grammar.rustpeg

// Written for peg 0.5.4

#![arguments(env: &mut Env)]

use ast::*;
use astutil::*;
use env::{Env, Symbol};
use span::{Node, Span};

////
// Prologue
////

box<ex> = e:ex { Box::new(e) }

node<ex> = l:#position e:ex r:#position { Node::new(e, Span::span(l, r)) }

// Lists of elements.
list0<ex> = e:ex ** _ { e }
list1<ex> = e:ex ++ _ { e }
cs0<ex> = e:ex ** (_ "," _) { e }
cs1<ex> = e:ex ++ (_ "," _) { e }

// A list containing 0+ before's, 1 single, and 0+ after's.
list_010<before, single, after> =
    before:list0<before> _ single:single _ after:list0<after> {
        let mut before = before;
        before.push(single);
        before.extend(after);
        before
    }
// A list containing *exactly* one element of a, and any of b.
list_eq1_n<a, b> = list_010<b, a, b>
// A list containing *at least* one element of a, and any of b.
list_ge1_n<a, b> = list_010<b, a, a / b>

////
// Whitespace
////

_ = #quiet<("\r"? "\n" directive? / [ \t])*>

directive = "#" [^\n]*

////
// 6.4.1 Keywords
////

K<E> = #quiet<e:E ![_a-zA-Z0-9] { e }>

////
// 6.4.2 Identifiers
////

// Identifiers.
identifier -> Node<Identifier> = node<identifier0>

identifier0 -> Identifier =
    n:$([_a-zA-Z] [_a-zA-Z0-9]*) {?
        if !env.reserved.contains(n) {
            Ok(Identifier {
                name: n.into(),
            })
        } else {
            Err("identifier")
        }
    }

////
// 6.4.3 Universal character names
////

// TODO

////
// 6.4.4 Constants
////

ohx = "0" [xX]
obb = "0" [bB]
dec = [0-9]
oct = [0-7]
hex = [0-9a-fA-F]
bin = [0-1]

pub constant -> Constant =
    &[0-9.] c:numeric_constant { c } /
    &['uUL] c:character_constant { Constant::Character(c) }

numeric_constant -> Constant =
    c:float_constant { Constant::Float(c) } /
    c:integer_constant { Constant::Integer(c) }

integer_constant -> Integer =
    n:integer_number suffix:integer_suffix {
        let (base, number) = n;
        Integer {
            base: base,
            number: number.to_owned().into_boxed_str(),
            suffix: suffix,
        }
    }

integer_number -> (IntegerBase, &'input str) =
    n:$([1-9] dec*) { (IntegerBase::Decimal, n) } /
    ohx n:$(hex+) { (IntegerBase::Hexadecimal, n) } /
    "0" n:$(oct+) { (IntegerBase::Octal, n) } /
    gnu<obb n:$(bin+) { (IntegerBase::Binary, n) }> /
    n:$("0") { (IntegerBase::Decimal, n) }

integer_suffix -> IntegerSuffix =
    #quiet<integer_suffix_inner> / #expected("integer suffix")

integer_suffix_inner -> IntegerSuffix =
    s:$(([uUlL] / gnu<[iIjJ]>)*) {? int_suffix(s) }

float_constant -> Float =
    n:float_number suffix:float_suffix {
        let (base, number) = n;
        Float {
            base: base,
            number: number.to_string().into_boxed_str(),
            suffix: suffix,
        }
    }

float_number -> (FloatBase, &'input str) =
    n:$(float_decimal) { (FloatBase::Decimal, n) } /
    ohx n:$(float_hexadecimal) { (FloatBase::Hexadecimal, n) }

float_decimal =
    dec* "." dec+ float_decimal_exp? /
    dec+ "." float_decimal_exp? /
    dec+ float_decimal_exp

float_decimal_exp = [eE][+-]?dec+

float_hexadecimal =
    hex* "." hex+ float_binary_exp /
    hex+ "." float_binary_exp /
    hex+ float_binary_exp

float_binary_exp = [pP][+-]?dec+

float_suffix -> FloatSuffix = #quiet<float_suffix_inner> / #expected("float literal suffix")

float_suffix_inner -> FloatSuffix =
    gnu<[iIjJ]> fmt:float_format {
        FloatSuffix {
            format: fmt,
            imaginary: true,
        }
    } /
    fmt:float_format imag:gnu<[iIjJ]>? {
        FloatSuffix {
            format: fmt,
            imaginary: imag.is_some(),
        }
    }

float_format -> FloatFormat =
    f:ts18661_float_suffix { FloatFormat::TS18661Format(f) } /
    [fF] { FloatFormat::Float } /
    [lL] { FloatFormat::LongDouble } /
    { FloatFormat::Double }

character_constant -> String =
    c:$([LuU]? "'" character+ "'") { String::from(c) }

character = [^'\\\n] / escape_sequence

escape_sequence = "\\" (['"?\\abcfnrtv] / oct*<1,3> / "x" hex+)

////
// 6.4.5 String literal
////

pub string_literal -> Node<Vec<String>> = s:node<list1<string_literal0>> { s }

string_literal0 -> String =
    s:$(encoding_prefix? "\"" string_char* "\"") { String::from(s) }

encoding_prefix = "u8" / [uUL]

string_char = [^"\\\n] / escape_sequence

////
// 6.5.1 Primary expression
////

primary_expression -> Box<Node<Expression>> = box<node<primary_expression0>>

primary_expression0 -> Expression =
    a:identifier { Expression::Identifier(Box::new(a)) } /
    a:node<constant> { Expression::Constant(Box::new(a)) } /
    a:string_literal { Expression::StringLiteral(Box::new(a)) } /
    "(" _ a:expression0 _ ")" { a } /
    a:node<generic_selection> { Expression::GenericSelection(Box::new(a)) } /
    gnu<gnu_primary_expression>

generic_selection -> GenericSelection =
    K<"_Generic"> _ "(" _ e:assignment_expression _ "," _ a:cs1<node<generic_association>> _ ")" {
        GenericSelection {
            expression: e,
            associations: a,
        }
    }

generic_association -> GenericAssociation =
    t:type_name _ ":" _ e:assignment_expression {
        let span = Span::span(t.span.start, e.span.end);
        GenericAssociation::Type(Node::new(GenericAssociationType {
            type_name: t,
            expression: e,
        }, span))
    } /
    K<"default"> _ ":" _ e:assignment_expression {
        GenericAssociation::Default(e)
    }

