willbooster-tree-sitter-ruby 2.0.4

/// <reference types="tree-sitter-cli/dsl" />
// @ts-check

const PREC = {
  COMMENT: -2,
  CURLY_BLOCK: 1,
  DO_BLOCK: -1,

  AND: -2,
  OR: -2,
  NOT: 5,
  DEFINED: 10,
  ALIAS: 11,
  ASSIGN: 15,
  RESCUE: 16,
  CONDITIONAL: 20,
  RANGE: 25,
  BOOLEAN_OR: 30,
  BOOLEAN_AND: 35,
  RELATIONAL: 40,
  COMPARISON: 45,
  BITWISE_OR: 50,
  BITWISE_AND: 55,
  CALL: 56,
  SHIFT: 60,
  ADDITIVE: 65,
  MULTIPLICATIVE: 70,
  UNARY_MINUS: 75,
  EXPONENTIAL: 80,
  COMPLEMENT: 85,
};

// Regex sources reach src/grammar.json as written, so they keep upstream's spelling, and tree-sitter's regex parser
// rejects an unescaped `[` in a character class.
// oxlint-disable no-control-regex, no-useless-escape, unicorn/no-hex-escape -- See above.
const IDENTIFIER_CHARS = /[^\x00-\x1F\s:;`"'@$#.,|^&<=>+\-*/\\%?!~()\[\]{}]*/;
const LOWER_ALPHA_CHAR = /[^\x00-\x1F\sA-Z0-9:;`"'@$#.,|^&<=>+\-*/\\%?!~()\[\]{}]/;
const ALPHA_CHAR = /[^\x00-\x1F\s0-9:;`"'@$#.,|^&<=>+\-*/\\%?!~()\[\]{}]/;
// oxlint-enable no-control-regex, no-useless-escape, unicorn/no-hex-escape

// oxlint-disable-next-line unicorn/prefer-module -- This package is CommonJS, so tree-sitter loads grammar.js as CommonJS.
module.exports = grammar({
  name: 'ruby',
  inline: ($) => [$._arg_rhs, $._call_operator],
  externals: ($) => [
    $._line_break,
    $._no_line_break,

    // Delimited literals
    $.simple_symbol,
    $._string_start,
    $._symbol_start,
    $._subshell_start,
    $._regex_start,
    $._string_array_start,
    $._symbol_array_start,
    $._heredoc_body_start,
    $.string_content,
    $.heredoc_content,
    $._string_end,
    $.heredoc_end,
    $.heredoc_beginning,

    // Tokens that require lookahead
    '/',
    $._block_ampersand,
    $._splat_star,
    $._unary_minus,
    $._unary_minus_num,
    $._binary_minus,
    $._binary_star,
    $._bitwise_and,
    $._singleton_class_left_angle_left_langle,
    $.hash_key_symbol,
    $._identifier_suffix,
    $._constant_suffix,
    $._hash_splat_star_star,
    $._binary_star_star,
    $._element_reference_bracket,
    $._short_interpolation,
    $._line_comment,
    $._uninterpreted,
  ],

  extras: ($) => [$.comment, $.heredoc_body, /\s/, /\\\r?\n/],

  word: ($) => $.identifier,

  supertypes: ($) => [
    $._statement,
    $._arg,
    $._method_name,
    $._expression,
    $._variable,
    $._primary,
    $._simple_numeric,
    $._lhs,
    $._nonlocal_variable,
    $._pattern_top_expr_body,
    $._pattern_expr,
    $._pattern_expr_basic,
    $._pattern_primitive,
    $._pattern_constant,
  ],

  rules: {
    program: ($) => seq(optional($._statements), optional(choice(seq(/__END__/, $.uninterpreted)))),

    // External extras must yield to the internal lexer after __END__.
    uninterpreted: ($) => choice(/(.|\s)*/, $._uninterpreted),

    block_body: ($) => $._statements,

    _statements: ($) =>
      choice(
        seq(repeat1(choice(seq($._statement, $._terminator), $.empty_statement)), optional($._statement)),
        $._statement
      ),

    begin_block: ($) => seq('BEGIN', '{', optional($._statements), '}'),
    end_block: ($) => seq('END', '{', optional($._statements), '}'),

    _statement: ($) =>
      choice(
        $.undef,
        $.alias,
        $.if_modifier,
        $.unless_modifier,
        $.while_modifier,
        $.until_modifier,
        $.rescue_modifier,
        $.begin_block,
        $.end_block,
        $._expression
      ),

    method: ($) => seq('def', $._method_rest),

    singleton_method: ($) =>
      seq(
        'def',
        seq(choice(field('object', $._variable), seq('(', field('object', $._arg), ')')), choice('.', '::')),
        $._method_rest
      ),

