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carbon-lang/explorer/syntax/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/paren_contents.h"
#include "explorer/ast/pattern.h"
#include "explorer/ast/value_category.h"
#include "explorer/common/arena.h"
#include "explorer/common/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 <ImplKind> impl_kind
%type <Nonnull<Expression*>> 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 <ClassExtensibility> class_declaration_extensibility
%type <std::optional<Nonnull<Expression*>>> class_declaration_extends
%type <Nonnull<Declaration*>> declaration
%type <Nonnull<FunctionDeclaration*>> function_declaration
%type <Nonnull<AliasDeclaration*>> alias_declaration
%type <std::vector<Nonnull<Declaration*>>> declaration_list
%type <std::vector<Nonnull<Declaration*>>> interface_body
%type <std::vector<Nonnull<Declaration*>>> impl_body
%type <Nonnull<Statement*>> statement
%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<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 <std::optional<Nonnull<Pattern*>>> receiver
%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
AND
API
ARROW
AS
AUTO
AWAIT
BASE
BOOL
BREAK
CARET
CASE
CHOICE
CLASS
COLON
COLON_BANG
COMMA
CONTINUATION
CONTINUATION_TYPE
CONTINUE
DEFAULT
DOUBLE_ARROW
ELSE
EQUAL
EQUAL_EQUAL
EXTENDS
EXTERNAL
FALSE
FN
FN_TYPE
FOR
FORALL
GREATER
GREATER_EQUAL
GREATER_GREATER
IF
IMPL
IMPORT
IN
INTERFACE
IS
LEFT_CURLY_BRACE
LEFT_PARENTHESIS
LEFT_SQUARE_BRACKET
LESS
LESS_EQUAL
LESS_LESS
LET
LIBRARY
MATCH
MINUS
NOT
OR
PACKAGE
PERCENT
PERIOD
PIPE
PLUS
RETURN
RETURNED
RIGHT_CURLY_BRACE
RIGHT_PARENTHESIS
RIGHT_SQUARE_BRACKET
RUN
SELF
SEMICOLON
SLASH
STRING
THEN
TRUE
TYPE
UNDERSCORE
UNIMPL_EXAMPLE
VAR
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 declaration_list
{
*ast = AST({.package = $1.first,
.is_api = $1.second,
.imports = std::move($2),
.declarations = std::move($3)});
}
;
package_directive:
PACKAGE identifier optional_library_path api_or_impl SEMICOLON
{ $$ = {LibraryName({.package = $2, .path = $3}), $4}; }
;
import_directive:
IMPORT identifier optional_library_path SEMICOLON
{ $$ = LibraryName({.package = $2, .path = $3}); }
;
import_directives:
// Empty
{ $$ = std::vector<LibraryName>(); }
| import_directives import_directive
{
$$ = std::move($1);
$$.push_back($2);
}
;
optional_library_path:
// Empty
{ $$ = ""; }
| LIBRARY string_literal
{ $$ = $2; }
;
api_or_impl:
API
{ $$ = true; }
| IMPL
{ $$ = false; }
;
primary_expression:
identifier
{ $$ = arena->New<IdentifierExpression>(context.source_loc(), $1); }
| designator
{
// `.Foo` is rewritten to `.Self.Foo`.
