Embed highlight.js with a custom Aria grammar

Author: Enrico Granata

_config.yml

@@ -41,6 +41,12 @@ titles_from_headings:
 include:
   - blog/
 
+highlighter: none
+markdown: kramdown
+kramdown:
+  syntax_highlighter_opts:
+    disable: true
+
 # Exclude from processing.
 # The following items will not be processed, by default.
 # Any item listed under the `exclude:` key here will be automatically added to

_includes/head-custom.html

@@ -0,0 +1,14 @@
+<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/highlight.js@11/styles/github.min.css">
+
+<script type="module">
+    import hljs from "https://cdn.jsdelivr.net/npm/highlight.js@11/es/core.min.js";
+    import aria from "/assets/js/aria.js";
+
+    hljs.registerLanguage("aria", aria);
+
+    document.addEventListener("DOMContentLoaded", () => {
+        document.querySelectorAll("pre code").forEach(block => {
+            hljs.highlightElement(block);
+        });
+    });
+</script>

assets/js/aria.js

@@ -0,0 +1,165 @@
+// assets/js/aria.js
+/** @typedef {import('highlight.js').HLJSApi} HLJSApi */
+/** @param {HLJSApi} hljs */
+export default function (hljs) {
+    // ---------- Lexical ----------
+
+    const LINE_COMMENT = hljs.COMMENT('#', '$');
+    const SHEBANG = hljs.SHEBANG({ binary: '' });
+
+    // escapes: \n \t \\ \xNN \u{...}
+    const ESCAPE = {
+        className: 'subst',
+        begin: /\\(?:[nt\\]|x[0-9A-Fa-f]{2}|u\{[0-9A-Fa-f]+\})/
+    };
+    const SQ_STRING = { className: 'string', begin: /'/, end: /'/, contains: [ESCAPE] };
+    const DQ_STRING = { className: 'string', begin: /"/, end: /"/, contains: [ESCAPE] };
+
+    // numbers
+    const HEX_INT = { className: 'number', begin: /0x[0-9A-Fa-f]+(?:_[0-9A-Fa-f]+)*/ };
+    const OCT_INT = { className: 'number', begin: /0o[0-7]+(?:_[0-7]+)*/ };
+    const BIN_INT = { className: 'number', begin: /0b[01]+(?:_[01]+)*/ };
+    const DEC_INT = { className: 'number', begin: /-?(?:0|[1-9][0-9]*)(?:_[0-9]+)*/ };
+    const DEC_FLOAT = {
+        className: 'number',
+        // -? DIGITS '.' DIGITS (exp)?
+        begin: /-?(?:0|[1-9][0-9]*)\.[0-9]+(?:[eE][+-]?[0-9]+)?/,
+        illegal: /_/ // no underscores in floats
+    };
+
+    // identifiers (approx)
+    const IDENT = /[A-Za-z_$][\w$]*/u;
+
+    // ---------- Keywords ----------
+
+    const KEYWORDS = {
+        keyword: [
+            'assert', 'else', 'elsif', 'extension', 'if', 'include', 'match', 'return', 'throw', 'while',
+            'val', 'var', 'type', 'func', 'operator', 'struct', 'enum', 'mixin', 'import', 'from', 'in',
+            'and', 'case', 'isa', 'instance', 'reverse', 'try', 'catch', 'break', 'continue', 'for'
+        ].join(' '),
+        literal: 'true false',
+        built_in: 'println assert',
+        type: 'Int Float String Bool Result Maybe Any'
+    };
+
+    // ---------- Declarations & titles ----------
+
+    const FUNC_DEF = {
+        className: 'function',
+        begin: new RegExp(`\\bfunc\\s+(${IDENT.source})\\s*\\(`),
+        beginScope: { 1: 'title.function' },
+        end: /\)/,
+        excludeEnd: true,
+        keywords: KEYWORDS,
+        contains: [LINE_COMMENT, DQ_STRING, SQ_STRING, DEC_FLOAT, HEX_INT, OCT_INT, BIN_INT, DEC_INT]
+    };
+
+    const METHOD_DEF = {
+        className: 'function',
+        begin: new RegExp(`\\b(?:instance|type)\\s+func\\s+(${IDENT.source})\\s*\\(`),
