Prism.languages.antlr4 = {
  comment: /\/\/.*|\/\*[\s\S]*?(?:\*\/|$)/,
  string: {
    pattern: /'(?:\\.|[^\\'\r\n])*'/,
    greedy: true,
  },
  'character-class': {
    pattern: /\[(?:\\.|[^\\\]\r\n])*\]/,
    greedy: true,
    alias: 'regex',
    inside: {
      range: {
        pattern: /([^[]|(?:^|[^\\])(?:\\\\)*\\\[)-(?!\])/,
        lookbehind: true,
        alias: 'punctuation',
      },
      escape:
        /\\(?:u(?:[a-fA-F\d]{4}|\{[a-fA-F\d]+\})|[pP]\{[=\w-]+\}|[^\r\nupP])/,
      punctuation: /[\[\]]/,
    },
  },
  action: {
    pattern: /\{(?:[^{}]|\{(?:[^{}]|\{(?:[^{}]|\{[^{}]*\})*\})*\})*\}/,
    greedy: true,
    inside: {
      content: {
        // this might be C, C++, Python, Java, C#, or any other language ANTLR4 compiles to
        pattern: /(\{)[\s\S]+(?=\})/,
        lookbehind: true,
      },
      punctuation: /[{}]/,
    },
  },
  command: {
    pattern:
      /(->\s*(?!\s))(?:\s*(?:,\s*)?\b[a-z]\w*(?:\s*\([^()\r\n]*\))?)+(?=\s*;)/i,
    lookbehind: true,
    inside: {
      function: /\b\w+(?=\s*(?:[,(]|$))/,
      punctuation: /[,()]/,
    },
  },
  annotation: {
    pattern: /@\w+(?:::\w+)*/,
    alias: 'keyword',
  },
  label: {
    pattern: /#[ \t]*\w+/,
    alias: 'punctuation',
  },
  keyword:
    /\b(?:catch|channels|finally|fragment|grammar|import|lexer|locals|mode|options|parser|returns|throws|tokens)\b/,
  definition: [
    {
      pattern: /\b[a-z]\w*(?=\s*:)/,
      alias: ['rule', 'class-name'],
    },
    {
      pattern: /\b[A-Z]\w*(?=\s*:)/,
      alias: ['token', 'constant'],
    },
  ],
  constant: /\b[A-Z][A-Z_]*\b/,
  operator: /\.\.|->|[|~]|[*+?]\??/,
  punctuation: /[;:()=]/,
};

Prism.languages.g4 = Prism.languages.antlr4;