nvchad/tree-sitter-c/grammar.js
2022-08-07 15:46:45 +05:30

1083 lines
26 KiB
JavaScript

const PREC = {
PAREN_DECLARATOR: -10,
ASSIGNMENT: -1,
CONDITIONAL: -2,
DEFAULT: 0,
LOGICAL_OR: 1,
LOGICAL_AND: 2,
INCLUSIVE_OR: 3,
EXCLUSIVE_OR: 4,
BITWISE_AND: 5,
EQUAL: 6,
RELATIONAL: 7,
SIZEOF: 8,
SHIFT: 9,
ADD: 10,
MULTIPLY: 11,
CAST: 12,
UNARY: 13,
CALL: 14,
FIELD: 15,
SUBSCRIPT: 16
};
module.exports = grammar({
name: 'c',
extras: $ => [
/\s|\\\r?\n/,
$.comment,
],
inline: $ => [
$._statement,
$._top_level_item,
$._type_identifier,
$._field_identifier,
$._statement_identifier,
$._non_case_statement,
$._assignment_left_expression,
],
conflicts: $ => [
[$._type_specifier, $._declarator],
[$._type_specifier, $._declarator, $.macro_type_specifier],
[$._type_specifier, $._expression],
[$._type_specifier, $._expression, $.macro_type_specifier],
[$._type_specifier, $.macro_type_specifier],
[$.sized_type_specifier],
[$.attributed_statement],
[$._declaration_modifiers, $.attributed_statement],
],
word: $ => $.identifier,
rules: {
translation_unit: $ => repeat($._top_level_item),
_top_level_item: $ => choice(
$.function_definition,
$.linkage_specification,
$.declaration,
$._statement,
$.attributed_statement,
$.type_definition,
$._empty_declaration,
$.preproc_if,
$.preproc_ifdef,
$.preproc_include,
$.preproc_def,
$.preproc_function_def,
$.preproc_call
),
// Preprocesser
preproc_include: $ => seq(
preprocessor('include'),
field('path', choice(
$.string_literal,
$.system_lib_string,
$.identifier,
alias($.preproc_call_expression, $.call_expression),
)),
'\n'
),
preproc_def: $ => seq(
preprocessor('define'),
field('name', $.identifier),
field('value', optional($.preproc_arg)),
'\n'
),
preproc_function_def: $ => seq(
preprocessor('define'),
field('name', $.identifier),
field('parameters', $.preproc_params),
field('value', optional($.preproc_arg)),
'\n'
),
preproc_params: $ => seq(
token.immediate('('), commaSep(choice($.identifier, '...')), ')'
),
preproc_call: $ => seq(
field('directive', $.preproc_directive),
field('argument', optional($.preproc_arg)),
'\n'
),
...preprocIf('', $ => $._top_level_item),
...preprocIf('_in_field_declaration_list', $ => $._field_declaration_list_item),
preproc_directive: $ => /#[ \t]*[a-zA-Z]\w*/,
preproc_arg: $ => token(prec(-1, repeat1(/.|\\\r?\n/))),
_preproc_expression: $ => choice(
$.identifier,
alias($.preproc_call_expression, $.call_expression),
$.number_literal,
$.char_literal,
$.preproc_defined,
alias($.preproc_unary_expression, $.unary_expression),
alias($.preproc_binary_expression, $.binary_expression),
alias($.preproc_parenthesized_expression, $.parenthesized_expression)
),
preproc_parenthesized_expression: $ => seq(
'(',
$._preproc_expression,
')'
),
preproc_defined: $ => choice(
prec(PREC.CALL, seq('defined', '(', $.identifier, ')')),
seq('defined', $.identifier),
),
preproc_unary_expression: $ => prec.left(PREC.UNARY, seq(
field('operator', choice('!', '~', '-', '+')),
field('argument', $._preproc_expression)
)),
preproc_call_expression: $ => prec(PREC.CALL, seq(
field('function', $.identifier),
field('arguments', alias($.preproc_argument_list, $.argument_list))
)),
preproc_argument_list: $ => seq(
'(',
commaSep($._preproc_expression),
')'
),
preproc_binary_expression: $ => {
const table = [
['+', PREC.ADD],
['-', PREC.ADD],
['*', PREC.MULTIPLY],
['/', PREC.MULTIPLY],
['%', PREC.MULTIPLY],
['||', PREC.LOGICAL_OR],
['&&', PREC.LOGICAL_AND],
['|', PREC.INCLUSIVE_OR],
['^', PREC.EXCLUSIVE_OR],
['&', PREC.BITWISE_AND],
['==', PREC.EQUAL],
['!=', PREC.EQUAL],