    _method_rest: ($) =>
      seq(
        field('name', $._method_name),
        choice(
          $._body_expr,
          seq(
            field('parameters', alias($.parameters, $.method_parameters)),
            choice(seq(optional($._terminator), optional(field('body', $.body_statement)), 'end'), $._body_expr)
          ),
          seq(
            optional(field('parameters', alias($.bare_parameters, $.method_parameters))),
            $._terminator,
            optional(field('body', $.body_statement)),
            'end'
          )
        )
      ),

    rescue_modifier_arg: ($) => prec(PREC.RESCUE, seq(field('body', $._arg), 'rescue', field('handler', $._arg))),

    rescue_modifier_expression: ($) =>
      prec(PREC.RESCUE, seq(field('body', $._expression), 'rescue', field('handler', $._arg))),

    _body_expr: ($) => seq('=', field('body', choice($._arg, alias($.rescue_modifier_arg, $.rescue_modifier)))),

    parameters: ($) => seq('(', commaSep($._formal_parameter), ')'),

    bare_parameters: ($) => seq($._simple_formal_parameter, repeat(seq(',', $._formal_parameter))),

    block_parameters: ($) =>
      seq(
        '|',
        seq(commaSep($._formal_parameter), optional(',')),
        optional(seq(';', sep1(field('locals', $.identifier), ','))), // Block shadow args e.g. {|; a, b| ...}
        '|'
      ),

    _formal_parameter: ($) => choice($._simple_formal_parameter, alias($.parameters, $.destructured_parameter)),

    _simple_formal_parameter: ($) =>
      choice(
        $.identifier,
        $.splat_parameter,
        $.hash_splat_parameter,
        $.hash_splat_nil,
        $.forward_parameter,
        $.block_parameter,
        $.keyword_parameter,
        $.optional_parameter
      ),

    forward_parameter: () => '...',

    splat_parameter: ($) => prec.right(-2, seq('*', field('name', optional($.identifier)))),
    hash_splat_parameter: ($) => seq('**', field('name', optional($.identifier))),
    hash_splat_nil: () => seq('**', 'nil'),
    block_parameter: ($) => seq('&', field('name', optional($.identifier))),
    keyword_parameter: ($) =>
      prec.right(
        PREC.BITWISE_OR + 1,
        seq(field('name', $.identifier), token.immediate(':'), field('value', optional($._arg)))
      ),
    optional_parameter: ($) => prec(PREC.BITWISE_OR + 1, seq(field('name', $.identifier), '=', field('value', $._arg))),

    class: ($) =>
      seq(
        'class',
        field('name', choice($.constant, $.scope_resolution)),
        choice(seq(field('superclass', $.superclass), $._terminator), optional($._terminator)),
        optional(field('body', $.body_statement)),
        'end'
      ),

    superclass: ($) => seq('<', $._expression),

    singleton_class: ($) =>
      seq(
        'class',
        alias($._singleton_class_left_angle_left_langle, '<<'),
        field('value', $._arg),
        $._terminator,
        optional(field('body', $.body_statement)),
        'end'
      ),

    module: ($) =>
      seq(
        'module',
        field('name', choice($.constant, $.scope_resolution)),
        optional($._terminator),
        optional(field('body', $.body_statement)),
        'end'
      ),

    return_command: ($) => prec.left(seq('return', alias($.command_argument_list, $.argument_list))),
    yield_command: ($) => prec.left(seq('yield', alias($.command_argument_list, $.argument_list))),
    break_command: ($) => prec.left(seq('break', alias($.command_argument_list, $.argument_list))),
    next_command: ($) => prec.left(seq('next', alias($.command_argument_list, $.argument_list))),
    return: ($) => prec.left(seq('return', optional($.argument_list))),
    yield: ($) => prec.left(seq('yield', optional($.argument_list))),
    break: ($) => prec.left(seq('break', optional($.argument_list))),
    next: ($) => prec.left(seq('next', optional($.argument_list))),
    redo: ($) => prec.left(seq('redo', optional($.argument_list))),
    retry: ($) => prec.left(seq('retry', optional($.argument_list))),

    if_modifier: ($) => prec(PREC.RESCUE, seq(field('body', $._statement), 'if', field('condition', $._expression))),

    unless_modifier: ($) =>
      prec(PREC.RESCUE, seq(field('body', $._statement), 'unless', field('condition', $._expression))),

    while_modifier: ($) =>
      prec(PREC.RESCUE, seq(field('body', $._statement), 'while', field('condition', $._expression))),

    until_modifier: ($) =>
      prec(PREC.RESCUE, seq(field('body', $._statement), 'until', field('condition', $._expression))),

    rescue_modifier: ($) =>
      prec(PREC.RESCUE, seq(field('body', $._statement), 'rescue', field('handler', $._expression))),

    while: ($) => seq('while', field('condition', $._statement), field('body', $.do)),

    until: ($) => seq('until', field('condition', $._statement), field('body', $.do)),

    for: ($) =>
      seq('for', field('pattern', choice($._lhs, $.left_assignment_list)), field('value', $.in), field('body', $.do)),

    in: ($) => seq('in', $._arg),
    do: ($) => seq(choice('do', $._terminator), optional($._statements), 'end'),

