ExternalASTMerger.h source code [clang_source_code/include/clang/AST/ExternalASTMerger.h]

1	//===--- ExternalASTMerger.h - Merging External AST Interface ---- C++ --===//
2	//
3	// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4	// See https://llvm.org/LICENSE.txt for license information.
5	// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6	//
7	//===----------------------------------------------------------------------===//
8	//
9	// This file declares the ExternalASTMerger, which vends a combination of ASTs
10	// from several different ASTContext/FileManager pairs
11	//
12	//===----------------------------------------------------------------------===//
13	#ifndef LLVM_CLANG_AST_EXTERNALASTMERGER_H
14	#define LLVM_CLANG_AST_EXTERNALASTMERGER_H
15
16	#include "clang/AST/ASTImporter.h"
17	#include "clang/AST/ExternalASTSource.h"
18	#include "llvm/Support/raw_ostream.h"
19
20	namespace clang {
21
22	/// ExternalASTSource implementation that merges information from several
23	/// ASTContexts.
24	///
25	/// ExtermalASTMerger maintains a vector of ASTImporters that it uses to import
26	/// (potentially incomplete) Decls and DeclContexts from the source ASTContexts
27	/// in response to ExternalASTSource API calls.
28	///
29	/// When lookup occurs in the resulting imported DeclContexts, the original
30	/// DeclContexts need to be queried. Roughly, there are three cases here:
31	///
32	/// - The DeclContext of origin can be found by simple name lookup. In this
33	/// case, no additional state is required.
34	///
35	/// - The DeclContext of origin is different from what would be found by name
36	/// lookup. In this case, Origins contains an entry overriding lookup and
37	/// specifying the correct pair of DeclContext/ASTContext.
38	///
39	/// - The DeclContext of origin was determined by another ExterenalASTMerger.
40	/// (This is possible when the source ASTContext for one of the Importers has
41	/// its own ExternalASTMerger). The origin must be properly forwarded in this
42	/// case.
43	///
44	/// ExternalASTMerger's job is to maintain the data structures necessary to
45	/// allow this. The data structures themselves can be extracted (read-only) and
46	/// copied for re-use.
47	class ExternalASTMerger : public ExternalASTSource {
48	public:
49	/// A single origin for a DeclContext. Unlike Decls, DeclContexts do
50	/// not allow their containing ASTContext to be determined in all cases.
51	struct DCOrigin {
52	DeclContext *DC;
53	ASTContext *AST;
54	};
55
56	typedef std::map<const DeclContext *, DCOrigin> OriginMap;
57	typedef std::vector<std::unique_ptr<ASTImporter>> ImporterVector;
58	private:
59	/// One importer exists for each source.
60	ImporterVector Importers;
61	/// Overrides in case name lookup would return nothing or would return
62	/// the wrong thing.
63	OriginMap Origins;
64	/// The installed log stream.
65	llvm::raw_ostream *LogStream;
66
67	public:
68	/// The target for an ExternalASTMerger.
69	///
70	/// ASTImporters require both ASTContext and FileManager to be able to
71	/// import SourceLocations properly.
72	struct ImporterTarget {
73	ASTContext &AST;
74	FileManager &FM;
75	};
76	/// A source for an ExternalASTMerger.
77	///
78	/// ASTImporters require both ASTContext and FileManager to be able to
79	/// import SourceLocations properly. Additionally, when import occurs for
80	/// a DeclContext whose origin has been overridden, then this
81	/// ExternalASTMerger must be able to determine that.
82	struct ImporterSource {
83	ASTContext &AST;
84	FileManager &FM;
85	const OriginMap &OM;
86	};
87
88	private:
89	/// The target for this ExtenralASTMerger.
90	ImporterTarget Target;
91
92	public:
93	ExternalASTMerger(const ImporterTarget &Target,
94	llvm::ArrayRef<ImporterSource> Sources);
95
96	/// Add a set of ASTContexts as possible origins.
97	///
98	/// Usually the set will be initialized in the constructor, but long-lived
99	/// ExternalASTMergers may need to import from new sources (for example,
100	/// newly-parsed source files).
101	///
102	/// Ensures that Importers does not gain duplicate entries as a result.
103	void AddSources(llvm::ArrayRef<ImporterSource> Sources);
104
105	/// Remove a set of ASTContexts as possible origins.
106	///
107	/// Sometimes an origin goes away (for example, if a source file gets
108	/// superseded by a newer version).
109	///
110	/// The caller is responsible for ensuring that this doesn't leave
111	/// DeclContexts that can't be completed.
112	void RemoveSources(llvm::ArrayRef<ImporterSource> Sources);
113
114	/// Implementation of the ExternalASTSource API.
115	bool FindExternalVisibleDeclsByName(const DeclContext *DC,
116	DeclarationName Name) override;
117
118	/// Implementation of the ExternalASTSource API.
119	void
120	FindExternalLexicalDecls(const DeclContext *DC,
121	llvm::function_ref<bool(Decl::Kind)> IsKindWeWant,
122	SmallVectorImpl<Decl *> &Result) override;
123
124	/// Implementation of the ExternalASTSource API.
125	void CompleteType(TagDecl *Tag) override;
126
127	/// Implementation of the ExternalASTSource API.
128	void CompleteType(ObjCInterfaceDecl *Interface) override;
129
130	/// Returns true if DC can be found in any source AST context.
131	bool CanComplete(DeclContext *DC);
132
133	/// Records an origin in Origins only if name lookup would find
134	/// something different or nothing at all.
135	void MaybeRecordOrigin(const DeclContext *ToDC, DCOrigin Origin);
136
137	/// Regardless of any checks, override the Origin for a DeclContext.
138	void ForceRecordOrigin(const DeclContext *ToDC, DCOrigin Origin);
139
140	/// Get a read-only view of the Origins map, for use in constructing
141	/// an ImporterSource for another ExternalASTMerger.
142	const OriginMap &GetOrigins() { return Origins; }
143
144	/// Returns true if Importers contains an ASTImporter whose source is
145	/// OriginContext.
146	bool HasImporterForOrigin(ASTContext &OriginContext);
147
148	/// Returns a reference to the ASTRImporter from Importers whose origin
149	/// is OriginContext. This allows manual import of ASTs while preserving the
150	/// OriginMap correctly.
151	ASTImporter &ImporterForOrigin(ASTContext &OriginContext);
152
153	/// Sets the current log stream.
154	void SetLogStream(llvm::raw_string_ostream &Stream) { LogStream = &Stream; }
155	private:
156	/// Records and origin in Origins.
157	void RecordOriginImpl(const DeclContext *ToDC, DCOrigin Origin,
158	ASTImporter &importer);
159
160	/// Performs an action for every DeclContext that is identified as
161	/// corresponding (either by forced origin or by name lookup) to DC.
162	template <typename CallbackType>
163	void ForEachMatchingDC(const DeclContext *DC, CallbackType Callback);
164
165	public:
166	/// Log something if there is a logging callback installed.
167	llvm::raw_ostream &logs() { return *LogStream; }
168
169	/// True if the log stream is not llvm::nulls();
170	bool LoggingEnabled() { return LogStream != &llvm::nulls(); }
171	};
172
173	} // end namespace clang
174
175	#endif
176