Template.h revision 162e1c1b487352434552147967c3dd296ebee2f7 
1//===------- SemaTemplate.h - C++ Templates ---------------------*- C++ -*-===/
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//===----------------------------------------------------------------------===/
8//
9//  This file provides types used in the semantic analysis of C++ templates.
10//
11//===----------------------------------------------------------------------===/
12#ifndef LLVM_CLANG_SEMA_TEMPLATE_H
13#define LLVM_CLANG_SEMA_TEMPLATE_H
14
15#include "clang/AST/DeclTemplate.h"
16#include "clang/AST/DeclVisitor.h"
17#include "llvm/ADT/SmallVector.h"
18#include <cassert>
19#include <utility>
20
21namespace clang {
22  /// \brief Data structure that captures multiple levels of template argument
23  /// lists for use in template instantiation.
24  ///
25  /// Multiple levels of template arguments occur when instantiating the
26  /// definitions of member templates. For example:
27  ///
28  /// \code
29  /// template<typename T>
30  /// struct X {
31  ///   template<T Value>
32  ///   struct Y {
33  ///     void f();
34  ///   };
35  /// };
36  /// \endcode
37  ///
38  /// When instantiating X<int>::Y<17>::f, the multi-level template argument
39  /// list will contain a template argument list (int) at depth 0 and a
40  /// template argument list (17) at depth 1.
41  class MultiLevelTemplateArgumentList {
42  public:
43    typedef std::pair<const TemplateArgument *, unsigned> ArgList;
44
45  private:
46    /// \brief The template argument lists, stored from the innermost template
47    /// argument list (first) to the outermost template argument list (last).
48    llvm::SmallVector<ArgList, 4> TemplateArgumentLists;
49
50  public:
51    /// \brief Construct an empty set of template argument lists.
52    MultiLevelTemplateArgumentList() { }
53
54    /// \brief Construct a single-level template argument list.
55    explicit
56    MultiLevelTemplateArgumentList(const TemplateArgumentList &TemplateArgs) {
57      addOuterTemplateArguments(&TemplateArgs);
58    }
59
60    /// \brief Determine the number of levels in this template argument
61    /// list.
62    unsigned getNumLevels() const { return TemplateArgumentLists.size(); }
63
64    /// \brief Retrieve the template argument at a given depth and index.
65    const TemplateArgument &operator()(unsigned Depth, unsigned Index) const {
66      assert(Depth < TemplateArgumentLists.size());
67      assert(Index < TemplateArgumentLists[getNumLevels() - Depth - 1].second);
68      return TemplateArgumentLists[getNumLevels() - Depth - 1].first[Index];
69    }
70
71    /// \brief Determine whether there is a non-NULL template argument at the
72    /// given depth and index.
73    ///
74    /// There must exist a template argument list at the given depth.
75    bool hasTemplateArgument(unsigned Depth, unsigned Index) const {
76      assert(Depth < TemplateArgumentLists.size());
77
78      if (Index >= TemplateArgumentLists[getNumLevels() - Depth - 1].second)
79        return false;
80
81      return !(*this)(Depth, Index).isNull();
82    }
83
84    /// \brief Clear out a specific template argument.
85    void setArgument(unsigned Depth, unsigned Index,
86                     TemplateArgument Arg) {
87      assert(Depth < TemplateArgumentLists.size());
88      assert(Index < TemplateArgumentLists[getNumLevels() - Depth - 1].second);
89      const_cast<TemplateArgument&>(
90                TemplateArgumentLists[getNumLevels() - Depth - 1].first[Index])
91        = Arg;
92    }
93
94    /// \brief Add a new outermost level to the multi-level template argument
95    /// list.
96    void addOuterTemplateArguments(const TemplateArgumentList *TemplateArgs) {
97      TemplateArgumentLists.push_back(ArgList(TemplateArgs->data(),
98                                              TemplateArgs->size()));
99    }
100
101    /// \brief Add a new outmost level to the multi-level template argument
102    /// list.
103    void addOuterTemplateArguments(const TemplateArgument *Args,
104                                   unsigned NumArgs) {
105      TemplateArgumentLists.push_back(ArgList(Args, NumArgs));
106    }
107
108    /// \brief Retrieve the innermost template argument list.
109    const ArgList &getInnermost() const {
110      return TemplateArgumentLists.front();
111    }
112  };
113
114  /// \brief The context in which partial ordering of function templates occurs.
115  enum TPOC {
116    /// \brief Partial ordering of function templates for a function call.
117    TPOC_Call,
118    /// \brief Partial ordering of function templates for a call to a
119    /// conversion function.
120    TPOC_Conversion,
121    /// \brief Partial ordering of function templates in other contexts, e.g.,
122    /// taking the address of a function template or matching a function
123    /// template specialization to a function template.
124    TPOC_Other
125  };
126
127  // This is lame but unavoidable in a world without forward
128  // declarations of enums.  The alternatives are to either pollute
129  // Sema.h (by including this file) or sacrifice type safety (by
130  // making Sema.h declare things as enums).
131  class TemplatePartialOrderingContext {
132    TPOC Value;
133  public:
134    TemplatePartialOrderingContext(TPOC Value) : Value(Value) {}
135    operator TPOC() const { return Value; }
136  };
137
138  /// \brief Captures a template argument whose value has been deduced
139  /// via c++ template argument deduction.
140  class DeducedTemplateArgument : public TemplateArgument {
141    /// \brief For a non-type template argument, whether the value was
142    /// deduced from an array bound.
143    bool DeducedFromArrayBound;
144
145  public:
146    DeducedTemplateArgument()
147      : TemplateArgument(), DeducedFromArrayBound(false) { }
148
149    DeducedTemplateArgument(const TemplateArgument &Arg,
150                            bool DeducedFromArrayBound = false)
151      : TemplateArgument(Arg), DeducedFromArrayBound(DeducedFromArrayBound) { }
152
153    /// \brief Construct an integral non-type template argument that
154    /// has been deduced, possibly from an array bound.
155    DeducedTemplateArgument(const llvm::APSInt &Value,
156                            QualType ValueType,
157                            bool DeducedFromArrayBound)
158      : TemplateArgument(Value, ValueType),
159        DeducedFromArrayBound(DeducedFromArrayBound) { }
160
161    /// \brief For a non-type template argument, determine whether the
162    /// template argument was deduced from an array bound.
163    bool wasDeducedFromArrayBound() const { return DeducedFromArrayBound; }
164
165    /// \brief Specify whether the given non-type template argument
166    /// was deduced from an array bound.
167    void setDeducedFromArrayBound(bool Deduced) {
168      DeducedFromArrayBound = Deduced;
169    }
170  };
171
172  /// \brief A stack-allocated class that identifies which local
173  /// variable declaration instantiations are present in this scope.
174  ///
175  /// A new instance of this class type will be created whenever we
176  /// instantiate a new function declaration, which will have its own
177  /// set of parameter declarations.
178  class LocalInstantiationScope {
179  public:
180    /// \brief A set of declarations.
181    typedef llvm::SmallVector<Decl *, 4> DeclArgumentPack;
182
183  private:
184    /// \brief Reference to the semantic analysis that is performing
185    /// this template instantiation.
186    Sema &SemaRef;
187
188    typedef llvm::DenseMap<const Decl *,
189                           llvm::PointerUnion<Decl *, DeclArgumentPack *> >
190      LocalDeclsMap;
191
192    /// \brief A mapping from local declarations that occur
193    /// within a template to their instantiations.
194    ///
195    /// This mapping is used during instantiation to keep track of,
196    /// e.g., function parameter and variable declarations. For example,
197    /// given:
198    ///
199    /// \code
200    ///   template<typename T> T add(T x, T y) { return x + y; }
201    /// \endcode
202    ///
203    /// when we instantiate add<int>, we will introduce a mapping from
204    /// the ParmVarDecl for 'x' that occurs in the template to the
205    /// instantiated ParmVarDecl for 'x'.
206    ///
207    /// For a parameter pack, the local instantiation scope may contain a
208    /// set of instantiated parameters. This is stored as a DeclArgumentPack
209    /// pointer.
210    LocalDeclsMap LocalDecls;
211
212    /// \brief The set of argument packs we've allocated.
213    llvm::SmallVector<DeclArgumentPack *, 1> ArgumentPacks;
214
215    /// \brief The outer scope, which contains local variable
216    /// definitions from some other instantiation (that may not be
217    /// relevant to this particular scope).
218    LocalInstantiationScope *Outer;
219
220    /// \brief Whether we have already exited this scope.
221    bool Exited;
222
223    /// \brief Whether to combine this scope with the outer scope, such that
224    /// lookup will search our outer scope.
225    bool CombineWithOuterScope;
226
227    /// \brief If non-NULL, the template parameter pack that has been
228    /// partially substituted per C++0x [temp.arg.explicit]p9.
229    NamedDecl *PartiallySubstitutedPack;
230
231    /// \brief If \c PartiallySubstitutedPack is non-null, the set of
232    /// explicitly-specified template arguments in that pack.
233    const TemplateArgument *ArgsInPartiallySubstitutedPack;
234
235    /// \brief If \c PartiallySubstitutedPack, the number of
236    /// explicitly-specified template arguments in
237    /// ArgsInPartiallySubstitutedPack.
238    unsigned NumArgsInPartiallySubstitutedPack;
239
240    // This class is non-copyable
241    LocalInstantiationScope(const LocalInstantiationScope &);
242    LocalInstantiationScope &operator=(const LocalInstantiationScope &);
243
244  public:
245    LocalInstantiationScope(Sema &SemaRef, bool CombineWithOuterScope = false)
246      : SemaRef(SemaRef), Outer(SemaRef.CurrentInstantiationScope),
247        Exited(false), CombineWithOuterScope(CombineWithOuterScope),
248        PartiallySubstitutedPack(0)
249    {
250      SemaRef.CurrentInstantiationScope = this;
251    }
252
253    ~LocalInstantiationScope() {
254      Exit();
255    }
256
257    const Sema &getSema() const { return SemaRef; }
258
259    /// \brief Exit this local instantiation scope early.
260    void Exit() {
261      if (Exited)
262        return;
263
264      for (unsigned I = 0, N = ArgumentPacks.size(); I != N; ++I)
265        delete ArgumentPacks[I];
266
267      SemaRef.CurrentInstantiationScope = Outer;
268      Exited = true;
269    }
270
271    /// \brief Find the instantiation of the declaration D within the current
272    /// instantiation scope.
273    ///
274    /// \param D The declaration whose instantiation we are searching for.
275    ///
276    /// \returns A pointer to the declaration or argument pack of declarations
277    /// to which the declaration \c D is instantiataed, if found. Otherwise,
278    /// returns NULL.
279    llvm::PointerUnion<Decl *, DeclArgumentPack *> *
280    findInstantiationOf(const Decl *D);
281
282    void InstantiatedLocal(const Decl *D, Decl *Inst);
283    void InstantiatedLocalPackArg(const Decl *D, Decl *Inst);
284    void MakeInstantiatedLocalArgPack(const Decl *D);
285
286    /// \brief Note that the given parameter pack has been partially substituted
287    /// via explicit specification of template arguments
288    /// (C++0x [temp.arg.explicit]p9).
289    ///
290    /// \param Pack The parameter pack, which will always be a template
291    /// parameter pack.
292    ///
293    /// \param ExplicitArgs The explicitly-specified template arguments provided
294    /// for this parameter pack.
295    ///
296    /// \param NumExplicitArgs The number of explicitly-specified template
297    /// arguments provided for this parameter pack.
298    void SetPartiallySubstitutedPack(NamedDecl *Pack,
299                                     const TemplateArgument *ExplicitArgs,
300                                     unsigned NumExplicitArgs);
301
302    /// \brief Retrieve the partially-substitued template parameter pack.
303    ///
304    /// If there is no partially-substituted parameter pack, returns NULL.
305    NamedDecl *getPartiallySubstitutedPack(
306                                      const TemplateArgument **ExplicitArgs = 0,
307                                           unsigned *NumExplicitArgs = 0) const;
308  };
309
310  class TemplateDeclInstantiator
311    : public DeclVisitor<TemplateDeclInstantiator, Decl *>
312  {
313    Sema &SemaRef;
314    Sema::ArgumentPackSubstitutionIndexRAII SubstIndex;
315    DeclContext *Owner;
316    const MultiLevelTemplateArgumentList &TemplateArgs;
317
318    /// \brief A list of out-of-line class template partial
319    /// specializations that will need to be instantiated after the
320    /// enclosing class's instantiation is complete.
321    llvm::SmallVector<std::pair<ClassTemplateDecl *,
322                                ClassTemplatePartialSpecializationDecl *>, 4>
323      OutOfLinePartialSpecs;
324
325  public:
326    TemplateDeclInstantiator(Sema &SemaRef, DeclContext *Owner,
327                             const MultiLevelTemplateArgumentList &TemplateArgs)
328      : SemaRef(SemaRef), SubstIndex(SemaRef, -1), Owner(Owner),
329        TemplateArgs(TemplateArgs) { }
330
331    // FIXME: Once we get closer to completion, replace these manually-written
332    // declarations with automatically-generated ones from
333    // clang/AST/DeclNodes.inc.
334    Decl *VisitTranslationUnitDecl(TranslationUnitDecl *D);
335    Decl *VisitLabelDecl(LabelDecl *D);
336    Decl *VisitNamespaceDecl(NamespaceDecl *D);
337    Decl *VisitNamespaceAliasDecl(NamespaceAliasDecl *D);
338    Decl *VisitTypedefNameDecl(TypedefNameDecl *D, bool IsTypeAlias);
339    Decl *VisitTypedefDecl(TypedefDecl *D);
340    Decl *VisitTypeAliasDecl(TypeAliasDecl *D);
341    Decl *VisitVarDecl(VarDecl *D);
342    Decl *VisitAccessSpecDecl(AccessSpecDecl *D);
343    Decl *VisitFieldDecl(FieldDecl *D);
344    Decl *VisitIndirectFieldDecl(IndirectFieldDecl *D);
345    Decl *VisitStaticAssertDecl(StaticAssertDecl *D);
346    Decl *VisitEnumDecl(EnumDecl *D);
347    Decl *VisitEnumConstantDecl(EnumConstantDecl *D);
348    Decl *VisitFriendDecl(FriendDecl *D);
349    Decl *VisitFunctionDecl(FunctionDecl *D,
350                            TemplateParameterList *TemplateParams = 0);
351    Decl *VisitCXXRecordDecl(CXXRecordDecl *D);
352    Decl *VisitCXXMethodDecl(CXXMethodDecl *D,
353                             TemplateParameterList *TemplateParams = 0);
354    Decl *VisitCXXConstructorDecl(CXXConstructorDecl *D);
355    Decl *VisitCXXDestructorDecl(CXXDestructorDecl *D);
356    Decl *VisitCXXConversionDecl(CXXConversionDecl *D);
357    ParmVarDecl *VisitParmVarDecl(ParmVarDecl *D);
358    Decl *VisitClassTemplateDecl(ClassTemplateDecl *D);
359    Decl *VisitClassTemplatePartialSpecializationDecl(
360                                    ClassTemplatePartialSpecializationDecl *D);
361    Decl *VisitFunctionTemplateDecl(FunctionTemplateDecl *D);
362    Decl *VisitTemplateTypeParmDecl(TemplateTypeParmDecl *D);
363    Decl *VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D);
364    Decl *VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D);
365    Decl *VisitUsingDirectiveDecl(UsingDirectiveDecl *D);
366    Decl *VisitUsingDecl(UsingDecl *D);
367    Decl *VisitUsingShadowDecl(UsingShadowDecl *D);
368    Decl *VisitUnresolvedUsingValueDecl(UnresolvedUsingValueDecl *D);
369    Decl *VisitUnresolvedUsingTypenameDecl(UnresolvedUsingTypenameDecl *D);
370
371    // Base case. FIXME: Remove once we can instantiate everything.
372    Decl *VisitDecl(Decl *D) {
373      unsigned DiagID = SemaRef.getDiagnostics().getCustomDiagID(
374                                                            Diagnostic::Error,
375                                                   "cannot instantiate %0 yet");
376      SemaRef.Diag(D->getLocation(), DiagID)
377        << D->getDeclKindName();
378
379      return 0;
380    }
381
382    typedef
383      llvm::SmallVectorImpl<std::pair<ClassTemplateDecl *,
384                                     ClassTemplatePartialSpecializationDecl *> >
385        ::iterator
386      delayed_partial_spec_iterator;
387
388    /// \brief Return an iterator to the beginning of the set of
389    /// "delayed" partial specializations, which must be passed to
390    /// InstantiateClassTemplatePartialSpecialization once the class
391    /// definition has been completed.
392    delayed_partial_spec_iterator delayed_partial_spec_begin() {
393      return OutOfLinePartialSpecs.begin();
394    }
395
396    /// \brief Return an iterator to the end of the set of
397    /// "delayed" partial specializations, which must be passed to
398    /// InstantiateClassTemplatePartialSpecialization once the class
399    /// definition has been completed.
400    delayed_partial_spec_iterator delayed_partial_spec_end() {
401      return OutOfLinePartialSpecs.end();
402    }
403
404    // Helper functions for instantiating methods.
405    TypeSourceInfo *SubstFunctionType(FunctionDecl *D,
406                             llvm::SmallVectorImpl<ParmVarDecl *> &Params);
407    bool InitFunctionInstantiation(FunctionDecl *New, FunctionDecl *Tmpl);
408    bool InitMethodInstantiation(CXXMethodDecl *New, CXXMethodDecl *Tmpl);
409
410    TemplateParameterList *
411      SubstTemplateParams(TemplateParameterList *List);
412
413    bool SubstQualifier(const DeclaratorDecl *OldDecl,
414                        DeclaratorDecl *NewDecl);
415    bool SubstQualifier(const TagDecl *OldDecl,
416                        TagDecl *NewDecl);
417
418    ClassTemplatePartialSpecializationDecl *
419    InstantiateClassTemplatePartialSpecialization(
420                                              ClassTemplateDecl *ClassTemplate,
421                           ClassTemplatePartialSpecializationDecl *PartialSpec);
422  };
423}
424
425#endif // LLVM_CLANG_SEMA_TEMPLATE_H
426