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parser.ypp
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parser.ypp
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// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// -----------------------------------------------------------------------------
// Bison Configuration
// -----------------------------------------------------------------------------
%require "3.2"
%language "c++"
// We don't need a separate header for Bison locations.
%define api.location.file none
// Use a type-safe C++ variant for semantic values
%define api.value.type variant
// Have Bison generate the functions ‘make_TEXT’ and ‘make_NUMBER’, but also
// ‘make_YYEOF’, for the end of input.
%define api.token.constructor
// Generate the parser as `::Carbon::Parser`.
%define api.namespace { Carbon }
%define api.parser.class { Parser }
// Make parse error messages more detailed
%define parse.error verbose
// Enable support for parser debugging
%define parse.trace true
// Generate location structs.
%locations
// Parameters to the parser and lexer.
//
// Parameters to the parser are stored therein as protected data members, and
// thus available to its methods.
// "inout" parameters passed to both the parser and the lexer.
%param {Nonnull<Arena*> arena}
%param {yyscan_t yyscanner}
%param {ParseAndLexContext& context}
// "out" parameter passed to the parser, where the AST is written.
%parse-param {std::optional<AST>* ast}
// No shift-reduce conflicts are expected.
// See README.md#precedence-and-associativity for a description of how
// operator precedence is expressed.
%expect 0
// -----------------------------------------------------------------------------
%code top {
#include <algorithm>
#include <cstdarg>
#include <cstdio>
#include <cstdlib>
#include <vector>
#include "explorer/syntax/parse_and_lex_context.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/FormatVariadic.h"
#include "llvm/Support/raw_ostream.h"
} // %code top
%code requires {
#include <optional>
#include "explorer/ast/ast.h"
#include "explorer/ast/declaration.h"
#include "explorer/ast/expression.h"
#include "explorer/ast/expression_category.h"
#include "explorer/ast/paren_contents.h"
#include "explorer/ast/pattern.h"
#include "explorer/base/arena.h"
#include "explorer/base/nonnull.h"
#include "explorer/syntax/bison_wrap.h"
namespace Carbon {
class ParseAndLexContext;
} // namespace Carbon
typedef void* yyscan_t;
} // %code requires
%code {
void Carbon::Parser::error(const location_type&, const std::string& message) {
context.RecordSyntaxError(message);
}
} // %code
%token <int> integer_literal
%token <std::string> identifier
%token <IntrinsicExpression::Intrinsic> intrinsic_identifier
%token <std::string> sized_type_literal
%token <std::string> string_literal
%type <std::string> designator
%type <Nonnull<Expression*>> impl_type
%type <Nonnull<Expression*>> no_impl_type
%type <std::pair<LibraryName, bool>> package_directive
%type <LibraryName> import_directive
%type <std::vector<LibraryName>> import_directives
%type <std::string> optional_library_path
%type <bool> api_or_impl
%type <VirtualOverride> fn_virtual_override_intro
%type <VirtualOverride> destructor_virtual_override_intro
%type <ClassExtensibility> class_declaration_extensibility
%type <Nonnull<Declaration*>> declaration
%type <Nonnull<Declaration*>> namespace_declaration
%type <BisonWrap<DeclaredName>> declared_name
%type <Nonnull<FunctionDeclaration*>> function_declaration
%type <Nonnull<DestructorDeclaration*>> destructor_declaration
%type <Nonnull<ExtendBaseDeclaration*>> extend_base_declaration
%type <Nonnull<MixDeclaration*>> mix_declaration
%type <Nonnull<AliasDeclaration*>> alias_declaration
%type <Nonnull<ImplDeclaration*>> impl_declaration
%type <Nonnull<ImplDeclaration*>> extend_impl_declaration
%type <Nonnull<MatchFirstDeclaration*>> match_first_declaration
%type <std::vector<Nonnull<ImplDeclaration*>>> match_first_declaration_list
%type <std::vector<Nonnull<Declaration*>>> top_level_declaration_list
%type <std::vector<Nonnull<Declaration*>>> class_body
