// 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
//
// Note that 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.
//
// x-macros come in three forms:
//   CARBON_PARSE_NODE_KIND(Name)
//     Used as a fallback if other macros are missing.
//   CARBON_PARSE_NODE_KIND_BRACKET(Name, BracketName)
//     Defines a bracketed node kind. BracketName should refer to the node kind
//     that is the _start_ of the bracketed range.
//   CARBON_PARSE_NODE_KIND_CHILD_COUNT(Name, ChildCount)
//     Defines a parse node with a set number of children, often 0. This count
//     must be correct even when the node contains errors.
//
// Macro definitions  will be removed at the end of this file to clean up.

#if !(defined(CARBON_PARSE_NODE_KIND) ||          \
      (defined(CARBON_PARSE_NODE_KIND_BRACKET) && \
       defined(CARBON_PARSE_NODE_KIND_CHILD_COUNT)))
#error "Must define CARBON_PARSE_NODE_KIND family x-macros to use this file."
#endif

// The BRACKET and CHILD_COUNT macros will use CARBON_PARSE_NODE_KIND by default
// when undefined.
#ifndef CARBON_PARSE_NODE_KIND_BRACKET
#define CARBON_PARSE_NODE_KIND_BRACKET(Name, ...) CARBON_PARSE_NODE_KIND(Name)
#endif
#ifndef CARBON_PARSE_NODE_KIND_CHILD_COUNT
#define CARBON_PARSE_NODE_KIND_CHILD_COUNT(Name, ...) \
  CARBON_PARSE_NODE_KIND(Name)
#endif

// The end of the file.
CARBON_PARSE_NODE_KIND_CHILD_COUNT(FileEnd, 0)

// An empty declaration, such as `;`.
CARBON_PARSE_NODE_KIND_CHILD_COUNT(EmptyDeclaration, 0)

// A name.
CARBON_PARSE_NODE_KIND_CHILD_COUNT(DeclaredName, 0)

// `package`:
//   PackageIntroducer
//   _external_: DeclaredName
//     _external_: Literal
//   PackageLibrary
//   PackageApi or PackageImpl
// PackageDirective
CARBON_PARSE_NODE_KIND_CHILD_COUNT(PackageIntroducer, 0)
CARBON_PARSE_NODE_KIND_CHILD_COUNT(PackageApi, 0)
CARBON_PARSE_NODE_KIND_CHILD_COUNT(PackageImpl, 0)
CARBON_PARSE_NODE_KIND_CHILD_COUNT(PackageLibrary, 1)
CARBON_PARSE_NODE_KIND_BRACKET(PackageDirective, PackageIntroducer)

// A code block:
//   CodeBlockStart
//   _external_: statements
// CodeBlock
CARBON_PARSE_NODE_KIND_CHILD_COUNT(CodeBlockStart, 0)
CARBON_PARSE_NODE_KIND_BRACKET(CodeBlock, CodeBlockStart)

// `fn`:
//     FunctionIntroducer
//     DeclaredName
//     _external_: ParameterList
//       _external_: type expression
//     ReturnType
//   FunctionDefinitionStart
//   _external_: statements
// FunctionDefinition
//
// The above is a definition; for a declaration, FunctionDeclaration will end it
// where FunctionDefinitionStart is for a definition.
CARBON_PARSE_NODE_KIND_CHILD_COUNT(FunctionIntroducer, 0)
CARBON_PARSE_NODE_KIND_CHILD_COUNT(ReturnType, 1)
CARBON_PARSE_NODE_KIND_BRACKET(FunctionDefinitionStart, FunctionIntroducer)
CARBON_PARSE_NODE_KIND_BRACKET(FunctionDefinition, FunctionDefinitionStart)
CARBON_PARSE_NODE_KIND_BRACKET(FunctionDeclaration, FunctionIntroducer)

// A parameter list:
//   ParamertListStart
//   _external_: expression
//   ParameterListComma
// ParameterList
//
// Expressions and ParameterListComma may repeat with ParameterListComma as a
// separator.
CARBON_PARSE_NODE_KIND_CHILD_COUNT(ParameterListStart, 0)
CARBON_PARSE_NODE_KIND_CHILD_COUNT(ParameterListComma, 0)
CARBON_PARSE_NODE_KIND_BRACKET(ParameterList, ParameterListStart)

// A pattern binding, such as `name: Type`:
//   DeclaredName
//   _external_: type expression
// PatternBinding
CARBON_PARSE_NODE_KIND_CHILD_COUNT(PatternBinding, 2)