    case: ($) =>
      seq(
        'case',
        optional(seq(optional($._line_break), field('value', $._statement))),
        optional($._terminator),
        repeat($.when),
        optional($.else),
        'end'
      ),

    case_match: ($) =>
      seq(
        'case',
        seq(optional($._line_break), field('value', $._statement)),
        optional($._terminator),
        repeat1(field('clauses', $.in_clause)),
        optional(field('else', $.else)),
        'end'
      ),

    when: ($) => seq('when', commaSep1(field('pattern', $.pattern)), choice($._terminator, field('body', $.then))),

    in_clause: ($) =>
      seq(
        'in',
        field('pattern', $._pattern_top_expr_body),
        field('guard', optional($._guard)),
        choice($._terminator, field('body', $.then))
      ),

    pattern: ($) => choice($._arg, $.splat_argument),

    _guard: ($) => choice($.if_guard, $.unless_guard),

    if_guard: ($) => seq('if', field('condition', $._expression)),

    unless_guard: ($) => seq('unless', field('condition', $._expression)),

    _pattern_top_expr_body: ($) =>
      prec(
        -1,
        choice(
          $._pattern_expr,
          alias($._array_pattern_n, $.array_pattern),
          alias($._find_pattern_body, $.find_pattern),
          alias($._hash_pattern_body, $.hash_pattern)
        )
      ),

    _array_pattern_n: ($) =>
      prec.right(
        choice(
          seq($._pattern_expr, alias(',', $.splat_parameter)),
          seq($._pattern_expr, ',', choice($._pattern_expr, $._array_pattern_n)),
          seq($.splat_parameter, repeat(seq(',', $._pattern_expr)))
        )
      ),

    _pattern_expr: ($) => choice($.as_pattern, $._pattern_expr_alt),

    as_pattern: ($) => seq(field('value', $._pattern_expr), '=>', field('name', $.identifier)),

    _pattern_expr_alt: ($) => choice($.alternative_pattern, $._pattern_expr_basic),

    alternative_pattern: ($) =>
      seq(
        field('alternatives', $._pattern_expr_basic),
        repeat1(seq('|', field('alternatives', $._pattern_expr_basic)))
      ),

    _array_pattern_body: ($) => choice($._pattern_expr, $._array_pattern_n),

    array_pattern: ($) =>
      prec.right(
        -1,
        choice(
          seq('[', optional($._array_pattern_body), ']'),
          seq(field('class', $._pattern_constant), token.immediate('['), optional($._array_pattern_body), ']'),
          seq(field('class', $._pattern_constant), token.immediate('('), optional($._array_pattern_body), ')')
        )
      ),

    _find_pattern_body: ($) => seq($.splat_parameter, repeat1(seq(',', $._pattern_expr)), ',', $.splat_parameter),
    find_pattern: ($) =>
      choice(
        seq('[', $._find_pattern_body, ']'),
        seq(field('class', $._pattern_constant), token.immediate('['), $._find_pattern_body, ']'),
        seq(field('class', $._pattern_constant), token.immediate('('), $._find_pattern_body, ')')
      ),

    _hash_pattern_body: ($) =>
      prec.right(
        choice(
          seq(commaSep1($.keyword_pattern), optional(',')),
          seq(commaSep1($.keyword_pattern), ',', $._hash_pattern_any_rest),
          $._hash_pattern_any_rest
        )
      ),

    keyword_pattern: ($) =>
      prec.right(
        -1,
        seq(
          field(
            'key',
            choice(
              alias($.identifier, $.hash_key_symbol),
              alias($.constant, $.hash_key_symbol),
              alias($.identifier_suffix, $.hash_key_symbol),
              alias($.constant_suffix, $.hash_key_symbol),
              $.string
            )
          ),
          token.immediate(':'),
          optional(field('value', $._pattern_expr))
        )
      ),

    _hash_pattern_any_rest: ($) => choice($.hash_splat_parameter, $.hash_splat_nil),

    hash_pattern: ($) =>
      prec.right(
        -1,
        choice(
          seq('{', optional($._hash_pattern_body), '}'),
          seq(field('class', $._pattern_constant), token.immediate('['), $._hash_pattern_body, ']'),
          seq(field('class', $._pattern_constant), token.immediate('('), $._hash_pattern_body, ')')
        )
      ),

    _pattern_expr_basic: ($) =>
      prec.right(
        -1,
        choice($._pattern_value, $.identifier, $.array_pattern, $.find_pattern, $.hash_pattern, $.parenthesized_pattern)
      ),

    parenthesized_pattern: ($) => seq('(', $._pattern_expr, ')'),

    _pattern_value: ($) =>
      prec.right(
        -1,
        choice(
          $._pattern_primitive,
          alias($._pattern_range, $.range),
          $.variable_reference_pattern,
          $.expression_reference_pattern,
          $._pattern_constant
        )
      ),