['>', PREC.RELATIONAL],
['>=', PREC.RELATIONAL],
['<=', PREC.RELATIONAL],
['<', PREC.RELATIONAL],
['<<', PREC.SHIFT],
['>>', PREC.SHIFT],
];
return choice(...table.map(([operator, precedence]) => {
return prec.left(precedence, seq(
field('left', $._preproc_expression),
field('operator', operator),
field('right', $._preproc_expression)
))
}));
},
// Main Grammar
function_definition: $ => seq(
optional($.ms_call_modifier),
$._declaration_specifiers,
field('declarator', $._declarator),
field('body', $.compound_statement)
),
declaration: $ => seq(
$._declaration_specifiers,
commaSep1(field('declarator', choice(
$._declarator,
$.init_declarator
))),
';'
),
type_definition: $ => seq(
'typedef',
repeat($.type_qualifier),
field('type', $._type_specifier),
commaSep1(field('declarator', $._type_declarator)),
';'
),
_declaration_modifiers: $ => choice(
$.storage_class_specifier,
$.type_qualifier,
$.attribute_specifier,
$.attribute_declaration,
$.ms_declspec_modifier
),
_declaration_specifiers: $ => seq(
repeat($._declaration_modifiers),
field('type', $._type_specifier),
repeat($._declaration_modifiers),
),
linkage_specification: $ => seq(
'extern',
field('value', $.string_literal),
field('body', choice(
$.function_definition,
$.declaration,
$.declaration_list
))
),
attribute_specifier: $ => seq(
'__attribute__',
'(',
$.argument_list,
')'
),
attribute: $ => seq(
optional(seq(field('prefix', $.identifier), '::')),
field('name', $.identifier),
optional($.argument_list)
),
attribute_declaration: $ => seq(
'[[',
commaSep1($.attribute),
']]'
),
ms_declspec_modifier: $ => seq(
'__declspec',
'(',
$.identifier,
')',
),
ms_based_modifier: $ => seq(
'__based',
$.argument_list,
),
ms_call_modifier: $ => choice(
'__cdecl',
'__clrcall',
'__stdcall',
'__fastcall',
'__thiscall',
'__vectorcall'
),
ms_restrict_modifier: $ => '__restrict',
ms_unsigned_ptr_modifier: $ => '__uptr',
ms_signed_ptr_modifier: $ => '__sptr',
ms_unaligned_ptr_modifier: $ => choice('_unaligned', '__unaligned'),
ms_pointer_modifier: $ => choice(
$.ms_unaligned_ptr_modifier,
$.ms_restrict_modifier,
$.ms_unsigned_ptr_modifier,
$.ms_signed_ptr_modifier,
),
declaration_list: $ => seq(
'{',
repeat($._top_level_item),
'}'
),
_declarator: $ => choice(
$.attributed_declarator,
$.pointer_declarator,
$.function_declarator,
$.array_declarator,
$.parenthesized_declarator,
$.identifier
),
_field_declarator: $ => choice(
alias($.attributed_field_declarator, $.attributed_declarator),
alias($.pointer_field_declarator, $.pointer_declarator),
alias($.function_field_declarator, $.function_declarator),
alias($.array_field_declarator, $.array_declarator),
alias($.parenthesized_field_declarator, $.parenthesized_declarator),
$._field_identifier
),
_type_declarator: $ => choice(
alias($.attributed_type_declarator, $.attributed_declarator),
alias($.pointer_type_declarator, $.pointer_declarator),
alias($.function_type_declarator, $.function_declarator),
alias($.array_type_declarator, $.array_declarator),
alias($.parenthesized_type_declarator, $.parenthesized_declarator),
$._type_identifier
),
_abstract_declarator: $ => choice(
$.abstract_pointer_declarator,
$.abstract_function_declarator,
$.abstract_array_declarator,
$.abstract_parenthesized_declarator,
),
parenthesized_declarator: $ => prec.dynamic(PREC.PAREN_DECLARATOR, seq(
'(',
$._declarator,
')'
)),
parenthesized_field_declarator: $ => prec.dynamic(PREC.PAREN_DECLARATOR, seq(
'(',
$._field_declarator,
')'
)),
parenthesized_type_declarator: $ => prec.dynamic(PREC.PAREN_DECLARATOR, seq(
'(',
$._type_declarator,
')'
)),
