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carbon-lang/toolchain/parse/state.def
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Richard Smith 071c5daddf Fix handling of generic self: Self. (#7922) 
We previously discarded a `generic` applied to `self`, resulting in
silently treating `generic self: Self` as a runtime parameter and
producing a weird error on `template self: Self`.

Instead of forcibly making all `self` parameters non-runtime, change the
*default* for a parameter named `self` to be runtime.

This is only a partial fix; more work is required to support `fn
F(generic self)` with an omitted type.
2026-10-09 00:15:38 +00:00

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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
//
// This is an X-macro header. It does not use `#include` guards, and instead is
// designed to be `#include`ed after the x-macro is defined in order for its
// inclusion to expand to the desired output. Macro definitions are cleaned up
// at the end of this file.
//
// Supported x-macros are:
// - CARBON_PARSE_STATE(Name)
// Defines a parser state.
//
// Parser states may be clustered when there are multiple related variants,
// named `StateAsVariant`. When there are variants, they share a common helper
// function for most logic.
//
// The comments before each state describe the portion of the grammar that the
// state is implementing, by giving an example of each kind of token sequence
// that this state handles. In these examples, `<...>` indicates a sequence of
// tokens handled by some other state, and `<???>` indicates a sequence of
// invalid tokens. A trailing `<???> ;` indicates an attempt to skip to the end
// of the declaration, which may or may not actually find a `;` token.
//
// The position in the token stream before the state is indicated by the caret
// `^` on the line below the example, and all tokens consumed by the state are
// underlined by the caret and following `~`s. If no tokens are consumed, the
// caret will point between tokens. Therefore, the position in the token stream
// after the state is the first token in the example after the underlined
// region.
//
// Following each set of examples, the output states for that situation are
// listed. States are numbered in the order they'll be executed; in other
// words, `1` is the top of the state stack. The comment `(state done)`
// indicates that no new states are added to the stack.
#ifndef CARBON_PARSE_STATE
#error "Must define the x-macro to use this file."
#define CARBON_PARSE_STATE(Name)
#endif
// Use CARBON_PARSE_STATE_VARIANTSN(Kind, Variant1, Variant2, ...) to generate
// KindAsVariant1, KindAsVariant2, ... states.
#define CARBON_PARSE_STATE_VARIANT(Kind, Variant) \
CARBON_PARSE_STATE(Kind##As##Variant)
#define CARBON_PARSE_STATE_VARIANTS2(Kind, Variant1, Variant2) \
CARBON_PARSE_STATE_VARIANT(Kind, Variant1) \
CARBON_PARSE_STATE_VARIANT(Kind, Variant2)
#define CARBON_PARSE_STATE_VARIANTS3(Kind, Variant1, Variant2, Variant3) \
CARBON_PARSE_STATE_VARIANT(Kind, Variant1) \
CARBON_PARSE_STATE_VARIANTS2(Kind, Variant2, Variant3)
#define CARBON_PARSE_STATE_VARIANTS4(Kind, Variant1, Variant2, Variant3, \
Variant4) \
CARBON_PARSE_STATE_VARIANT(Kind, Variant1) \
CARBON_PARSE_STATE_VARIANTS3(Kind, Variant2, Variant3, Variant4)
#define CARBON_PARSE_STATE_VARIANTS5(Kind, Variant1, Variant2, Variant3, \
Variant4, Variant5) \
CARBON_PARSE_STATE_VARIANT(Kind, Variant1) \
CARBON_PARSE_STATE_VARIANTS4(Kind, Variant2, Variant3, Variant4, Variant5)
// Used as a default for State initialization in some cases. Should
// not be put on the state stack.
CARBON_PARSE_STATE(Invalid)
// Handles an index expression:
//
// a[0]
// ^
// 1. Expr
// 2. IndexExprFinish
CARBON_PARSE_STATE(IndexExpr)
// Handles finishing the index expression.
//
// a[0]
// ^
// (state done)
CARBON_PARSE_STATE(IndexExprFinish)
// Handles the array keyword and opening paren in an array expression.
//
// array(T, N)
// ^~~~~~
// 1. Expr
// 2. ArrayExprComma
CARBON_PARSE_STATE(ArrayExpr)
// Handles ',' in an array expression.
//
// array(T, N)
// ^
// 1. Expr
// 2. ArrayExprFinish
CARBON_PARSE_STATE(ArrayExprComma)
// Handles finishing the array expression.
//
// array(T, N)
// ^
// (state done)
CARBON_PARSE_STATE(ArrayExprFinish)
// Handles the start of a form literal.
//
// form ( <...>
// ^~~~~~
// 1. PrimitiveForm
// 2. FormLiteralFinish
//
// form <???>
// ^~~~
// 1. FormLiteralFinish
CARBON_PARSE_STATE(FormLiteral)
// Handles the category modifier and type of a form literal.
//
// form ( val <...>
// ^~~
// form ( var <...>
// ^~~
// form ( ref <...>
// ^~~
// form ( <???>
// ^
// 1. Expr
// 2. PrimitiveFormFinish
CARBON_PARSE_STATE(PrimitiveForm)
// Finishes handling of PrimitiveForm.
//
// form ( <...> )
// ^
// form <???>
// ^
CARBON_PARSE_STATE(PrimitiveFormFinish)
// Handles the end of a form literal.
//
// form ( <...> )
// ^
// form ( <???> )
// ^~~~~~~
// form <???>
// ^
// (state done)
CARBON_PARSE_STATE(FormLiteralFinish)
// Handles the `typeof` keyword and opening paren in a `typeof` expression.
//
// typeof(x)
// ^~~~~~~
// 1. Expr
// 2. TypeOfExprFinish
CARBON_PARSE_STATE(TypeOfExpr)
// Handles finishing the `typeof` expression.
//
// typeof(x)
// ^
// (state done)
CARBON_PARSE_STATE(TypeOfExprFinish)
// Handles the `{` of a brace expression.
//
// {}
// ^
// 1. BraceExprFinishAsUnknown
//
// { <...> }
// ^
// 1. BraceExprParamAsUnknown
// 2. BraceExprFinishAsUnknown
CARBON_PARSE_STATE(BraceExpr)
// Handles a brace expression parameter. Note this will always start as unknown,
// but should be known after the first valid parameter. All later inconsistent
// parameters are invalid.
//
// { .foo <...> }
// ^
// 1. PeriodAsStruct
// 2. BraceExprParamAfterDesignatorAs(Type|Value|Unknown)
//
// { <???>
// ^
// 1. BraceExprParamFinishAs(Type|Value|Unknown)
CARBON_PARSE_STATE_VARIANTS3(BraceExprParam, Type, Value, Unknown)
// Handles a brace expression parameter after the initial designator. This
// should be at a `:` or `=`, depending on whether it's a type or value literal.
