source: node_modules/prismjs/components/prism-crystal.js

(function (Prism) {
        Prism.languages.crystal = Prism.languages.extend('ruby', {
                'keyword': [
                        /\b(?:__DIR__|__END_LINE__|__FILE__|__LINE__|abstract|alias|annotation|as|asm|begin|break|case|class|def|do|else|elsif|end|ensure|enum|extend|for|fun|if|ifdef|include|instance_sizeof|lib|macro|module|next|of|out|pointerof|private|protected|ptr|require|rescue|return|select|self|sizeof|struct|super|then|type|typeof|undef|uninitialized|union|unless|until|when|while|with|yield)\b/,
                        {
                                pattern: /(\.\s*)(?:is_a|responds_to)\?/,
                                lookbehind: true
                        }
                ],
                'number': /\b(?:0b[01_]*[01]|0o[0-7_]*[0-7]|0x[\da-fA-F_]*[\da-fA-F]|(?:\d(?:[\d_]*\d)?)(?:\.[\d_]*\d)?(?:[eE][+-]?[\d_]*\d)?)(?:_(?:[uif](?:8|16|32|64))?)?\b/,
                'operator': [
                        /->/,
                        Prism.languages.ruby.operator,
                ],
                'punctuation': /[(){}[\].,;\\]/,
        });

        Prism.languages.insertBefore('crystal', 'string-literal', {
                'attribute': {
                        pattern: /@\[.*?\]/,
                        inside: {
                                'delimiter': {
                                        pattern: /^@\[|\]$/,
                                        alias: 'punctuation'
                                },
                                'attribute': {
                                        pattern: /^(\s*)\w+/,
                                        lookbehind: true,
                                        alias: 'class-name'
                                },
                                'args': {
                                        pattern: /\S(?:[\s\S]*\S)?/,
                                        inside: Prism.languages.crystal
                                },
                        }
                },
                'expansion': {
                        pattern: /\{(?:\{.*?\}|%.*?%)\}/,
                        inside: {
                                'content': {
                                        pattern: /^(\{.)[\s\S]+(?=.\}$)/,
                                        lookbehind: true,
                                        inside: Prism.languages.crystal
                                },
                                'delimiter': {
                                        pattern: /^\{[\{%]|[\}%]\}$/,
                                        alias: 'operator'
                                }
                        }
                },
                'char': {
                        pattern: /'(?:[^\\\r\n]{1,2}|\\(?:.|u(?:[A-Fa-f0-9]{1,4}|\{[A-Fa-f0-9]{1,6}\})))'/,
                        greedy: true
                }
        });

}(Prism));