abstract_parenthesized_declarator: $ => prec(1, seq(
'(',
$._abstract_declarator,
')'
)),
attributed_declarator: $ => prec.right(seq(
$._declarator,
repeat1($.attribute_declaration),
)),
attributed_field_declarator: $ => prec.right(seq(
$._field_declarator,
repeat1($.attribute_declaration),
)),
attributed_type_declarator: $ => prec.right(seq(
$._type_declarator,
repeat1($.attribute_declaration),
)),
pointer_declarator: $ => prec.dynamic(1, prec.right(seq(
optional($.ms_based_modifier),
'*',
repeat($.ms_pointer_modifier),
repeat($.type_qualifier),
field('declarator', $._declarator)
))),
pointer_field_declarator: $ => prec.dynamic(1, prec.right(seq(
optional($.ms_based_modifier),
'*',
repeat($.ms_pointer_modifier),
repeat($.type_qualifier),
field('declarator', $._field_declarator)
))),
pointer_type_declarator: $ => prec.dynamic(1, prec.right(seq(
optional($.ms_based_modifier),
'*',
repeat($.ms_pointer_modifier),
repeat($.type_qualifier),
field('declarator', $._type_declarator)
))),
abstract_pointer_declarator: $ => prec.dynamic(1, prec.right(seq('*',
repeat($.type_qualifier),
field('declarator', optional($._abstract_declarator))
))),
function_declarator: $ => prec(1,
seq(
field('declarator', $._declarator),
field('parameters', $.parameter_list),
repeat($.attribute_specifier),
)),
function_field_declarator: $ => prec(1, seq(
field('declarator', $._field_declarator),
field('parameters', $.parameter_list)
)),
function_type_declarator: $ => prec(1, seq(
field('declarator', $._type_declarator),
field('parameters', $.parameter_list)
)),
abstract_function_declarator: $ => prec(1, seq(
field('declarator', optional($._abstract_declarator)),
field('parameters', $.parameter_list)
)),
array_declarator: $ => prec(1, seq(
field('declarator', $._declarator),
'[',
repeat($.type_qualifier),
field('size', optional(choice($._expression, '*'))),
']'
)),
array_field_declarator: $ => prec(1, seq(
field('declarator', $._field_declarator),
'[',
repeat($.type_qualifier),
field('size', optional(choice($._expression, '*'))),
']'
)),
array_type_declarator: $ => prec(1, seq(
field('declarator', $._type_declarator),
'[',
repeat($.type_qualifier),
field('size', optional(choice($._expression, '*'))),
']'
)),
abstract_array_declarator: $ => prec(1, seq(
field('declarator', optional($._abstract_declarator)),
'[',
repeat($.type_qualifier),
field('size', optional(choice($._expression, '*'))),
']'
)),
init_declarator: $ => seq(
field('declarator', $._declarator),
'=',
field('value', choice($.initializer_list, $._expression))
),
compound_statement: $ => seq(
'{',
repeat($._top_level_item),
'}'
),
storage_class_specifier: $ => choice(
'extern',
'static' ,
'auto',
'register',
'inline'
),
type_qualifier: $ => choice(
'const',
'volatile',
'restrict',
'_Atomic'
),
_type_specifier: $ => choice(
$.struct_specifier,
$.union_specifier,
$.enum_specifier,
$.macro_type_specifier,
$.sized_type_specifier,
$.primitive_type,
$._type_identifier
),
sized_type_specifier: $ => seq(
repeat1(choice(
'signed',
'unsigned',
'long',
'short'
)),
field('type', optional(choice(
prec.dynamic(-1, $._type_identifier),
$.primitive_type
)))
),
primitive_type: $ => token(choice(
'bool',
'char',
'int',
'float',
'double',
'void',
'size_t',
'ssize_t',
'intptr_t',
'uintptr_t',
'charptr_t',
...[8, 16, 32, 64].map(n => `int${n}_t`),
...[8, 16, 32, 64].map(n => `uint${n}_t`),
...[8, 16, 32, 64].map(n => `char${n}_t`)
)),
enum_specifier: $ => seq(
'enum',
choice(
seq(
field('name', $._type_identifier),
field('body', optional($.enumerator_list))
),
field('body', $.enumerator_list)
