SwiftSyntax

Overview

SwiftSyntax is a source accurate tree representation of Swift source code. It allows Swift tools to parse, inspect, generate, and transform Swift source code.

Articles

• Working with SwiftSyntax

  Learn the basics of working with Swift source code with the SwiftSyntax library.

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• Updating a Macro to a New Major swift-syntax Version

  Guidance of how to version macros when a new major swift-syntax version is released.

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• Glossary

  Glossary of terms and abbreviations used in SwiftSyntax

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Tutorials

• Introduction to SwiftSyntax

  SwiftSyntax provides the foundation for tools that inspect, manipulate, and transform Swift source code.

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Contributing

These articles are intended for developers wishing to contribute to SwiftSyntax

• Changing Syntax Nodes

  Discover the steps necessary to add, remove, and update syntax nodes

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• When to use protocols in SwiftSyntax

  Learn when to use protocols value types like ExprSyntax over protocols like ExprSyntaxProtocol.

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• @_spi attribute

  Learn when SwiftSyntax exposes declaration annotated as @_spi.

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• Language Features Usable in swift-syntax

  Defines which language features the swift-syntax package can use.

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Syntax

• struct Syntax

  A Syntax node represents a tree of nodes with tokens at the leaves. Each node has accessors for its known children, and allows efficient iteration over the children through its children property.

• protocol SyntaxCollection

Trivia

• struct Trivia

  Trivia represent pieces of the source code that are not relevant to represent its semantic structure.

• enum TriviaPiece

  A contiguous stretch of a single kind of trivia. The constituent part of a Trivia collection.

• enum TriviaPosition

Tokens

• struct TokenSyntax

  A Syntax node representing a single token.

• enum TokenKind

  Enumerates the kinds of tokens in the Swift language.

• struct TokenSequence

  Sequence of tokens that are part of the provided Syntax node.

• enum SourcePresence

  An indicator of whether a Syntax node was found or written in the source.

Syntax Visitors

• class SyntaxVisitor
• class SyntaxAnyVisitor

  A SyntaxVisitor that can visit the nodes as generic Syntax values.

• class SyntaxRewriter

  / Automatically generated by generate-swift-syntax / Do not edit directly!

• enum SyntaxTreeViewMode

  Specifies how missing and unexpected nodes should be handled when traversing a syntax tree.

• enum SyntaxVisitorContinueKind

  The enum describes how the SyntaxVisitor should continue after visiting the current node.

• struct ReversedTokenSequence

  Reverse sequence of tokens that are part of the provided Syntax node.

Declarations

• struct DeclSyntax
• protocol DeclSyntaxProtocol

  Protocol to which all DeclSyntax nodes conform.

• struct MissingDeclSyntax

  In case the source code is missing a declaration, this node stands in place of the missing declaration.

• struct AccessorDeclSyntax
• struct ActorDeclSyntax
• struct AssociatedTypeDeclSyntax

  An associatedtype declaration

• struct ClassDeclSyntax

  A class declaration

• struct DeinitializerDeclSyntax

  A deint declaration

• struct EditorPlaceholderDeclSyntax

  An editor placeholder, e.g. <#declaration#> that is used in a position that expects a declaration.

• struct EnumCaseDeclSyntax

  A case declaration of a Swift enum. It can have 1 or more EnumCaseElements inside, each declaring a different case of the enum.

• struct EnumDeclSyntax

  A Swift enum declaration.

• struct ExtensionDeclSyntax
• struct FunctionDeclSyntax
• struct IfConfigDeclSyntax
• struct ImportDeclSyntax

  An import declaration

• struct InitializerDeclSyntax

  An init declaration

• struct MacroDeclSyntax
• struct MacroExpansionDeclSyntax
• struct OperatorDeclSyntax

  A Swift operator declaration.

• struct PoundSourceLocationSyntax
• struct PrecedenceGroupDeclSyntax

  A Swift precedencegroup declaration.

• struct ProtocolDeclSyntax

  A protocol declaration

• struct StructDeclSyntax

  A struct declaration

• struct SubscriptDeclSyntax
• struct TypeAliasDeclSyntax
• struct VariableDeclSyntax

  Declaration of one or more variables

Expressions

• struct ExprSyntax
• protocol ExprSyntaxProtocol

  Protocol to which all ExprSyntax nodes conform.

• struct MissingExprSyntax

  In case the source code is missing an expression, this node stands in place of the missing expression.

