Abstract interface for external sources of AST nodes. More...

#include "clang/AST/ExternalASTSource.h"

Inheritance diagram for clang::ExternalASTSource:

Classes
class	Deserializing
	RAII class for safely pairing a StartedDeserializing call with FinishedDeserializing. More...
struct	MemoryBufferSizes

Public Types
enum	ExtKind { EK_Always , EK_Never , EK_ReplyHazy }

Public Member Functions
	ExternalASTSource ()=default
virtual	~ExternalASTSource ()
uint32_t	getGeneration () const
	Get the current generation of this AST source.
virtual Decl *	GetExternalDecl (GlobalDeclID ID)
	Resolve a declaration ID into a declaration, potentially building a new declaration.
virtual Selector	GetExternalSelector (uint32_t ID)
	Resolve a selector ID into a selector.
virtual uint32_t	GetNumExternalSelectors ()
	Returns the number of selectors known to the external AST source.
virtual Stmt *	GetExternalDeclStmt (uint64_t Offset)
	Resolve the offset of a statement in the decl stream into a statement.
virtual CXXCtorInitializer **	GetExternalCXXCtorInitializers (uint64_t Offset)
	Resolve the offset of a set of C++ constructor initializers in the decl stream into an array of initializers.
virtual CXXBaseSpecifier *	GetExternalCXXBaseSpecifiers (uint64_t Offset)
	Resolve the offset of a set of C++ base specifiers in the decl stream into an array of specifiers.
virtual void	updateOutOfDateIdentifier (const IdentifierInfo &II)
	Update an out-of-date identifier.
virtual bool	FindExternalVisibleDeclsByName (const DeclContext DC, DeclarationName Name, const DeclContext OriginalDC)
	Find all declarations with the given name in the given context, and add them to the context by calling SetExternalVisibleDeclsForName or SetNoExternalVisibleDeclsForName.
virtual bool	LoadExternalSpecializations (const Decl *D, bool OnlyPartial)
	Load all the external specializations for the Decl.
virtual bool	LoadExternalSpecializations (const Decl *D, ArrayRef< TemplateArgument > TemplateArgs)
	Load all the specializations for the Decl.
virtual void	completeVisibleDeclsMap (const DeclContext *DC)
	Ensures that the table of all visible declarations inside this context is up to date.
virtual Module *	getModule (unsigned ID)
	Retrieve the module that corresponds to the given module ID.
virtual std::optional< ASTSourceDescriptor >	getSourceDescriptor (unsigned ID)
	Return a descriptor for the corresponding module, if one exists.
virtual ExtKind	hasExternalDefinitions (const Decl *D)
virtual bool	wasThisDeclarationADefinition (const FunctionDecl *FD)
	True if this function declaration was a definition before in its own module.
virtual void	FindExternalLexicalDecls (const DeclContext DC, llvm::function_ref< bool(Decl::Kind)> IsKindWeWant, SmallVectorImpl< Decl > &Result)
	Finds all declarations lexically contained within the given DeclContext, after applying an optional filter predicate.
void	FindExternalLexicalDecls (const DeclContext DC, SmallVectorImpl< Decl > &Result)
	Finds all declarations lexically contained within the given DeclContext.
virtual void	FindFileRegionDecls (FileID File, unsigned Offset, unsigned Length, SmallVectorImpl< Decl * > &Decls)
	Get the decls that are contained in a file in the Offset/Length range.
virtual void	CompleteRedeclChain (const Decl *D)
	Gives the external AST source an opportunity to complete the redeclaration chain for a declaration.
virtual void	CompleteType (TagDecl *Tag)
	Gives the external AST source an opportunity to complete an incomplete type.
virtual void	CompleteType (ObjCInterfaceDecl *Class)
	Gives the external AST source an opportunity to complete an incomplete Objective-C class.
virtual void	ReadComments ()
	Loads comment ranges.
virtual void	StartedDeserializing ()
	Notify ExternalASTSource that we started deserialization of a decl or type so until FinishedDeserializing is called there may be decls that are initializing.
virtual void	FinishedDeserializing ()
	Notify ExternalASTSource that we finished the deserialization of a decl or type.
virtual void	StartTranslationUnit (ASTConsumer *Consumer)
	Function that will be invoked when we begin parsing a new translation unit involving this external AST source.
virtual void	PrintStats ()
	Print any statistics that have been gathered regarding the external AST source.
virtual bool	layoutRecordType (const RecordDecl Record, uint64_t &Size, uint64_t &Alignment, llvm::DenseMap< const FieldDecl , uint64_t > &FieldOffsets, llvm::DenseMap< const CXXRecordDecl , CharUnits > &BaseOffsets, llvm::DenseMap< const CXXRecordDecl , CharUnits > &VirtualBaseOffsets)
	Perform layout on the given record.
MemoryBufferSizes	getMemoryBufferSizes () const
	Return the amount of memory used by memory buffers, breaking down by heap-backed versus mmap'ed memory.
virtual void	getMemoryBufferSizes (MemoryBufferSizes &sizes) const