$$ = arena->New<SimpleMemberAccessExpression>(
context.source_loc(),
arena->New<DotSelfExpression>(context.source_loc()), $1);
}
| PERIOD SELF
{ $$ = arena->New<DotSelfExpression>(context.source_loc()); }
| integer_literal
{ $$ = arena->New<IntLiteral>(context.source_loc(), $1); }
| string_literal
{ $$ = arena->New<StringLiteral>(context.source_loc(), $1); }
| 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($1).substr(1), val)) {
context.RecordSyntaxError(
llvm::formatv("Invalid type literal: {0}", $1));
YYERROR;
} else if ($1[0] != 'i' || val != 32) {
context.RecordSyntaxError(
llvm::formatv("Only i32 is supported for now: {0}", $1));
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
{ $$ = arena->New<TypeTypeLiteral>(context.source_loc()); }
| CONTINUATION_TYPE
{ $$ = arena->New<ContinuationTypeLiteral>(context.source_loc()); }
| paren_expression { $$ = $1; }
| struct_literal { $$ = $1; }
| struct_type_literal { $$ = $1; }
| LEFT_SQUARE_BRACKET expression SEMICOLON expression RIGHT_SQUARE_BRACKET
{ $$ = arena->New<ArrayTypeLiteral>(context.source_loc(), $2, $4); }
;
postfix_expression:
primary_expression
| postfix_expression designator
{
$$ = arena->New<SimpleMemberAccessExpression>(context.source_loc(), $1,
$2);
}
| postfix_expression PERIOD LEFT_PARENTHESIS expression RIGHT_PARENTHESIS
{
$$ = arena->New<CompoundMemberAccessExpression>(context.source_loc(), $1,
$4);
}
| postfix_expression LEFT_SQUARE_BRACKET expression RIGHT_SQUARE_BRACKET
{ $$ = arena->New<IndexExpression>(context.source_loc(), $1, $3); }
| intrinsic_identifier tuple
{ $$ = arena->New<IntrinsicExpression>($1, $2, context.source_loc()); }
| postfix_expression tuple
{ $$ = arena->New<CallExpression>(context.source_loc(), $1, $2); }
| postfix_expression POSTFIX_STAR
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Ptr,
std::vector<Nonnull<Expression*>>({$1}));
}
| postfix_expression UNARY_STAR
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Ptr,
std::vector<Nonnull<Expression*>>({$1}));
}
;
ref_deref_expression:
postfix_expression
| PREFIX_STAR ref_deref_expression
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Deref,
std::vector<Nonnull<Expression*>>({$2}));
}
| UNARY_STAR ref_deref_expression
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Deref,
std::vector<Nonnull<Expression*>>({$2}));
}
| AMPERSAND ref_deref_expression
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::AddressOf,
std::vector<Nonnull<Expression*>>({$2}));
}
;
fn_type_expression:
FN_TYPE tuple ARROW type_expression
{ $$ = arena->New<FunctionTypeLiteral>(context.source_loc(), $2, $4); }
;
type_expression:
ref_deref_expression
| bitwise_and_expression
| fn_type_expression
;
minus_expression:
// ref_deref_expression excluded due to precedence diamond.
MINUS ref_deref_expression
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Neg,
std::vector<Nonnull<Expression*>>({$2}));
}
;
complement_expression:
// ref_deref_expression excluded due to precedence diamond.
CARET ref_deref_expression
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Complement,
std::vector<Nonnull<Expression*>>({$2}));
}
;
unary_expression:
// ref_deref_expression excluded due to precedence diamond.
minus_expression
| complement_expression
;
// A simple_binary_operand is an operand of a binary operator
// that is not itself a binary operator expression.
simple_binary_operand:
ref_deref_expression
| unary_expression
;
multiplicative_lhs:
simple_binary_operand
| multiplicative_expression
;
multiplicative_expression:
multiplicative_lhs BINARY_STAR simple_binary_operand
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Mul,
std::vector<Nonnull<Expression*>>({$1, $3}));
}
;
additive_operand:
simple_binary_operand
| multiplicative_expression
;
additive_lhs:
simple_binary_operand
| additive_expression
;
additive_expression:
multiplicative_expression
| additive_lhs PLUS additive_operand
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Add,
std::vector<Nonnull<Expression*>>({$1, $3}));
}
| additive_lhs MINUS additive_operand
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Sub,
std::vector<Nonnull<Expression*>>({$1, $3}));
}
;
modulo_expression:
simple_binary_operand PERCENT simple_binary_operand
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Mod,
std::vector<Nonnull<Expression*>>({$1, $3}));
}
;
bitwise_and_lhs:
simple_binary_operand
| bitwise_and_expression
;
bitwise_and_expression:
bitwise_and_lhs AMPERSAND simple_binary_operand
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::BitwiseAnd,
std::vector<Nonnull<Expression*>>({$1, $3}));
}
;
bitwise_or_lhs:
simple_binary_operand
| bitwise_or_expression
;
bitwise_or_expression:
bitwise_or_lhs PIPE simple_binary_operand
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::BitwiseOr,
std::vector<Nonnull<Expression*>>({$1, $3}));
}
;
bitwise_xor_lhs:
simple_binary_operand
| bitwise_xor_expression
;
bitwise_xor_expression:
bitwise_xor_lhs CARET simple_binary_operand
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::BitwiseXor,
std::vector<Nonnull<Expression*>>({$1, $3}));
}
;
bitwise_expression:
bitwise_and_expression
| bitwise_or_expression
| bitwise_xor_expression
;
bit_shift_expression:
simple_binary_operand LESS_LESS simple_binary_operand
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::BitShiftLeft,
std::vector<Nonnull<Expression*>>({$1, $3}));
}
| simple_binary_operand GREATER_GREATER simple_binary_operand
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::BitShiftRight,
std::vector<Nonnull<Expression*>>({$1, $3}));
}
;
as_expression:
simple_binary_operand AS simple_binary_operand
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::As,
std::vector<Nonnull<Expression*>>{$1, $3});
}
;
unimpl_expression:
// ref_deref_expression excluded due to precedence diamond.
