feat: add custom C++ syntax highlighting support (#556)

antora-ui/src/css/cpp-highlight.css

@@ -0,0 +1,36 @@
+/**
+ * cpp-highlight.css - Custom C++ syntax highlighting styles
+ * This replaces highlight.js's C++ highlighting for consistent styling
+ */
+
+/* C++ Keywords - blue, bold */
+code.cpp-highlight .cpp-keyword,
+.doc pre.highlight code.cpp-highlight .cpp-keyword {
+  color: #00f;
+  font-weight: bold;
+}
+
+/* C++ Strings - dark red */
+code.cpp-highlight .cpp-string,
+.doc pre.highlight code.cpp-highlight .cpp-string {
+  color: #a31515;
+}
+
+/* C++ Preprocessor directives - purple */
+code.cpp-highlight .cpp-preprocessor,
+.doc pre.highlight code.cpp-highlight .cpp-preprocessor {
+  color: #6f008a;
+}
+
+/* C++ Comments - green, italic */
+code.cpp-highlight .cpp-comment,
+.doc pre.highlight code.cpp-highlight .cpp-comment {
+  color: #008000;
+  font-style: italic;
+}
+
+/* Base text in C++ blocks - plain black (identifiers, function names, etc.) */
+code.cpp-highlight,
+.doc pre.highlight code.cpp-highlight {
+  color: inherit;
+}

antora-ui/src/css/site.css

@@ -14,6 +14,7 @@
 @import "header.css";
 @import "footer.css";
 @import "highlight.css";
+@import "cpp-highlight.css";
 @import "print.css";
 @import "tailwindcss/base";
 @import "tailwindcss/components";