    _pattern_range: ($) => {
      const begin = field('begin', $._pattern_primitive);
      const end = field('end', $._pattern_primitive);
      const operator = field('operator', choice('..', '...'));
      return choice(seq(begin, operator, end), seq(operator, end), seq(begin, operator));
    },

    _pattern_primitive: ($) => choice($._pattern_literal, $._pattern_lambda),

    _pattern_lambda: ($) => prec.right(-1, $.lambda),

    _pattern_literal: ($) =>
      prec.right(
        -1,
        choice(
          $._literal,
          $.string,
          $.subshell,
          $.heredoc_beginning,
          $.regex,
          $.string_array,
          $.symbol_array,
          $._keyword_variable
        )
      ),

    _keyword_variable: ($) => prec.right(-1, choice($.nil, $.self, $.true, $.false, $.line, $.file, $.encoding)),

    line: () => '__LINE__',
    file: () => '__FILE__',
    encoding: () => '__ENCODING__',

    variable_reference_pattern: ($) => seq('^', field('name', choice($.identifier, $._nonlocal_variable))),

    expression_reference_pattern: ($) => seq('^', '(', field('value', $._expression), ')'),

    _pattern_constant: ($) =>
      prec.right(-1, choice($.constant, alias($._pattern_constant_resolution, $.scope_resolution))),

    _pattern_constant_resolution: ($) =>
      seq(optional(field('scope', $._pattern_constant)), '::', field('name', $.constant)),

    if: ($) =>
      seq(
        'if',
        field('condition', $._statement),
        choice($._terminator, field('consequence', $.then)),
        field('alternative', optional(choice($.else, $.elsif))),
        'end'
      ),

    unless: ($) =>
      seq(
        'unless',
        field('condition', $._statement),
        choice($._terminator, field('consequence', $.then)),
        field('alternative', optional(choice($.else, $.elsif))),
        'end'
      ),

    elsif: ($) =>
      seq(
        'elsif',
        field('condition', $._statement),
        choice($._terminator, field('consequence', $.then)),
        field('alternative', optional(choice($.else, $.elsif)))
      ),

    else: ($) => seq('else', optional($._terminator), optional($._statements)),

    // oxlint-disable-next-line unicorn/no-thenable -- `then` is a grammar rule, whose name is the node type that trees and queries expose.
    then: ($) =>
      choice(seq($._terminator, $._statements), seq(optional($._terminator), 'then', optional($._statements))),

    begin: ($) => seq('begin', optional($._terminator), optional($._body_statement), 'end'),

    ensure: ($) => seq('ensure', optional($._statements)),

    rescue: ($) =>
      seq(
        'rescue',
        field('exceptions', optional($.exceptions)),
        field('variable', optional($.exception_variable)),
        choice($._terminator, field('body', $.then))
      ),

    exceptions: ($) => commaSep1(choice($._arg, $.splat_argument)),

    exception_variable: ($) => seq('=>', $._lhs),

    body_statement: ($) => $._body_statement,

    _body_statement: ($) =>
      choice(
        seq($._statements, repeat(choice($.rescue, $.else, $.ensure))),
        seq(optional($._statements), repeat1(choice($.rescue, $.else, $.ensure)))
      ),

    // Method calls without parentheses (aka "command calls") are only allowed
    // in certain positions, like the top-level of a statement, the condition
    // of a postfix control-flow operator like `if`, or as the value of a
    // control-flow statement like `return`. In many other places, they're not
    // allowed.
    //
    // Because of this distinction, a lot of rules have two variants: the
    // normal variant, which can appear anywhere that an expression is valid,
    // and the "command" varaint, which is only valid in a more limited set of
    // positions, because it can contain "command calls".
    //
    // The `_expression` rule can appear in relatively few places, but can
    // contain command calls. The `_arg` rule can appear in many more places,
    // but cannot contain command calls (unless they are wrapped in parens).
    // This naming convention is based on Ruby's standard grammar.
    _expression: ($) =>
      choice(
        alias($.command_binary, $.binary),
        alias($.command_unary, $.unary),
        alias($.command_assignment, $.assignment),
        alias($.command_operator_assignment, $.operator_assignment),
        alias($.command_call, $.call),
        alias($.command_call_with_block, $.call),
        prec.left(alias($._chained_command_call, $.call)),
        alias($.return_command, $.return),
        alias($.yield_command, $.yield),
        alias($.break_command, $.break),
        alias($.next_command, $.next),
        $.match_pattern,
        $.test_pattern,
        $._arg
      ),

    match_pattern: ($) => prec(100, seq(field('value', $._arg), '=>', field('pattern', $._pattern_top_expr_body))),

    test_pattern: ($) => prec(100, seq(field('value', $._arg), 'in', field('pattern', $._pattern_top_expr_body))),

    _arg: ($) =>
      choice(
        alias($._unary_minus_pow, $.unary),
        $._primary,
        $.assignment,
        $.operator_assignment,
        $.conditional,
        $.range,
        $.binary,
        $.unary
      ),