• struct ArrayExprSyntax
• struct ArrowExprSyntax
• struct AsExprSyntax
• struct AssignmentExprSyntax
• struct AwaitExprSyntax
• struct BinaryOperatorExprSyntax
• struct BooleanLiteralExprSyntax
• struct BorrowExprSyntax
• struct CanImportExprSyntax
• struct CanImportVersionInfoSyntax
• struct ClosureExprSyntax
• struct ConsumeExprSyntax
• struct CopyExprSyntax
• struct DeclReferenceExprSyntax
• struct DictionaryExprSyntax
• struct DiscardAssignmentExprSyntax
• struct EditorPlaceholderExprSyntax
• struct FloatLiteralExprSyntax
• struct ForceUnwrapExprSyntax
• struct FunctionCallExprSyntax
• struct GenericSpecializationExprSyntax
• struct IfExprSyntax
• struct InOutExprSyntax
• struct InfixOperatorExprSyntax
• struct IntegerLiteralExprSyntax
• struct IsExprSyntax

  Checks if an expression is of a given type.

• struct KeyPathExprSyntax
• struct MacroExpansionExprSyntax
• struct MemberAccessExprSyntax

  An expression that access a member like a function or a property.

• struct NilLiteralExprSyntax
• struct OptionalChainingExprSyntax
• struct PackElementExprSyntax
• struct PackExpansionExprSyntax
• struct PatternExprSyntax
• struct PostfixIfConfigExprSyntax
• struct PostfixOperatorExprSyntax
• struct PrefixOperatorExprSyntax
• struct RegexLiteralExprSyntax
• struct SequenceExprSyntax
• struct SimpleStringLiteralExprSyntax

  A simple string that can’t contain string interpolation and cannot have raw string delimiters.

• struct StringLiteralExprSyntax
• struct SubscriptCallExprSyntax
• struct SuperExprSyntax
• struct SwitchExprSyntax
• struct TernaryExprSyntax
• struct TryExprSyntax
• struct TupleExprSyntax
• struct TypeExprSyntax
• struct UnresolvedAsExprSyntax
• struct UnresolvedIsExprSyntax
• struct UnresolvedTernaryExprSyntax

Patterns

• struct PatternSyntax
• protocol PatternSyntaxProtocol

  Protocol to which all PatternSyntax nodes conform.

• struct MissingPatternSyntax

  In case the source code is missing a pattern, this node stands in place of the missing pattern.

• struct ExpressionPatternSyntax
• struct IdentifierPatternSyntax
• struct IsTypePatternSyntax
• struct TuplePatternSyntax
• struct ValueBindingPatternSyntax
• struct WildcardPatternSyntax

Statements

• struct StmtSyntax
• protocol StmtSyntaxProtocol

  Protocol to which all StmtSyntax nodes conform.

• struct MissingStmtSyntax

  In case the source code is missing a statement, this node stands in place of the missing statement.

• struct BreakStmtSyntax
• struct ContinueStmtSyntax
• struct DeferStmtSyntax
• struct DiscardStmtSyntax
• struct DoStmtSyntax
• struct ExpressionStmtSyntax
• struct FallThroughStmtSyntax
• struct ForStmtSyntax
• struct GuardStmtSyntax
• struct LabeledStmtSyntax
• struct RepeatStmtSyntax
• struct ReturnStmtSyntax
• struct ThenStmtSyntax

  A statement used to indicate the produced value from an if/switch expression.

• struct ThrowStmtSyntax
• struct WhileStmtSyntax
• struct YieldStmtSyntax

Types

• struct TypeSyntax
• protocol TypeSyntaxProtocol

  Protocol to which all TypeSyntax nodes conform.

• struct MissingTypeSyntax

  In case the source code is missing a type, this node stands in place of the missing type.

• struct ArrayTypeSyntax
• struct AttributedTypeSyntax
• struct ClassRestrictionTypeSyntax
• struct CompositionTypeSyntax
• struct DictionaryTypeSyntax
• struct FunctionTypeSyntax
• struct IdentifierTypeSyntax
• struct ImplicitlyUnwrappedOptionalTypeSyntax
• struct MemberTypeSyntax
• struct MetatypeTypeSyntax
• struct NamedOpaqueReturnTypeSyntax
• struct OptionalTypeSyntax
• struct PackElementTypeSyntax
• struct PackExpansionTypeSyntax
• struct SomeOrAnyTypeSyntax
• struct SuppressedTypeSyntax
• struct TupleTypeSyntax

Collections

• struct SyntaxChildren

  Collection that contains the present child Syntax nodes of the given node.

• struct SyntaxChildrenIndex

  An index in a syntax children collection.