//
// { .foo = bar <...> }
// ^
// 1. Expr
// 2. BraceExprParamFinishAsValue
//
// { .foo: bar <...> }
// ^
// 1. Expr
// 2. BraceExprParamFinishAsType
//
// { .foo <???>
// ^
// 1. BraceExprParamFinishAs(Type|Value|Unknown)
CARBON_PARSE_STATE_VARIANTS3(BraceExprParamAfterDesignator, Type, Value,
Unknown)
// Handles the end of a brace expression parameter.
//
// { <...> }
// ^
// (state done)
//
// { .foo = bar, <...> }
// ^
// 1. BraceExprParamAsValue
//
// { .foo: bar, <...> }
// ^
// 1. BraceExprParamAsType
//
// { <???> , <...> }
// ^
// 1. BraceExprParamAsUnknown
CARBON_PARSE_STATE_VARIANTS3(BraceExprParamFinish, Type, Value, Unknown)
// Handles the `}` of a brace expression.
//
// { <...> }
// ^
// (state done)
CARBON_PARSE_STATE_VARIANTS3(BraceExprFinish, Type, Value, Unknown)
// Handles a call expression `(...)`.
//
// F()
// ^
// 1. CallExprFinish
//
// F( <...>
// ^
// 1. Expr
// 2. TupleLiteralElementFinish
// 3. CallExprFinish
CARBON_PARSE_STATE(CallExpr)
// Handles finishing the call expression.
//
// F(a, b)
// ^
// (state done)
CARBON_PARSE_STATE(CallExprFinish)
// Handles processing at the `{` on a typical code block.
//
// if (cond) {
// ^
// 1. StatementScopeLoop
// 2. CodeBlockFinish
//
// if (cond) <???>
// ^
// 1. Statement
// 2. CodeBlockFinish
CARBON_PARSE_STATE(CodeBlock)
// Handles processing at the `}` on a typical code block, after a statement
// scope is done.
//
// if (cond) { <...> }
// ^
// (state done)
CARBON_PARSE_STATE(CodeBlockFinish)
// Handles a declaration name and parameters, such as `Foo[T: type](x: T)`.
//
// name . <...>
// ^~~~~~
// 1. DeclNameAndParams
//
// name [ <...> ]
// ^~~~
// 1. PatternListAsImplicit
// 2. DeclNameAndParamsAfterImplicit
//
// name ( <...> )
// ^~~~
// 1. PatternListAsExplicit
// 2. DeclNameAndParamsAfterParams
//
// name <...>
// ^~~~
// (state done)
//
// <???>
// ^
// (state done)
CARBON_PARSE_STATE(DeclNameAndParams)
// Inside a declaration, conditionally starts explicit parameter handling. Only
// used after implicit parameters.
//
// name [ <...> ] ( <...> )
// ^
// 1. PatternListAsExplicit
// 2. DeclNameAndParamsAfterParams
//
// name [ <...> ] <???>
// ^
// (state done)
CARBON_PARSE_STATE(DeclNameAndParamsAfterImplicit)
// Inside a declaration, conditionally starts another qualified name. Only used
// after regular parameters.
//
// name [ <...> ] ( <...> ) .
// ^
// 1. DeclNameAndParams
//
// name [ <...> ] ( <...> ) <...>
// ^
// (state done)
CARBON_PARSE_STATE(DeclNameAndParamsAfterParams)
// Handles processing of a declaration. Things like fn, class, interface, and so
// on.
//
// abstract
// ^~~~~~~~
// base class
// ^~~~
// default
// ^~~~~~~
// export import
// ^~~~~~
// extend base
// ^~~~~~
// final
// ^~~~~
// override fn
// ^~~~~~~~
// private
// ^~~~~~~
// protected
// ^~~~~~~~~
// virtual
// ^~~~~~~
// 1. Decl
//
// adapt <...>
// ^~~~~
// 1. AdaptAfterIntroducer
//
// alias <...>
// ^~~~~
// 1. Alias
//
// base : <...>
// ^~~~
// 1. BaseAfterIntroducer
//
// choice <...>
// ^~~~~~
// 1. ChoiceIntroducer
//
// class <...>
// ^~~~~
// 1. TypeAfterIntroducerAsClass
//
// constraint <...>
// ^~~~~~~~~~
// 1. TypeAfterIntroducerAsNamedConstraint
//
// export <name> <...>
// ^~~~~~
// 1. ExportName
//
// fn <...>
// ^~
// 1. FunctionIntroducer
//
// friend <...>
// ^~~~~~
// 1. FriendDecl
//
// impl <...>
// ^~~~
// 1. ImplAfterIntroducer
//
// import <...> (in packaging directives)
// ^~~~~~
// 1. Import
//
// inline <...>
// ^~~~~~
// 1. InlineDeclAfterIntroducer (variant is Regular)
//
// interface <...>
// ^~~~~~~~~
// 1. TypeAfterIntroducerAsInterface
//
// let <...> (variant is Regular)
// ^~~
// 1. Let
//
// let <...> (variant is Interface)
// ^~~
// 1. AssociatedConstant
//
// library <...> (in packaging directives)
// ^~~~~~~
// 1. Library
//
// match_first <...>
// ^~~~~~~~~
// 1. MatchFirst
//
// namespace <...>
// ^~~~~~~~~
// 1. Namespace
//
// package <...> (in packaging directives)
// ^~~~~~~
// 1. Package
//
// require <...>
// ^~~~~~~
// 1. RequireAfterIntroducer
//
// observe <...>
// ^~~~~~~
// 1. ObserveAfterIntroducer
//
// var <...> (variant is Regular)
// ^~~
// 1. VarAsRegular
//
// ;
// ^
// (state done)
//
// <???> ;
// ^~~~~~~
// (state done)
CARBON_PARSE_STATE_VARIANTS3(Decl, Class, Interface, Regular)
// Handles processing of a declaration scope, which contains a sequence of
// declarations.
//
// }
// ^
// <eof>
// ^
// (state done)
//
// <...>
// ^
// 1. DeclAs(Class|Interface|Regular)
// 2. DeclScopeLoopAs(Class|Interface|Regular)
//
CARBON_PARSE_STATE_VARIANTS3(DeclScopeLoop, Class, Interface, Regular)
// Handles processing of an inline declaration.
//
// inline Cpp "..." ;
// ^~~~~~~~~~~
// (state done)
CARBON_PARSE_STATE(InlineDeclAfterIntroducer)
// Handles periods. Only does one `.<expression>` segment; the source is
// responsible for handling chaining.
//
// The forms of this are:
// - Member access expressions.
// - Designated names in structs.
//
// Expressions have member accesses such as `x.y`, while structs have
// designators such as `.z`.