%type <std::vector<Nonnull<Declaration*>>> mixin_body
%type <std::vector<Nonnull<Declaration*>>> interface_body
%type <std::vector<Nonnull<Declaration*>>> impl_body
%type <Nonnull<Statement*>> statement
%type <Nonnull<Statement*>> assign_statement
%type <AssignOperator> assign_operator
%type <Nonnull<If*>> if_statement
%type <std::optional<Nonnull<Block*>>> optional_else
%type <std::pair<Nonnull<Expression*>, bool>> return_expression
%type <Nonnull<Block*>> block
%type <std::vector<Nonnull<Statement*>>> statement_list
%type <Nonnull<Expression*>> primary_expression
%type <Nonnull<Expression*>> postfix_expression
%type <Nonnull<Expression*>> ref_deref_expression
%type <Nonnull<Expression*>> type_expression
%type <Nonnull<Expression*>> fn_type_expression
%type <Nonnull<Expression*>> minus_expression
%type <Nonnull<Expression*>> complement_expression
%type <Nonnull<Expression*>> unary_expression
%type <Nonnull<Expression*>> simple_binary_operand
%type <Nonnull<Expression*>> multiplicative_lhs
%type <Nonnull<Expression*>> multiplicative_expression
%type <Nonnull<Expression*>> additive_operand
%type <Nonnull<Expression*>> additive_lhs
%type <Nonnull<Expression*>> additive_expression
%type <Nonnull<Expression*>> modulo_expression
%type <Nonnull<Expression*>> bitwise_and_lhs
%type <Nonnull<Expression*>> bitwise_and_expression
%type <Nonnull<Expression*>> bitwise_or_lhs
%type <Nonnull<Expression*>> bitwise_or_expression
%type <Nonnull<Expression*>> bitwise_xor_lhs
%type <Nonnull<Expression*>> bitwise_xor_expression
%type <Nonnull<Expression*>> bitwise_expression
%type <Nonnull<Expression*>> bit_shift_expression
%type <Nonnull<Expression*>> as_expression
%type <Nonnull<Expression*>> unimpl_expression
%type <Nonnull<Expression*>> value_expression
%type <Nonnull<Expression*>> comparison_operand
%type <Nonnull<Expression*>> comparison_expression
%type <Nonnull<Expression*>> not_expression
%type <Nonnull<Expression*>> predicate_expression
%type <Nonnull<Expression*>> and_or_operand
%type <Nonnull<Expression*>> and_lhs
%type <Nonnull<Expression*>> and_expression
%type <Nonnull<Expression*>> or_lhs
%type <Nonnull<Expression*>> or_expression
%type <Nonnull<WhereClause*>> where_clause
%type <std::vector<Nonnull<WhereClause*>>> where_clause_list
%type <Nonnull<Expression*>> where_expression
%type <Nonnull<Expression*>> type_or_where_expression
%type <Nonnull<Expression*>> statement_expression
%type <Nonnull<Expression*>> if_expression
%type <Nonnull<Expression*>> expression
%type <Nonnull<Expression*>> mixin_import
%type <Nonnull<GenericBinding*>> generic_binding
%type <Nonnull<Pattern*>> deduced_param
%type <std::vector<Nonnull<AstNode*>>> deduced_params
%type <std::vector<Nonnull<AstNode*>>> impl_deduced_params
%type <std::vector<Nonnull<AstNode*>>> deduced_param_list
%type <Nonnull<Pattern*>> pattern
%type <Nonnull<Pattern*>> non_expression_pattern
%type <BisonWrap<ReturnTerm>> return_term
%type <Nonnull<Expression*>> paren_expression
%type <Nonnull<StructLiteral*>> struct_literal
%type <std::vector<FieldInitializer>> struct_literal_contents
%type <Nonnull<StructTypeLiteral*>> struct_type_literal
%type <std::vector<FieldInitializer>> struct_type_literal_contents
%type <Nonnull<TupleLiteral*>> tuple
%type <std::string> binding_lhs
%type <Nonnull<BindingPattern*>> variable_declaration
%type <ParenContents<Expression>> paren_expression_base
%type <ParenContents<Expression>> paren_expression_contents
%type <Nonnull<Pattern*>> paren_pattern
%type <Nonnull<TuplePattern*>> tuple_pattern
%type <Nonnull<TuplePattern*>> maybe_empty_tuple_pattern
%type <std::optional<Nonnull<TuplePattern*>>> type_params
%type <ParenContents<Pattern>> paren_pattern_base
%type <ParenContents<Pattern>> paren_pattern_contents
%type <Nonnull<AlternativeSignature*>> alternative
%type <std::vector<Nonnull<AlternativeSignature*>>> alternative_list
%type <std::vector<Nonnull<AlternativeSignature*>>> alternative_list_contents
%type <BisonWrap<Match::Clause>> clause
%type <std::vector<Match::Clause>> clause_list
%type <Operator> comparison_operator;
%token
// Most tokens have their spelling defined in lexer.lpp.
