module.exports = grammar({
  name: 'dust',

  rules: {
    source: $ => repeat(choice(
      $.comment,
      $.identifier,
      $.value,
      $.tool,
      $.operator,
    )),

    comment: $ => seq('#', /.*/),

    identifier: $ => /[a-zA-Z|_|.]+(_[a-zA-Z]+)*/,

    value: $ => choice(
      $.integer,
      $.float,
      $.string,
      $.list,
      $.empty,
      $.boolean,
      $.function,
    ), 

    tool: $ => choice(
      "random",
      "random_boolean",
      "random_integer",
      "random_string",
      "random_float",
    ),

    operator: $ => choice(
      '=',
      '-',
      '+',
      '/',
      '|',
      '&',
      ';',
      "->",
    ),

    float: $ => /\d+\.\d*/,
    
    integer: $ => /\d+/,

    string: $ => /("|')(.*?)("|')/,

    function: $ => /{(.*?)}/,

    empty: $ => "()",

    boolean: $ => choice(
      "true",
      "false"
    ),

    list: $ => seq(
      '(',
      repeat1(seq($.value, optional(','))),
      ')'
    ),
  }
});