    _unary_minus_pow: ($) =>
      seq(field('operator', alias($._unary_minus_num, '-')), field('operand', alias($._pow, $.binary))),
    _pow: ($) =>
      prec.right(
        PREC.EXPONENTIAL,
        seq(
          field('left', $._simple_numeric),
          field('operator', alias($._binary_star_star, '**')),
          field('right', $._arg)
        )
      ),

    _primary: ($) =>
      choice(
        $.parenthesized_statements,
        $._lhs,
        alias($._function_identifier_call, $.call),
        $.call,
        $.array,
        $.string_array,
        $.symbol_array,
        $.hash,
        $.subshell,
        $._literal,
        $.string,
        $.character,
        $.chained_string,
        $.regex,
        $.lambda,
        $.method,
        $.singleton_method,
        $.class,
        $.singleton_class,
        $.module,
        $.begin,
        $.while,
        $.until,
        $.if,
        $.unless,
        $.for,
        $.case,
        $.case_match,
        $.return,
        $.yield,
        $.break,
        $.next,
        $.redo,
        $.retry,
        alias($.parenthesized_unary, $.unary),
        $.heredoc_beginning
      ),

    parenthesized_statements: ($) => seq('(', optional($._statements), ')'),

    element_reference: ($) =>
      prec.left(
        1,
        seq(
          field('object', $._primary),
          alias($._element_reference_bracket, '['),
          optional($._argument_list_with_trailing_comma),
          ']',
          optional(field('block', choice($.block, $.do_block)))
        )
      ),

    scope_resolution: ($) =>
      prec.left(
        PREC.CALL + 1,
        seq(choice('::', seq(field('scope', $._primary), token.immediate('::'))), field('name', $.constant))
      ),

    _call_operator: () => choice('.', '&.', token.immediate('::')),
    _call: ($) =>
      prec.left(
        PREC.CALL,
        seq(
          field('receiver', $._primary),
          field('operator', $._call_operator),
          field('method', choice($.identifier, $.operator, $.constant, $._function_identifier))
        )
      ),

    command_call: ($) =>
      seq(
        choice($._call, $._chained_command_call, field('method', choice($._variable, $._function_identifier))),
        field('arguments', alias($.command_argument_list, $.argument_list))
      ),

    command_call_with_block: ($) => {
      const receiver = choice($._call, field('method', choice($._variable, $._function_identifier)));
      const args = field('arguments', alias($.command_argument_list, $.argument_list));
      const block = field('block', $.block);
      const doBlock = field('block', $.do_block);
      return choice(
        seq(receiver, prec(PREC.CURLY_BLOCK, seq(args, block))),
        seq(receiver, prec(PREC.DO_BLOCK, seq(args, doBlock)))
      );
    },

    _chained_command_call: ($) =>
      seq(
        field('receiver', alias($.command_call_with_block, $.call)),
        field('operator', $._call_operator),
        field('method', choice($.identifier, $._function_identifier, $.operator, $.constant))
      ),

    call: ($) => {
      const receiver = choice($._call, field('method', choice($._variable, $._function_identifier)));

      const args = field('arguments', $.argument_list);
      const receiverArguments = seq(
        choice(receiver, prec.left(PREC.CALL, seq(field('receiver', $._primary), field('operator', $._call_operator)))),
        args
      );

      const block = field('block', $.block);
      const doBlock = field('block', $.do_block);
      return choice(
        receiverArguments,
        prec(PREC.CURLY_BLOCK, seq(receiverArguments, block)),
        prec(PREC.DO_BLOCK, seq(receiverArguments, doBlock)),
        prec(PREC.CURLY_BLOCK, seq(receiver, block)),
        prec(PREC.DO_BLOCK, seq(receiver, doBlock))
      );
    },

    command_argument_list: ($) => prec.right(commaSep1($._argument)),

    argument_list: ($) => prec.right(seq(token.immediate('('), optional($._argument_list_with_trailing_comma), ')')),

    _argument_list_with_trailing_comma: ($) => prec.right(seq(commaSep1($._argument), optional(','))),

    _argument: ($) =>
      prec.left(
        choice($._expression, $.splat_argument, $.hash_splat_argument, $.forward_argument, $.block_argument, $.pair)
      ),

    forward_argument: () => '...',
    splat_argument: ($) => prec.right(seq(alias($._splat_star, '*'), optional($._arg))),
    hash_splat_argument: ($) => prec.right(seq(alias($._hash_splat_star_star, '**'), optional($._arg))),
    block_argument: ($) => prec.right(seq(alias($._block_ampersand, '&'), optional($._arg))),

    do_block: ($) =>
      seq(
        'do',
        optional($._terminator),
        optional(seq(field('parameters', $.block_parameters), optional($._terminator))),
        optional(field('body', $.body_statement)),
        'end'
      ),

    block: ($) =>
      prec(
        PREC.CURLY_BLOCK,
        seq('{', field('parameters', optional($.block_parameters)), optional(field('body', $.block_body)), '}')
      ),