Protected Member Functions
uint32_t	incrementGeneration (ASTContext &C)
	Increment the current generation.

Static Protected Member Functions
static DeclContextLookupResult	SetExternalVisibleDeclsForName (const DeclContext DC, DeclarationName Name, ArrayRef< NamedDecl > Decls)
static DeclContextLookupResult	SetNoExternalVisibleDeclsForName (const DeclContext *DC, DeclarationName Name)

Friends
class	ExternalSemaSource
virtual bool	isA (const void *ClassID) const
	LLVM-style RTTI.
static bool	classof (const ExternalASTSource *S)

Detailed Description

Abstract interface for external sources of AST nodes.

External AST sources provide AST nodes constructed from some external source, such as a precompiled header. External AST sources can resolve types and declarations from abstract IDs into actual type and declaration nodes, and read parts of declaration contexts.

Definition at line 63 of file ExternalASTSource.h.

Member Enumeration Documentation

◆ ExtKind

enum clang::ExternalASTSource::ExtKind

Enumerator
EK_Always
EK_Never
EK_ReplyHazy

Definition at line 191 of file ExternalASTSource.h.

Constructor & Destructor Documentation

◆ ExternalASTSource()

clang::ExternalASTSource::ExternalASTSource ( )

default

Referenced by classof(), clang::ExternalSemaSource::classof(), and clang::ExternalASTSource::Deserializing::Deserializing().

◆ ~ExternalASTSource()

ExternalASTSource::~ExternalASTSource ( )

virtualdefault

Member Function Documentation

◆ classof()

bool clang::ExternalASTSource::classof ( const ExternalASTSource * S )

inlinestatic

Definition at line 329 of file ExternalASTSource.h.

References ExternalASTSource(), and isA().

◆ CompleteRedeclChain()

void ExternalASTSource::CompleteRedeclChain ( const Decl * D )

virtual

Gives the external AST source an opportunity to complete the redeclaration chain for a declaration.

Called each time we need the most recent declaration of a declaration after the generation count is incremented.

Reimplemented in clang::ASTReader, and clang::MultiplexExternalSemaSource.

Definition at line 49 of file ExternalASTSource.cpp.

◆ CompleteType() [1/2]

void ExternalASTSource::CompleteType ( ObjCInterfaceDecl * Class )

virtual

Gives the external AST source an opportunity to complete an incomplete Objective-C class.

This routine will only be invoked if the "externally completed" bit is set on the ObjCInterfaceDecl via the function ObjCInterfaceDecl::setExternallyCompleted().

Reimplemented in clang::ExternalASTMerger, clang::HLSLExternalSemaSource, and clang::MultiplexExternalSemaSource.

Definition at line 53 of file ExternalASTSource.cpp.

References clang::Class.

◆ CompleteType() [2/2]

void ExternalASTSource::CompleteType ( TagDecl * Tag )

virtual

Gives the external AST source an opportunity to complete an incomplete type.

Reimplemented in clang::ExternalASTMerger, clang::HLSLExternalSemaSource, and clang::MultiplexExternalSemaSource.

Definition at line 51 of file ExternalASTSource.cpp.

Referenced by clang::ExternalASTMerger::CompleteType(), clang::ExternalASTMerger::CompleteType(), and clang::ASTNodeImporter::VisitRecordDecl().

◆ completeVisibleDeclsMap()

void ExternalASTSource::completeVisibleDeclsMap ( const DeclContext * DC )

virtual

Ensures that the table of all visible declarations inside this context is up to date.

The default implementation of this function is a no-op.

