(function(Prism) {
  Prism.languages.crystal = Prism.languages.extend('ruby', {
    keyword: [
      /\b(?:abstract|alias|as|asm|begin|break|case|class|def|do|else|elsif|end|ensure|enum|extend|for|fun|if|include|instance_sizeof|lib|macro|module|next|of|out|pointerof|private|protected|rescue|return|require|select|self|sizeof|struct|super|then|type|typeof|uninitialized|union|unless|until|when|while|with|yield|__DIR__|__END_LINE__|__FILE__|__LINE__)\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/,
  });

  var rest = Prism.util.clone(Prism.languages.crystal);

  Prism.languages.insertBefore('crystal', 'string', {
    attribute: {
      pattern: /@\[.+?\]/,
      alias: 'attr-name',
      inside: {
        delimiter: {
          pattern: /^@\[|\]$/,
          alias: 'tag',
        },
        rest: rest,
      },
    },

    expansion: [
      {
        pattern: /\{\{.+?\}\}/,
        inside: {
          delimiter: {
            pattern: /^\{\{|\}\}$/,
            alias: 'tag',
          },
          rest: rest,
        },
      },
      {
        pattern: /\{%.+?%\}/,
        inside: {
          delimiter: {
            pattern: /^\{%|%\}$/,
            alias: 'tag',
          },
          rest: rest,
        },
      },
    ],
  });
})(Prism);