)
),
enumerator_list: $ => seq(
'{',
commaSep($.enumerator),
optional(','),
'}'
),
struct_specifier: $ => seq(
'struct',
optional($.ms_declspec_modifier),
choice(
seq(
field('name', $._type_identifier),
field('body', optional($.field_declaration_list))
),
field('body', $.field_declaration_list)
)
),
union_specifier: $ => seq(
'union',
optional($.ms_declspec_modifier),
choice(
seq(
field('name', $._type_identifier),
field('body', optional($.field_declaration_list))
),
field('body', $.field_declaration_list)
)
),
field_declaration_list: $ => seq(
'{',
repeat($._field_declaration_list_item),
'}'
),
_field_declaration_list_item: $ => choice(
$.field_declaration,
$.preproc_def,
$.preproc_function_def,
$.preproc_call,
alias($.preproc_if_in_field_declaration_list, $.preproc_if),
alias($.preproc_ifdef_in_field_declaration_list, $.preproc_ifdef),
),
field_declaration: $ => seq(
$._declaration_specifiers,
commaSep(field('declarator', $._field_declarator)),
optional($.bitfield_clause),
';'
),
bitfield_clause: $ => seq(':', $._expression),
enumerator: $ => seq(
field('name', $.identifier),
optional(seq('=', field('value', $._expression)))
),
variadic_parameter: $ => seq(
'...',
),
parameter_list: $ => seq(
'(',
commaSep(choice($.parameter_declaration, $.variadic_parameter)),
')'
),
parameter_declaration: $ => seq(
$._declaration_specifiers,
optional(field('declarator', choice(
$._declarator,
$._abstract_declarator
)))
),
// Statements
attributed_statement: $ => seq(
repeat1($.attribute_declaration),
$._statement
),
_statement: $ => choice(
$.case_statement,
$._non_case_statement
),
_non_case_statement: $ => choice(
$.attributed_statement,
$.labeled_statement,
$.compound_statement,
$.expression_statement,
$.if_statement,
$.switch_statement,
$.do_statement,
$.while_statement,
$.for_statement,
$.return_statement,
$.break_statement,
$.continue_statement,
$.goto_statement
),
labeled_statement: $ => seq(
field('label', $._statement_identifier),
':',
$._statement
),
expression_statement: $ => seq(
optional(choice(
$._expression,
$.comma_expression
)),
';'
),
if_statement: $ => prec.right(seq(
'if',
field('condition', $.parenthesized_expression),
field('consequence', $._statement),
optional(seq(
'else',
field('alternative', $._statement)
))
)),
switch_statement: $ => seq(
'switch',
field('condition', $.parenthesized_expression),
field('body', $.compound_statement)
),
case_statement: $ => prec.right(seq(
choice(
seq('case', field('value', $._expression)),
'default'
),
':',
repeat(choice(
$._non_case_statement,
$.declaration,
$.type_definition
))
)),
while_statement: $ => seq(
'while',
field('condition', $.parenthesized_expression),
field('body', $._statement)
),
do_statement: $ => seq(
'do',
field('body', $._statement),
'while',
field('condition', $.parenthesized_expression),
';'
),
for_statement: $ => seq(
'for',
'(',
choice(
field('initializer', $.declaration),
seq(field('initializer', optional(choice($._expression, $.comma_expression))), ';')
),
field('condition', optional(choice($._expression, $.comma_expression))), ';',
field('update', optional(choice($._expression, $.comma_expression))),
')',
field('body', $._statement)
),
return_statement: $ => seq(
'return',
optional(choice($._expression, $.comma_expression)),
';'
),
break_statement: $ => seq(
'break', ';'
),
continue_statement: $ => seq(
'continue', ';'
),
goto_statement: $ => seq(
'goto',
field('label', $._statement_identifier),
';'
),
// Expressions
_expression: $ => choice(
$.conditional_expression,
$.assignment_expression,