Reimplemented in clang::ASTReader, clang::ExternalSource, and clang::MultiplexExternalSemaSource.

Definition at line 112 of file ExternalASTSource.cpp.

Referenced by clang::DeclContext::lookups().

◆ FindExternalLexicalDecls() [1/2]

void ExternalASTSource::FindExternalLexicalDecls	(	const DeclContext *	DC,
		llvm::function_ref< bool(Decl::Kind)>	IsKindWeWant,
		SmallVectorImpl< Decl * > &	Result )

virtual

Finds all declarations lexically contained within the given DeclContext, after applying an optional filter predicate.

Parameters

IsKindWeWant a predicate function that returns true if the passed declaration kind is one we are looking for.

The default implementation of this method is a no-op.

Reimplemented in clang::ASTReader, clang::ExternalASTMerger, and clang::MultiplexExternalSemaSource.

Definition at line 114 of file ExternalASTSource.cpp.

References clang::Result.

Referenced by FindExternalLexicalDecls().

◆ FindExternalLexicalDecls() [2/2]

void clang::ExternalASTSource::FindExternalLexicalDecls	(	const DeclContext *	DC,
		SmallVectorImpl< Decl * > &	Result )

inline

Finds all declarations lexically contained within the given DeclContext.

Definition at line 213 of file ExternalASTSource.h.

References FindExternalLexicalDecls(), and clang::Result.

◆ FindExternalVisibleDeclsByName()

bool ExternalASTSource::FindExternalVisibleDeclsByName	(	const DeclContext *	DC,
		DeclarationName	Name,
		const DeclContext *	OriginalDC )

virtual

Find all declarations with the given name in the given context, and add them to the context by calling SetExternalVisibleDeclsForName or SetNoExternalVisibleDeclsForName.

Parameters

DC	The context for lookup in. `DC` should be a primary context.
Name	The name to look for.
OriginalDC	The original context for lookup. `OriginalDC` can provide more information than `DC`. e.g., The same namespace can appear in multiple module units. So we need the `OriginalDC` to tell us what the module the lookup come from.

Returns: true if any declarations might have been found, false if we definitely have no declarations with tbis name.

The default implementation of this method is a no-op returning false.

Reimplemented in clang::ASTReader, clang::ExternalASTMerger, clang::ExternalSource, and clang::MultiplexExternalSemaSource.

Definition at line 97 of file ExternalASTSource.cpp.

◆ FindFileRegionDecls()

void ExternalASTSource::FindFileRegionDecls	(	FileID	File,
		unsigned	Offset,
		unsigned	Length,
		SmallVectorImpl< Decl * > &	Decls )

virtual

Get the decls that are contained in a file in the Offset/Length range.

Length can be 0 to indicate a point at Offset instead of a range.

Reimplemented in clang::ASTReader, and clang::MultiplexExternalSemaSource.

Definition at line 45 of file ExternalASTSource.cpp.

References clang::File.

◆ FinishedDeserializing()

void ExternalASTSource::FinishedDeserializing ( )

virtual

Notify ExternalASTSource that we finished the deserialization of a decl or type.

Must be paired with StartedDeserializing.

The default implementation of this method is a no-op.

Reimplemented in clang::ASTReader, and clang::MultiplexExternalSemaSource.

Definition at line 59 of file ExternalASTSource.cpp.

◆ GetExternalCXXBaseSpecifiers()

CXXBaseSpecifier * ExternalASTSource::GetExternalCXXBaseSpecifiers ( uint64_t Offset )

virtual

Resolve the offset of a set of C++ base specifiers in the decl stream into an array of specifiers.

The default implementation of this method is a no-op.

Reimplemented in clang::ASTReader, and clang::MultiplexExternalSemaSource.

Definition at line 93 of file ExternalASTSource.cpp.

◆ GetExternalCXXCtorInitializers()

CXXCtorInitializer ** ExternalASTSource::GetExternalCXXCtorInitializers ( uint64_t Offset )

virtual

Resolve the offset of a set of C++ constructor initializers in the decl stream into an array of initializers.

The default implementation of this method is a no-op.

Reimplemented in clang::ASTReader, and clang::MultiplexExternalSemaSource.

Definition at line 88 of file ExternalASTSource.cpp.