    _arg_rhs: ($) => choice($._arg, alias($.rescue_modifier_arg, $.rescue_modifier)),
    assignment: ($) =>
      prec.right(
        PREC.ASSIGN,
        choice(
          seq(
            field('left', choice($._lhs, $.left_assignment_list)),
            '=',
            field('right', choice($._arg_rhs, $.splat_argument, $.right_assignment_list))
          )
        )
      ),

    command_assignment: ($) =>
      prec.right(
        PREC.ASSIGN,
        seq(
          field('left', choice($._lhs, $.left_assignment_list)),
          '=',
          field('right', choice($._expression, alias($.rescue_modifier_expression, $.rescue_modifier)))
        )
      ),

    operator_assignment: ($) =>
      prec.right(
        PREC.ASSIGN,
        seq(
          field('left', $._lhs),
          field('operator', choice('+=', '-=', '*=', '**=', '/=', '||=', '|=', '&&=', '&=', '%=', '>>=', '<<=', '^=')),
          field('right', $._arg_rhs)
        )
      ),

    command_operator_assignment: ($) =>
      prec.right(
        PREC.ASSIGN,
        seq(
          field('left', $._lhs),
          field('operator', choice('+=', '-=', '*=', '**=', '/=', '||=', '|=', '&&=', '&=', '%=', '>>=', '<<=', '^=')),
          field('right', choice($._expression, alias($.rescue_modifier_expression, $.rescue_modifier)))
        )
      ),

    conditional: ($) =>
      prec.right(
        PREC.CONDITIONAL,
        seq(field('condition', $._arg), '?', field('consequence', $._arg), ':', field('alternative', $._arg))
      ),

    range: ($) => {
      const begin = field('begin', $._arg);
      const end = field('end', $._arg);
      const operator = field('operator', choice('..', '...'));
      return prec.right(PREC.RANGE, choice(seq(begin, operator, end), seq(operator, end), seq(begin, operator)));
    },

    binary: ($) => {
      // oxlint-disable typescript/unbound-method -- The DSL's `prec` functions do not use `this`.
      /** @type {[(precedence: number, rule: RuleOrLiteral) => Rule, number, RuleOrLiteral][]} */
      const operators = [
        [prec.left, PREC.AND, 'and'],
        [prec.left, PREC.OR, 'or'],
        [prec.left, PREC.BOOLEAN_OR, '||'],
        [prec.left, PREC.BOOLEAN_AND, '&&'],
        [prec.left, PREC.SHIFT, choice('<<', '>>')],
        [prec.left, PREC.COMPARISON, choice('<', '<=', '>', '>=')],
        [prec.left, PREC.BITWISE_AND, alias($._bitwise_and, '&')],
        [prec.left, PREC.BITWISE_OR, choice('^', '|')],
        [prec.left, PREC.ADDITIVE, choice('+', alias($._binary_minus, '-'))],
        [prec.left, PREC.MULTIPLICATIVE, choice('/', '%', alias($._binary_star, '*'))],
        [prec.right, PREC.RELATIONAL, choice('==', '!=', '===', '<=>', '=~', '!~')],
        [prec.right, PREC.EXPONENTIAL, alias($._binary_star_star, '**')],
      ];
      // oxlint-enable typescript/unbound-method

      return choice(
        ...operators.map(([fn, precedence, operator]) =>
          fn(precedence, seq(field('left', $._arg), field('operator', operator), field('right', $._arg)))
        )
      );
    },

    command_binary: ($) =>
      prec.left(
        seq(field('left', $._expression), field('operator', choice('or', 'and')), field('right', $._expression))
      ),

    unary: ($) => {
      // oxlint-disable typescript/unbound-method -- The DSL's `prec` functions do not use `this`.
      /** @type {[(precedence: number, rule: RuleOrLiteral) => Rule, number, RuleOrLiteral][]} */
      const operators = [
        [prec, PREC.DEFINED, 'defined?'],
        [prec.right, PREC.NOT, 'not'],
        [prec.right, PREC.UNARY_MINUS, choice(alias($._unary_minus, '-'), alias($._binary_minus, '-'), '+')],
        [prec.right, PREC.COMPLEMENT, choice('!', '~')],
      ];
      // oxlint-enable typescript/unbound-method
      return choice(
        ...operators.map(([fn, precedence, operator]) =>
          fn(precedence, seq(field('operator', operator), field('operand', $._arg)))
        )
      );
    },

    command_unary: ($) => {
      // oxlint-disable typescript/unbound-method -- The DSL's `prec` functions do not use `this`.
      /** @type {[(precedence: number, rule: RuleOrLiteral) => Rule, number, RuleOrLiteral][]} */
      const operators = [
        [prec, PREC.DEFINED, 'defined?'],
        [prec.right, PREC.NOT, 'not'],
        [prec.right, PREC.UNARY_MINUS, choice(alias($._unary_minus, '-'), '+')],
        [prec.right, PREC.COMPLEMENT, choice('!', '~')],
      ];
      // oxlint-enable typescript/unbound-method
      return choice(
        ...operators.map(([fn, precedence, operator]) =>
          fn(precedence, seq(field('operator', operator), field('operand', $._expression)))
        )
      );
    },

    parenthesized_unary: ($) =>
      prec(PREC.CALL, seq(field('operator', choice('defined?', 'not')), field('operand', $.parenthesized_statements))),

    unary_literal: ($) =>
      prec.right(
        PREC.UNARY_MINUS,
        seq(field('operator', choice(alias($._unary_minus_num, '-'), '+')), field('operand', $._simple_numeric))
      ),