ref_deref_expression UNIMPL_EXAMPLE ref_deref_expression
{
$$ = arena->New<UnimplementedExpression>(context.source_loc(),
"ExampleInfix", $1, $3);
}
;
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
;
/* TODO: Add NOT_EQUAL */
comparison_operator:
EQUAL_EQUAL
{ $$ = Operator::Eq; }
| LESS
{ $$ = Operator::Less; }
| LESS_EQUAL
{ $$ = Operator::LessEq; }
| GREATER
{ $$ = Operator::Greater; }
| GREATER_EQUAL
{ $$ = Operator::GreaterEq; }
;
comparison_expression:
value_expression
| comparison_operand comparison_operator comparison_operand
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), $2,
std::vector<Nonnull<Expression*>>({$1, $3}));
}
;
not_expression:
NOT ref_deref_expression
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Not,
std::vector<Nonnull<Expression*>>({$2}));
}
;
predicate_expression:
// ref_deref_expression excluded due to precedence diamond.
not_expression
| comparison_expression
;
and_or_operand:
ref_deref_expression
| predicate_expression
;
and_lhs:
and_or_operand
| and_expression
;
and_expression:
// predicate_expression excluded due to precedence diamond.
and_lhs AND and_or_operand
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::And,
std::vector<Nonnull<Expression*>>({$1, $3}));
}
;
or_lhs:
and_or_operand
| or_expression
;
or_expression:
// predicate_expression excluded due to precedence diamond.
or_lhs OR and_or_operand
{
$$ = arena->New<OperatorExpression>(
context.source_loc(), Operator::Or,
std::vector<Nonnull<Expression*>>({$1, $3}));
}
;
where_clause:
comparison_operand IS comparison_operand
{ $$ = arena->New<IsWhereClause>(context.source_loc(), $1, $3); }
| comparison_operand EQUAL_EQUAL comparison_operand
{ $$ = arena->New<EqualsWhereClause>(context.source_loc(), $1, $3); }
;
where_clause_list:
where_clause
{ $$ = {$1}; }
| where_clause_list AND where_clause
{
$$ = std::move($1);
$$.push_back($3);
}
;
where_expression:
type_expression WHERE where_clause_list
{
auto* self =
arena -> New<GenericBinding>(context.source_loc(), ".Self", $1);
$$ = arena->New<WhereExpression>(context.source_loc(), self, $3);
}
;
type_or_where_expression:
type_expression
| where_expression
;
statement_expression:
ref_deref_expression
| predicate_expression
| and_expression
| or_expression
| where_expression
;
if_expression:
statement_expression
| IF expression THEN if_expression ELSE if_expression
{ $$ = arena->New<IfExpression>(context.source_loc(), $2, $4, $6); }
;
expression:
if_expression
;
designator: PERIOD identifier { $$ = $2; }
;
paren_expression: paren_expression_base
{ $$ = ExpressionFromParenContents(arena, context.source_loc(), $1); }
;
tuple: paren_expression_base
{ $$ = TupleExpressionFromParenContents(arena, context.source_loc(), $1); }
;
paren_expression_base:
LEFT_PARENTHESIS RIGHT_PARENTHESIS
{ $$ = {.elements = {}, .has_trailing_comma = false}; }
| LEFT_PARENTHESIS paren_expression_contents RIGHT_PARENTHESIS
{ $$ = $2; }
| LEFT_PARENTHESIS paren_expression_contents COMMA RIGHT_PARENTHESIS
{
$$ = $2;
$$.has_trailing_comma = true;
}
;
paren_expression_contents:
expression
{ $$ = {.elements = {$1}, .has_trailing_comma = false}; }