// table-begin
ABSTRACT
ADDR
ALIAS
AMPERSAND
AMPERSAND_EQUAL
AND
API
ARROW
AS
AUTO
BASE
BOOL
BREAK
CARET
CARET_EQUAL
CASE
CHOICE
CLASS
COLON
COLON_BANG
COMMA
CONSTRAINT
CONTINUE
DEFAULT
DESTRUCTOR
DOUBLE_ARROW
ELSE
EQUAL
EQUAL_EQUAL
EXTEND
FALSE
FN
FN_TYPE
FOR
FORALL
GREATER
GREATER_EQUAL
GREATER_GREATER
GREATER_GREATER_EQUAL
IF
IMPL
IMPLS
IMPORT
IN
INTERFACE
LEFT_CURLY_BRACE
LEFT_PARENTHESIS
LEFT_SQUARE_BRACKET
LESS
LESS_EQUAL
LESS_LESS
LESS_LESS_EQUAL
LET
LIBRARY
MATCH
MATCH_FIRST
MINUS
MINUS_EQUAL
MINUS_MINUS
MIX
MIXIN
NAMESPACE
NOT
NOT_EQUAL
OR
OR_EQUAL
PACKAGE
PERCENT
PERCENT_EQUAL
PERIOD
PIPE
PIPE_EQUAL
PLUS
PLUS_EQUAL
PLUS_PLUS
REQUIRE
RETURN
RETURNED
RIGHT_CURLY_BRACE
RIGHT_PARENTHESIS
RIGHT_SQUARE_BRACKET
SELF
SEMICOLON
SLASH
SLASH_EQUAL
STAR_EQUAL
STRING
TEMPLATE
THEN
TRUE
TYPE
UNDERSCORE
UNIMPL_EXAMPLE
VAR
VIRTUAL
WHERE
WHILE
// table-end
// Used to track EOF.
END_OF_FILE 0
// Only used for precedence.
FNARROW "-> in return type"
// The lexer determines the arity and fixity of each `*` based on whitespace
// and adjacent tokens. UNARY_STAR indicates that the operator is unary but
// could be either prefix or postfix.
UNARY_STAR "unary *"
PREFIX_STAR "prefix *"
POSTFIX_STAR "postfix *"
BINARY_STAR "binary *"
;
%start input
%%
input: package_directive import_directives top_level_declaration_list
{
*ast = AST({.package = $[package_directive].first,
.is_api = $[package_directive].second,
.imports = std::move($[import_directives]),
.declarations = std::move($[top_level_declaration_list])});
}
;
package_directive:
PACKAGE identifier optional_library_path api_or_impl SEMICOLON
{
$$ = {LibraryName(
{.package = $[identifier], .path = $[optional_library_path]}),
$[api_or_impl]};
}
;
import_directive:
IMPORT identifier optional_library_path SEMICOLON
{
$$ = LibraryName(
{.package = $[identifier], .path = $[optional_library_path]});
}
;
import_directives:
// Empty
{ $$ = std::vector<LibraryName>(); }
| import_directives[accumulated_import_directives] import_directive
{
$$ = std::move($[accumulated_import_directives]);
$$.push_back($[import_directive]);
}
;
optional_library_path:
// Empty
{ $$ = ""; }
| LIBRARY string_literal
{ $$ = $[string_literal]; }
;
api_or_impl:
API
{ $$ = true; }
| IMPL
{ $$ = false; }
;
primary_expression:
identifier
{
$$ =
arena->New<IdentifierExpression>(context.source_loc(), $[identifier]);
}
| designator
{
// `.Foo` is rewritten to `.Self.Foo`.