$.binary_expression,
$.unary_expression,
$.update_expression,
$.cast_expression,
$.pointer_expression,
$.sizeof_expression,
$.subscript_expression,
$.call_expression,
$.field_expression,
$.compound_literal_expression,
$.identifier,
$.number_literal,
$.string_literal,
$.true,
$.false,
$.null,
$.concatenated_string,
$.char_literal,
$.parenthesized_expression
),
comma_expression: $ => seq(
field('left', $._expression),
',',
field('right', choice($._expression, $.comma_expression))
),
conditional_expression: $ => prec.right(PREC.CONDITIONAL, seq(
field('condition', $._expression),
'?',
field('consequence', $._expression),
':',
field('alternative', $._expression)
)),
_assignment_left_expression: $ => choice(
$.identifier,
$.call_expression,
$.field_expression,
$.pointer_expression,
$.subscript_expression,
$.parenthesized_expression
),
assignment_expression: $ => prec.right(PREC.ASSIGNMENT, seq(
field('left', $._assignment_left_expression),
field('operator', choice(
'=',
'*=',
'/=',
'%=',
'+=',
'-=',
'<<=',
'>>=',
'&=',
'^=',
'|='
)),
field('right', $._expression)
)),
pointer_expression: $ => prec.left(PREC.CAST, seq(
field('operator', choice('*', '&')),
field('argument', $._expression)
)),
unary_expression: $ => prec.left(PREC.UNARY, seq(
field('operator', choice('!', '~', '-', '+')),
field('argument', $._expression)
)),
binary_expression: $ => {
const table = [
['+', PREC.ADD],
['-', PREC.ADD],
['*', PREC.MULTIPLY],
['/', PREC.MULTIPLY],
['%', PREC.MULTIPLY],
['||', PREC.LOGICAL_OR],
['&&', PREC.LOGICAL_AND],
['|', PREC.INCLUSIVE_OR],
['^', PREC.EXCLUSIVE_OR],
['&', PREC.BITWISE_AND],
['==', PREC.EQUAL],
['!=', PREC.EQUAL],
['>', PREC.RELATIONAL],
['>=', PREC.RELATIONAL],
['<=', PREC.RELATIONAL],
['<', PREC.RELATIONAL],
['<<', PREC.SHIFT],
['>>', PREC.SHIFT],
];
return choice(...table.map(([operator, precedence]) => {
return prec.left(precedence, seq(
field('left', $._expression),
field('operator', operator),
field('right', $._expression)
))
}));
},
update_expression: $ => {
const argument = field('argument', $._expression);
const operator = field('operator', choice('--', '++'));
return prec.right(PREC.UNARY, choice(
seq(operator, argument),
seq(argument, operator),
));
},
cast_expression: $ => prec(PREC.CAST, seq(
'(',
field('type', $.type_descriptor),
')',
field('value', $._expression)
)),
type_descriptor: $ => seq(
repeat($.type_qualifier),
field('type', $._type_specifier),
repeat($.type_qualifier),
field('declarator', optional($._abstract_declarator))
),
sizeof_expression: $ => prec(PREC.SIZEOF, seq(
'sizeof',
choice(
field('value', $._expression),
seq('(', field('type', $.type_descriptor), ')')
)
)),
subscript_expression: $ => prec(PREC.SUBSCRIPT, seq(
field('argument', $._expression),
'[',
field('index', $._expression),
']'
)),
call_expression: $ => prec(PREC.CALL, seq(
field('function', $._expression),
field('arguments', $.argument_list)
)),
argument_list: $ => seq('(', commaSep($._expression), ')'),
field_expression: $ => seq(
prec(PREC.FIELD, seq(
field('argument', $._expression),
field('operator', choice('.', '->'))
)),
field('field', $._field_identifier)
),
compound_literal_expression: $ => seq(
'(',
field('type', $.type_descriptor),
')',
field('value', $.initializer_list)
),
parenthesized_expression: $ => seq(
'(',
choice($._expression, $.comma_expression),
')'
),
initializer_list: $ => seq(
'{',
commaSep(choice(
$.initializer_pair,
$._expression,
$.initializer_list
)),
optional(','),
'}'
),
initializer_pair: $ => seq(
field('designator', repeat1(choice($.subscript_designator, $.field_designator))),