    _literal: ($) => choice($.simple_symbol, $.delimited_symbol, $._numeric),

    _numeric: ($) => choice($._simple_numeric, alias($.unary_literal, $.unary)),

    _simple_numeric: ($) => choice($.integer, $.float, $.complex, $.rational),

    right_assignment_list: ($) => prec(-1, commaSep1(choice($._arg, $.splat_argument))),

    left_assignment_list: ($) => $._mlhs,
    _mlhs: ($) =>
      prec.left(-1, seq(commaSep1(choice($._lhs, $.rest_assignment, $.destructured_left_assignment)), optional(','))),
    destructured_left_assignment: ($) => prec(-1, seq('(', $._mlhs, ')')),

    rest_assignment: ($) => prec(-1, seq('*', optional($._lhs))),

    _function_identifier: ($) => choice(alias($.identifier_suffix, $.identifier), alias($.constant_suffix, $.constant)),
    _function_identifier_call: ($) => prec.left(field('method', $._function_identifier)),
    _lhs: ($) =>
      prec.left(
        choice($._variable, $.true, $.false, $.nil, $.scope_resolution, $.element_reference, alias($._call, $.call))
      ),

    _variable: ($) => prec.right(choice($.self, $.super, $._nonlocal_variable, $.identifier, $.constant)),

    operator: () =>
      choice(
        '..',
        '|',
        '^',
        '&',
        '<=>',
        '==',
        '===',
        '=~',
        '>',
        '>=',
        '<',
        '<=',
        '+',
        '!=',
        '-',
        '*',
        '/',
        '%',
        '!',
        '!~',
        '**',
        '<<',
        '>>',
        '~',
        '+@',
        '-@',
        '~@',
        '[]',
        '[]=',
        '`'
      ),

    _method_name: ($) =>
      choice(
        $.identifier,
        $._function_identifier,
        $.constant,
        $.setter,
        $.simple_symbol,
        $.delimited_symbol,
        $.operator,
        $._nonlocal_variable
      ),

    _nonlocal_variable: ($) => choice($.instance_variable, $.class_variable, $.global_variable),

    setter: ($) => seq(field('name', $.identifier), token.immediate('=')),

    undef: ($) => seq('undef', commaSep1($._method_name)),
    alias: ($) => seq('alias', field('name', $._method_name), field('alias', $._method_name)),

    comment: ($) =>
      choice(
        $._line_comment,
        token(
          prec(
            PREC.COMMENT,
            choice(
              seq('#', /.*/),
              seq(/=begin.*\r?\n/, repeat(choice(/[^=]/, /=[^e]/, /=e[^n]/, /=en[^d]/)), /[\s*]*=end.*/)
            )
          )
        )
      ),

    integer: () => /0[bB][01](_?[01])*|0[oO]?[0-7](_?[0-7])*|(0[dD])?\d(_?\d)*|0[xX][0-9a-fA-F](_?[0-9a-fA-F])*/,
    _int_or_float: ($) => choice($.integer, $.float),
    // oxlint-disable-next-line no-useless-escape -- The regex source reaches src/grammar.json as written, so it keeps upstream's spelling.
    float: () => /\d(_?\d)*(\.\d)?(_?\d)*([eE][\+-]?\d(_?\d)*)?/,
    complex: ($) =>
      choice(
        seq($._int_or_float, token.immediate('i')),
        seq(alias($._int_or_float, $.rational), token.immediate('ri'))
      ),
    rational: ($) => seq($._int_or_float, token.immediate('r')),
    super: () => 'super',
    self: () => 'self',
    true: () => 'true',
    false: () => 'false',
    nil: () => 'nil',

    constant: () => token(seq(/[A-Z]/, IDENTIFIER_CHARS)),
    constant_suffix: ($) => choice(token(seq(/[A-Z]/, IDENTIFIER_CHARS, /[?]/)), $._constant_suffix),
    identifier: () => token(seq(LOWER_ALPHA_CHAR, IDENTIFIER_CHARS)),
    identifier_suffix: ($) => choice(token(seq(LOWER_ALPHA_CHAR, IDENTIFIER_CHARS, /[?]/)), $._identifier_suffix),
    instance_variable: () => token(seq('@', ALPHA_CHAR, IDENTIFIER_CHARS)),
    class_variable: () => token(seq('@@', ALPHA_CHAR, IDENTIFIER_CHARS)),