//
// . name
// ^~~~~~
// -> name
// ^~~~~~~
// . base (variant is not Decl)
// ^~~~~~
// -> base (variant is not Decl)
// ^~~~~~~
// . <???> (<???> consumed if it is a keyword)
// ^
// -> <???> (<???> consumed if it is a keyword)
// ^~
// (state done)
//
// expr . ( <...> )
// ^
// 1. OnlyParenExpr
// 2. CompoundMemberAccess
//
// expr -> ( <...> )
// ^~
// 1. OnlyParenExpr
// 2. CompoundPointerMemberAccess
CARBON_PARSE_STATE_VARIANTS2(Period, Expr, Struct)
// Handles a compound member access after we parse the name expression.
//
// expr . ( expr )
// ^
CARBON_PARSE_STATE(CompoundMemberAccess)
// Handles a compound pointer member access after we parse the name expression.
//
// expr -> ( expr )
// ^
CARBON_PARSE_STATE(CompoundPointerMemberAccess)
// Handles `->name` expressions. Identical to PeriodAsExpr except for the
// leading token.
//
// -> name
// ^~~~~~~
// (state done)
//
// -> <???> (<???> consumed if it is a keyword)
// ^~
// (state done)
CARBON_PARSE_STATE(ArrowExpr)
// Handles processing of an expression.
//
// if <...>
// ^~
// 1. Expr
// 2. IfExprCondition
// 3. IfExprFinish
//
// <prefix operator> <...>
// ^~~~~~~~~~~~~~~~~
// 1. Expr
// 2. ExprLoopForPrefix
//
// <...>
// ^
// 1. ExprInPostfix
// 2. ExprLoop
CARBON_PARSE_STATE(Expr)
// Handles the initial part of postfix expressions, such as an identifier or
// literal value, then proceeds to the loop.
//
// identifier
// ^~~~~~~~~~
// literal
// ^~~~~~~
// self
// ^~~~
// Self
// ^~~~
// 1. ExprInPostfixLoop
//
// {
// ^
// 1. BraceExpr
// 2. ExprInPostfixLoop
//
// (
// ^
// 1. ParenExpr
// 2. ExprInPostfixLoop
//
// array
// ^
// 1. ArrayExpr
// 2. ExprInPostfixLoop
//
// form
// ^
// 1. FormExpr
// 2. ExprInPostfixLoop
//
// <???>
// ^
// (state done)
CARBON_PARSE_STATE(ExprInPostfix)
// Handles looping through elements following the initial postfix expression,
// such as designators or parenthesized parameters.
//
// expr . <...>
// ^
// 1. PeriodAsExpr
// 2. ExprInPostfixLoop
//
// expr -> <...>
// ^
// 1. ArrowExpr
// 2. ExprInPostfixLoop
//
// expr ( <...> )
// ^
// 1. CallExpr
// 2. ExprInPostfixLoop
//
// expr [ <...> ]
// ^
// 1. IndexExprStart
// 2. ExprInPostfixLoop
//
// <...>
// ^
// (state done)
CARBON_PARSE_STATE(ExprInPostfixLoop)
// Handles processing of an expression.
//
// expr <infix operator> <...>
// ^~~~~~~~~~~~~~~~
// 1. Expr
// 2. ExprLoopForBinary
//
// expr <postfix operator>
// ^~~~~~~~~~~~~~~~~~
// 1. ExprLoop
//
// expr <short circuit operator> <...>
// ^~~~~~~~~~~~~~~~~~~~~~~~
// 1. Expr
// 2. ExprLoopForShortCircuitOperator
//
// expr <...>
// ^
// (state done)
CARBON_PARSE_STATE(ExprLoop)
// Completes an ExprLoop pass by adding an infix operator, then goes back
// to ExprLoop.
//
// expr <infix operator> expr <...>
// ^
// 1. ExprLoop
CARBON_PARSE_STATE(ExprLoopForInfixOperator)
// Completes an ExprLoop pass by adding a prefix operator, then goes back
// to ExprLoop.
//
// <prefix operator> expr <...>
// ^
// 1. ExprLoop
CARBON_PARSE_STATE(ExprLoopForPrefixOperator)
// Completes an ExprLoop pass by adding a short circuit operator, then goes back
// to ExprLoop.
//
// expr <short circuit operator> expr <...>
// ^
// 1. ExprLoop
CARBON_PARSE_STATE_VARIANTS2(ExprLoopForShortCircuitOperator, And, Or)
// Completes the condition of an `if` expression and handles the `then` token.
//
// if expr then <...>
// ^~~~
// 1. Expr
// 2. IfExprFinishThen
//
// if expr <???>
// ^
// (state done)
CARBON_PARSE_STATE(IfExprFinishCondition)
// Completes the first alternative in an `if` expression and handles the `else`
// token.
//
// if expr then expr else <...>
// ^~~~
// 1. Expr
// 2. IfExprFinishElse
//
// if expr then expr <???>
// ^
// (state done)
CARBON_PARSE_STATE(IfExprFinishThen)
// Completes the second alternative in an `if` expression.
//
// if expr then expr else expr
// ^
// (state done)
CARBON_PARSE_STATE(IfExprFinishElse)
// Completes an IfExpr.
//
// if expr then expr else expr
// ^
// if <???>
// ^
// (state done)
CARBON_PARSE_STATE(IfExprFinish)
// Handles the beginning of a requirement expression after a `where` operator in
// an expression.
// TODO: Also a `require` declaration?
//
// expr where .designator = <...>
// ^~~~~~~~~~~~~
// 1. Expr
// 2. RequirementOperatorFinish
// expr where <...>
// ^
// 1. Expr
// 2. RequirementOperator
CARBON_PARSE_STATE(RequirementBegin)
// Handles a requirement operator in a `where` expression.
//
// expr where expr impls <...>
// ^~~~
// expr where expr = <...>
// ^
// expr where expr == <...>
// ^~
// 1. Expr
// 2. RequirementOperatorFinish
CARBON_PARSE_STATE(RequirementOperator)
// Finishes a requirement operator in a `where` expression.
//
// expr where expr impls expr
// ^
// expr where expr = expr
// ^
// expr where expr == expr
// ^
// (state done)
// expr where expr impls expr and
// ^~~
// expr where expr = expr and
// ^~~
// expr where expr == expr and
// ^~~
// 1. RequirementBegin
CARBON_PARSE_STATE(RequirementOperatorFinish)
// Finishes an `where` expression.
//
// expr where requirement
// ^
// (state done)
CARBON_PARSE_STATE(WhereFinish)
// Handles the `;` for an expression statement, which is different from most
// keyword statements.
//
// expr ;
// ^
// expr <???> ;
// ^~~~~~~
// (state done)
CARBON_PARSE_STATE(ExprStatementFinish)
// Handles a `friend` declaration.
//
// friend <identifier> ;
// ^~~~~~~~~~~~~~
// friend ??? ;
// ^~~~~
// (state done)
CARBON_PARSE_STATE(FriendDecl)
// Handles a function's introducer.