//// 6.5.2 Postfix operators

postfix_expression -> Box<Node<Expression>> = box<node<postfix_expression0>>

#[cache]
postfix_expression0 -> Expression =
    e:node<postfix_expression1> _ t:list0<node<postfix_expressionT>> { apply_ops(t, e).node }

postfix_expression1 -> Expression =
    compound_literal /
    primary_expression0

postfix_expressionT -> Operation =
    index_operator /
    "(" _ e:cs0<node<assignment_expression0>> _ ")" { Operation::Call(e) } /
    o:node<member_operator> _ i:identifier { Operation::Member(o, i) } /
    o:node<postfix_operator> { Operation::Unary(o) }

index_operator -> Operation =
    i:node<index_operator0> { Operation::Binary(Node::new(BinaryOperator::Index, i.span), i.node) }

index_operator0 -> Node<Expression> =
    "[" _ e:node<expression0> _ "]" { e }

member_operator -> MemberOperator =
    "." { MemberOperator::Direct } /
    "->" { MemberOperator::Indirect }

postfix_operator -> UnaryOperator =
    "++" { UnaryOperator::PostIncrement } /
    "--" { UnaryOperator::PostDecrement }

compound_literal -> Expression =
    n:node<compound_literal_inner> { Expression::CompoundLiteral(Box::new(n)) }

compound_literal_inner -> CompoundLiteral =
    "(" _ t:type_name _ ")" _ "{" _ i:cs1<node<initializer_list_item>> _ ","? _ "}" {
        CompoundLiteral {
            type_name: t,
            initializer_list: i,
        }
    }

////
// 6.5.3 Unary operators
////

unary_expression -> Box<Node<Expression>> = box<node<unary_expression0>>

unary_expression0 -> Expression =
    postfix_expression0 /
    unary_prefix /
    unary_cast /
    sizeof_expression /
    alignof_expression /
    gnu<K<"__extension__">> _ e:unary_expression0 { e }

unary_prefix -> Expression =
    n:node<unary_prefix_inner> { Expression::UnaryOperator(Box::new(n)) }

unary_prefix_inner -> UnaryOperatorExpression =
    op:node<prefix_operator> _ e:unary_expression {
        UnaryOperatorExpression {
            operator: op,
            operand: e,
        }
    }

prefix_operator -> UnaryOperator =
    "++" { UnaryOperator::PreIncrement } /
    "--" { UnaryOperator::PreDecrement } /
    K<"sizeof"> { UnaryOperator::SizeOf }

unary_cast -> Expression =
    n:node<unary_cast_inner> { Expression::UnaryOperator(Box::new(n)) }

unary_cast_inner -> UnaryOperatorExpression =
    op:node<unary_operator> _ e:cast_expression {
        UnaryOperatorExpression {
            operator: op,
            operand: e,
        }
    }

unary_operator -> UnaryOperator =
    "&"!"&" { UnaryOperator::Address } /
    "*" { UnaryOperator::Indirection } /
    "+" { UnaryOperator::Plus } /
    "-" { UnaryOperator::Minus } /
    "~" { UnaryOperator::Complement } /
    "!" { UnaryOperator::Negate }

sizeof_expression -> Expression =
    K<"sizeof"> _ "(" _ t:type_name _ ")" {
        Expression::SizeOf(Box::new(t))
    }

alignof_expression -> Expression =
    K<"_Alignof" / gnu<"__alignof" "__"?>> _ "(" _ t:type_name _ ")" {
        Expression::AlignOf(Box::new(t))
    }

////
// 6.5.4 Cast expressions
////

cast_expression -> Box<Node<Expression>> = box<node<cast_expression0>>

cast_expression0 -> Expression =
    c:node<cast_expression_inner> { Expression::Cast(Box::new(c)) } /
    unary_expression0

cast_expression_inner -> CastExpression =
    "(" _ t:type_name _ ")" _ e:cast_expression {
        CastExpression {
            type_name: t,
            expression: e,
        }
    }

////
// 6.5.5 -- 6.5.14 Binary operators
////

binary_expression -> Box<Node<Expression>> = box<binary_expression0>

binary_expression0 -> Node<Expression> = #infix<binary_operand> {
#L  x o:infix<"||"> y { infix(o, BinaryOperator::LogicalOr, x, y) }
#L  x o:infix<"&&"> y { infix(o, BinaryOperator::LogicalAnd, x, y) }
#L  x o:infix<"|"> y { infix(o, BinaryOperator::BitwiseOr, x, y) }
#L  x o:infix<"^"> y { infix(o, BinaryOperator::BitwiseXor, x, y) }
#L  x o:infix<"&"!"&"> y { infix(o, BinaryOperator::BitwiseAnd, x, y) }
#L  x o:infix<"=="> y { infix(o, BinaryOperator::Equals, x, y) }
    x o:infix<"!="> y { infix(o, BinaryOperator::NotEquals, x, y) }
#L  x o:infix<"<"> y { infix(o, BinaryOperator::Less, x, y) }
    x o:infix<">"> y { infix(o, BinaryOperator::Greater, x, y) }
    x o:infix<"<="> y { infix(o, BinaryOperator::LessOrEqual, x, y) }
    x o:infix<">="> y { infix(o, BinaryOperator::GreaterOrEqual, x, y) }
#L  x o:infix<"<<"> y { infix(o, BinaryOperator::ShiftLeft, x, y) }
    x o:infix<">>"> y { infix(o, BinaryOperator::ShiftRight, x, y) }
#L  x o:infix<"+"> y { infix(o, BinaryOperator::Plus, x, y) }
    x o:infix<"-"> y { infix(o, BinaryOperator::Minus, x, y) }
#L  x o:infix<"*"> y { infix(o, BinaryOperator::Multiply, x, y) }
    x o:infix<"/"> y { infix(o, BinaryOperator::Divide, x, y) }
    x o:infix<"%"> y { infix(o, BinaryOperator::Modulo, x, y) }
}