antora-ui/src/js/vendor/cpp-highlight.js

@@ -0,0 +1,199 @@
+/**
+ * cpp-highlight.js - Lightweight C++ syntax highlighter
+ *
+ * Categories:
+ *   - keyword     : Language keywords (const, while, if, etc.)
+ *   - string      : String and character literals
+ *   - preprocessor: Preprocessor directives (#include, #define, etc.)
+ *   - comment     : C and C++ style comments
+ */
+
+const CppHighlight = (function () {
+  'use strict'
+
+  const KEYWORDS = new Set([
+    // Storage class
+    'auto', 'register', 'static', 'extern', 'mutable', 'thread_local',
+    // Type qualifiers
+    'const', 'volatile', 'constexpr', 'consteval', 'constinit',
+    // Type specifiers
+    'void', 'bool', 'char', 'short', 'int', 'long', 'float', 'double',
+    'signed', 'unsigned', 'wchar_t', 'char8_t', 'char16_t', 'char32_t',
+    // Complex types
+    'class', 'struct', 'union', 'enum', 'typename', 'typedef',
+    // Control flow
+    'if', 'else', 'switch', 'case', 'default', 'for', 'while', 'do',
+    'break', 'continue', 'return', 'goto',
+    // Exception handling
+    'try', 'catch', 'throw', 'noexcept',
+    // OOP
+    'public', 'private', 'protected', 'virtual', 'override', 'final',
+    'friend', 'this', 'operator', 'new', 'delete',
+    // Templates
+    'template', 'concept', 'requires',
+    // Namespace
+    'namespace', 'using',
+    // Other
+    'sizeof', 'alignof', 'alignas', 'decltype', 'typeid',
+    'static_cast', 'dynamic_cast', 'const_cast', 'reinterpret_cast',
+    'static_assert', 'inline', 'explicit', 'export', 'module', 'import',
+    'co_await', 'co_yield', 'co_return',
+    // Literals
+    'true', 'false', 'nullptr', 'NULL',
+  ])
+
+  function escapeHtml (text) {
+    return text
+      .replace(/&/g, '&')
+      .replace(/</g, '&lt;')
+      .replace(/>/g, '&gt;')
+  }
+
+  function span (cls, content) {
+    return `<span class="cpp-${cls}">${escapeHtml(content)}</span>`
+  }
+
+  function highlight (code) {
+    const result = []
+    let i = 0
+    const n = code.length
+
+    while (i < n) {
+      // Line comment
+      if (code[i] === '/' && code[i + 1] === '/') {
+        let end = i + 2
+        while (end < n && code[end] !== '\n') end++
+        result.push(span('comment', code.slice(i, end)))
+        i = end
+        continue
+      }
+
+      // Block comment
+      if (code[i] === '/' && code[i + 1] === '*') {
+        let end = i + 2
+        while (end < n - 1 && !(code[end] === '*' && code[end + 1] === '/')) end++
+        end += 2
+        result.push(span('comment', code.slice(i, end)))
+        i = end
+        continue
+      }
+
+      // Preprocessor directive (at start of line or after whitespace)
+      if (code[i] === '#') {
+        // Check if # is at line start (allow leading whitespace)
+        let checkPos = i - 1
+        while (checkPos >= 0 && (code[checkPos] === ' ' || code[checkPos] === '\t')) checkPos--
+        if (checkPos < 0 || code[checkPos] === '\n') {
+          let end = i + 1
+          // Handle line continuation with backslash
+          while (end < n) {
+            if (code[end] === '\n') {
+              if (code[end - 1] === '\\') {
+                end++
+                continue
+              }
+              break
+            }
+            end++
+          }
+          result.push(span('preprocessor', code.slice(i, end)))
+          i = end
+          continue
+        }
+      }
+
+      // Raw string literal R"delimiter(...)delimiter"
+      if (code[i] === 'R' && code[i + 1] === '"') {
+        let delimEnd = i + 2
+        while (delimEnd < n && code[delimEnd] !== '(') delimEnd++
+        const delimiter = code.slice(i + 2, delimEnd)
+        const endMarker = ')' + delimiter + '"'
+        let end = delimEnd + 1
+        while (end < n) {
+          if (code.slice(end, end + endMarker.length) === endMarker) {
+            end += endMarker.length
+            break
+          }
+          end++
+        }
+        result.push(span('string', code.slice(i, end)))
+        i = end
+        continue
+      }
+
+      // String literal (with optional prefix)
+      if (code[i] === '"' ||
+        ((code[i] === 'L' || code[i] === 'u' || code[i] === 'U') && code[i + 1] === '"') ||
+        (code[i] === 'u' && code[i + 1] === '8' && code[i + 2] === '"')) {
+        const start = i
+        if (code[i] === 'u' && code[i + 1] === '8') i += 2
+        else if (code[i] !== '"') i++
+        i++ // skip opening quote
+        while (i < n && code[i] !== '"') {
+          if (code[i] === '\\' && i + 1 < n) i += 2
+          else i++
+        }
+        i++ // skip closing quote
+        result.push(span('string', code.slice(start, i)))
+        continue
+      }
+
+      // Character literal
+      if (code[i] === '\'' ||
+        ((code[i] === 'L' || code[i] === 'u' || code[i] === 'U') && code[i + 1] === '\'') ||
+        (code[i] === 'u' && code[i + 1] === '8' && code[i + 2] === '\'')) {
+        const start = i
+        if (code[i] === 'u' && code[i + 1] === '8') i += 2
+        else if (code[i] !== '\'') i++
+        i++ // skip opening quote
+        while (i < n && code[i] !== '\'') {
+          if (code[i] === '\\' && i + 1 < n) i += 2
+          else i++
+        }
+        i++ // skip closing quote
+        result.push(span('string', code.slice(start, i)))
+        continue
+      }
+
+      // Identifier or keyword
+      if (/[a-zA-Z_]/.test(code[i])) {
+        let end = i + 1
+        while (end < n && /[a-zA-Z0-9_]/.test(code[end])) end++
+        const word = code.slice(i, end)
+        if (KEYWORDS.has(word)) {
+          result.push(span('keyword', word))
+        } else {
+          result.push(escapeHtml(word))
+        }
+        i = end
+        continue
+      }
+
+      // Default: single character
+      result.push(escapeHtml(code[i]))
+      i++
+    }
+
+    return result.join('')
+  }
+
+  function highlightElement (el) {
+    el.innerHTML = highlight(el.textContent)
+  }
+
+  function highlightAll (selector = 'code.cpp, code.c++, pre.cpp, pre.c++') {
+    document.querySelectorAll(selector).forEach(highlightElement)
+  }
+
+  return {
+    highlight,
+    highlightElement,
+    highlightAll,
+    KEYWORDS,
+  }
+})()
+
+// CommonJS / ES module support
+if (typeof module !== 'undefined' && module.exports) {
+  module.exports = CppHighlight
+}