//
// fn <...>
// ^
// 1. DeclNameAndParams
// 2. FunctionAfterParams
CARBON_PARSE_STATE(FunctionIntroducer)
// Handles a lambda's introducer.
//
// fn <...>
// ^
// 1. LambdaIntroducer
// 2. LambdaAfterIntroducer
CARBON_PARSE_STATE(LambdaIntroducer)
// Handles processing of a lambda after the introducer.
//
// fn [ <...> ] <...>
// ^
// 1. PatternListAsImplicit
// 2. LambdaAfterImplicitParams
//
// fn ( <...> ) <...>
// ^
// 1. PatternListAsExplicit
// 2. LambdaAfterParams
//
// fn <...>
// ^
// 1. LambdaAfterParams
CARBON_PARSE_STATE(LambdaAfterIntroducer)
// Handles processing of a lambda after implicit parameters.
//
// fn [ <...> ] ( <...> ) <...>
// ^
// 1. PatternListAsExplicit
// 2. LambdaAfterParams
//
// fn [ <...> ] <...>
// ^
// 1. LambdaAfterParams
CARBON_PARSE_STATE(LambdaAfterImplicitParams)
// Handles processing of a lambda after optional parameters.
//
// fn <...> -> <...>
// ^
// 1. ReturnTypeOrFormExpr (Reused)
// 2. FunctionReturnTypeFinish
// 3. LambdaBody
//
// fn <...> ->? <...>
// ^
// 1. FunctionReturnFormFinish
// 2. LambdaBody
//
// fn <...> => <...>
// ^
// 1. Expr
// 2. LambdaBodyFinish
//
// fn <...> { <...> }
// ^
// 1. StatementScopeLoop
// 2. LambdaBodyFinish
CARBON_PARSE_STATE(LambdaAfterParams)
// Handles processing of a lambda body.
//
// fn <...> -> <...> { <...> }
// ^
// 1. StatementScopeLoop
// 2. LambdaBodyFinish
//
// fn <...> -> <...> => <...>
// ^
// 1. Expr
// 2. LambdaBodyFinish
CARBON_PARSE_STATE(LambdaBody)
// Finishes a lambda expression.
//
// fn <...> }
// ^
// fn <...> => expr
// ^
// (state done)
CARBON_PARSE_STATE(LambdaBodyFinish)
// Handles processing of a function's syntax after `)`, primarily the
// possibility a `->` return type is there. Always enqueues signature finish
// handling.
//
// fn F(<...>) -> <...>
// ^~
// 1. Expr
//
// fn F(...) -> ...
// ^~
// 1. ReturnTypeOrFormExpr
// 2. FunctionReturnTypeFinish
// 3. FunctionSignatureFinish
//
// fn F(<...>) ->? <...>
// ^~~
// 1. Expr
// 2. FunctionReturnFormFinish
// 3. FunctionSignatureFinish
//
// fn F(<...>) <...>
// ^
// 1. FunctionSignatureFinish
CARBON_PARSE_STATE(FunctionAfterParams)
// Handles the expression following a `->` in a function or lambda, which may
// begin with `ref` to specify a primitive return form.
//
// -> ref expr ...
// ^~~
// 1. Expr
// 2. PrimitiveFormFinish
//
// -> expr ...
// ^
// 1. Expr
CARBON_PARSE_STATE(ReturnTypeOrFormExpr)
// Finishes a function return type.
//
// fn F(<...>) -> expr <...>
// ^
// (state done)
CARBON_PARSE_STATE(FunctionReturnTypeFinish)
// Finishes a function return form.
//
// fn F(<...>) ->? expr <...>
// ^
// (state done)
CARBON_PARSE_STATE(FunctionReturnFormFinish)
// Finishes a function signature. If it's a declaration, the function is done;
// otherwise, this also starts definition processing.
//
// fn <...> ;
// ^
// (state done)
//
// fn <...> {
// ^
// 1. StatementScopeLoop
// 2. FunctionDefinitionFinish
//
// fn <...> <???> ;
// ^~~~~~~
// (state done)
CARBON_PARSE_STATE(FunctionSignatureFinish)
// Finishes a function definition.
//
// fn <...> }
// ^
// fn <...> ;
// ^
// (state done)
CARBON_PARSE_STATE(FunctionDefinitionFinish)
// Finishes a function with a terse body.
//
// fn <...> => expr ;
// ^
// (state done)
CARBON_PARSE_STATE(FunctionTerseBodyFinish)
// Handles `export <name>`.
//
// export Name;
// ^
// 1. DeclNameAndParams
// 2. ExportFinish
CARBON_PARSE_STATE(ExportName)
// Finishes an `export <name>`.
//
// export Name;
// ^
// (state done)
CARBON_PARSE_STATE(ExportNameFinish)
// Handles `import`.
//
// import pkgname [library "libname"] ;
// ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// import library "libname" ;
// ^~~~~~~~~~~~~~~~~~~
// import <???> ;
// ^~~~~~~
// (state done)
CARBON_PARSE_STATE(Import)
// Handles `library` in declaration form.
//
// library "libname" ;
// ^~~~~~~~~~~
// library <???> ;
// ^~~~~~~
// (state done)
CARBON_PARSE_STATE(Library)
// Handles `match_first` and opens the block.
//
// match_first { <...>
// ^~~~~~~~~~~~~
// 1. DeclScopeLoopAsRegular
// 2. MatchFirstFinish
CARBON_PARSE_STATE(MatchFirst)
// Handles closing the `match_first` block.
//
// match_first { <...> }
// ^
// (state done)
CARBON_PARSE_STATE(MatchFirstFinish)
// Handles `namespace`.
//
// namespace <...>
// ^
// 1. DeclNameAndParams
// 2. NamespaceFinish
CARBON_PARSE_STATE(Namespace)
// Handles `namespace` after the name.
//
// namespace <...> ;
// ^
// namespace <...> <???> ;
// ^~~~~~~
// (state done)
CARBON_PARSE_STATE(NamespaceFinish)
// Handles `package`.
//
// package pkgname [library "libname"] ;
// ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// package <???> ;
// ^~~~~~~
// (state done)
CARBON_PARSE_STATE(Package)
// Handles `alias` after the introducer.
//
// alias <...>
// ^
// 1. DeclNameAndParams
// 2. AliasInitializer
CARBON_PARSE_STATE(Alias)
// Handles `alias` after the name.
//
// alias <...> = <...> ;
// ^
// 1. Expr
// 2. AliasFinish
//
// alias <???>
// ^
// (state done)
CARBON_PARSE_STATE(AliasAfterName)
// Handles `alias` at the end.
//
// alias <...> ;
// ^
// alias <???>
// ^
// (state done)
CARBON_PARSE_STATE(AliasFinish)
// Starts parsing a pattern in a comma-separated list. The variants mark
// whether it is part of an implicit parameter list, struct pattern or a tuple
// pattern.