// `var`:
//   VariableIntroducer
//   _external_: PatternBinding
//   optional VariableInitializer
//   optional _external_: expression
// VariableDeclaration
//
// The VariableInitializer and following expression are paired: either both will
// be present, or neither will.
CARBON_PARSE_NODE_KIND_CHILD_COUNT(VariableIntroducer, 0)
CARBON_PARSE_NODE_KIND_CHILD_COUNT(VariableInitializer, 0)
CARBON_PARSE_NODE_KIND_BRACKET(VariableDeclaration, VariableIntroducer)

// An expression statement:
//   _external_: expression
// ExpressionStatement
CARBON_PARSE_NODE_KIND_CHILD_COUNT(ExpressionStatement, 1)

// `break`:
//   BreakStatementStart
// BreakStatement
CARBON_PARSE_NODE_KIND_CHILD_COUNT(BreakStatementStart, 0)
CARBON_PARSE_NODE_KIND_CHILD_COUNT(BreakStatement, 1)

// `continue`:
//   ContinueStatementStart
// ContinueStatement
CARBON_PARSE_NODE_KIND_CHILD_COUNT(ContinueStatementStart, 0)
CARBON_PARSE_NODE_KIND_CHILD_COUNT(ContinueStatement, 1)

// `return`:
//   ReturnStatementStart
//   _external_: expression
// ReturnStatement
//
// The child expression is optional.
CARBON_PARSE_NODE_KIND_CHILD_COUNT(ReturnStatementStart, 0)
CARBON_PARSE_NODE_KIND_BRACKET(ReturnStatement, ReturnStatementStart)

// `for`:
//     ForHeaderStart
//       VariableIntroducer
//       _external_: PatternBinding
//         _external_: type expression
//     ForIn
//     _external_: expression
//   ForHeader
//   _external_: CodeBlock
// ForStatement
//
// Versus a normal `var`, ForIn replaces VariableDeclaration.
CARBON_PARSE_NODE_KIND_CHILD_COUNT(ForHeaderStart, 0)
CARBON_PARSE_NODE_KIND_BRACKET(ForIn, VariableIntroducer)
CARBON_PARSE_NODE_KIND_BRACKET(ForHeader, ForHeaderStart)
CARBON_PARSE_NODE_KIND_CHILD_COUNT(ForStatement, 2)

// `if` + `else`:
//     IfConditionStart
//     _external_: expression
//   IfCondition
//   _external_: CodeBlock
//   IfStatementElse
//   _external_: CodeBlock or IfStatement
// IfStatement
//
// IfStatementElse and the following node are optional based on `else` presence.
CARBON_PARSE_NODE_KIND_CHILD_COUNT(IfConditionStart, 0)
CARBON_PARSE_NODE_KIND_BRACKET(IfCondition, IfConditionStart)
CARBON_PARSE_NODE_KIND_CHILD_COUNT(IfStatementElse, 0)
CARBON_PARSE_NODE_KIND_BRACKET(IfStatement, IfCondition)

// `while`:
//     WhileConditionStart
//     _external_: expression
//   WhileCondition
//   _external_: CodeBlock
// WhileStatement
CARBON_PARSE_NODE_KIND_CHILD_COUNT(WhileConditionStart, 0)
CARBON_PARSE_NODE_KIND_BRACKET(WhileCondition, WhileConditionStart)
CARBON_PARSE_NODE_KIND_CHILD_COUNT(WhileStatement, 2)

// Parenthesized expressions:
//   ParenExpressionOrTupleLiteralStart
//   _external_: expression
// ParenExpression

// Tuples:
//   ParenExpressionOrTupleLiteralStart
//   _external_: expression
//   TupleLiteralComma
// TupleLiteral
//
// Expressions and TupleLiteralComma may repeat with TupleLiteralComma as a
// separator.
CARBON_PARSE_NODE_KIND_CHILD_COUNT(ParenExpressionOrTupleLiteralStart, 0)
CARBON_PARSE_NODE_KIND_BRACKET(ParenExpression,
                               ParenExpressionOrTupleLiteralStart)
CARBON_PARSE_NODE_KIND_CHILD_COUNT(TupleLiteralComma, 0)
CARBON_PARSE_NODE_KIND_BRACKET(TupleLiteral, ParenExpressionOrTupleLiteralStart)

// Call expressions, such as `a()`:
//     _external_: expression
//   CallExpressionStart
//   _external_: expression
//   CallExpressionComma
// CallExpression
//
// Expressions and CallExpressionComma may repeat with CallExpressionComma as a
// separator.
CARBON_PARSE_NODE_KIND_CHILD_COUNT(CallExpressionStart, 1)
CARBON_PARSE_NODE_KIND_CHILD_COUNT(CallExpressionComma, 0)
CARBON_PARSE_NODE_KIND_BRACKET(CallExpression, CallExpressionStart)