antora-ui/src/js/vendor/highlight.bundle.js

@@ -2,11 +2,92 @@
   'use strict'
 
   var hljs = require('highlight.js/lib/common')
+  var CppHighlight = require('./cpp-highlight')
 
   // Only register languages not included in common bundle
   hljs.registerLanguage('cmake', require('highlight.js/lib/languages/cmake'))
 
-  hljs.highlightAll()
+  // Replace C++ highlighting AFTER highlight.js processes blocks
+  // Let hljs work initially, then replace C++ blocks with custom highlighter
+  function processCppBlocks () {
+    // Selectors for C++ code blocks that highlight.js has already processed
+    var cppSelectors = [
+      'code.language-cpp.hljs',
+      'code.language-c++.hljs',
+      'code[data-lang="cpp"].hljs',
+      'code[data-lang="c++"].hljs',
+      '.doc pre.highlight code[data-lang="cpp"].hljs',
+      '.doc pre.highlight code[data-lang="c++"].hljs',
+    ]
+
+    var processedCount = 0
+
+    cppSelectors.forEach(function (selector) {
+      try {
+        document.querySelectorAll(selector).forEach(function (el) {
+          // Skip if already processed
+          if (el.classList.contains('cpp-highlight')) return
+
+          // Replace highlight.js's C++ highlighting with our custom highlighter
+          // This gives us full control over C++ syntax highlighting
+          CppHighlight.highlightElement(el)
+
+          // Mark as processed with our custom highlighter
+          el.classList.add('cpp-highlight')
+          processedCount++
+        })
+      } catch (e) {
+        console.warn('cpp-highlight error:', selector, e)
+      }
+    })
+
+    if (processedCount > 0) {
+      console.log('cpp-highlight: Replaced ' + processedCount + ' C++ code blocks')
+    }
+  }
+
+  // Process C++ blocks after highlight.js runs
+  function initHighlighting () {
+    // First, let highlight.js process everything
+    hljs.highlightAll()
+
+    // Then, replace C++ blocks with our custom highlighter
+    // Use setTimeout to ensure highlight.js is completely done
+    setTimeout(function () {
+      processCppBlocks()
+    }, 0)
+  }
+
+  // Process when DOM is ready
+  if (document.readyState === 'loading') {
+    document.addEventListener('DOMContentLoaded', initHighlighting)
+  } else {
+    // DOM already loaded
+    initHighlighting()
+  }
+
+  // Also use MutationObserver to catch dynamically added content
+  // Process C++ blocks after highlight.js processes new content
+  if (typeof window.MutationObserver !== 'undefined') {
+    var observer = new window.MutationObserver(function (mutations) {
+      var shouldProcess = false
+      mutations.forEach(function (mutation) {
+        if (mutation.addedNodes.length > 0) {
+          shouldProcess = true
+        }
+      })
+      if (shouldProcess) {
+        // Wait a bit for highlight.js to process new content
+        setTimeout(function () {
+          processCppBlocks()
+        }, 100)
+      }
+    })
+    observer.observe(document.body || document.documentElement, {
+      childList: true,
+      subtree: true,
+    })
+  }
 
   window.hljs = hljs
 })()