//
// <...>
// ^
// 1. Pattern
// 2. PatternListElementCheckForDefaultValue
// 2. PatternListElementFinishAs(Tuple|Struct|Explicit|Implicit)
//
// .foo = <...> (variant is Struct)
// ^
// 1. PeriodAsStruct
// 2. StructPatternFieldAfterDesignator
// 3. PatternListElementCheckForDefaultValue
// 4. PatternListElementFinishAsStruct
//
// _ <...> (variant is Struct)
// ^
// 1. StructPatternUnderscore
// 2. PatternListElementFinishAsStruct
CARBON_PARSE_STATE_VARIANTS4(PatternListElement, Tuple, Struct, Explicit,
Implicit)
// Some pattern list elements support optional default value expressions,
// this state checks for the `=` and if present parses it before moving on
// to finish the list element.
//
// <...> = <...>
// ^
// 1. Expr
// 2. PatternListElementFinishDefaultValue
//
// <...>
// ^
// (state done)
CARBON_PARSE_STATE(PatternListElementCheckForDefaultValue)
// After parsing the default value Expr this state attaches that Expr
// as a default value to the pattern.
//
// <...> = <...>
// ^
// (state done)
CARBON_PARSE_STATE(PatternListElementFinishDefaultValue)
// Finishes parsing a pattern in a comma-separated list, including the
// optional trailing `,`. If there are more patterns, enqueues another
// pattern parsing state.
//
// <...> , ) (variant is Tuple)
// ^
// (state done)
// SPECIAL: parent becomes PatternListFinishAsTuple
//
// <...> , } (variant is Struct)
// ^
// (state done)
//
// <...> , ] (variant is Implicit)
// ^
// (state done)
//
// <...> , <...>
// ^
// 1. PatternListElementAs(Tuple|Struct|Explicit|Implicit)
// SPECIAL (variant is Tuple): parent becomes PatternListFinishAsTuple
//
// <...>
// ^
// (state done)
CARBON_PARSE_STATE_VARIANTS4(PatternListElementFinish, Tuple, Struct, Explicit,
Implicit)
// Handles processing of a tuple pattern (parentheses), implicit parameter
// list (square brackets) or struct pattern (braces).
//
// ( ) (variant is Tuple or Explicit)
// ^
// [ ] (variant is Implicit)
// ^
// { } (variant is Struct)
// ^
// 1. PatternListFinishAs(Tuple|Struct|Explicit|Implicit)
//
// ( <...> ) (variant is Explicit)
// ^
// [ <...> ] (variant is Implicit)
// ^
// 1. PatternListElementAs(Explicit|Implicit)
// 2. PatternListFinishAs(Explicit|Implicit)
//
// ( <...> ) (variant is Tuple)
// ^
// 1. PatternListElementAsTuple
// 2. PatternListFinishAsParen (SPECIAL: may be replaced)
//
// { <...> } (variant is Struct)
// ^
// 1. PatternListElementAsStruct
// 2. PatternListFinishAsStruct
CARBON_PARSE_STATE_VARIANTS4(PatternList, Tuple, Struct, Explicit, Implicit)
// Handles processing of a parameter list `]`, `)` or `}`.
//
// ( <...> ) (variant is Paren, Tuple or Explicit)
// ^
// [ <...> ] (variant is Implicit)
// ^
// { <...> } (variant is Struct)
// ^
// (state done)
CARBON_PARSE_STATE_VARIANTS5(PatternListFinish, Paren, Tuple, Struct, Explicit,
Implicit)
//
// <...> ,
// ^
// (state done)
//
// <...> }
// ^
// (state done)
CARBON_PARSE_STATE(StructPatternDesignatedFieldFinish)
// Handles a struct pattern parameter after the initial designator.
// .foo = <...>
// ^
// 1. Pattern
// 2. StructPatternDesignatedFieldFinish
//
// .foo <???> = <...>
// ^~~~~~~
// 1. Pattern
// 2. StructPatternDesignatedFieldFinish
//
// .foo <???> , <...>
// ^~~~~~
// 1. StructPatternDesignatedFieldFinish
//
// .foo <???> } <...>
// ^~~~~~
// 1. StructPatternDesignatedFieldFinish
CARBON_PARSE_STATE(StructPatternFieldAfterDesignator)
// Handles the processing of an '_' element in a struct pattern
// _ }
// ^
// (state done)
//
// _ : <???>
// ^
// 1. BindingPattern
//
// _ :? <???>
// ^
// 1. BindingPattern
CARBON_PARSE_STATE(StructPatternUnderscore)
// Handles the processing of a `(condition)` up through the expression.
//
// if/while/match { (invalid)
// ^
// 1. ParenConditionAs(If|While|Match)Finish
//
// if/while/match ( <...> )
// ^
// if/while/match <???>
// ^
// 1. Expr
// 2. ParenConditionAs(If|While|Match)Finish
CARBON_PARSE_STATE_VARIANTS3(ParenCondition, If, While, Match)
// Finishes the processing of a `(condition)` after the expression.
//
// if/while/match ( expr )
// ^
// if/while/match {
// ^
// if/while/match <???> {
// ^
// (state done)
CARBON_PARSE_STATE_VARIANTS3(ParenConditionFinish, If, While, Match)
// Handles compound member access `(` after `->` or `.`
//
// ( <...> )
// ^
// 1. Expr
// 2. OnlyParenExprFinish
CARBON_PARSE_STATE(OnlyParenExpr)
// Handles the `)` after `->(` <...> or `.(` <...>
//
// ( <...> )
// ^
CARBON_PARSE_STATE(OnlyParenExprFinish)
// Handles the `(` of an expression that's presumed to be a parenthesized
// single expression, but may later be reclassified as a tuple literal.
//
// ( )
// ^
// 1. TupleLiteralFinish
//
// ( <...> )
// ^
// 1. Expr
// 2. ExprAfterOpenParenFinish
// 3. ParenExprFinish (SPECIAL: may be replaced)
CARBON_PARSE_STATE(ParenExpr)
// Handles the `)` of a tuple literal.
//
// ( <...> )
// ^
// (state done)
CARBON_PARSE_STATE(TupleLiteralFinish)
// Handles the end of an expression following an open parenthesis.
//
// ( <...> , )
// ^
// (state done)
// SPECIAL: parent becomes TupleLiteralFinish
//
// ( <...> , <...> )
// ^
// 1. Expr
// 2. TupleLiteralElementFinish
// SPECIAL: parent becomes TupleLiteralFinish
//
// ( <...> )
// ^
// (state done)
CARBON_PARSE_STATE(ExprAfterOpenParenFinish)
// Handles the end of an expression that is known to be an element of a tuple
// literal expression.