// A designator expression, such as `a.b`:
//   _external_: DesignatedName or lhs expression
//   _external_: DesignatedName
// DesignatorExpression
CARBON_PARSE_NODE_KIND_CHILD_COUNT(DesignatedName, 0)
CARBON_PARSE_NODE_KIND_CHILD_COUNT(DesignatorExpression, 2)

// A literal.
CARBON_PARSE_NODE_KIND_CHILD_COUNT(Literal, 0)

// A reference to an identifier.
CARBON_PARSE_NODE_KIND_CHILD_COUNT(NameReference, 0)

// A prefix operator:
//   _external_: expression
// PrefixOperator
CARBON_PARSE_NODE_KIND_CHILD_COUNT(PrefixOperator, 1)

// An infix operator:
//   _external_: lhs expression
//   _external_: rhs expression
// InfixOperator
CARBON_PARSE_NODE_KIND_CHILD_COUNT(InfixOperator, 2)

// A postfix operator:
//   _external_: expression
// PostfixOperator
CARBON_PARSE_NODE_KIND_CHILD_COUNT(PostfixOperator, 1)

// Struct literals, such as `{.a = 0}`:
//   StructLiteralOrStructTypeLiteralStart
//       _external_: DesignatedName
//     StructFieldDesignator
//     _external_: expression
//   StructFieldValue
//   StructComma
// StructLiteral
//
//
// Struct type literals, such as `{.a: i32}`:
//       _external_: DesignatedName
//     StructFieldDesignator
//     _external_: type expression
//   StructFieldType
//   StructComma
// StructTypeLiteral
//
// Elements (StructFieldValue and StructFieldType, respectively) and StructComma
// may repeat with StructComma as a separator.
//
// When a valid StructFieldType or StructFieldValue cannot be formed, elements
// may be replaced by StructFieldUnknown, which may have a preceding sibling
// StructFieldDesignator if one was successfully parsed.
CARBON_PARSE_NODE_KIND_CHILD_COUNT(StructLiteralOrStructTypeLiteralStart, 0)
CARBON_PARSE_NODE_KIND_CHILD_COUNT(StructFieldDesignator, 1)
CARBON_PARSE_NODE_KIND_CHILD_COUNT(StructFieldValue, 2)
CARBON_PARSE_NODE_KIND_CHILD_COUNT(StructFieldType, 2)
CARBON_PARSE_NODE_KIND_CHILD_COUNT(StructFieldUnknown, 0)
CARBON_PARSE_NODE_KIND_CHILD_COUNT(StructComma, 0)
CARBON_PARSE_NODE_KIND_BRACKET(StructLiteral,
                               StructLiteralOrStructTypeLiteralStart)
CARBON_PARSE_NODE_KIND_BRACKET(StructTypeLiteral,
                               StructLiteralOrStructTypeLiteralStart)

// `interface`:
//   _external_: DeclaredName
//     InterfaceBodyStart
//     _external_: statements
//   InterfaceBodyEnd
// InterfaceDefinition
CARBON_PARSE_NODE_KIND_CHILD_COUNT(InterfaceBodyStart, 0)
CARBON_PARSE_NODE_KIND_BRACKET(InterfaceBody, InterfaceBodyStart)
CARBON_PARSE_NODE_KIND_BRACKET(InterfaceDefinition, DeclaredName)

// A pattern binding for `self` deduced parameter:
//   `self`
//   _external_: type expression
// SelfDeducedParameter
CARBON_PARSE_NODE_KIND_CHILD_COUNT(SelfDeducedParameter, 0)

// A pattern binding for `addr self` deduced parameter:
//   `addr self`
//   _external_: type expression
// SelfDeducedParameter
// CARBON_PARSE_NODE_KIND_CHILD_COUNT(SelfDeducedParameterAddress, 1)
CARBON_PARSE_NODE_KIND_CHILD_COUNT(Address, 1)
CARBON_PARSE_NODE_KIND_CHILD_COUNT(SelfType, 0)

// Deduced parameters, such as `[self: Self]`:
//   DeducedParameterListStart
//   _external_: Address or PatternBinding
// DeducedParameterList
CARBON_PARSE_NODE_KIND_CHILD_COUNT(DeducedParameterListStart, 0)
CARBON_PARSE_NODE_KIND_BRACKET(DeducedParameterList, DeducedParameterListStart)

#undef CARBON_PARSE_NODE_KIND
#undef CARBON_PARSE_NODE_KIND_BRACKET
#undef CARBON_PARSE_NODE_KIND_CHILD_COUNT