'=',
field('value', choice($._expression, $.initializer_list))
),
subscript_designator: $ => seq('[', $._expression, ']'),
field_designator: $ => seq('.', $._field_identifier),
number_literal: $ => {
const separator = "'";
const hex = /[0-9a-fA-F]/;
const decimal = /[0-9]/;
const hexDigits = seq(repeat1(hex), repeat(seq(separator, repeat1(hex))));
const decimalDigits = seq(repeat1(decimal), repeat(seq(separator, repeat1(decimal))));
return token(seq(
optional(/[-\+]/),
optional(choice('0x', '0b')),
choice(
seq(
choice(
decimalDigits,
seq('0b', decimalDigits),
seq('0x', hexDigits)
),
optional(seq('.', optional(hexDigits)))
),
seq('.', decimalDigits)
),
optional(seq(
/[eEpP]/,
optional(seq(
optional(/[-\+]/),
hexDigits
))
)),
repeat(choice('u', 'l', 'U', 'L', 'f', 'F'))
))
},
char_literal: $ => seq(
choice('L\'', 'u\'', 'U\'', 'u8\'', '\''),
choice(
$.escape_sequence,
token.immediate(/[^\n']/)
),
'\''
),
concatenated_string: $ => seq(
$.string_literal,
repeat1($.string_literal)
),
string_literal: $ => seq(
choice('L"', 'u"', 'U"', 'u8"', '"'),
repeat(choice(
token.immediate(prec(1, /[^\\"\n]+/)),
$.escape_sequence
)),
'"',
),
escape_sequence: $ => token(prec(1, seq(
'\\',
choice(
/[^xuU]/,
/\d{2,3}/,
/x[0-9a-fA-F]{2,}/,
/u[0-9a-fA-F]{4}/,
/U[0-9a-fA-F]{8}/
)
))),
system_lib_string: $ => token(seq(
'<',
repeat(choice(/[^>\n]/, '\\>')),
'>'
)),
true: $ => token(choice('TRUE', 'true')),
false: $ => token(choice('FALSE', 'false')),
null: $ => 'NULL',
identifier: $ => /[a-zA-Z_]\w*/,
_type_identifier: $ => alias($.identifier, $.type_identifier),
_field_identifier: $ => alias($.identifier, $.field_identifier),
_statement_identifier: $ => alias($.identifier, $.statement_identifier),
_empty_declaration: $ => seq(
$._type_specifier,
';'
),
macro_type_specifier: $ => prec.dynamic(-1, seq(
field('name', $.identifier),
'(',
field('type', $.type_descriptor),
')'
)),
// http://stackoverflow.com/questions/13014947/regex-to-match-a-c-style-multiline-comment/36328890#36328890
comment: $ => token(choice(
seq('//', /(\\(.|\r?\n)|[^\\\n])*/),
seq(
'/*',
/[^*]*\*+([^/*][^*]*\*+)*/,
'/'
)
)),
},
supertypes: $ => [
$._expression,
$._statement,
$._type_specifier,
$._declarator,
$._field_declarator,
$._type_declarator,
$._abstract_declarator,
]
});
module.exports.PREC = PREC
function preprocIf (suffix, content) {
function elseBlock ($) {
return choice(
suffix ? alias($['preproc_else' + suffix], $.preproc_else) : $.preproc_else,
suffix ? alias($['preproc_elif' + suffix], $.preproc_elif) : $.preproc_elif,
);
}
return {
['preproc_if' + suffix]: $ => seq(
preprocessor('if'),
field('condition', $._preproc_expression),
'\n',
repeat(content($)),
field('alternative', optional(elseBlock($))),
preprocessor('endif')
),
['preproc_ifdef' + suffix]: $ => seq(
choice(preprocessor('ifdef'), preprocessor('ifndef')),
field('name', $.identifier),
repeat(content($)),
field('alternative', optional(elseBlock($))),
preprocessor('endif')
),
['preproc_else' + suffix]: $ => seq(
preprocessor('else'),
repeat(content($))
),
['preproc_elif' + suffix]: $ => seq(
preprocessor('elif'),
field('condition', $._preproc_expression),
'\n',
repeat(content($)),
field('alternative', optional(elseBlock($))),
)
}
}
function preprocessor (command) {
return alias(new RegExp('#[ \t]*' + command), '#' + command)
}
function commaSep (rule) {
return optional(commaSep1(rule))
}
function commaSep1 (rule) {
return seq(rule, repeat(seq(',', rule)))
}
function commaSepTrailing (recurSymbol, rule) {
return choice(rule, seq(recurSymbol, ',', rule))
}