//
// ( <...> , )
// ^
// (state done)
//
// ( <...> , <...> )
// ^
// 1. Expr
// 2. TupleLiteralElementFinish
//
// ( <...> )
// ^
// (state done)
CARBON_PARSE_STATE(TupleLiteralElementFinish)
// Handles the `)` of a parenthesized single expression.
//
// ( <...> )
// ^
// (state done)
CARBON_PARSE_STATE(ParenExprFinish)
// Handles processing of a pattern.
//
// ( <...> )
// ^
// 1. PatternListAsTuple
//
// var <...>
// ^
//
// 1. VariablePattern
//
// unused <...>
// ^
// 1. UnusedPattern
//
// [identifier|self] [:|:?]
// ^
// template <...>
// ^
// ref <...>
// ^
// 1. BindingPattern
//
// <...>
// ^
// 1. Expr
// 2. ExprPattern
CARBON_PARSE_STATE(Pattern)
// Tracks that we are parsing an expression as an expression pattern.
//
// <...>
// ^
// (state done)
CARBON_PARSE_STATE(ExprPattern)
// Handles the initial part of a binding pattern, enqueuing type expression
// processing.
//
// TODO: treat `ref` as a unary pattern operator in order to avoid ambiguity
// with `ref` in expression patterns. See issue #6342.
//
// name: <...> (not contextually a generic parameter)
// ^~~~~
// _: <...> (not contextually a generic parameter)
// ^~
// ref name: <...> (not contextually a generic parameter)
// ^~~~~~~~~
// ref _: <...> (not contextually a generic parameter)
// ^~~~~~
// runtime [ref] name: <...>
// ^~~~~~~~~~~~~~~~~~~
// runtime [ref] _: <...>
// ^~~~~~~~~~~~~~~~
// [runtime] [ref] self: <...>
// ^~~~~~~~~~~~~~~~~~~~~
// 1. Expr
// 2. BindingPatternFinishAsRegular
//
// name: <...> (contextually a generic parameter)
// ^~~~~
// _: <...> (contextually a generic parameter)
// ^~
// template/generic name: <...>
// ^~~~~~~~~~~~~~~~~~~~~~
// template/generic _: <...>
// ^~~~~~~~~~~~~~~~~~~
// template/generic self: <...>
// ^~~~~~~~~~~~~~~~~~~~~~
// 1. Expr
// 2. BindingPatternFinishAsGeneric
//
// name:? <...>
// ^~~~~~
// self:? <...>
// ^~~~~~
// _:? <...>
// ^~~
// 1. Expr
// 2. BindingPatternFinishAsForm
//
// [ref] self (not followed by `:` or `:?`)
// ^~~~~~~~~~
// 1. (state done)
//
// <???>
// ^
// 1. BindingPatternFinishAsRegular
CARBON_PARSE_STATE(BindingPattern)
// Finishes binding pattern processing.
//
// name: type
// ^
// (state done)
CARBON_PARSE_STATE_VARIANTS3(BindingPatternFinish, Generic, Regular, Form)
// Handles `var` in a pattern context.
//
// var <...>
// ^~~
// 1. Pattern
// 2. FinishVariablePattern
CARBON_PARSE_STATE(VariablePattern)
// Finishes `var` in a pattern context.
//
// var <...>
// ^
// (state done)
CARBON_PARSE_STATE(FinishVariablePattern)
// Handles `unused` in a pattern context.
//
// unused <...>
// ^~~~~~
// 1. Pattern
// 2. FinishUnusedPattern
CARBON_PARSE_STATE(UnusedPattern)
// Finishes `unused` in a pattern context.
//
// unused <...>
// ^
// (state done)
CARBON_PARSE_STATE(FinishUnusedPattern)
// Handles a single statement. While typically within a statement block, this
// can also be used for error recovery where we expect a statement block and
// are missing braces.
//
// break <...>
// ^~~~~
// 1. StatementBreakFinish
//
// continue <...>
// ^~~~~~~~
// 1. StatementContinueFinish
//
// for <...>
// ^~~
// 1. StatementForHeader
// 2. StatementForFinish
//
// if <...>
// ^
// 1. StatementIf
//
// return <...>
// ^
// 1. StatementReturn
//
// returned <...>
// ^
// 1. VarAsReturned
//
// while <...>
// ^
// 1. StatementWhile
//
// <...>
// ^
// 1. Expr
// 2. ExprStatementFinish
//
// match <...>
// ^
// 1. MatchIntroducer
//
// ... <...>
// ^~~
// 1. Statement
// 2. StatementPackExpansionFinish
//
// <decl introducer or modifier>
// ^
// 1. Decl
CARBON_PARSE_STATE(Statement)
// Handles `break` processing at the `;`.
//
// break ;
// ^
// (state done)
CARBON_PARSE_STATE(StatementBreakFinish)
// Handles `continue` processing at the `;`.
//
// continue ;
// ^
// (state done)
CARBON_PARSE_STATE(StatementContinueFinish)
// Handles `for` processing of `(`, proceeding to a pattern before continuing.
//
// for ( <...> )
// ^
// for <???>
// ^
// 1. Pattern
// 2. StatementForHeaderIn
CARBON_PARSE_STATE(StatementForHeader)
// Handles `for` processing of `in`, proceeding to an expression before
// continuing.
//
// for ( <...> in <...> )
// ^~
// for ( <...> : <...> )
// ^
// for ( <...> <???> )
// ^
// 1. Expr
// 2. StatementForHeaderFinish
CARBON_PARSE_STATE(StatementForHeaderIn)
// Handles `for` processing of `)`, proceeding to the statement block.
//
// for ( <...> ) <...>
// ^
// 1. CodeBlock
CARBON_PARSE_STATE(StatementForHeaderFinish)
// Handles `for` processing after the final `}`.
//
// for ( <...> ) { <...> }
// ^
// (state done)
CARBON_PARSE_STATE(StatementForFinish)
// Handles `if` processing at the start.
//
// if <...>
// ^~
// 1. ParenConditionAsIf
// 2. StatementIfConditionFinish
CARBON_PARSE_STATE(StatementIf)
// Handles `if` processing between the condition and start of the first code
// block.
//
// if ( <...> ) <...>
// ^
// 1. CodeBlock
// 2. StatementIfThenBlockFinish
CARBON_PARSE_STATE(StatementIfConditionFinish)
// Handles `if` processing after the end of the first code block, with the
// optional `else`.
//
// if ( <...> ) { <...> } else if <...>
// ^~~~
// 1. StatementIf
// 2. StatementIfElseBlockFinish
//
// if ( <...> ) { <...> } else <...>
// ^~~~
// 1. CodeBlock
// 2. StatementIfElseBlockFinish
//
// if ( <...> ) { <...> } <...>
// (state done)
CARBON_PARSE_STATE(StatementIfThenBlockFinish)
// Handles `if` processing after a provided `else` code block.