$$ = arena->New<SimpleMemberAccessExpression>(
context.source_loc(),
arena->New<DotSelfExpression>(context.source_loc()), $[designator]);
}
| PERIOD SELF
{ $$ = arena->New<DotSelfExpression>(context.source_loc()); }
| integer_literal
{ $$ = arena->New<IntLiteral>(context.source_loc(), $[integer_literal]); }
| string_literal
{ $$ = arena->New<StringLiteral>(context.source_loc(), $[string_literal]); }
| TRUE
{ $$ = arena->New<BoolLiteral>(context.source_loc(), true); }
| FALSE
{ $$ = arena->New<BoolLiteral>(context.source_loc(), false); }
| sized_type_literal
{
int val = 0;
if (!llvm::to_integer(llvm::StringRef($[sized_type_literal]).substr(1),
val)) {
context.RecordSyntaxError(
llvm::formatv("Invalid type literal: {0}", $[sized_type_literal]));
YYERROR;
} else if ($[sized_type_literal][0] != 'i' || val != 32) {
context.RecordSyntaxError(llvm::formatv(
"Only i32 is supported for now: {0}", $[sized_type_literal]));
YYERROR;
} else {
$$ = arena->New<IntTypeLiteral>(context.source_loc());
}
}
| SELF
// TODO: Should we create a new TypeLiteral for `Self`?
{ $$ = arena->New<IdentifierExpression>(context.source_loc(), "Self"); }
| STRING
{ $$ = arena->New<StringTypeLiteral>(context.source_loc()); }
| BOOL
{ $$ = arena->New<BoolTypeLiteral>(context.source_loc()); }
| TYPE
{ $$ = arena->New<TypeTypeLiteral>(context.source_loc()); }
| paren_expression { $$ = $[paren_expression]; }
| struct_literal { $$ = $[struct_literal]; }
| struct_type_literal { $$ = $[struct_type_literal]; }
| LEFT_SQUARE_BRACKET expression[type_expression] SEMICOLON
expression[size_expression] RIGHT_SQUARE_BRACKET
{
$$ = arena->New<ArrayTypeLiteral>(context.source_loc(),
$[type_expression], $[size_expression]);
}
| LEFT_SQUARE_BRACKET expression[type_expression] SEMICOLON RIGHT_SQUARE_BRACKET
{
$$ = arena->New<ArrayTypeLiteral>(context.source_loc(),
$[type_expression]);
}
;
postfix_expression:
primary_expression
| postfix_expression[child_postfix_expression] designator
{
$$ = arena->New<SimpleMemberAccessExpression>(
context.source_loc(), $[child_postfix_expression], $[designator]);
}
| postfix_expression[child_postfix_expression] ARROW identifier
{
auto deref = arena->New<OperatorExpression>(
context.source_loc(), Operator::Deref,
std::vector<Nonnull<Expression*>>({$[child_postfix_expression]}));
$$ = arena->New<SimpleMemberAccessExpression>(context.source_loc(), deref,
$[identifier]);
}
| postfix_expression[child_postfix_expression] PERIOD LEFT_PARENTHESIS
expression RIGHT_PARENTHESIS
{
$$ = arena->New<CompoundMemberAccessExpression>(
context.source_loc(), $[child_postfix_expression], $[expression]);
}
| postfix_expression[child_postfix_expression] ARROW LEFT_PARENTHESIS expression
RIGHT_PARENTHESIS
{
auto deref = arena->New<OperatorExpression>(
context.source_loc(), Operator::Deref,
std::vector<Nonnull<Expression*>>({$[child_postfix_expression]}));
$$ = arena->New<CompoundMemberAccessExpression>(context.source_loc(),
deref, $[expression]);
}
| postfix_expression[child_postfix_expression] LEFT_SQUARE_BRACKET expression
RIGHT_SQUARE_BRACKET
{
$$ = arena->New<IndexExpression>(
context.source_loc(), $[child_postfix_expression], $[expression]);
}
| intrinsic_identifier tuple
{
$$ = arena->New<IntrinsicExpression>($[intrinsic_identifier], $[tuple],
context.source_loc());
}
| postfix_expression[child_postfix_expression] tuple
{
$$ = arena->New<CallExpression>(context.source_loc(),
$[child_postfix_expression], $[tuple]);