    global_variable: () => /\$(-[a-zA-Z0-9_]|[!@&`'+~=/\\,;.<>*$?:"]|[0-9]+|[a-zA-Z_][a-zA-Z0-9_]*)/,

    chained_string: ($) => seq($.string, repeat1($.string)),

    character: () => /\?(\\\S(\{[0-9A-Fa-f]*\}|[0-9A-Fa-f]*|-\S([MC]-\S)?)?|\S)/,

    interpolation: ($) =>
      choice(seq('#{', optional($._statements), '}'), seq($._short_interpolation, $._nonlocal_variable)),

    string: ($) => seq(alias($._string_start, '"'), optional($._literal_contents), alias($._string_end, '"')),

    subshell: ($) => seq(alias($._subshell_start, '`'), optional($._literal_contents), alias($._string_end, '`')),

    string_array: ($) =>
      seq(
        alias($._string_array_start, '%w('),
        optional(/\s+/),
        sep(alias($._literal_contents, $.bare_string), /\s+/),
        optional(/\s+/),
        alias($._string_end, ')')
      ),

    symbol_array: ($) =>
      seq(
        alias($._symbol_array_start, '%i('),
        optional(/\s+/),
        sep(alias($._literal_contents, $.bare_symbol), /\s+/),
        optional(/\s+/),
        alias($._string_end, ')')
      ),

    delimited_symbol: ($) =>
      seq(alias($._symbol_start, ':"'), optional($._literal_contents), alias($._string_end, '"')),

    regex: ($) => seq(alias($._regex_start, '/'), optional($._literal_contents), alias($._string_end, '/')),

    heredoc_body: ($) =>
      seq($._heredoc_body_start, repeat(choice($.heredoc_content, $.interpolation, $.escape_sequence)), $.heredoc_end),

    _literal_contents: ($) => repeat1(choice($.string_content, $.interpolation, $.escape_sequence)),

    // https://ruby-doc.org/core-2.5.0/doc/syntax/literals_rdoc.html#label-Strings
    escape_sequence: () =>
      token(
        seq(
          '\\',
          choice(
            /[^ux0-7]/, // single character
            /x[0-9a-fA-F]{1,2}/, // hex code
            /[0-7]{1,3}/, // octal
            /u[0-9a-fA-F]{4}/, // single unicode
            /u\{[0-9a-fA-F ]+\}/ // multiple unicode
          )
        )
      ),

    array: ($) => seq('[', optional($._argument_list_with_trailing_comma), ']'),

    hash: ($) => seq('{', optional(seq(commaSep1(choice($.pair, $.hash_splat_argument)), optional(','))), '}'),

    pair: ($) =>
      prec.right(
        choice(
          seq(field('key', $._arg), '=>', field('value', $._arg)),
          seq(field('key', choice($.string)), token.immediate(':'), field('value', $._arg)),
          seq(
            field(
              'key',
              choice(
                $.hash_key_symbol,
                alias($.identifier, $.hash_key_symbol),
                alias($.constant, $.hash_key_symbol),
                alias($.identifier_suffix, $.hash_key_symbol),
                alias($.constant_suffix, $.hash_key_symbol)
              )
            ),
            token.immediate(':'),
            choice(
              field('value', optional($._arg)),
              // This alternative never matches, because '_no_line_break' tokens do not exist.
              // The purpose is give a hint to the scanner that it should not produce any line-break
              // terminators at this point.
              $._no_line_break
            )
          )
        )
      ),

    lambda: ($) =>
      seq(
        '->',
        field(
          'parameters',
          optional(choice(alias($.parameters, $.lambda_parameters), alias($.bare_parameters, $.lambda_parameters)))
        ),
        field('body', choice($.block, $.do_block))
      ),

    empty_statement: () => prec(-1, ';'),

    _terminator: ($) => choice($._line_break, ';'),
  },
});

/**
 * Creates a rule to optionally match one or more of the rules separated by `separator`
 *
 * @param {RuleOrLiteral} rule
 *
 * @param {RuleOrLiteral} separator
 *
 * @returns {ChoiceRule}
 */
function sep(rule, separator) {
  return optional(sep1(rule, separator));
}

/**
 * Creates a rule to match one or more of the rules separated by `separator`
 *
 * @param {RuleOrLiteral} rule
 *
 * @param {RuleOrLiteral} separator
 *
 * @returns {SeqRule}
 */
function sep1(rule, separator) {
  return seq(rule, repeat(seq(separator, rule)));
}

/**
 * Creates a rule to match one or more of the rules separated by a comma
 *
 * @param {RuleOrLiteral} rule
 *
 * @returns {SeqRule}
 */
function commaSep1(rule) {
  return sep1(rule, ',');
}

/**
 * Creates a rule to optionally match one or more of the rules separated by a comma
 *
 * @param {RuleOrLiteral} rule
 *
 * @returns {ChoiceRule}
 */
function commaSep(rule) {
  return optional(commaSep1(rule));
}