//
// if ( <...> ) { <...> } else { <...> }
// ^
// (state done)
CARBON_PARSE_STATE(StatementIfElseBlockFinish)
// Handles `return` processing.
//
// return ;
// ^~~~~~
// 1. StatementReturnFinish
//
// return var <...>
// ^~~~~~~~~~
// 1. StatementReturnFinish
//
// return <...>
// ^~~~~~
// 1. Expr
// 2. StatementReturnFinish
CARBON_PARSE_STATE(StatementReturn)
// Handles `return` processing at the `;`.
//
// return <...> ;
// ^
// (state done)
CARBON_PARSE_STATE(StatementReturnFinish)
// Handles a pack expansion statement after its body.
//
// ... <statement>
// ^
// (state done)
CARBON_PARSE_STATE(StatementPackExpansionFinish)
// Handles processing of statements within a scope.
//
// { <...> }
// ^
// (state done)
//
// { <...> <...> }
// ^
// 1. Statement
// 2. StatementScopeLoop
CARBON_PARSE_STATE(StatementScopeLoop)
// Handles `while` processing.
//
// while <...>
// ^~~~~
// 1. ParenConditionAsWhile
// 2. StatementWhileConditionFinish
CARBON_PARSE_STATE(StatementWhile)
// Handles `while` processing between the condition and start of the code block.
//
// while ( <...> ) <...>
// ^
// 1. CodeBlock
// 2. StatementWhileBlockFinish
CARBON_PARSE_STATE(StatementWhileConditionFinish)
// Handles `while` processing after the end of the code block.
//
// while ( <...> ) { <...> }
// ^
// (state done)
CARBON_PARSE_STATE(StatementWhileBlockFinish)
// Handles parsing after the declaration scope of a type.
//
// class/impl/interface/constraint <...> { <...> }
// ^
// (state done)
CARBON_PARSE_STATE_VARIANTS4(DeclDefinitionFinish, Class, Impl, Interface,
NamedConstraint)
// Handles processing of a type after its introducer.
//
// class/interface/constraint <...>
// ^
// 1. DeclNameAndParams
// 2. DeclOrDefinitionAs(Class|Interface|NamedConstraint)
CARBON_PARSE_STATE_VARIANTS3(TypeAfterIntroducer, Class, Interface,
NamedConstraint)
// Handles processing of a type after its optional parameters.
//
// class/impl/interface/constraint name ( <...> ) {
// ^
// 1. DeclScopeLoopAs(Class|Regular)
// 2. DeclDefinitionFinishAs(Class|Impl|Interface|NamedConstraint)
//
// class/impl/interface/constraint name ( <...> ) ;
// ^
// class/impl/interface/constraint name ( <...> ) <???>
// ^
// (state done)
CARBON_PARSE_STATE_VARIANTS4(DeclOrDefinition, Class, Impl, Interface,
NamedConstraint)
// Handles processing of an `adapt T` declaration after the introducer.
//
// adapt T ;
// ^
// 1. Expr
// 2. AdaptDecl
CARBON_PARSE_STATE(AdaptAfterIntroducer)
// Handles processing of a completed `adapt T` declaration.
//
// adapt T ;
// ^
// adapt T <???> ;
// ^~~~~~~
// (state done)
CARBON_PARSE_STATE(AdaptDecl)
// Handles processing of a `base: B` after the introducer.
//
// base: B ;
// ^
// 1. Expr
// 2. BaseDecl
// base <???> ;
// ^~~~~
// (state done)
CARBON_PARSE_STATE(BaseAfterIntroducer)
// Handles processing of a completed `base: B` declaration.
//
// base: B ;
// ^
// base: B <???> ;
// ^~~~~~~
// (state done)
CARBON_PARSE_STATE(BaseDecl)
// Handles processing of an `impl...as` declaration after the introducer.
//
// impl forall [ <...>
// ^~~~~~
// 1. PatternListAsImplicit
// 2. ImplAfterForall
// 3. DeclOrDefinitionAsImpl
// impl as <...>
// ^~
// 1. Expr
// 2. DeclOrDefinitionAsImpl
// impl TypeExpression as <...>
// ^
// 1. Expr
// 2. ImplBeforeAs
// 3. DeclOrDefinitionAsImpl
CARBON_PARSE_STATE(ImplAfterIntroducer)
// Handles processing of an `impl forall` declaration after the implicit
// parameter list.
//
// impl forall [ <...> ] as <...>
// ^~
// 1. Expr
// impl forall [ <...> ] TypeExpression as <...>
// ^
// 1. Expr
// 2. ImplBeforeAs
CARBON_PARSE_STATE(ImplAfterForall)
// Handles processing of the `as` in an `impl` declaration after the type
// expression.
//
// impl TypeExpression as <...>
// ^~
// 1. Expr
CARBON_PARSE_STATE(ImplBeforeAs)
// Handles processing of a `require...impls` declaration after the introducer.
//
// require impls <...>
// ^~~~~
// 1. Expr
// 2. RequireDecl
// require TypeExpression impls <...>
// ^
// 1. Expr
// 2. RequireBeforeImpls
// 3. RequireDecl
CARBON_PARSE_STATE(RequireAfterIntroducer)
// Handles processing of the `impls` in a `require` declaration after the type
// expression.
//
// require TypeExpression impls <...>
// ^~~~~
// 1. Expr
CARBON_PARSE_STATE(RequireBeforeImpls)
// Handles processing of a completed `require` declaration.
//
// require TypeExpression impls FacetTypeExpression ;
// ^
// (state done)
CARBON_PARSE_STATE(RequireDecl)
// Handles processing of an `observe` declaration after the introducer.
//
// observe TypeExpression <...>
// ^
// 1. Expr
// 2. ObserveOperator
CARBON_PARSE_STATE(ObserveAfterIntroducer)
// Handles processing of an operator in an `observe` declaration.
//
// observe TypeExpression == TypeExpression <...>
// ^~
// 1. Expr
// 2. ObserveFinishOperator
// observe TypeExpression impls <...>
// ^~~~~
// 1. Expr
// 2. ObserveFinishOperator
CARBON_PARSE_STATE(ObserveOperator)
// Finishes an operator in an `observe` declaration.
//
// observe TypeExpression == TypeExpression <...>
// ^
// 1. ObserveOperator
// observe TypeExpression == TypeExpression ;
// ^
// 1. ObserveDecl
CARBON_PARSE_STATE(ObserveFinishOperator)
// Handles processing of a completed `observe` declaration.
//
// observe <...> ;
// ^
// (state done)
CARBON_PARSE_STATE(ObserveDecl)
// Handles the start of a `var` or `returned var` in a non-class context.