◆ GetExternalDecl()

Decl * ExternalASTSource::GetExternalDecl ( GlobalDeclID ID )

virtual

Resolve a declaration ID into a declaration, potentially building a new declaration.

This method only needs to be implemented if the AST source ever passes back decl sets as VisibleDeclaration objects.

The default implementation of this method is a no-op.

Reimplemented in clang::ASTReader, and clang::MultiplexExternalSemaSource.

Definition at line 73 of file ExternalASTSource.cpp.

◆ GetExternalDeclStmt()

Stmt * ExternalASTSource::GetExternalDeclStmt ( uint64_t Offset )

virtual

Resolve the offset of a statement in the decl stream into a statement.

This operation is meant to be used via a LazyOffsetPtr. It only needs to be implemented if the AST source uses methods like FunctionDecl::setLazyBody when building decls.

The default implementation of this method is a no-op.

Reimplemented in clang::ASTReader, and clang::MultiplexExternalSemaSource.

Definition at line 83 of file ExternalASTSource.cpp.

◆ GetExternalSelector()

Selector ExternalASTSource::GetExternalSelector ( uint32_t ID )

virtual

Resolve a selector ID into a selector.

This operation only needs to be implemented if the AST source returns non-zero for GetNumKnownSelectors().

The default implementation of this method is a no-op.

Reimplemented in clang::ASTReader, and clang::MultiplexExternalSemaSource.

Definition at line 75 of file ExternalASTSource.cpp.

Referenced by AddClassMessageCompletions().

◆ getGeneration()

uint32_t clang::ExternalASTSource::getGeneration ( ) const

inline

Get the current generation of this AST source.

This number is incremented each time the AST source lazily extends an existing entity.

Definition at line 96 of file ExternalASTSource.h.

Referenced by clang::ASTReader::markIdentifierUpToDate(), and clang::ASTReader::ReadMethodPool().

◆ getMemoryBufferSizes() [1/2]

MemoryBufferSizes clang::ExternalASTSource::getMemoryBufferSizes ( ) const

inline

Return the amount of memory used by memory buffers, breaking down by heap-backed versus mmap'ed memory.

Definition at line 318 of file ExternalASTSource.h.

References getMemoryBufferSizes().

Referenced by getMemoryBufferSizes(), and clang::MultiplexExternalSemaSource::getMemoryBufferSizes().

◆ getMemoryBufferSizes() [2/2]

void ExternalASTSource::getMemoryBufferSizes ( MemoryBufferSizes & sizes ) const

virtual

Reimplemented in clang::ASTReader, and clang::MultiplexExternalSemaSource.

Definition at line 118 of file ExternalASTSource.cpp.

◆ getModule()

virtual Module * clang::ExternalASTSource::getModule ( unsigned ID )

inlinevirtual

Retrieve the module that corresponds to the given module ID.

Reimplemented in clang::ASTReader, and clang::MultiplexExternalSemaSource.

Definition at line 186 of file ExternalASTSource.h.

◆ GetNumExternalSelectors()

uint32_t ExternalASTSource::GetNumExternalSelectors ( )

virtual

Returns the number of selectors known to the external AST source.

The default implementation of this method is a no-op.

Reimplemented in clang::ASTReader, and clang::MultiplexExternalSemaSource.

Definition at line 79 of file ExternalASTSource.cpp.

Referenced by AddClassMessageCompletions().

◆ getSourceDescriptor()

std::optional< ASTSourceDescriptor > ExternalASTSource::getSourceDescriptor ( unsigned ID )

virtual

Return a descriptor for the corresponding module, if one exists.

Reimplemented in clang::ASTReader.

Definition at line 32 of file ExternalASTSource.cpp.

◆ hasExternalDefinitions()

ExternalASTSource::ExtKind ExternalASTSource::hasExternalDefinitions ( const Decl * D )

virtual

Reimplemented in clang::ASTReader, and clang::MultiplexExternalSemaSource.

Definition at line 37 of file ExternalASTSource.cpp.

References EK_ReplyHazy.

Referenced by clang::Decl::shouldEmitInExternalSource().

◆ incrementGeneration()

uint32_t ExternalASTSource::incrementGeneration ( ASTContext & C )

protected

Increment the current generation.

Definition at line 120 of file ExternalASTSource.cpp.

References clang::C.

Referenced by clang::ASTReader::ReadAST().