+        beginScope: { 1: 'title.function' },
+        end: /\)/,
+        excludeEnd: true,
+        keywords: KEYWORDS,
+        contains: [LINE_COMMENT, DQ_STRING, SQ_STRING, DEC_FLOAT, HEX_INT, OCT_INT, BIN_INT, DEC_INT]
+    };
+
+    // operator symbols from grammar
+    const OP_SYM = /\+\-|u\-|\+|\-|\*|\/|%|<<|>>|==|<=|>=|<|>|\&|\||\^|\(\)|\[\]=|\[\]/;
+    const OP_DEF = {
+        className: 'function',
+        begin: new RegExp(`\\b(?:reverse\\s+)?operator\\s+(${OP_SYM.source})\\s*\\(`),
+        beginScope: { 1: 'title.function' },
+        end: /\)/,
+        excludeEnd: true,
+        keywords: KEYWORDS,
+        contains: [LINE_COMMENT]
+    };
+
+    const TYPE_LIKE_DEF = {
+        className: 'class',
+        variants: [
+            { begin: new RegExp(`\\bstruct\\s+(${IDENT.source})\\b`) },
+            { begin: new RegExp(`\\benum\\s+(${IDENT.source})\\b`) },
+            { begin: new RegExp(`\\bmixin\\s+(${IDENT.source})\\b`) }
+        ],
+        beginScope: { 1: 'title.class' }
+    };
+
+    const EXTENSION_DEF = {
+        begin: new RegExp(`\\bextension\\s+(${IDENT.source})\\b`),
+        beginScope: { 1: 'type' }
+    };
+
+    const ENUM_CASE_DECL = {
+        className: 'constant',
+        begin: new RegExp(`\\bcase\\s+(${IDENT.source})\\b`),
+        beginScope: { 1: 'constant' }
+    };
+
+    const ENUM_CASE_USE = {
+        className: 'constant',
+        begin: new RegExp(`::\\s*(${IDENT.source})`),
+        beginScope: { 1: 'constant' }
+    };
+
+    // lambdas: |args| => ...
+    const LAMBDA_HEAD = {
+        begin: /\|/,
+        end: /\|\s*=>/,
+        excludeEnd: true,
+        contains: [LINE_COMMENT, { className: 'params', begin: /[^|]+/ }],
+        relevance: 1
+    };
+
+    // postfix try-protocol
+    const TRY_PROTOCOL = { className: 'operator', begin: /\?\?|\!\!/ };
+
+    // compound assign ops used in statements
+    const ASSIGN_OP = { className: 'operator', begin: /\+=|-=|\*=|\/=|%=/, relevance: 0 };
+
+    const INDEXING = {
+        begin: /\[/, end: /\]/,
+        contains: [LINE_COMMENT, DQ_STRING, SQ_STRING, DEC_FLOAT, HEX_INT, OCT_INT, BIN_INT, DEC_INT],
+        relevance: 0
+    };
+
+    const OBJECT_WRITE = {
+        begin: /\{/, end: /\}/,
+        contains: [LINE_COMMENT, DQ_STRING, SQ_STRING, INDEXING],
+        relevance: 0
+    };
+
+    const IMPORTS = {
+        begin: /\bimport\b/, end: /;/,
+        keywords: KEYWORDS,
+        contains: [LINE_COMMENT, { begin: /\bfrom\b/, className: 'keyword' }],
+        relevance: 0
+    };
+
+    // ---------- REPL transcript support ----------
+    // Prompt line: 〉...
+    const REPL_PROMPT = { className: 'meta', begin: /^〉\s?/m, relevance: 0 };
+    // Continuation lines: ::: ...
+    const REPL_CONT = { className: 'meta', begin: /^:::\s?/m, relevance: 0 };
+
+    return {
+        name: 'Aria',
+        aliases: ['aria'],
+        keywords: KEYWORDS,
+        contains: [
+            SHEBANG,
+            REPL_PROMPT, REPL_CONT,
+            LINE_COMMENT,
+            DQ_STRING, SQ_STRING,
+            DEC_FLOAT, HEX_INT, OCT_INT, BIN_INT, DEC_INT,
+            FUNC_DEF, METHOD_DEF, OP_DEF,
+            TYPE_LIKE_DEF, EXTENSION_DEF,
+            ENUM_CASE_DECL, ENUM_CASE_USE,
+            LAMBDA_HEAD, TRY_PROTOCOL, ASSIGN_OP,
+            INDEXING, OBJECT_WRITE,
+            IMPORTS
+        ]
+    };
+}