| paren_expression_contents COMMA expression
{
$$ = $1;
$$.elements.push_back($3);
}
;
struct_literal:
LEFT_CURLY_BRACE struct_literal_contents RIGHT_CURLY_BRACE
{ $$ = arena->New<StructLiteral>(context.source_loc(), $2); }
| LEFT_CURLY_BRACE struct_literal_contents COMMA RIGHT_CURLY_BRACE
{ $$ = arena->New<StructLiteral>(context.source_loc(), $2); }
;
struct_literal_contents:
designator EQUAL expression
{ $$ = {FieldInitializer($1, $3)}; }
| struct_literal_contents COMMA designator EQUAL expression
{
$$ = $1;
$$.push_back(FieldInitializer($3, $5));
}
;
struct_type_literal:
LEFT_CURLY_BRACE RIGHT_CURLY_BRACE
{ $$ = arena->New<StructTypeLiteral>(context.source_loc()); }
| LEFT_CURLY_BRACE struct_type_literal_contents RIGHT_CURLY_BRACE
{ $$ = arena->New<StructTypeLiteral>(context.source_loc(), $2); }
| LEFT_CURLY_BRACE struct_type_literal_contents COMMA RIGHT_CURLY_BRACE
{ $$ = arena->New<StructTypeLiteral>(context.source_loc(), $2); }
;
struct_type_literal_contents:
designator COLON expression
{ $$ = {FieldInitializer($1, $3)}; }
| struct_type_literal_contents COMMA designator COLON expression
{
$$ = $1;
$$.push_back(FieldInitializer($3, $5));
}
;
// In many cases, using `pattern` recursively will result in ambiguities.
// When that happens, it's necessary to factor out two separate productions,
// one for when the sub-pattern is an expression, and one for when it is not.
// To facilitate this, non-terminals besides `pattern` whose names contain
// `pattern` are structured to be disjoint from `expression`, unless otherwise
// specified.
pattern:
non_expression_pattern
{ $$ = $1; }
| expression
{ $$ = arena->New<ExpressionPattern>($1); }
;
non_expression_pattern:
AUTO
{ $$ = arena->New<AutoPattern>(context.source_loc()); }
| binding_lhs COLON pattern
{
$$ = arena->New<BindingPattern>(context.source_loc(), $1, $3,
std::nullopt);
}
| binding_lhs COLON_BANG expression
{ $$ = arena->New<GenericBinding>(context.source_loc(), $1, $3); }
| paren_pattern
{ $$ = $1; }
| postfix_expression tuple_pattern
{
ErrorOr<Nonnull<AlternativePattern*>> alternative_pattern =
AlternativePattern::Create(arena, context.source_loc(), $1, $2);
if (alternative_pattern.ok()) {
$$ = *alternative_pattern;
} else {
context.RecordSyntaxError(std::move(alternative_pattern).error());
YYERROR;
}
}
| VAR non_expression_pattern
{ $$ = arena->New<VarPattern>(context.source_loc(), $2); }
;
binding_lhs:
identifier { $$ = $1; }
| UNDERSCORE { $$ = AnonymousName; }
;
paren_pattern: paren_pattern_base
{ $$ = PatternFromParenContents(arena, context.source_loc(), $1); }
;
paren_pattern_base:
LEFT_PARENTHESIS paren_pattern_contents RIGHT_PARENTHESIS
{ $$ = $2; }
| LEFT_PARENTHESIS paren_pattern_contents COMMA RIGHT_PARENTHESIS
{
$$ = $2;
$$.has_trailing_comma = true;
}
;
// paren_pattern is analogous to paren_expression, but in order to avoid
// ambiguities, it must be disjoint from paren_expression, meaning it must
// contain at least one non_expression_pattern. The structure of this rule
// is very different from the corresponding expression rule because is has to
// enforce that requirement.