• struct AccessorDeclListSyntax
• struct ArrayElementListSyntax
• struct ArrayElementSyntax
• struct AttributeListSyntax

  A list of attributes that can be attached to a declaration.

• struct AttributeSyntax

  An @ attribute.

• struct AvailabilityArgumentListSyntax
• struct AvailabilityArgumentSyntax

  A single argument to an @available argument like *, iOS 10.1, or message: "This has been deprecated".

• struct CatchClauseListSyntax
• struct CatchClauseSyntax
• struct CatchItemListSyntax
• struct CatchItemSyntax
• struct ClosureCaptureListSyntax
• struct ClosureCaptureSyntax
• struct ClosureParameterListSyntax
• struct ClosureParameterSyntax
• struct ClosureShorthandParameterListSyntax
• struct ClosureShorthandParameterSyntax
• struct CodeBlockItemListSyntax
• struct CodeBlockItemSyntax

  A CodeBlockItem is any Syntax node that appears on its own line inside a CodeBlock.

• struct CompositionTypeElementListSyntax
• struct CompositionTypeElementSyntax
• struct ConditionElementListSyntax
• struct ConditionElementSyntax
• struct DeclModifierListSyntax
• struct DeclModifierSyntax
• struct DeclNameArgumentListSyntax
• struct DeclNameArgumentSyntax
• struct DesignatedTypeListSyntax
• struct DesignatedTypeSyntax
• struct DictionaryElementListSyntax
• struct DictionaryElementSyntax
• struct DifferentiabilityArgumentListSyntax
• struct DifferentiabilityArgumentSyntax

  A differentiability argument: either the “self” identifier, a function parameter name, or a function parameter index.

• struct DocumentationAttributeArgumentListSyntax

  The arguments of the ‘@_documentation’ attribute

• struct DocumentationAttributeArgumentSyntax
• struct EffectsAttributeArgumentListSyntax

  The arguments of the ‘@_effects’ attribute. These will be parsed during the SIL stage.

• struct EnumCaseElementListSyntax

  A collection of 0 or more EnumCaseElements.

• struct EnumCaseElementSyntax

  An element of an enum case, containing the name of the case and, optionally, either associated values or an assignment to a raw value.

• struct EnumCaseParameterListSyntax
• struct EnumCaseParameterSyntax
• struct ExprListSyntax

  A list of expressions connected by operators. This list is contained by a SequenceExprSyntax.

• struct FunctionParameterListSyntax
• struct FunctionParameterSyntax
• struct GenericArgumentListSyntax
• struct GenericArgumentSyntax
• struct GenericParameterListSyntax
• struct GenericParameterSyntax
• struct GenericRequirementListSyntax
• struct GenericRequirementSyntax
• struct IfConfigClauseListSyntax
• struct IfConfigClauseSyntax
• struct ImportPathComponentListSyntax
• struct ImportPathComponentSyntax
• struct InheritedTypeListSyntax
• struct InheritedTypeSyntax
• struct KeyPathComponentListSyntax
• struct KeyPathComponentSyntax
• struct LabeledExprListSyntax
• struct LabeledExprSyntax
• struct MemberBlockItemListSyntax
• struct MemberBlockItemSyntax

  A member declaration of a type consisting of a declaration and an optional semicolon;

• struct MultipleTrailingClosureElementListSyntax
• struct MultipleTrailingClosureElementSyntax
• struct ObjCSelectorPieceListSyntax
• struct ObjCSelectorPieceSyntax

  A piece of an Objective-C selector. Either consisting of just an identifier for a nullary selector, an identifier and a colon for a labeled argument or just a colon for an unlabeled argument

• struct PatternBindingListSyntax
• struct PatternBindingSyntax

  Defines variables inside a variable declaration.

• struct PlatformVersionItemListSyntax
• struct PlatformVersionItemSyntax

  A single platform/version pair in an attribute, e.g. iOS 10.1.

• struct PrecedenceGroupAttributeListSyntax
• struct PrecedenceGroupRelationSyntax

  Specify the new precedence group’s relation to existing precedence groups.

• struct PrecedenceGroupAssignmentSyntax

  Specifies the precedence of an operator when used in an operation that includes optional chaining.

• struct PrecedenceGroupAssociativitySyntax

  Specifies how a sequence of operators with the same precedence level are grouped together in the absence of grouping parentheses.