◆ isA()

virtual bool clang::ExternalASTSource::isA ( const void * ClassID ) const

inlinevirtual

LLVM-style RTTI.

Reimplemented in clang::ExternalSemaSource, and clang::MultiplexExternalSemaSource.

Definition at line 328 of file ExternalASTSource.h.

Referenced by classof(), clang::ExternalSemaSource::classof(), clang::MultiplexExternalSemaSource::classof(), and clang::ExternalSemaSource::isA().

◆ layoutRecordType()

bool ExternalASTSource::layoutRecordType	(	const RecordDecl *	Record,
		uint64_t &	Size,
		uint64_t &	Alignment,
		llvm::DenseMap< const FieldDecl *, uint64_t > &	FieldOffsets,
		llvm::DenseMap< const CXXRecordDecl *, CharUnits > &	BaseOffsets,
		llvm::DenseMap< const CXXRecordDecl *, CharUnits > &	VirtualBaseOffsets )

virtual

Perform layout on the given record.

This routine allows the external AST source to provide an specific layout for a record, overriding the layout that would normally be constructed. It is intended for clients who receive specific layout details rather than source code (such as LLDB). The client is expected to fill in the field offsets, base offsets, virtual base offsets, and complete object size.

Parameters

Record	The record whose layout is being requested.
Size	The final size of the record, in bits.
Alignment	The final alignment of the record, in bits.
FieldOffsets	The offset of each of the fields within the record, expressed in bits. All of the fields must be provided with offsets.
BaseOffsets	The offset of each of the direct, non-virtual base classes. If any bases are not given offsets, the bases will be laid out according to the ABI.
VirtualBaseOffsets	The offset of each of the virtual base classes (either direct or not). If any bases are not given offsets, the bases will be laid out according to the ABI.

Returns: true if the record layout was provided, false otherwise.

Reimplemented in clang::LayoutOverrideSource, and clang::MultiplexExternalSemaSource.

Definition at line 65 of file ExternalASTSource.cpp.

◆ LoadExternalSpecializations() [1/2]

bool ExternalASTSource::LoadExternalSpecializations	(	const Decl *	D,
		ArrayRef< TemplateArgument >	TemplateArgs )

virtual

Load all the specializations for the Decl.

Parameters

D	with the same template args specified by
TemplateArgs.

Return true if any new specializations get loaded. Return false otherwise.

Reimplemented in clang::ASTReader, and clang::MultiplexExternalSemaSource.

Definition at line 107 of file ExternalASTSource.cpp.

◆ LoadExternalSpecializations() [2/2]

bool ExternalASTSource::LoadExternalSpecializations	(	const Decl *	D,
		bool	OnlyPartial )

virtual

Load all the external specializations for the Decl.

Parameters

D	if
OnlyPartial	is false. Otherwise, load all the external partial specializations for the
D.

Return true if any new specializations get loaded. Return false otherwise.

Reimplemented in clang::ASTReader, and clang::MultiplexExternalSemaSource.

Definition at line 103 of file ExternalASTSource.cpp.

Referenced by clang::RedeclarableTemplateDecl::loadLazySpecializationsImpl(), and clang::RedeclarableTemplateDecl::loadLazySpecializationsImpl().

◆ PrintStats()

void ExternalASTSource::PrintStats ( )

virtual

Print any statistics that have been gathered regarding the external AST source.

The default implementation of this method is a no-op.

Reimplemented in clang::ASTReader, and clang::MultiplexExternalSemaSource.

Definition at line 63 of file ExternalASTSource.cpp.

◆ ReadComments()

void ExternalASTSource::ReadComments ( )

virtual

Loads comment ranges.

Reimplemented in clang::ASTReader, and clang::MultiplexExternalSemaSource.

Definition at line 55 of file ExternalASTSource.cpp.

◆ SetExternalVisibleDeclsForName()

DeclContext::lookup_result ExternalASTSource::SetExternalVisibleDeclsForName	(	const DeclContext *	DC,
		DeclarationName	Name,
		ArrayRef< NamedDecl * >	Decls )

staticprotected

Definition at line 1634 of file DeclBase.cpp.

References clang::StoredDeclsList::getLookupResult(), clang::DeclContext::getParentASTContext(), clang::DeclContext::LookupPtr, and clang::StoredDeclsList::replaceExternalDecls().