}
| postfix_expression[child_postfix_expression] POSTFIX_STAR
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Ptr,
std::vector<Nonnull<Expression*>>({$[child_postfix_expression]}));
}
| postfix_expression[child_postfix_expression] UNARY_STAR
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Ptr,
std::vector<Nonnull<Expression*>>({$[child_postfix_expression]}));
}
;
ref_deref_expression:
postfix_expression
| PREFIX_STAR ref_deref_expression[child_ref_deref_expression]
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Deref,
std::vector<Nonnull<Expression*>>({$[child_ref_deref_expression]}));
}
| UNARY_STAR ref_deref_expression[child_ref_deref_expression]
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Deref,
std::vector<Nonnull<Expression*>>({$[child_ref_deref_expression]}));
}
| AMPERSAND ref_deref_expression[child_ref_deref_expression]
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::AddressOf,
std::vector<Nonnull<Expression*>>({$[child_ref_deref_expression]}));
}
;
fn_type_expression:
FN_TYPE tuple ARROW type_expression
{
$$ = arena->New<FunctionTypeLiteral>(context.source_loc(), $[tuple],
$[type_expression]);
}
;
type_expression:
ref_deref_expression
| bitwise_and_expression
| fn_type_expression
;
minus_expression:
// ref_deref_expression excluded due to precedence diamond.
MINUS ref_deref_expression
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Neg,
std::vector<Nonnull<Expression*>>({$[ref_deref_expression]}));
}
;
complement_expression:
// ref_deref_expression excluded due to precedence diamond.
CARET ref_deref_expression
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Complement,
std::vector<Nonnull<Expression*>>({$[ref_deref_expression]}));
}
;
unary_expression:
// ref_deref_expression excluded due to precedence diamond.
minus_expression
| complement_expression
;
// A simple_binary_operand is an operand of a binary operator
// that is not itself a binary operator expression.
simple_binary_operand:
ref_deref_expression
| unary_expression
;
multiplicative_lhs:
simple_binary_operand
| multiplicative_expression
;
multiplicative_expression:
multiplicative_lhs BINARY_STAR simple_binary_operand
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Mul,
std::vector<Nonnull<Expression*>>(
{$[multiplicative_lhs], $[simple_binary_operand]}));
}
| multiplicative_lhs SLASH simple_binary_operand
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Div,
std::vector<Nonnull<Expression*>>(
{$[multiplicative_lhs], $[simple_binary_operand]}));
}
;
additive_operand:
simple_binary_operand
| multiplicative_expression
;
additive_lhs:
simple_binary_operand
| additive_expression
;
additive_expression:
multiplicative_expression
| additive_lhs PLUS additive_operand
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Add,
std::vector<Nonnull<Expression*>>(
{$[additive_lhs], $[additive_operand]}));
}
| additive_lhs MINUS additive_operand
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Sub,
std::vector<Nonnull<Expression*>>(
{$[additive_lhs], $[additive_operand]}));
}
;
modulo_expression:
simple_binary_operand[lhs_simple_binary_operand] PERCENT
simple_binary_operand[rhs_simple_binary_operand]
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Mod,
std::vector<Nonnull<Expression*>>(
{$[lhs_simple_binary_operand], $[rhs_simple_binary_operand]}));
}
;
bitwise_and_lhs:
simple_binary_operand
| bitwise_and_expression
;
bitwise_and_expression:
bitwise_and_lhs AMPERSAND simple_binary_operand
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::BitwiseAnd,
std::vector<Nonnull<Expression*>>(
{$[bitwise_and_lhs], $[simple_binary_operand]}));
}
;
bitwise_or_lhs:
simple_binary_operand
| bitwise_or_expression
;
bitwise_or_expression:
bitwise_or_lhs PIPE simple_binary_operand
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::BitwiseOr,
std::vector<Nonnull<Expression*>>(
{$[bitwise_or_lhs], $[simple_binary_operand]}));
}
;
bitwise_xor_lhs:
simple_binary_operand
| bitwise_xor_expression
;
bitwise_xor_expression:
bitwise_xor_lhs CARET simple_binary_operand
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::BitwiseXor,
std::vector<Nonnull<Expression*>>(
{$[bitwise_xor_lhs], $[simple_binary_operand]}));
}
;
bitwise_expression:
bitwise_and_expression
| bitwise_or_expression
| bitwise_xor_expression
;
bit_shift_expression:
simple_binary_operand[lhs_simple_binary_operand] LESS_LESS
simple_binary_operand[rhs_simple_binary_operand]
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::BitShiftLeft,
std::vector<Nonnull<Expression*>>(
{$[lhs_simple_binary_operand], $[rhs_simple_binary_operand]}));
}
| simple_binary_operand[lhs_simple_binary_operand] GREATER_GREATER
simple_binary_operand[rhs_simple_binary_operand]
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::BitShiftRight,
std::vector<Nonnull<Expression*>>(
{$[lhs_simple_binary_operand], $[rhs_simple_binary_operand]}));
}
;
as_expression:
simple_binary_operand[lhs_simple_binary_operand] AS
simple_binary_operand[rhs_simple_binary_operand]
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::As,
std::vector<Nonnull<Expression*>>{$[lhs_simple_binary_operand],
$[rhs_simple_binary_operand]});
}
;
unimpl_expression:
// ref_deref_expression excluded due to precedence diamond.
ref_deref_expression[lhs_ref_deref_expression] UNIMPL_EXAMPLE
ref_deref_expression[rhs_ref_deref_expression]
{
$$ = arena->New<UnimplementedExpression>(
context.source_loc(), "ExampleInfix", $[lhs_ref_deref_expression],
$[rhs_ref_deref_expression]);
}
;
value_expression:
// ref_deref_expression excluded due to precedence diamond.
additive_expression
| as_expression
| bitwise_expression
| bit_shift_expression
| fn_type_expression
| modulo_expression
| unary_expression
| unimpl_expression
;
comparison_operand:
ref_deref_expression
| value_expression
;
comparison_operator:
EQUAL_EQUAL
{ $$ = Operator::Eq; }
| LESS
{ $$ = Operator::Less; }
| LESS_EQUAL
{ $$ = Operator::LessEq; }
| GREATER
{ $$ = Operator::Greater; }
| GREATER_EQUAL
{ $$ = Operator::GreaterEq; }
| NOT_EQUAL
{ $$ = Operator::NotEq; }
;
comparison_expression:
value_expression
| comparison_operand[lhs_simple_binary_operand] comparison_operator
comparison_operand[rhs_simple_binary_operand]
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), $[comparison_operator],
std::vector<Nonnull<Expression*>>(
{$[lhs_simple_binary_operand], $[rhs_simple_binary_operand]}));
}
;
not_expression:
NOT ref_deref_expression
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Not,
std::vector<Nonnull<Expression*>>({$[ref_deref_expression]}));
}
;
predicate_expression:
// ref_deref_expression excluded due to precedence diamond.
not_expression
| comparison_expression
;
and_or_operand:
ref_deref_expression
| predicate_expression
;
and_lhs:
and_or_operand
| and_expression
;
and_expression:
// predicate_expression excluded due to precedence diamond.
