

site/decodal-site/src/style.css

@@ -114,7 +114,7 @@ main.playground {
 }
 
 .markdown pre,
-.pane pre {
+.output-pane pre {
   background: #0f172a;
   border-radius: 10px;
   color: #e5e7eb;
@@ -133,6 +133,34 @@ main.playground {
   padding: 1px 4px;
 }
 
+.tok-keyword {
+  color: #93c5fd;
+  font-weight: 700;
+}
+
+.tok-type {
+  color: #67e8f9;
+}
+
+.tok-literal,
+.tok-number {
+  color: #fbbf24;
+}
+
+.tok-string,
+.tok-regex {
+  color: #86efac;
+}
+
+.tok-comment {
+  color: #94a3b8;
+  font-style: italic;
+}
+
+.tok-operator {
+  color: #f9a8d4;
+}
+
 .playground-page {
   height: calc(100vh - 104px);
 }
@@ -194,13 +222,43 @@ button:disabled {
   text-transform: uppercase;
 }
 
-textarea {
-  border: 0;
+.editor-wrap {
+  background: #0f172a;
   flex: 1;
+  min-height: 0;
+  position: relative;
+}
+
+.editor-wrap pre,
+.editor-wrap textarea {
+  border: 0;
+  box-sizing: border-box;
   font: 14px/1.5 ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;
-  outline: none;
+  inset: 0;
+  margin: 0;
+  overflow: auto;
   padding: 14px;
+  position: absolute;
+  tab-size: 2;
+  white-space: pre;
+}
+
+.editor-wrap pre {
+  color: #e5e7eb;
+  pointer-events: none;
+}
+
+.editor-wrap textarea {
+  background: transparent;
+  caret-color: #e5e7eb;
+  color: transparent;
+  outline: none;
   resize: none;
+  width: 100%;
+}
+
+.editor-wrap textarea::selection {
+  background: rgb(59 130 246 / 0.35);
 }
 
 .output-pane pre {