infix<ex> = _ n:node<ex> _ { n }

binary_operand -> Node<Expression> = node<cast_expression0>

////
// 6.5.15 Conditional operator
////

conditional_expression -> Box<Node<Expression>> = box<node<conditional_expression0>>

conditional_expression0 -> Expression =
    a:binary_expression0 _ t:conditional_expressionT? {
        if let Some((b, c)) = t {
            let span = Span::span(a.span.start, c.span.end);
            Expression::Conditional(Box::new(Node::new(ConditionalExpression {
                condition: Box::new(a),
                then_expression: b,
                else_expression: c,
            }, span)))
        } else {
            a.node
        }
    }

conditional_expressionT -> (Box<Node<Expression>>, Box<Node<Expression>>) =
    "?" _ a:node<expression0> _ ":" _ b:node<conditional_expression0> { (Box::new(a), Box::new(b)) }

////
// 6.5.16 Assignment operators
////

assignment_expression -> Box<Node<Expression>> = box<node<assignment_expression0>>

assignment_expression0 -> Expression =
    n:node<assignment_expression_inner> { Expression::BinaryOperator(Box::new(n)) } /
    conditional_expression0

assignment_expression_inner -> BinaryOperatorExpression =
    a:unary_expression _ op:node<assignment_operator> _ b:assignment_expression {
        BinaryOperatorExpression {
            operator: op,
            lhs: a,
            rhs: b,
        }
    }

assignment_operator -> BinaryOperator =
    "=" { BinaryOperator::Assign } /
    "*=" { BinaryOperator::AssignMultiply } /
    "/=" { BinaryOperator::AssignDivide } /
    "%=" { BinaryOperator::AssignModulo } /
    "+=" { BinaryOperator::AssignPlus } /
    "-=" { BinaryOperator::AssignMinus } /
    "<<=" { BinaryOperator::AssignShiftLeft } /
    ">>=" { BinaryOperator::AssignShiftRight } /
    "&=" { BinaryOperator::AssignBitwiseAnd } /
    "^=" { BinaryOperator::AssignBitwiseXor } /
    "|=" { BinaryOperator::AssignBitwiseOr }

////
// 6.5.17 Comma operator
////

pub expression -> Box<Node<Expression>> = box<node<expression0>>

expression0 -> Expression =
    e:node<assignment_expression0> _ t:list0<expressionT> {
        if t.len() > 0 {
            let mut t  = t;
            t.insert(0, e);
            Expression::Comma(Box::new(t))
        } else {
            e.node
        }
    }

expressionT -> Node<Expression> =
    "," _ e:node<assignment_expression0> { e }

////
// 6.6 Constant expressions
////

constant_expression -> Box<Node<Expression>> = conditional_expression
constant_expression0 -> Expression = conditional_expression0

////
// 6.7 Declarations
////

pub declaration -> Node<Declaration> = node<declaration0>

declaration0 -> Declaration =
    gnu<K<"__extension__">>? _ d:declaration1 _ ";" {
        Declaration {
            specifiers: d.0,
            declarators: d.1,
        }
    }

declaration_seq<h, t> = h:h _ t:t { (concat(h, t.0), t.1) }

declaration1 -> (Vec<Node<DeclarationSpecifier>>, Vec<Node<InitDeclarator>>) =
    declaration_seq<declaration_specifiers_unique, declaration2>

declaration2 -> (Vec<Node<DeclarationSpecifier>>, Vec<Node<InitDeclarator>>) =
    declaration_seq<declaration_typedef, declaration_typedef_tail> /
    declaration_seq<declaration_unique_type, declaration_tail<declaration_specifiers_unique>> /
    declaration_seq<declaration_nonunique_type, declaration_tail<declaration_specifiers_nonunique>>

// What can follow a type specifier keyword or typename in a declaration
declaration_tail<s> = declaration_seq<s, declaration_tail1<s>>
declaration_tail1<s> =
    declaration_seq<declaration_typedef, declaration_typedef_tail1<s>> /
    d:declaration_init_declarators { (Vec::new(), d) }

// What can follow a typedef keyword
declaration_typedef_tail -> (Vec<Node<DeclarationSpecifier>>, Vec<Node<InitDeclarator>>) =
    declaration_seq<declaration_specifiers_unique, declaration_typedef_tail0>

declaration_typedef_tail0 -> (Vec<Node<DeclarationSpecifier>>, Vec<Node<InitDeclarator>>) =
    declaration_seq<declaration_unique_type, declaration_typedef_tail1<declaration_specifiers_unique>> /
    declaration_seq<declaration_nonunique_type, declaration_typedef_tail1<declaration_specifiers_nonunique>>

// What can follow after typedef + type name
declaration_typedef_tail1<s> = s:s _ d:declaration_type_declarators { (s, d) }

declaration_unique_type -> Vec<Node<DeclarationSpecifier>> =
    n:node<declaration_specifier_unique_type0> { vec![ n ] }

declaration_nonunique_type -> Vec<Node<DeclarationSpecifier>> =
    n:node<declaration_specifier_nonunique_type0> { vec![ n ] }

declaration_specifiers -> Vec<Node<DeclarationSpecifier>> =
    s:declaration_specifiers_unique _ t:declaration_specifiers_tail { concat(s, t) }

declaration_specifiers_tail -> Vec<Node<DeclarationSpecifier>> =
    t:declaration_unique_type _ s:declaration_specifiers_unique { concat(t, s) } /
    t:declaration_nonunique_type _ s:declaration_specifiers_nonunique { concat(t, s) }

declaration_specifiers_unique -> Vec<Node<DeclarationSpecifier>> =
    list0<node<declaration_specifier_nontype>>