paren_pattern_contents:
non_expression_pattern
{ $$ = {.elements = {$1}, .has_trailing_comma = false}; }
| paren_expression_contents COMMA non_expression_pattern
{
$$ = ParenExpressionToParenPattern(arena, $1);
$$.elements.push_back($3);
}
| paren_pattern_contents COMMA expression
{
$$ = $1;
$$.elements.push_back(arena->New<ExpressionPattern>($3));
}
| paren_pattern_contents COMMA non_expression_pattern
{
$$ = $1;
$$.elements.push_back($3);
}
;
tuple_pattern: paren_pattern_base
{ $$ = TuplePatternFromParenContents(arena, context.source_loc(), $1); }
;
// Unlike most `pattern` nonterminals, this one overlaps with `expression`,
// so it should be used only when prior context (such as an introducer)
// rules out the possibility of an `expression` at this point.
maybe_empty_tuple_pattern:
LEFT_PARENTHESIS RIGHT_PARENTHESIS
{
$$ = arena->New<TuplePattern>(context.source_loc(),
std::vector<Nonnull<Pattern*>>());
}
| tuple_pattern
{ $$ = $1; }
;
clause:
CASE pattern DOUBLE_ARROW block
{ $$ = Match::Clause($2, $4); }
| DEFAULT DOUBLE_ARROW block
{
$$ = Match::Clause(arena->New<BindingPattern>(
context.source_loc(), std::string(AnonymousName),
arena->New<AutoPattern>(context.source_loc()),
ValueCategory::Let),
$3);
}
;
clause_list:
// Empty
{ $$ = {}; }
| clause_list clause
{
$$ = $1;
$$.push_back($2);
}
;
statement:
statement_expression EQUAL expression SEMICOLON
{ $$ = arena->New<Assign>(context.source_loc(), $1, $3); }
| VAR pattern SEMICOLON
{
$$ = arena->New<VariableDefinition>(
context.source_loc(), $2, std::nullopt, ValueCategory::Var,
VariableDefinition::DefinitionType::Var);
}
| VAR pattern EQUAL expression SEMICOLON
{
$$ = arena->New<VariableDefinition>(
context.source_loc(), $2, $4, ValueCategory::Var,
VariableDefinition::DefinitionType::Var);
}
| RETURNED VAR variable_declaration SEMICOLON
{
$$ = arena->New<VariableDefinition>(
context.source_loc(), $3, std::nullopt, ValueCategory::Var,
VariableDefinition::DefinitionType::Returned);
}
| RETURNED VAR variable_declaration EQUAL expression SEMICOLON
{
$$ = arena->New<VariableDefinition>(
context.source_loc(), $3, $5, ValueCategory::Var,
VariableDefinition::DefinitionType::Returned);
}
| LET pattern EQUAL expression SEMICOLON
{
$$ = arena->New<VariableDefinition>(
context.source_loc(), $2, $4, ValueCategory::Let,
VariableDefinition::DefinitionType::Var);
}
| statement_expression SEMICOLON
{ $$ = arena->New<ExpressionStatement>(context.source_loc(), $1); }
| if_statement
{ $$ = $1; }
| WHILE LEFT_PARENTHESIS expression RIGHT_PARENTHESIS block
{ $$ = arena->New<While>(context.source_loc(), $3, $5); }
| BREAK SEMICOLON
{ $$ = arena->New<Break>(context.source_loc()); }
| CONTINUE SEMICOLON
{ $$ = arena->New<Continue>(context.source_loc()); }
| RETURN return_expression SEMICOLON
{
auto [return_exp, is_omitted_exp] = $2;
$$ = arena->New<ReturnExpression>(context.source_loc(), return_exp,
is_omitted_exp);
}
| RETURN VAR SEMICOLON
{ $$ = arena->New<ReturnVar>(context.source_loc()); }
| MATCH LEFT_PARENTHESIS expression RIGHT_PARENTHESIS LEFT_CURLY_BRACE
clause_list RIGHT_CURLY_BRACE
{ $$ = arena->New<Match>(context.source_loc(), $3, $6); }
| CONTINUATION identifier block
{ $$ = arena->New<Continuation>(context.source_loc(), $2, $3); }