• struct PrecedenceGroupNameListSyntax
• struct PrecedenceGroupNameSyntax
• struct PrimaryAssociatedTypeListSyntax
• struct PrimaryAssociatedTypeSyntax
• struct SimpleStringLiteralSegmentListSyntax

  String literal segments that only can contain non string interpolated or extended escaped strings

• struct StringSegmentSyntax
• struct SpecializeAttributeArgumentListSyntax

  A collection of arguments for the @_specialize attribute

• struct LabeledSpecializeArgumentSyntax

  A labeled argument for the @_specialize attribute like exported: true

• struct SpecializeAvailabilityArgumentSyntax

  The availability argument for the _specialize attribute

• struct SpecializeTargetFunctionArgumentSyntax

  A labeled argument for the @_specialize attribute with a function decl value like target: myFunc(_:)

• struct GenericWhereClauseSyntax

  A where clause that places additional constraints on generic parameters like where Element: Hashable.

• struct StringLiteralSegmentListSyntax
• struct StringSegmentSyntax
• struct ExpressionSegmentSyntax
• struct SwitchCaseItemListSyntax
• struct SwitchCaseItemSyntax
• struct SwitchCaseListSyntax
• struct SwitchCaseSyntax
• struct TuplePatternElementListSyntax
• struct TuplePatternElementSyntax
• struct TupleTypeElementListSyntax
• struct TupleTypeElementSyntax
• struct UnexpectedNodesSyntax

  A collection of syntax nodes that occurred in the source code but could not be used to form a valid syntax tree.

• struct VersionComponentListSyntax
• struct VersionComponentSyntax

  An element to represent a single component in a version, like .1.

• struct YieldedExpressionListSyntax
• struct YieldedExpressionSyntax

Attributes

• struct AttributeListSyntax

  A list of attributes that can be attached to a declaration.

• struct AttributeSyntax

  An @ attribute.

• struct BackDeployedAttributeArgumentsSyntax

  A collection of arguments for the @backDeployed attribute

• struct ConventionAttributeArgumentsSyntax

  The arguments for the ‘@convention(…)’.

• struct ConventionWitnessMethodAttributeArgumentsSyntax

  The arguments for the ‘@convention(witness_method: …)’.

• struct DerivativeAttributeArgumentsSyntax

  The arguments for the ‘@derivative(of:)’ and ‘@transpose(of:)’ attributes: the ‘of:’ label, the original declaration name, and an optional differentiability parameter list.

• struct DifferentiabilityArgumentListSyntax
• struct DifferentiabilityArgumentSyntax

  A differentiability argument: either the “self” identifier, a function parameter name, or a function parameter index.

• struct DifferentiabilityArgumentsSyntax

  The differentiability arguments.

• struct DifferentiabilityWithRespectToArgumentSyntax

  A clause containing differentiability parameters.

• struct DifferentiableAttributeArgumentsSyntax

  The arguments for the @differentiable attribute: an optional differentiability kind, an optional differentiability parameter clause, and an optional ‘where’ clause.

• struct DocumentationAttributeArgumentListSyntax

  The arguments of the ‘@_documentation’ attribute

• struct DocumentationAttributeArgumentSyntax
• struct DynamicReplacementAttributeArgumentsSyntax

  The arguments for the ‘@_dynamicReplacement’ attribute

• struct EffectsAttributeArgumentListSyntax

  The arguments of the ‘@_effects’ attribute. These will be parsed during the SIL stage.

• struct ExposeAttributeArgumentsSyntax

  The arguments for the ‘@_expose’ attribute

• struct ImplementsAttributeArgumentsSyntax

  The arguments for the @_implements attribute of the form Type, methodName(arg1Label:arg2Label:)

• struct LabeledSpecializeArgumentSyntax

  A labeled argument for the @_specialize attribute like exported: true

• struct ObjCSelectorPieceListSyntax
• struct ObjCSelectorPieceSyntax

  A piece of an Objective-C selector. Either consisting of just an identifier for a nullary selector, an identifier and a colon for a labeled argument or just a colon for an unlabeled argument

• struct OpaqueReturnTypeOfAttributeArgumentsSyntax

  The arguments for the ‘@_opaqueReturnTypeOf()’.

• struct OriginallyDefinedInAttributeArgumentsSyntax

  The arguments for the ‘@_originallyDefinedIn’ attribute

• struct PlatformVersionItemListSyntax
• struct PlatformVersionItemSyntax

  A single platform/version pair in an attribute, e.g. iOS 10.1.

