(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);