declaration_specifiers_nonunique  -> Vec<Node<DeclarationSpecifier>> =
    list0<node<declaration_specifier_nontype / declaration_specifier_nonunique_type0>>

declaration_specifier_nontype -> DeclarationSpecifier =
    s:storage_class_specifier { DeclarationSpecifier::StorageClass(s) } /
    s:type_qualifier { DeclarationSpecifier::TypeQualifier(s) } /
    s:function_specifier { DeclarationSpecifier::Function(s) } /
    s:alignment_specifier { DeclarationSpecifier::Alignment(s) } /
    s:gnu<attribute_specifier> { DeclarationSpecifier::Extension(s) }

declaration_typedef -> Vec<Node<DeclarationSpecifier>> =
    s:node<declaration_typedef0> { vec![ s ] }

declaration_typedef0 -> DeclarationSpecifier =
    s:storage_class_typedef { DeclarationSpecifier::StorageClass(s) }

declaration_specifier_unique_type0 -> DeclarationSpecifier =
    s:node<type_specifier_unique> { DeclarationSpecifier::TypeSpecifier(s) }

declaration_specifier_nonunique_type0 -> DeclarationSpecifier =
    s:node<type_specifier_nonunique> { DeclarationSpecifier::TypeSpecifier(s) }

declaration_init_declarators -> Vec<Node<InitDeclarator>> = cs0<node<init_declarator>>

declaration_type_declarators -> Vec<Node<InitDeclarator>> = cs0<node<type_declarator>>

init_declarator -> InitDeclarator =
    d:init_declarator_declarator _ e:gnu<init_declarator_gnu>? _ i:node<init_declarator_init>?
    {
        InitDeclarator {
            declarator: with_ext(d, e),
            initializer: i,
        }
    }

init_declarator_declarator -> Node<Declarator> =
    d:declarator {
        env.handle_declarator(&d, Symbol::Identifier);
        d
    }

init_declarator_init -> Initializer =
    "=" _ i:initializer { i }

init_declarator_gnu -> Vec<Node<Extension>> =
    l:asm_label? _ a:attribute_specifier_list { l.into_iter().chain(a).collect() }

type_declarator -> InitDeclarator =
    d:declarator _ e:gnu<init_declarator_gnu>?
    {
        env.handle_declarator(&d, Symbol::Typename);
        InitDeclarator {
            declarator: with_ext(d, e),
            initializer: None,
        }
    }

////
// 6.7.1 Storage-class specifiers
////

storage_class_specifier -> Node<StorageClassSpecifier> = node<storage_class_specifier0>

storage_class_specifier0 -> StorageClassSpecifier =
    K<"extern"> { StorageClassSpecifier::Extern } /
    K<"static"> { StorageClassSpecifier::Static } /
    K<"_Thread_local"> { StorageClassSpecifier::ThreadLocal } /
    K<"auto"> { StorageClassSpecifier::Auto } /
    K<"register"> { StorageClassSpecifier::Register }

storage_class_typedef -> Node<StorageClassSpecifier> = node<storage_class_typedef0>

storage_class_typedef0 -> StorageClassSpecifier =
    K<"typedef"> { StorageClassSpecifier::Typedef }

////
// 6.7.2 Type specifiers
////

// ISO 2011, 6.7.2, §2. Void, _Bool, _Atomic, typedef names, struct/unions, and enum
// specifiers can only appear once in declaration specifiers or specifier-qualifiers.
// This resolves the ambiguity with typedef names.
type_specifier_unique -> TypeSpecifier =
    K<"void"> { TypeSpecifier::Void } /
    K<"_Bool"> { TypeSpecifier::Bool } /
    K<"_Atomic"> _ "(" _ t:type_name _ ")" { TypeSpecifier::Atomic(t) } /
    s:node<struct_or_union_specifier> { TypeSpecifier::Struct(s) } /
    e:node<enum_specifier> { TypeSpecifier::Enum(e) } /
    t:typedef_name { TypeSpecifier::TypedefName(t) }

type_specifier_nonunique -> TypeSpecifier =
    K<"char"> { TypeSpecifier::Char } /
    K<"short"> { TypeSpecifier::Short } /
    K<"int"> { TypeSpecifier::Int } /
    K<"long"> { TypeSpecifier::Long } /
    K<"float"> { TypeSpecifier::Float } /
    K<"double"> { TypeSpecifier::Double } /
    K<"signed" / gnu<"__signed" "__"?>> { TypeSpecifier::Signed } /
    K<"unsigned"> { TypeSpecifier::Unsigned } /
    K<"_Complex" / gnu<"__complex" "__"?>> { TypeSpecifier::Complex } /
    t:K<ts18661_float_type_specifier> { TypeSpecifier::TS18661Float(t) } /
    gnu<typeof_specifier>

struct_or_union_specifier -> StructType =
    t:node<struct_or_union> _ i:identifier? _ d:struct_or_union_body {
        StructType {
            kind: t,
            identifier: i,
            declarations: d,
        }
    } /
    t:node<struct_or_union> _ i:identifier {
        StructType {
            kind: t,
            identifier: Some(i),
            declarations: None,
        }
    }

struct_or_union_body -> Option<Vec<Node<StructDeclaration>>> =
    "{" _ d:list1<node<struct_declaration>> _ "}" { Some(d) } /
    gnu<"{" _ "}"> { Some(Vec::new()) } /
    { None }

struct_or_union -> StructKind =
    K<"struct"> { StructKind::Struct } /
    K<"union"> { StructKind::Union }

struct_declaration -> StructDeclaration =
    f:node<struct_field> { StructDeclaration::Field(f) } /
    s:static_assert { StructDeclaration::StaticAssert(s) } /
    gnu<K<"__extension__">> _ d:struct_declaration { d }

struct_field -> StructField =
    s:specifier_qualifiers _ d:cs0<node<struct_declarator>> _ ";" {
        StructField {
            specifiers: s,
            declarators: d,
        }
    }