• struct SpecializeAttributeArgumentListSyntax

  A collection of arguments for the @_specialize attribute

• struct SpecializeAvailabilityArgumentSyntax

  The availability argument for the _specialize attribute

• struct SpecializeTargetFunctionArgumentSyntax

  A labeled argument for the @_specialize attribute with a function decl value like target: myFunc(_:)

• struct UnavailableFromAsyncAttributeArgumentsSyntax

  The arguments for the ‘@_unavailableFromAsync’ attribute

• struct UnderscorePrivateAttributeArgumentsSyntax

  The arguments for the ‘@_private’ attribute

Miscellaneous Syntax

• struct AccessorBlockSyntax
• struct AccessorEffectSpecifiersSyntax
• struct AccessorParametersSyntax
• struct AvailabilityConditionSyntax
• struct AvailabilityLabeledArgumentSyntax

  An argument to an @available attribute that consists of a label and a value, e.g. message: "This has been deprecated".

• struct ClosureCaptureClauseSyntax
• struct ClosureCaptureSpecifierSyntax
• struct ClosureParameterClauseSyntax
• struct ClosureSignatureSyntax
• struct CodeBlockSyntax
• struct ConformanceRequirementSyntax
• struct DeclModifierDetailSyntax
• struct DeclNameArgumentsSyntax
• struct DeinitializerEffectSpecifiersSyntax
• struct EnumCaseParameterClauseSyntax
• struct FunctionEffectSpecifiersSyntax
• struct FunctionParameterClauseSyntax
• struct FunctionSignatureSyntax
• struct GenericArgumentClauseSyntax
• struct GenericParameterClauseSyntax

  The parameter clause that defines the generic parameters.

• struct InheritanceClauseSyntax
• struct InitializerClauseSyntax
• struct KeyPathOptionalComponentSyntax
• struct KeyPathPropertyComponentSyntax
• struct KeyPathSubscriptComponentSyntax
• struct LayoutRequirementSyntax
• struct MatchingPatternConditionSyntax
• struct MemberBlockSyntax
• struct MissingSyntax

  In case the source code is missing a syntax node, this node stands in place of the missing node.

• struct OperatorPrecedenceAndTypesSyntax

  A clause to specify precedence group in infix operator declarations, and designated types in any operator declaration.

• struct OptionalBindingConditionSyntax
• struct PlatformVersionSyntax

  An argument to @available that restricts the availability on a certain platform to a version, e.g. iOS 10 or swift 3.4.

• struct PoundSourceLocationArgumentsSyntax
• struct PrimaryAssociatedTypeClauseSyntax
• struct ReturnClauseSyntax
• struct SameTypeRequirementSyntax
• struct SourceFileSyntax
• struct SwitchCaseLabelSyntax
• struct SwitchDefaultLabelSyntax
• struct TypeAnnotationSyntax
• struct TypeEffectSpecifiersSyntax
• struct TypeInitializerClauseSyntax
• struct VersionTupleSyntax

  A version number like 1.2.0. Only the first version component is required. There might be an arbitrary number of following components.

• struct WhereClauseSyntax
• struct YieldedExpressionsClauseSyntax

Traits

• protocol BracedSyntax

  / Automatically generated by generate-swift-syntax / Do not edit directly!

• protocol DeclGroupSyntax
• protocol EffectSpecifiersSyntax
• protocol FreestandingMacroExpansionSyntax
• protocol NamedDeclSyntax
• protocol MissingNodeSyntax

  Represents a layout node that is missing in the source file.

• protocol ParenthesizedSyntax
• protocol WithAttributesSyntax
• protocol WithCodeBlockSyntax
• protocol WithGenericParametersSyntax

  Syntax nodes that have generic parameters.

• protocol WithModifiersSyntax
• protocol WithStatementsSyntax
• protocol WithTrailingCommaSyntax

Syntax Position

• struct AbsolutePosition

  An absolute position in a source file as text - the absolute utf8Offset from the start of the file.

• struct ByteSourceRange
• struct SourceLocation

  Represents a source location in a Swift file.

• class SourceLocationConverter

  Converts AbsolutePositions of syntax nodes to SourceLocations, and vice-versa. The AbsolutePositions must be originating from nodes that are part of the same tree that was used to initialize this class.

• struct SourceRange

  Represents a half-open range in a Swift file.

• struct SourceLength

  The length a syntax node spans in the source code. From any AbsolutePosition you reach a node’s end location by adding its UTF-8 length.

Internals

• protocol SyntaxProtocol

  Provide common functionality for specialized syntax nodes. Extend this protocol to provide common functionality for all syntax nodes.

• class SyntaxArena

  A syntax arena owns the memory for all syntax nodes within it.

• enum SyntaxEnum

  Enum to exhaustively switch over all different syntax nodes.

• protocol SyntaxHashable

  Protocol that provides a common Hashable implementation for all syntax nodes

• struct SyntaxIdentifier

  Provides a stable and unique identity for Syntax nodes.