Referenced by clang::ASTReader::completeVisibleDeclsMap(), clang::ExternalSource::completeVisibleDeclsMap(), clang::ASTReader::FindExternalVisibleDeclsByName(), and clang::ExternalASTMerger::FindExternalVisibleDeclsByName().

◆ SetNoExternalVisibleDeclsForName()

DeclContext::lookup_result ExternalASTSource::SetNoExternalVisibleDeclsForName	(	const DeclContext *	DC,
		DeclarationName	Name )

staticprotected

Definition at line 1619 of file DeclBase.cpp.

References clang::DeclContext::getParentASTContext(), and clang::DeclContext::LookupPtr.

◆ StartedDeserializing()

void ExternalASTSource::StartedDeserializing ( )

virtual

Notify ExternalASTSource that we started deserialization of a decl or type so until FinishedDeserializing is called there may be decls that are initializing.

Must be paired with FinishedDeserializing.

The default implementation of this method is a no-op.

Reimplemented in clang::ASTReader, and clang::MultiplexExternalSemaSource.

Definition at line 57 of file ExternalASTSource.cpp.

◆ StartTranslationUnit()

void ExternalASTSource::StartTranslationUnit ( ASTConsumer * Consumer )

virtual

Function that will be invoked when we begin parsing a new translation unit involving this external AST source.

The default implementation of this method is a no-op.

Reimplemented in clang::ASTReader, and clang::MultiplexExternalSemaSource.

Definition at line 61 of file ExternalASTSource.cpp.

◆ updateOutOfDateIdentifier()

virtual void clang::ExternalASTSource::updateOutOfDateIdentifier ( const IdentifierInfo & II )

inlinevirtual

Update an out-of-date identifier.

Reimplemented in clang::ASTReader.

Definition at line 144 of file ExternalASTSource.h.

◆ wasThisDeclarationADefinition()

bool ExternalASTSource::wasThisDeclarationADefinition ( const FunctionDecl * FD )

virtual

True if this function declaration was a definition before in its own module.

Reimplemented in clang::ASTReader, and clang::MultiplexExternalSemaSource.

Definition at line 41 of file ExternalASTSource.cpp.

◆ ExternalSemaSource

friend class ExternalSemaSource

friend

Definition at line 64 of file ExternalASTSource.h.

References ExternalSemaSource.

Referenced by ExternalSemaSource.

The documentation for this class was generated from the following files:

include/clang/AST/ExternalASTSource.h
lib/AST/DeclBase.cpp
lib/AST/ExternalASTSource.cpp

Classes

Public Types

Public Member Functions

Protected Member Functions

Static Protected Member Functions

Friends

Detailed Description

Member Enumeration Documentation

◆ ExtKind

Constructor & Destructor Documentation

◆ ExternalASTSource()

◆ ~ExternalASTSource()

Member Function Documentation

◆ classof()

◆ CompleteRedeclChain()

◆ CompleteType() [1/2]

◆ CompleteType() [2/2]

◆ completeVisibleDeclsMap()

◆ FindExternalLexicalDecls() [1/2]

◆ FindExternalLexicalDecls() [2/2]

◆ FindExternalVisibleDeclsByName()

◆ FindFileRegionDecls()

◆ FinishedDeserializing()

◆ GetExternalCXXBaseSpecifiers()

◆ GetExternalCXXCtorInitializers()

◆ GetExternalDecl()

◆ GetExternalDeclStmt()

◆ GetExternalSelector()

◆ getGeneration()

◆ getMemoryBufferSizes() [1/2]

◆ getMemoryBufferSizes() [2/2]

◆ getModule()

◆ GetNumExternalSelectors()

◆ getSourceDescriptor()

◆ hasExternalDefinitions()

◆ incrementGeneration()

◆ isA()

◆ layoutRecordType()

◆ LoadExternalSpecializations() [1/2]

◆ LoadExternalSpecializations() [2/2]

◆ PrintStats()

◆ ReadComments()

◆ SetExternalVisibleDeclsForName()

◆ SetNoExternalVisibleDeclsForName()

◆ StartedDeserializing()

◆ StartTranslationUnit()

◆ updateOutOfDateIdentifier()

◆ wasThisDeclarationADefinition()

Friends And Related Symbol Documentation

◆ ExternalSemaSource