specifier_qualifiers -> Vec<Node<SpecifierQualifier>> =
    list_eq1_n<node<specifier_qualifier_unique_type0>, node<specifier_qualifier_qualifier0>> /
    list_ge1_n<node<specifier_qualifier_nonunique_type0>, node<specifier_qualifier_qualifier0>>

specifier_qualifier_unique_type0 -> SpecifierQualifier =
    s:node<type_specifier_unique> { SpecifierQualifier::TypeSpecifier(s) }

specifier_qualifier_nonunique_type0 -> SpecifierQualifier =
    s:node<type_specifier_nonunique> { SpecifierQualifier::TypeSpecifier(s) }

specifier_qualifier_qualifier0 -> SpecifierQualifier =
    q:type_qualifier { SpecifierQualifier::TypeQualifier(q) }

struct_declarator -> StructDeclarator =
    d:declarator? _ ":" _ e:constant_expression a:gnu<attribute_specifier_list>? {
        StructDeclarator {
            declarator: d.map(|d| with_ext(d, a)),
            bit_width: Some(e),
        }
    } /
    d:declarator _ a:gnu<attribute_specifier_list>? {
        StructDeclarator {
            declarator: Some(with_ext(d, a)),
            bit_width: None,
        }
    }

enum_specifier -> EnumType =
    K<"enum"> _ i:identifier? _ "{" _ e:cs1<node<enumerator>> _ ","? _ "}" {
        EnumType {
            identifier: i,
            enumerators: e,
        }
    } /
    K<"enum"> _ i:identifier {
        EnumType {
            identifier: Some(i),
            enumerators: Vec::new(),
        }
    }

enumerator -> Enumerator =
    i:identifier _ e:enumerator_constant? {
        env.add_symbol(&i.node.name, Symbol::Identifier);
        Enumerator {
            identifier: i,
            expression: e,
        }
    }

enumerator_constant -> Box<Node<Expression>> =
    "=" _ e:constant_expression { e }

////
// 6.7.3 Type qualifiers
////

type_qualifier -> Node<TypeQualifier> = node<type_qualifier0>

type_qualifier0 -> TypeQualifier =
    K<"const"    / gnu<"__const">> { TypeQualifier::Const } /
    K<"restrict" / gnu<"__restrict" "__"?>> { TypeQualifier::Restrict } /
    K<"volatile" / gnu<"__volatile" "__"?>> { TypeQualifier::Volatile } /
    clang<K<"_Nonnull">> { TypeQualifier::Nonnull } /
    clang<K<"_Null_unspecified">> { TypeQualifier::NullUnspecified } /
    clang<K<"_Nullable">> { TypeQualifier::Nullable } /
    // 6.7.2.4: _Atomics followed by a "(" are interpreted as type specifiers.
    K<"_Atomic"> _ !"(" { TypeQualifier::Atomic }

////
// 6.7.4 Function specifiers
////

function_specifier -> Node<FunctionSpecifier> = node<function_specifier0>

function_specifier0 -> FunctionSpecifier =
    K<"inline" / gnu<"__inline" "__"?>> { FunctionSpecifier::Inline } /
    K<"_Noreturn"> { FunctionSpecifier::Noreturn }

////
// 6.7.5 Alignment specifiers
////

alignment_specifier -> Node<AlignmentSpecifier> = node<alignment_specifier0>

alignment_specifier0 -> AlignmentSpecifier =
    K<"_Alignas"> _ "(" _ t:type_name _ ")" { AlignmentSpecifier::Type(t) } /
    K<"_Alignas"> _ "(" _ e:constant_expression _ ")" { AlignmentSpecifier::Constant(e) }

////
// 6.7.6 Declarators
////

declarator -> Node<Declarator> = node<declarator0>

declarator0 -> Declarator =
    attr:gnu<attribute_specifier_list>?
    pointer:list0<pointer> _
    kind:node<direct_declarator> _
    derived:list0<node<derived_declarator>>
    {
        Declarator {
            kind: kind,
            derived: concat(pointer, derived),
            extensions: attr.unwrap_or_default(),
        }
    }

direct_declarator -> DeclaratorKind =
    i:identifier { DeclaratorKind::Identifier(i) } /
    "(" _ d:declarator _ ")" { DeclaratorKind::Declarator(Box::new(d)) }

derived_declarator -> DerivedDeclarator =
    "[" _ a:node<array_declarator> { DerivedDeclarator::Array(a) } /
    "(" _ f:scoped<node<function_declarator>> _ ")" { DerivedDeclarator::Function(f) } /
    "(" _ p:cs0<identifier> _ ")" { DerivedDeclarator::KRFunction(p) }

array_declarator -> ArrayDeclarator =
    q:list0<type_qualifier> _ "]" {
        ArrayDeclarator {
            qualifiers: q,
            size: ArraySize::Unknown,
        }
    } /
    q:list0<type_qualifier> _ e:assignment_expression _ "]" {
        ArrayDeclarator {
            qualifiers: q,
            size: ArraySize::VariableExpression(e),
        }
    } /
    K<"static"> _ q:list0<type_qualifier> _ e:assignment_expression _ "]" {
        ArrayDeclarator {
            qualifiers: q,
            size: ArraySize::StaticExpression(e),
        }
    } /
    q:list1<type_qualifier> _ K<"static"> _ e:assignment_expression _ "]" {
        ArrayDeclarator {
            qualifiers: q,
            size: ArraySize::StaticExpression(e),
        }
    } /
    q:list0<type_qualifier> _ "*" _ "]" {
        ArrayDeclarator {
            qualifiers: q,
            size: ArraySize::VariableUnknown,
        }
    }

function_declarator -> FunctionDeclarator =
    p:cs1<parameter_declaration> _ e:ellipsis {
        FunctionDeclarator {
            parameters: p,
            ellipsis: e,
        }
    }

pointer -> Node<DerivedDeclarator> = node<pointer0>

pointer0 -> DerivedDeclarator =
    "*" _ q:list0<node<pointer_qualifier>> { DerivedDeclarator::Pointer(q) }

pointer_qualifier -> PointerQualifier =
    q:type_qualifier { PointerQualifier::TypeQualifier(q) } /
    e:gnu<attribute_specifier> { PointerQualifier::Extension(e) }

ellipsis -> Ellipsis =
    "," _ "..." { Ellipsis::Some } / { Ellipsis::None }

parameter_declaration -> Node<ParameterDeclaration> = node<parameter_declaration0>

parameter_declaration0 -> ParameterDeclaration =
    s:declaration_specifiers _ d:parameter_declarator _ a:gnu<attribute_specifier_list>? {
        ParameterDeclaration {
            specifiers: s,
            declarator: d,
            extensions: a.unwrap_or_default()
        }
    }

parameter_declarator -> Option<Node<Declarator>> =
    d:declarator {
        env.handle_declarator(&d, Symbol::Identifier);
        Some(d)
    } /
    d:abstract_declarator { Some(d) } /
    { None }