| RUN expression SEMICOLON
{ $$ = arena->New<Run>(context.source_loc(), $2); }
| AWAIT SEMICOLON
{ $$ = arena->New<Await>(context.source_loc()); }
| FOR LEFT_PARENTHESIS variable_declaration IN type_expression RIGHT_PARENTHESIS block
{ $$ = arena->New<For>(context.source_loc(), $3, $5, $7); }
;
if_statement:
IF LEFT_PARENTHESIS expression RIGHT_PARENTHESIS block optional_else
{ $$ = arena->New<If>(context.source_loc(), $3, $5, $6); }
;
optional_else:
// Empty
{ $$ = std::nullopt; }
| ELSE if_statement
{
$$ = arena->New<Block>(context.source_loc(),
std::vector<Nonnull<Statement*>>({$2}));
}
| ELSE block
{ $$ = $2; }
;
return_expression:
// Empty
{ $$ = {arena->New<TupleLiteral>(context.source_loc()), true}; }
| expression
{ $$ = {$1, false}; }
;
statement_list:
// Empty
{ $$ = {}; }
| statement_list statement
{
$$ = std::move($1);
$$.push_back($2);
}
;
block:
LEFT_CURLY_BRACE statement_list RIGHT_CURLY_BRACE
{ $$ = arena->New<Block>(context.source_loc(), std::move($2)); }
;
return_term:
// Empty
{ $$ = ReturnTerm::Omitted(context.source_loc()); }
| ARROW AUTO
{ $$ = ReturnTerm::Auto(context.source_loc()); }
| ARROW expression
{ $$ = ReturnTerm::Explicit($2); }
;
generic_binding:
identifier COLON_BANG expression
{
$$ = arena->New<GenericBinding>(context.source_loc(), std::move($1), $3);
}
;
deduced_param:
generic_binding
{ $$ = $1; }
| variable_declaration
{ $$ = $1; }
| ADDR variable_declaration
{ $$ = arena->New<AddrPattern>(context.source_loc(), $2); }
;
deduced_param_list:
// Empty
{ $$ = {}; }
| deduced_param
{ $$ = {$1}; }
| deduced_param_list COMMA deduced_param
{
$$ = $1; // TODO: can we std::move here?
$$.push_back($3);
}
;
deduced_params:
// Empty
{ $$ = std::vector<Nonnull<AstNode*>>(); }
| LEFT_SQUARE_BRACKET deduced_param_list RIGHT_SQUARE_BRACKET
{ $$ = $2; }
;
impl_deduced_params:
// Empty
{ $$ = std::vector<Nonnull<AstNode*>>(); }
| FORALL LEFT_SQUARE_BRACKET deduced_param_list RIGHT_SQUARE_BRACKET
{ $$ = $3; }
;
receiver:
// Empty
{ $$ = std::nullopt; }
| LEFT_CURLY_BRACE variable_declaration RIGHT_CURLY_BRACE
{ $$ = $2; }
| LEFT_CURLY_BRACE ADDR variable_declaration RIGHT_CURLY_BRACE
{ $$ = arena->New<AddrPattern>(context.source_loc(), $3); }
;
function_declaration:
FN identifier deduced_params receiver maybe_empty_tuple_pattern return_term block
{
ErrorOr<FunctionDeclaration*> fn = FunctionDeclaration::Create(
arena, context.source_loc(), $2, $3, $4, $5, $6, $7);
if (fn.ok()) {
$$ = *fn;
} else {
context.RecordSyntaxError(std::move(fn).error());
YYERROR;
}
}
| FN identifier deduced_params receiver maybe_empty_tuple_pattern return_term SEMICOLON
{
ErrorOr<FunctionDeclaration*> fn = FunctionDeclaration::Create(
arena, context.source_loc(), $2, $3, $4, $5, $6, std::nullopt);
if (fn.ok()) {
$$ = *fn;
} else {
context.RecordSyntaxError(std::move(fn).error());
YYERROR;
}
}
;
variable_declaration: identifier COLON pattern
{
$$ = arena->New<BindingPattern>(context.source_loc(), $1, $3,
std::nullopt);
}
;
alias_declaration: ALIAS identifier EQUAL expression SEMICOLON
{ $$ = arena->New<AliasDeclaration>(context.source_loc(), $2, $4); }
;
alternative:
identifier tuple
{ $$ = arena->New<AlternativeSignature>(context.source_loc(), $1, $2); }
| identifier
{
$$ = arena->New<AlternativeSignature>(