//
// var <...> (variant is Regular)
// ^
// 1. Pattern
// 2. VarAfterPattern
// 3. VarFinish
//
// returned var <...> (variant is Returned)
// ^~~~~~~~~~~~
// 1. Pattern
// 2. VarAfterPattern
// 3. VarFinish
//
// returned <???> ; (variant is Returned)
// ^~~~~~~~~~~~~~~~
// (state done)
CARBON_PARSE_STATE_VARIANTS2(Var, Regular, Returned)
// Handles `var` after the pattern, either followed by an initializer or the
// semicolon.
//
// var <...> = <...>
// ^
// var <...> <???> = <...>
// ^~~~~~~
// 1. Expr
//
// var <...> <...>
// ^
// (state done)
CARBON_PARSE_STATE(VarAfterPattern)
// Handles `var` parsing at the end.
//
// var <...> ;
// ^
// var <...> <???> ;
// ^~~~~~~
// (state done)
CARBON_PARSE_STATE(VarFinish)
// Handles the start of a `let`.
//
// let <...>
// ^
// 1. Pattern
// 2. LetAfterPattern
// 3. LetFinish
CARBON_PARSE_STATE(Let)
// Handles `let` after the pattern, optionally followed by an initializer. The
// initializer is required except in an associated constant declaration, but
// that is enforced by check.
//
// let <...> = <...>
// ^
// let <...> <???> = <...>
// ^~~~~~~
// 1. Expr
//
// let <...> ;
// ^
// let <...> <???> ;
// ^~~~~
// (state done)
CARBON_PARSE_STATE_VARIANTS2(LetAfterPattern, Regular, AssociatedConstant)
// Handles `let` parsing at the end.
//
// let <...> ;
// ^
// let <...> <???> ;
// ^~~~~~~
// (state done)
CARBON_PARSE_STATE_VARIANTS2(LetFinish, Regular, AssociatedConstant)
// Handles the start of an associated constant declaration (`let` in an
// interface context).
//
// let name :! <...>
// ^~~~~~~
// 1. AssociatedConstantFinish
// let <???> ;
// ^~~~~~~
// let name <???> ;
// ^~~~~~~~~~~~
// (state done)
CARBON_PARSE_STATE(AssociatedConstant)
// Handles a choice's introducer.
//
// choice <...>
// ^~~~~~
// 1. DeclNameAndParams
// 2. ChoiceDefinitionStart
// 3. ChoiceDefinitionFinish
CARBON_PARSE_STATE(ChoiceIntroducer)
// Handles processing of a choice after its optional parameters.
//
// choice name <...> {}
// ^
// (state done)
//
// choice name <...> { <...> }
// ^
// 1. ChoiceAlternative
//
// choice name <...> <???>
// ^
// (state done)
CARBON_PARSE_STATE(ChoiceDefinitionStart)
// Starts alternative parsing.
//
// name( <...> )
// ^~~~
// 1. ParamListAsRegular
// 2. ChoiceAlternativeFinish
// name <...>
// ^~~~
// 1. ChoiceAlternativeFinish
CARBON_PARSE_STATE(ChoiceAlternative)
// Finishes parsing a choice's alternative, including the optional trailing `,`.
// If there are more alternatives, enqueues another alternative parsing state.
//
// <...> , }
// ^
// (state done)
//
// <...> , <...>
// ^
// 1. ChoiceAlternative
//
// <...>
// ^
// (state done)
CARBON_PARSE_STATE(ChoiceAlternativeFinish)
// Finishes a choice definition.
//
// choice <...> }
// ^
// (state done)
CARBON_PARSE_STATE(ChoiceDefinitionFinish)
// Handles `match` introducer.
//
// match <...>
// ^~~~~
// 1. ParenConditionAsMatch
// 2. MatchConditionFinish
CARBON_PARSE_STATE(MatchIntroducer)
// Handles `match` cases block start after the condition.
//
// match (<...>) { <...> }
// ^
// 1. MatchCaseLoop
// 2. MatchStatementFinish
//
// match (<...>) <???>
// ^
// (state done)
CARBON_PARSE_STATE(MatchConditionFinish)
// Handles `match` cases.
//
// match (<...>) { case <...>}
// ^
// 1. MatchCaseIntroducer
// 2. MatchCaseLoop
// match (<...>) { default <...>}
// ^
// 1. MatchDefaultIntroducer
// 2. MatchCaseLoopAfterDefault
CARBON_PARSE_STATE(MatchCaseLoop)
// Handles `match` `case` introducer.
//
// match (<...>) { case <...>}
// ^~~~
// 1. Pattern
// 2. MatchCaseAfterPattern
CARBON_PARSE_STATE(MatchCaseIntroducer)
// Handles `match` case after pattern.
//
// match (<...>) { case <...> => <...> }
// ^
// 1. MatchCaseStart
// match (<...>) { case <...> if (<...>) }
// ^~~~
// 1. Expr
// 2. MatchCaseGuardFinish
// 3. MatchCaseStart
CARBON_PARSE_STATE(MatchCaseAfterPattern)
// Handles `match` case guard closing parenthesis.
//
// match (<...>) { case <...> if (<...>) => <...> }
// ^
// (state done)
CARBON_PARSE_STATE(MatchCaseGuardFinish)
// Handles `match` case `=>` and `{` opening statements block.
//
// match (<...>) { case <...> => {<...>} }
// ^~~~
// 1. StatementScopeLoop
// 2. MatchHandlerFinish
//
// match (<...>) { case <...> <???> }
// ^
// (state done)
//
// match (<...>) { case <...> => <???> }
// ^
// (state done)
CARBON_PARSE_STATE(MatchCaseStart)
// Handles `match` default introducer, `=>` and `{` opening statements block.
//
// match (<...>) { default => {<...>} }
// ^~~~~~~~~~~~
// 1. StatementScopeLoop
// 2. MatchHandlerFinish
//
// match (<...>) { default <???> }
// ^
// (state done)
//
// match (<...>) { default => <???> }
// ^
// (state done)
CARBON_PARSE_STATE(MatchDefaultIntroducer)
// Handles `match` handler block closing `}`.
//
// match (<...>) { case <...> => {<...>} }
// ^
// (state done)
//
// match (<...>) { default => {<...>} }
// ^
// (state done)
CARBON_PARSE_STATE(MatchHandlerFinish)
// Handles `match` cases after the `default` case.
//
// match (<...>) { default => {<...>} case <...> }
// ^~~~
// 1. MatchCaseLoopAfterDefault
//
// match (<...>) { default => {<...>} default <...> }
// ^~~~~~~
// 1. MatchCaseLoopAfterDefault
//
// match (<...>) { default => {<...>} }
// ^
// (state done)
CARBON_PARSE_STATE(MatchCaseLoopAfterDefault)
// Finishes `match` statement.
//
// match (<...>) {<...>}
// ^
// (state done)
CARBON_PARSE_STATE(MatchStatementFinish)
#undef CARBON_PARSE_STATE
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