////
// 6.7.7 Type names
////

type_name -> Node<TypeName> = node<type_name0>

type_name0 -> TypeName =
    s:specifier_qualifiers _ d:abstract_declarator? {
        TypeName {
            specifiers: s,
            declarator: d,
        }
    }

abstract_declarator -> Node<Declarator> = node<abstract_declarator0>

abstract_declarator0 -> Declarator =
    p:list0<pointer> _ k:node<direct_abstract_declarator> _ d:list0<derived_abstract_declarator> {
        Declarator {
            kind: k,
            derived: concat(p, d),
            extensions: Vec::new(),
        }
    } /
    p:list0<pointer> k:#position _ d:list1<derived_abstract_declarator> {
        Declarator {
            kind: Node::new(DeclaratorKind::Abstract, Span::span(k, k)),
            derived: concat(p, d),
            extensions: Vec::new(),
        }
    } /
    p:list1<pointer> k:#position {
        Declarator {
            kind: Node::new(DeclaratorKind::Abstract, Span::span(k, k)),
            derived: p,
            extensions: Vec::new(),
        }
    }

direct_abstract_declarator -> DeclaratorKind =
    "(" _ d:abstract_declarator _ ")" { DeclaratorKind::Declarator(Box::new(d)) }

derived_abstract_declarator -> Node<DerivedDeclarator> = node<derived_abstract_declarator0>

derived_abstract_declarator0 -> DerivedDeclarator =
    "[" _ a:node<abstract_array_declarator> { DerivedDeclarator::Array(a) } /
    "(" _ d:node<abstract_function_declarator> _ ")" { DerivedDeclarator::Function(d) }

abstract_array_declarator -> ArrayDeclarator =
    q:list0<type_qualifier> _ "]" {
        ArrayDeclarator {
            qualifiers: q,
            size: ArraySize::Unknown,
        }
    } /
    q:list0<type_qualifier> _ e:assignment_expression _ "]" {
        ArrayDeclarator {
            qualifiers: q,
            size: ArraySize::VariableExpression(e),
        }
    } /
    K<"static"> _ q:list0<type_qualifier> _ e:assignment_expression _ "]" {
        ArrayDeclarator {
            qualifiers: q,
            size: ArraySize::StaticExpression(e),
        }
    } /
    q:list1<type_qualifier> _ K<"static"> _ e:assignment_expression _ "]" {
        ArrayDeclarator {
            qualifiers: q,
            size: ArraySize::StaticExpression(e),
        }
    } /
    "*" _ "]" {
        ArrayDeclarator {
            qualifiers: Vec::new(),
            size: ArraySize::VariableUnknown,
        }
    }

abstract_function_declarator -> FunctionDeclarator =
    p:cs1<parameter_declaration> _ e:ellipsis {
        FunctionDeclarator {
            parameters: p,
            ellipsis: e,
        }
    } /
    {
        FunctionDeclarator {
            parameters: Vec::new(),
            ellipsis: Ellipsis::None,
        }
    }


////
// 6.7.8 Type definitions
////

typedef_name -> Node<Identifier> = #quiet<typedef_name0> / #expected("<typedef_name>")

typedef_name0 -> Node<Identifier> = i:identifier {?
    if env.is_typename(&i.node.name) {
        Ok(i)
    } else {
        Err("<unused>")
    }
}

////
// 6.7.9 Initialization
////

initializer -> Initializer =
    e:assignment_expression { Initializer::Expression(e) } /
    "{" _ i:cs1<node<initializer_list_item>> _ ","? _ "}" { Initializer::List(i) } /
    gnu<"{" _ "}"> { Initializer::List(Vec::new()) }

initializer_list_item -> InitializerListItem =
    d:designation? _ i:node<initializer> {
        InitializerListItem {
            designation: d.unwrap_or_default(),
            initializer: Box::new(i),
        }
    }

designation -> Vec<Node<Designator>> =
    d:list1<node<designator>> _ "=" { d } /
    d:gnu<node<colon_designation>> { vec! [ d ] } /
    d:gnu<node<array_designator>> { vec![ d ] }

colon_designation -> Designator =
    i:identifier _ ":" { Designator::Member(i) }

designator -> Designator =
    d:array_designator { d } /
    "." _ i:identifier { Designator::Member(i) }

array_designator -> Designator =
    "[" _ a:node<constant_expression0> _ b:gnu<range_designator_ext>? "]" {
        match b {
            Some(b) => {
                let span = Span::span(a.span.start, b.span.end);
                Designator::Range(Node::new(RangeDesignator { from: a, to: b }, span))
            }
            None => Designator::Index(a),
        }
    }

range_designator_ext -> Node<Expression> =
    "..." _ e:node<constant_expression0> { e }

////
// 6.7.10 Static assertions
////

static_assert -> Node<StaticAssert> = node<static_assert0>

static_assert0 -> StaticAssert =
   gnu<K<"__extension__">>?
   _ K<"_Static_assert"> _ "(" _ e:constant_expression _ "," _ s:string_literal _ ")" _ ";" {
        StaticAssert {
            expression: e,
            message: s,
        }
    }