and_lhs AND and_or_operand
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::And,
std::vector<Nonnull<Expression*>>({$[and_lhs], $[and_or_operand]}));
}
;
or_lhs:
and_or_operand
| or_expression
;
or_expression:
// predicate_expression excluded due to precedence diamond.
or_lhs OR and_or_operand
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Or,
std::vector<Nonnull<Expression*>>({$[or_lhs], $[and_or_operand]}));
}
;
where_clause:
comparison_operand[lhs_simple_binary_operand] IMPLS
comparison_operand[rhs_simple_binary_operand]
{
$$ = arena->New<ImplsWhereClause>(context.source_loc(),
$[lhs_simple_binary_operand],
$[rhs_simple_binary_operand]);
}
| comparison_operand[lhs_simple_binary_operand] EQUAL_EQUAL
comparison_operand[rhs_simple_binary_operand]
{
$$ = arena->New<EqualsWhereClause>(context.source_loc(),
$[lhs_simple_binary_operand],
$[rhs_simple_binary_operand]);
}
// TODO: .(expression) = expression
| designator EQUAL comparison_operand
{
$$ = arena->New<RewriteWhereClause>(context.source_loc(), $[designator],
$[comparison_operand]);
}
;
where_clause_list:
where_clause
{ $$ = {$[where_clause]}; }
| where_clause_list[accumulated_where_clause_list] AND where_clause
{
$$ = std::move($[accumulated_where_clause_list]);
$$.push_back($[where_clause]);
}
;
where_expression:
type_expression WHERE where_clause_list
{
auto* self = arena->New<GenericBinding>(
context.source_loc(), ".Self", $[type_expression],
GenericBinding::BindingKind::Checked);
$$ = arena->New<WhereExpression>(context.source_loc(), self,
$[where_clause_list]);
}
;
type_or_where_expression:
type_expression
| where_expression
;
statement_expression:
ref_deref_expression
| predicate_expression
| and_expression
| or_expression
| where_expression
;
if_expression:
statement_expression
| IF expression THEN if_expression[then_if_expression] ELSE
if_expression[else_if_expression]
{
$$ = arena->New<IfExpression>(context.source_loc(), $[expression],
$[then_if_expression],
$[else_if_expression]);
}
;
expression:
if_expression
;
designator:
PERIOD identifier { $$ = $[identifier]; }
| PERIOD BASE { $$ = "base"; }
;
paren_expression: paren_expression_base
{
$$ = ExpressionFromParenContents(arena, context.source_loc(),
$[paren_expression_base]);
}
;
tuple: paren_expression_base
{
$$ = TupleExpressionFromParenContents(arena, context.source_loc(),
$[paren_expression_base]);
}
;
paren_expression_base:
LEFT_PARENTHESIS RIGHT_PARENTHESIS
{ $$ = {.elements = {}, .has_trailing_comma = false}; }
| LEFT_PARENTHESIS paren_expression_contents RIGHT_PARENTHESIS
{ $$ = $[paren_expression_contents]; }
| LEFT_PARENTHESIS paren_expression_contents COMMA RIGHT_PARENTHESIS
{
$$ = $[paren_expression_contents];
$$.has_trailing_comma = true;
}
;
paren_expression_contents:
expression
{ $$ = {.elements = {$[expression]}, .has_trailing_comma = false}; }
| paren_expression_contents[accumulated_paren_expression_contents] COMMA
expression
{
$$ = std::move($[accumulated_paren_expression_contents]);
$$.elements.push_back($[expression]);
}
;
struct_literal:
LEFT_CURLY_BRACE RIGHT_CURLY_BRACE
{ $$ = arena->New<StructLiteral>(context.source_loc()); }
| LEFT_CURLY_BRACE struct_literal_contents RIGHT_CURLY_BRACE
{
$$ = arena->New<StructLiteral>(context.source_loc(),
$[struct_literal_contents]);
}
| LEFT_CURLY_BRACE struct_literal_contents COMMA RIGHT_CURLY_BRACE
{
$$ = arena->New<StructLiteral>(context.source_loc(),
$[struct_literal_contents]);
}
;
struct_literal_contents:
designator EQUAL expression
{ $$ = {FieldInitializer($[designator], $[expression])}; }
| struct_literal_contents[accumulated_struct_literal_contents] COMMA designator
EQUAL expression
{
$$ = std::move($[accumulated_struct_literal_contents]);
$$.push_back(FieldInitializer($[designator], $[expression]));
}
;
struct_type_literal:
LEFT_CURLY_BRACE struct_type_literal_contents RIGHT_CURLY_BRACE
{
$$ = arena->New<StructTypeLiteral>(context.source_loc(),
$[struct_type_literal_contents]);
}
| LEFT_CURLY_BRACE struct_type_literal_contents COMMA RIGHT_CURLY_BRACE
{
$$ = arena->New<StructTypeLiteral>(context.source_loc(),
$[struct_type_literal_contents]);
}
;
struct_type_literal_contents:
designator COLON expression
{ $$ = {FieldInitializer($[designator], $[expression])}; }
| struct_type_literal_contents[accumulated_struct_type_literal_contents] COMMA
designator COLON expression
{
$$ = std::move($[accumulated_struct_type_literal_contents]);
$$.push_back(FieldInitializer($[designator], $[expression]));
}
;
// In many cases, using `pattern` recursively will result in ambiguities.
// When that happens, it's necessary to factor out two separate productions,
// one for when the sub-pattern is an expression, and one for when it is not.
// To facilitate this, non-terminals besides `pattern` whose names contain
// `pattern` are structured to be disjoint from `expression`, unless otherwise
// specified.
pattern:
non_expression_pattern
{ $$ = $[non_expression_pattern]; }
| expression
{ $$ = arena->New<ExpressionPattern>($[expression]); }
;
non_expression_pattern:
AUTO
{ $$ = arena->New<AutoPattern>(context.source_loc()); }
| binding_lhs COLON pattern
{
$$ = arena->New<BindingPattern>(context.source_loc(), $[binding_lhs],
$[pattern], std::nullopt);
}
| binding_lhs COLON_BANG expression
{
$$ = arena->New<GenericBinding>(context.source_loc(), $[binding_lhs],
$[expression],
GenericBinding::BindingKind::Checked);
}
| TEMPLATE binding_lhs COLON_BANG expression
{
$$ = arena->New<GenericBinding>(context.source_loc(), $[binding_lhs],
$[expression],
GenericBinding::BindingKind::Template);
}
| paren_pattern
{ $$ = $[paren_pattern]; }
| postfix_expression tuple_pattern
{
ErrorOr<Nonnull<AlternativePattern*>> alternative_pattern =
AlternativePattern::Create(arena, context.source_loc(),
$[postfix_expression], $[tuple_pattern]);
if (alternative_pattern.ok()) {
$$ = *alternative_pattern;
} else {
context.RecordSyntaxError(std::move(alternative_pattern).error());
YYERROR;
}
}
| VAR non_expression_pattern[child_non_expression_pattern]
{
$$ = arena->New<VarPattern>(context.source_loc(),
$[child_non_expression_pattern]);
}
;
binding_lhs:
identifier { $$ = $[identifier]; }
| UNDERSCORE { $$ = AnonymousName; }
;
paren_pattern: paren_pattern_base
{
$$ = PatternFromParenContents(arena, context.source_loc(),
$[paren_pattern_base]);
}
;
paren_pattern_base:
LEFT_PARENTHESIS paren_pattern_contents RIGHT_PARENTHESIS
{ $$ = $[paren_pattern_contents]; }
| LEFT_PARENTHESIS paren_pattern_contents COMMA RIGHT_PARENTHESIS
{
$$ = $[paren_pattern_contents];
$$.has_trailing_comma = true;
}
;
// paren_pattern is analogous to paren_expression, but in order to avoid
// ambiguities, it must be disjoint from paren_expression, meaning it must
// contain at least one non_expression_pattern. The structure of this rule
// is very different from the corresponding expression rule because is has to
// enforce that requirement.
paren_pattern_contents: