1 //===- ModuleLoader.h - Module Loader 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 defines the ModuleLoader interface, which is responsible for
10 //  loading named modules.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_CLANG_LEX_MODULELOADER_H
15 #define LLVM_CLANG_LEX_MODULELOADER_H
16 
17 #include "clang/Basic/LLVM.h"
18 #include "clang/Basic/Module.h"
19 #include "clang/Basic/SourceLocation.h"
20 #include "llvm/ADT/ArrayRef.h"
21 #include "llvm/ADT/PointerIntPair.h"
22 #include "llvm/ADT/StringRef.h"
23 #include <utility>
24 
25 namespace clang {
26 
27 class GlobalModuleIndex;
28 class IdentifierInfo;
29 
30 /// A sequence of identifier/location pairs used to describe a particular
31 /// module or submodule, e.g., std.vector.
32 using ModuleIdPath = ArrayRef<std::pair<IdentifierInfo *, SourceLocation>>;
33 
34 /// Describes the result of attempting to load a module.
35 class ModuleLoadResult {
36 public:
37   enum LoadResultKind {
38     // We either succeeded or failed to load the named module.
39     Normal,
40 
41     // The module exists, but does not actually contain the named submodule.
42     // This should only happen if the named submodule was inferred from an
43     // umbrella directory, but not actually part of the umbrella header.
44     MissingExpected,
45 
46     // The module exists but cannot be imported due to a configuration mismatch.
47     ConfigMismatch,
48   };
49   llvm::PointerIntPair<Module *, 2, LoadResultKind> Storage;
50 
51   ModuleLoadResult() = default;
52   ModuleLoadResult(Module *M) : Storage(M, Normal) {}
53   ModuleLoadResult(LoadResultKind Kind) : Storage(nullptr, Kind) {}
54 
55   operator Module *() const { return Storage.getPointer(); }
56 
57   /// Determines whether this is a normal return, whether or not loading the
58   /// module was successful.
59   bool isNormal() const { return Storage.getInt() == Normal; }
60 
61   /// Determines whether the module, which failed to load, was
62   /// actually a submodule that we expected to see (based on implying the
63   /// submodule from header structure), but didn't materialize in the actual
64   /// module.
65   bool isMissingExpected() const { return Storage.getInt() == MissingExpected; }
66 
67   /// Determines whether the module failed to load due to a configuration
68   /// mismatch with an explicitly-named .pcm file from the command line.
69   bool isConfigMismatch() const { return Storage.getInt() == ConfigMismatch; }
70 };
71 
72 /// Abstract interface for a module loader.
73 ///
74 /// This abstract interface describes a module loader, which is responsible
75 /// for resolving a module name (e.g., "std") to an actual module file, and
76 /// then loading that module.
77 class ModuleLoader {
78   // Building a module if true.
79   bool BuildingModule;
80 
81 public:
82   explicit ModuleLoader(bool BuildingModule = false)
83       : BuildingModule(BuildingModule) {}
84 
85   virtual ~ModuleLoader();
86 
87   /// Returns true if this instance is building a module.
88   bool buildingModule() const {
89     return BuildingModule;
90   }
91 
92   /// Flag indicating whether this instance is building a module.
93   void setBuildingModule(bool BuildingModuleFlag) {
94     BuildingModule = BuildingModuleFlag;
95   }
96 
97   /// Attempt to load the given module.
98   ///
99   /// This routine attempts to load the module described by the given
100   /// parameters.  If there is a module cache, this may implicitly compile the
101   /// module before loading it.
102   ///
103   /// \param ImportLoc The location of the 'import' keyword.
104   ///
105   /// \param Path The identifiers (and their locations) of the module
106   /// "path", e.g., "std.vector" would be split into "std" and "vector".
107   ///
108   /// \param Visibility The visibility provided for the names in the loaded
109   /// module.
110   ///
111   /// \param IsInclusionDirective Indicates that this module is being loaded
112   /// implicitly, due to the presence of an inclusion directive. Otherwise,
113   /// it is being loaded due to an import declaration.
114   ///
115   /// \returns If successful, returns the loaded module. Otherwise, returns
116   /// NULL to indicate that the module could not be loaded.
117   virtual ModuleLoadResult loadModule(SourceLocation ImportLoc,
118                                       ModuleIdPath Path,
119                                       Module::NameVisibilityKind Visibility,
120                                       bool IsInclusionDirective) = 0;
121 
122   /// Attempt to create the given module from the specified source buffer.
123   /// Does not load the module or make any submodule visible; for that, use
124   /// loadModule and makeModuleVisible.
125   ///
126   /// \param Loc The location at which to create the module.
127   /// \param ModuleName The name of the module to create.
128   /// \param Source The source of the module: a (preprocessed) module map.
129   virtual void createModuleFromSource(SourceLocation Loc, StringRef ModuleName,
130                                       StringRef Source) = 0;
131 
132   /// Make the given module visible.
133   virtual void makeModuleVisible(Module *Mod,
134                                  Module::NameVisibilityKind Visibility,
135                                  SourceLocation ImportLoc) = 0;
136 
137   /// Load, create, or return global module.
138   /// This function returns an existing global module index, if one
139   /// had already been loaded or created, or loads one if it
140   /// exists, or creates one if it doesn't exist.
141   /// Also, importantly, if the index doesn't cover all the modules
142   /// in the module map, it will be update to do so here, because
143   /// of its use in searching for needed module imports and
144   /// associated fixit messages.
145   /// \param TriggerLoc The location for what triggered the load.
146   /// \returns Returns null if load failed.
147   virtual GlobalModuleIndex *loadGlobalModuleIndex(
148                                                 SourceLocation TriggerLoc) = 0;
149 
150   /// Check global module index for missing imports.
151   /// \param Name The symbol name to look for.
152   /// \param TriggerLoc The location for what triggered the load.
153   /// \returns Returns true if any modules with that symbol found.
154   virtual bool lookupMissingImports(StringRef Name,
155                                     SourceLocation TriggerLoc) = 0;
156 
157   bool HadFatalFailure = false;
158 };
159 
160 /// A module loader that doesn't know how to create or load modules.
161 class TrivialModuleLoader : public ModuleLoader {
162 public:
163   ModuleLoadResult loadModule(SourceLocation ImportLoc, ModuleIdPath Path,
164                               Module::NameVisibilityKind Visibility,
165                               bool IsInclusionDirective) override {
166     return {};
167   }
168 
169   void createModuleFromSource(SourceLocation ImportLoc, StringRef ModuleName,
170                               StringRef Source) override {}
171 
172   void makeModuleVisible(Module *Mod, Module::NameVisibilityKind Visibility,
173                          SourceLocation ImportLoc) override {}
174 
175   GlobalModuleIndex *loadGlobalModuleIndex(SourceLocation TriggerLoc) override {
176     return nullptr;
177   }
178 
179   bool lookupMissingImports(StringRef Name,
180                             SourceLocation TriggerLoc) override {
181     return false;
182   }
183 };
184 
185 } // namespace clang
186 
187 #endif // LLVM_CLANG_LEX_MODULELOADER_H
188