////
// 6.8 Statements and blocks
////

pub statement -> Box<Node<Statement>> = box<node<statement0>>

statement0 -> Statement =
    s:node<labeled_statement> { Statement::Labeled(s) } /
    scoped<compound_statement> /
    expression_statement /
    scoped<selection_statement> /
    scoped<iteration_statement> /
    jump_statement /
    gnu<asm_statement>

////
// 6.8.1 Labeled statements
////

labeled_statement -> LabeledStatement =
    l:node<label> _ ":" _ s:statement {
        LabeledStatement {
            label: l,
            statement: s,
        }
    }

label -> Label =
    i:identifier { Label::Identifier(i) } /
    K<"case"> _ e:constant_expression { Label::Case(e) } /
    K<"default"> { Label::Default }

////
// 6.8.2 Compound statement
////

compound_statement -> Statement =
    "{" _ b:list0<node<block_item>> _ "}" { Statement::Compound(b) }

block_item -> BlockItem =
    d:declaration { BlockItem::Declaration(d) } /
    s:static_assert { BlockItem::StaticAssert(s) } /
    s:node<statement0> { BlockItem::Statement(s) }

////
// 6.8.3 Expression and null statements
////

expression_statement -> Statement =
    e:expression? _ ";" { Statement::Expression(e) }

////
// 6.8.4 Selection statement
////

selection_statement -> Statement =
    s:node<if_statement> { Statement::If(s) } /
    s:node<switch_statement> { Statement::Switch(s) }

if_statement -> IfStatement =
    K<"if"> _ "(" _ e:expression _ ")" _ a:statement _ b:else_statement? {
        IfStatement {
            condition: e,
            then_statement: a,
            else_statement: b,
        }
    }

else_statement -> Box<Node<Statement>> = K<"else"> _ s:statement { s }

switch_statement -> SwitchStatement =
    K<"switch"> _ "(" _ e:expression _ ")" _ s:statement {
        SwitchStatement {
            expression: e,
            statement: s,
        }
    }

////
// 6.8.5 Iteration statement
////

iteration_statement -> Statement =
    s:node<while_statement> { Statement::While(s) } /
    s:node<do_while_statement> { Statement::DoWhile(s) } /
    s:node<for_statement> { Statement::For(s) }

while_statement -> WhileStatement =
    K<"while"> _ "(" _ e:expression _ ")" _ s:statement {
        WhileStatement {
            expression: e,
            statement: s,
        }
    }

do_while_statement -> DoWhileStatement =
    K<"do"> _ s:statement _ K<"while"> _ "(" _ e:expression _ ")" _ ";" {
        DoWhileStatement {
            statement: s,
            expression: e,
        }
    }

for_statement -> ForStatement =
    K<"for"> _ "(" _ a:node<for_initializer> _ b:expression? _ ";" _ c:expression? _ ")" _ s:statement {
        ForStatement {
            initializer: a,
            condition: b,
            step: c,
            statement: s,
        }
    }

for_initializer -> ForInitializer =
    e:expression _ ";" { ForInitializer::Expression(e) } /
    d:declaration { ForInitializer::Declaration(d) } /
    s:static_assert { ForInitializer::StaticAssert(s) } /
    ";" { ForInitializer::Empty }

////
// 6.8.6 Jump statements
////

jump_statement -> Statement =
    K<"goto"> _ i:identifier _ ";" { Statement::Goto(i) } /
    K<"continue"> _ ";" { Statement::Continue } /
    K<"break"> _ ";" { Statement::Break } /
    K<"return"> _ e:expression? _ ";" { Statement::Return(e) }

////
// 6.9 External definitions
////

scoped<e> = ({ env.enter_scope(); }) e:e? {? env.leave_scope(); e.ok_or("") }

pub translation_unit -> TranslationUnit =
    directive? _ d:list0<node<external_declaration>> _ { TranslationUnit(d) }

external_declaration -> ExternalDeclaration =
    d:declaration { ExternalDeclaration::Declaration(d) } /
    s:static_assert { ExternalDeclaration::StaticAssert(s) } /
    d:scoped<node<function_definition>> { ExternalDeclaration::FunctionDefinition(d) }

function_definition -> FunctionDefinition =
    gnu<K<"__extension__">>?
    _ a:declaration_specifiers _ b:declarator _ c:list0<declaration>
    _ d:node<compound_statement> {
        FunctionDefinition {
            specifiers: a,
            declarator: b,
            declarations: c,
            statement: d,
        }
    }

////
// GNU extensions
////

gnu<E> = &gnu_guard e:E { e }

gnu_guard = {? if env.extensions_gnu { Ok(()) } else { Err("gnu extensions disabled") } }

////
// GNU attributes
////

attribute_specifier_list -> Vec<Node<Extension>> =
    a:list0<attribute_specifier> { a.into_iter().flat_map(|v| v).collect() }

attribute_specifier -> Vec<Node<Extension>> =
    K<"__attribute__"> _ "((" _ a:cs0<node<attribute>> _ "))" { a }

attribute -> Extension =
    c:clang<node<attr_availability>> { Extension::AvailabilityAttribute(c) } /
    n:node<attribute_name> _ p:attribute_parameters? {
        Extension::Attribute(Attribute {
            name: n,
            arguments: p.unwrap_or_default(),
        })
    }

attribute_name -> String =
    n:$(#quiet<[_a-zA-Z][_a-zA-Z0-9]*>) { String::from(n) }

attribute_parameters -> Vec<Node<Expression>> =
    "(" _ e:cs0<node<assignment_expression0>> _ ")" { e }

attr_availability -> AvailabilityAttribute =
    K<"availability"> _ "(" _ p:identifier _ "," _ c:cs1<node<attr_availability_clause>> _ ")" {
        AvailabilityAttribute {
            platform: p,
            clauses: c,
        }
    }

attr_availability_clause -> AvailabilityClause =
    K<"introduced"> _ "=" _ v:node<attr_availability_version> { AvailabilityClause::Introduced(v) } /
    K<"deprecated"> _ "=" _ v:node<attr_availability_version> { AvailabilityClause::Deprecated(v) } /
    K<"obsoleted"> _ "=" _ v:node<attr_availability_version> { AvailabilityClause::Obsoleted(v) } /
    K<"unavailable"> { AvailabilityClause::Unavailable } /
    K<"message"> _ "=" _ s:string_literal { AvailabilityClause::Message(s) } /
    K<"replacement"> _ "=" _ s:string_literal { AvailabilityClause::Replacement(s) }

attr_availability_version -> AvailabilityVersion =
    a:$(dec+) b:("." $(dec+) )? c:("." $(dec+) )? {
        AvailabilityVersion {
            major: a.into(),
            minor: b.map(str::to_owned),
            subminor: c.map(str::to_owned),
        }
    }

