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//===--- ExternalASTMerger.h - Merging External AST Interface ---*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// This file declares the ExternalASTMerger, which vends a combination of ASTs
// from several different ASTContext/FileManager pairs
#include "clang/AST/ASTImporter.h"
#include "clang/AST/ExternalASTSource.h"
#include "llvm/Support/raw_ostream.h"
namespace clang {
/// ExternalASTSource implementation that merges information from several
/// ASTContexts.
/// ExtermalASTMerger maintains a vector of ASTImporters that it uses to import
/// (potentially incomplete) Decls and DeclContexts from the source ASTContexts
/// in response to ExternalASTSource API calls.
/// When lookup occurs in the resulting imported DeclContexts, the original
/// DeclContexts need to be queried. Roughly, there are three cases here:
/// - The DeclContext of origin can be found by simple name lookup. In this
/// case, no additional state is required.
/// - The DeclContext of origin is different from what would be found by name
/// lookup. In this case, Origins contains an entry overriding lookup and
/// specifying the correct pair of DeclContext/ASTContext.
/// - The DeclContext of origin was determined by another ExterenalASTMerger.
/// (This is possible when the source ASTContext for one of the Importers has
/// its own ExternalASTMerger). The origin must be properly forwarded in this
/// case.
/// ExternalASTMerger's job is to maintain the data structures necessary to
/// allow this. The data structures themselves can be extracted (read-only) and
/// copied for re-use.
class ExternalASTMerger : public ExternalASTSource {
/// A single origin for a DeclContext. Unlike Decls, DeclContexts do
/// not allow their containing ASTContext to be determined in all cases.
struct DCOrigin {
DeclContext *DC;
ASTContext *AST;
typedef std::map<const DeclContext *, DCOrigin> OriginMap;
typedef std::vector<std::unique_ptr<ASTImporter>> ImporterVector;
/// One importer exists for each source.
ImporterVector Importers;
/// Overrides in case name lookup would return nothing or would return
/// the wrong thing.
OriginMap Origins;
/// The installed log stream.
llvm::raw_ostream *LogStream;
/// The target for an ExternalASTMerger.
/// ASTImporters require both ASTContext and FileManager to be able to
/// import SourceLocations properly.
struct ImporterTarget {
ASTContext &AST;
FileManager &FM;
/// A source for an ExternalASTMerger.
/// ASTImporters require both ASTContext and FileManager to be able to
/// import SourceLocations properly. Additionally, when import occurs for
/// a DeclContext whose origin has been overridden, then this
/// ExternalASTMerger must be able to determine that.
struct ImporterSource {
ASTContext &AST;
FileManager &FM;
const OriginMap &OM;
/// The target for this ExtenralASTMerger.
ImporterTarget Target;
ExternalASTMerger(const ImporterTarget &Target,
llvm::ArrayRef<ImporterSource> Sources);
/// Add a set of ASTContexts as possible origins.
/// Usually the set will be initialized in the constructor, but long-lived
/// ExternalASTMergers may need to import from new sources (for example,
/// newly-parsed source files).
/// Ensures that Importers does not gain duplicate entries as a result.
void AddSources(llvm::ArrayRef<ImporterSource> Sources);
/// Remove a set of ASTContexts as possible origins.
/// Sometimes an origin goes away (for example, if a source file gets
/// superseded by a newer version).
/// The caller is responsible for ensuring that this doesn't leave
/// DeclContexts that can't be completed.
void RemoveSources(llvm::ArrayRef<ImporterSource> Sources);
/// Implementation of the ExternalASTSource API.
bool FindExternalVisibleDeclsByName(const DeclContext *DC,
DeclarationName Name) override;
/// Implementation of the ExternalASTSource API.
FindExternalLexicalDecls(const DeclContext *DC,
llvm::function_ref<bool(Decl::Kind)> IsKindWeWant,
SmallVectorImpl<Decl *> &Result) override;
/// Implementation of the ExternalASTSource API.
void CompleteType(TagDecl *Tag) override;
/// Implementation of the ExternalASTSource API.
void CompleteType(ObjCInterfaceDecl *Interface) override;
/// Returns true if DC can be found in any source AST context.
bool CanComplete(DeclContext *DC);
/// Records an origin in Origins only if name lookup would find
/// something different or nothing at all.
void MaybeRecordOrigin(const DeclContext *ToDC, DCOrigin Origin);
/// Regardless of any checks, override the Origin for a DeclContext.
void ForceRecordOrigin(const DeclContext *ToDC, DCOrigin Origin);
/// Get a read-only view of the Origins map, for use in constructing
/// an ImporterSource for another ExternalASTMerger.
const OriginMap &GetOrigins() { return Origins; }
/// Returns true if Importers contains an ASTImporter whose source is
/// OriginContext.
bool HasImporterForOrigin(ASTContext &OriginContext);
/// Returns a reference to the ASTRImporter from Importers whose origin
/// is OriginContext. This allows manual import of ASTs while preserving the
/// OriginMap correctly.
ASTImporter &ImporterForOrigin(ASTContext &OriginContext);
/// Sets the current log stream.
void SetLogStream(llvm::raw_string_ostream &Stream) { LogStream = &Stream; }
/// Records and origin in Origins.
void RecordOriginImpl(const DeclContext *ToDC, DCOrigin Origin,
ASTImporter &importer);
/// Performs an action for every DeclContext that is identified as
/// corresponding (either by forced origin or by name lookup) to DC.
template <typename CallbackType>
void ForEachMatchingDC(const DeclContext *DC, CallbackType Callback);
/// Log something if there is a logging callback installed.
llvm::raw_ostream &logs() { return *LogStream; }
/// True if the log stream is not llvm::nulls();
bool LoggingEnabled() { return LogStream != &llvm::nulls(); }
} // end namespace clang