context.source_loc(), $1,
arena->New<TupleLiteral>(context.source_loc()));
}
;
alternative_list:
// Empty
{ $$ = {}; }
| alternative_list_contents
{ $$ = $1; }
| alternative_list_contents COMMA
{ $$ = $1; }
;
alternative_list_contents:
alternative
{ $$ = {std::move($1)}; }
| alternative_list_contents COMMA alternative
{
$$ = $1;
$$.push_back(std::move($3));
}
;
type_params:
// Empty
{ $$ = std::nullopt; }
| tuple_pattern
{ $$ = $1; }
;
class_declaration_extensibility:
// Empty
{ $$ = Carbon::ClassExtensibility::None; }
| ABSTRACT
{ $$ = Carbon::ClassExtensibility::Abstract; }
| BASE
{ $$ = Carbon::ClassExtensibility::Base; }
;
class_declaration_extends:
// Empty
{ $$ = std::nullopt; }
| EXTENDS expression
{ $$ = $2; }
;
declaration:
function_declaration
{ $$ = $1; }
| class_declaration_extensibility CLASS identifier type_params class_declaration_extends LEFT_CURLY_BRACE declaration_list RIGHT_CURLY_BRACE
{
$$ = arena->New<ClassDeclaration>(
context.source_loc(), $3,
arena->New<SelfDeclaration>(context.source_loc()), $1, $4, $5, $7);
}
| CHOICE identifier type_params LEFT_CURLY_BRACE alternative_list RIGHT_CURLY_BRACE
{ $$ = arena->New<ChoiceDeclaration>(context.source_loc(), $2, $3, $5); }
| VAR variable_declaration SEMICOLON
{
$$ = arena->New<VariableDeclaration>(context.source_loc(), $2,
std::nullopt, ValueCategory::Var);
}
| VAR variable_declaration EQUAL expression SEMICOLON
{
$$ = arena->New<VariableDeclaration>(context.source_loc(), $2, $4,
ValueCategory::Var);
}
| LET variable_declaration EQUAL expression SEMICOLON
{
$$ = arena->New<VariableDeclaration>(context.source_loc(), $2, $4,
ValueCategory::Let);
}
| INTERFACE identifier type_params LEFT_CURLY_BRACE interface_body RIGHT_CURLY_BRACE
{
// TODO: Type of `Self` should be the interface being declared, not
// `Type`.
auto ty_ty = arena -> New<TypeTypeLiteral>(context.source_loc());
// TODO: Should this be switched to use a `SelfDeclaration` instead?
auto self =
arena -> New<GenericBinding>(context.source_loc(), "Self", ty_ty);
$$ = arena->New<InterfaceDeclaration>(context.source_loc(), $2, $3, self,
$5);
}
| impl_kind IMPL impl_deduced_params impl_type AS type_or_where_expression LEFT_CURLY_BRACE impl_body RIGHT_CURLY_BRACE
{
ErrorOr<ImplDeclaration*> impl = ImplDeclaration::Create(
arena, context.source_loc(), $1, $4, $6, $3, $8);
if (impl.ok()) {
$$ = *impl;
} else {
context.RecordSyntaxError(std::move(impl).error());
YYERROR;
}
}
| alias_declaration
{ $$ = $1; }
;
impl_kind:
// Internal
{ $$ = Carbon::ImplKind::InternalImpl; }
| EXTERNAL
{ $$ = Carbon::ImplKind::ExternalImpl; }
;
impl_type:
// Self
{ $$ = arena->New<IdentifierExpression>(context.source_loc(), "Self"); }
| type_expression
;
declaration_list:
// Empty
{ $$ = {}; }
| declaration_list declaration
{
$$ = $1;
$$.push_back(Nonnull<Declaration*>($2));
}
;
interface_body:
// Empty
{ $$ = {}; }
| interface_body function_declaration
{
$$ = $1;
$$.push_back($2);
}
| interface_body LET generic_binding SEMICOLON
{
$$ = $1;
$$.push_back(
arena->New<AssociatedConstantDeclaration>(context.source_loc(), $3));
}
;
impl_body:
// Empty
{ $$ = {}; }
| impl_body function_declaration
{
$$ = $1;
$$.push_back($2);
}
| impl_body alias_declaration
{
$$ = $1;
$$.push_back($2);
}
;
%%