////
// GNU assembler labels
////

asm_label -> Node<Extension> = node<asm_label0>

asm_label0 -> Extension =
    asm_label_keyword _ "(" _ s:string_literal _ ")" { Extension::AsmLabel(s) }

asm_label_keyword =
    #quiet<K<"asm"> / K<"__asm" "__"?>> / #expected("asm")

////
// GNU assembler statements
////

asm_statement -> Statement =
    s:node<asm_statement0> { Statement::Asm(s) }

asm_statement0 -> AsmStatement =
    K<"asm" / "__asm" "__"?> _ q:type_qualifier? _ "(" _
        a:string_literal _
        o:asm_ext<asm_operand_list, asm_ext<asm_operand_list, asm_ext<cs0<string_literal>, ()>>>? _
    ")" _ ";" {
        if let Some((o, (i, (c, ())))) = o {
            AsmStatement::GnuExtended(GnuExtendedAsmStatement {
                qualifier: q,
                template: a,
                outputs: o,
                inputs: i,
                clobbers: c,
            })
        } else {
            AsmStatement::GnuBasic(a)
        }
    }

asm_ext<e, t> = ":" _ e:e _ t:t? { (e, t.unwrap_or_default()) }

asm_operand_list -> Vec<Node<GnuAsmOperand>> = cs0<node<asm_operand>>

asm_operand -> GnuAsmOperand =
    i:("[" _ i:identifier _ "]" _ {i})? s:string_literal _ "(" _ e:node<expression0> _ ")" {
        GnuAsmOperand {
            symbolic_name: i,
            constraints: s,
            variable_name: e,
        }
    }

////
// GNU expression extensions
////

gnu_primary_expression -> Expression =
    statement_expression /
    offsetof_expression /
    va_arg_expression /
    keyword_expression

statement_expression -> Expression =
    "(" _ s:scoped<node<compound_statement>> _ ")" { Expression::Statement(Box::new(s)) }

va_arg_expression -> Expression =
    n:node<va_arg_expression_inner> { Expression::VaArg(Box::new(n)) }

va_arg_expression_inner -> VaArgExpression =
    K<"__builtin_va_arg"> _ "(" _ e:assignment_expression _ "," _ t:type_name _ ")" {
        VaArgExpression {
            va_list: e,
            type_name: t,
        }
    }

keyword_expression -> Expression =
    k:node<$(keyword_expression0)> {
        let ident = Identifier {
            name: k.node.to_string(),
        };
        Expression::Identifier(Box::new(Node::new(ident, k.span)))
    }

keyword_expression0 =
    K<"__func__"> /
    K<"__FUNCTION__"> /
    K<"__PRETTY_FUNCTION__">

offsetof_expression -> Expression =
    n:node<offsetof_expression_inner> { Expression::OffsetOf(Box::new(n)) }

offsetof_expression_inner -> OffsetOfExpression =
    K<"__builtin_offsetof"> _ "(" _ t:type_name _ "," _ d:node<offsetof_designator> _ ")" {
        OffsetOfExpression {
            type_name: t,
            designator: d,
        }
    }

offsetof_designator -> OffsetDesignator =
    i:identifier _ d:list0<node<offsetof_member>> {
        OffsetDesignator {
            base: i,
            members: d,
        }
    }

offsetof_member -> OffsetMember =
    "." _ i:identifier { OffsetMember::Member(i) } /
    "->" _ i:identifier { OffsetMember::IndirectMember(i) } /
    "[" _ e:node<expression0> _ "]" { OffsetMember::Index(e) }

////
// GNU typeof extension
////

typeof_specifier -> TypeSpecifier =
    K<"typeof" / "__typeof" "__"?> _ "(" _ e:node<typeof_specifier0> _ ")" { TypeSpecifier::TypeOf(e) }

typeof_specifier0 -> TypeOf =
    e:node<expression0> { TypeOf::Expression(e) } /
    t:type_name { TypeOf::Type(t) }

////
// ISO/IEC TS 18661 series floating point extensions
////

ts18661_float_type_specifier -> TS18661FloatType =
    ts18661_binary_float /
    ts18661_decimal_float

ts18661_binary_float -> TS18661FloatType =
    "_Float" width:ts18661_binary_width extended:"x"? {
        ts18661_float(true, width, extended.is_some())
    }

ts18661_binary_width -> usize =
    n:$("16" / "32" / "64" / "128") {
        n.parse().unwrap()
    }

ts18661_decimal_float -> TS18661FloatType =
    "_Decimal" width:ts18661_decimal_width extended:"x"? {
        ts18661_float(false, width, extended.is_some())
    }

ts18661_decimal_width -> usize =
    n:$("32" / "64" / "128") {
        n.parse().unwrap()
    }

ts18661_float_suffix -> TS18661FloatType =
    ("df" / "DF") { ts18661_float(false, 32, false) } /
    ("dd" / "DD") { ts18661_float(false, 64, false) } /
    ("dl" / "DL") { ts18661_float(false, 128, false) } /

    [fF] width:ts18661_binary_width extended:"x"? {
        ts18661_float(true, width, extended.is_some())
    } /
    [dD] width:ts18661_decimal_width extended:"x"? {
        ts18661_float(false, width, extended.is_some())
    }

////
// Clang extensions
////

clang<E> = &clang_guard e:E { e }

clang_guard = {? if env.extensions_clang { Ok(()) } else { Err("clang extensions disabled") } }