Ownership.h revision 5354e77e60e82828c7c2361f5c688c2667ab59cc 
1//===--- Ownership.h - Parser ownership helpers -----------------*- 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//
10//  This file contains classes for managing ownership of Stmt and Expr nodes.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_CLANG_SEMA_OWNERSHIP_H
15#define LLVM_CLANG_SEMA_OWNERSHIP_H
16
17#include "clang/Basic/LLVM.h"
18#include "llvm/ADT/ArrayRef.h"
19#include "llvm/ADT/PointerIntPair.h"
20
21//===----------------------------------------------------------------------===//
22// OpaquePtr
23//===----------------------------------------------------------------------===//
24
25namespace clang {
26  class Attr;
27  class CXXCtorInitializer;
28  class CXXBaseSpecifier;
29  class Decl;
30  class DeclGroupRef;
31  class Expr;
32  class NestedNameSpecifier;
33  class ParsedTemplateArgument;
34  class QualType;
35  class Stmt;
36  class TemplateName;
37  class TemplateParameterList;
38
39  /// OpaquePtr - This is a very simple POD type that wraps a pointer that the
40  /// Parser doesn't know about but that Sema or another client does.  The UID
41  /// template argument is used to make sure that "Decl" pointers are not
42  /// compatible with "Type" pointers for example.
43  template <class PtrTy>
44  class OpaquePtr {
45    void *Ptr;
46    explicit OpaquePtr(void *Ptr) : Ptr(Ptr) {}
47
48    typedef llvm::PointerLikeTypeTraits<PtrTy> Traits;
49
50  public:
51    OpaquePtr() : Ptr(0) {}
52
53    static OpaquePtr make(PtrTy P) { OpaquePtr OP; OP.set(P); return OP; }
54
55    template <typename T> T* getAs() const {
56      return get();
57    }
58
59    template <typename T> T getAsVal() const {
60      return get();
61    }
62
63    PtrTy get() const {
64      return Traits::getFromVoidPointer(Ptr);
65    }
66
67    void set(PtrTy P) {
68      Ptr = Traits::getAsVoidPointer(P);
69    }
70
71    operator bool() const { return Ptr != 0; }
72
73    void *getAsOpaquePtr() const { return Ptr; }
74    static OpaquePtr getFromOpaquePtr(void *P) { return OpaquePtr(P); }
75  };
76
77  /// UnionOpaquePtr - A version of OpaquePtr suitable for membership
78  /// in a union.
79  template <class T> struct UnionOpaquePtr {
80    void *Ptr;
81
82    static UnionOpaquePtr make(OpaquePtr<T> P) {
83      UnionOpaquePtr OP = { P.getAsOpaquePtr() };
84      return OP;
85    }
86
87    OpaquePtr<T> get() const { return OpaquePtr<T>::getFromOpaquePtr(Ptr); }
88    operator OpaquePtr<T>() const { return get(); }
89
90    UnionOpaquePtr &operator=(OpaquePtr<T> P) {
91      Ptr = P.getAsOpaquePtr();
92      return *this;
93    }
94  };
95}
96
97namespace llvm {
98  template <class T>
99  class PointerLikeTypeTraits<clang::OpaquePtr<T> > {
100  public:
101    static inline void *getAsVoidPointer(clang::OpaquePtr<T> P) {
102      // FIXME: Doesn't work? return P.getAs< void >();
103      return P.getAsOpaquePtr();
104    }
105    static inline clang::OpaquePtr<T> getFromVoidPointer(void *P) {
106      return clang::OpaquePtr<T>::getFromOpaquePtr(P);
107    }
108    enum { NumLowBitsAvailable = 0 };
109  };
110
111  template <class T>
112  struct isPodLike<clang::OpaquePtr<T> > { static const bool value = true; };
113}
114
115namespace clang {
116  // Basic
117  class DiagnosticBuilder;
118
119  // Determines whether the low bit of the result pointer for the
120  // given UID is always zero. If so, ActionResult will use that bit
121  // for it's "invalid" flag.
122  template<class Ptr>
123  struct IsResultPtrLowBitFree {
124    static const bool value = false;
125  };
126
127  /// ActionResult - This structure is used while parsing/acting on
128  /// expressions, stmts, etc.  It encapsulates both the object returned by
129  /// the action, plus a sense of whether or not it is valid.
130  /// When CompressInvalid is true, the "invalid" flag will be
131  /// stored in the low bit of the Val pointer.
132  template<class PtrTy,
133           bool CompressInvalid = IsResultPtrLowBitFree<PtrTy>::value>
134  class ActionResult {
135    PtrTy Val;
136    bool Invalid;
137
138  public:
139    ActionResult(bool Invalid = false)
140      : Val(PtrTy()), Invalid(Invalid) {}
141    ActionResult(PtrTy val) : Val(val), Invalid(false) {}
142    ActionResult(const DiagnosticBuilder &) : Val(PtrTy()), Invalid(true) {}
143
144    // These two overloads prevent void* -> bool conversions.
145    ActionResult(const void *);
146    ActionResult(volatile void *);
147
148    bool isInvalid() const { return Invalid; }
149    bool isUsable() const { return !Invalid && Val; }
150
151    PtrTy get() const { return Val; }
152    // FIXME: Replace with get.
153    PtrTy release() const { return Val; }
154    PtrTy take() const { return Val; }
155    template <typename T> T *takeAs() { return static_cast<T*>(get()); }
156
157    void set(PtrTy V) { Val = V; }
158
159    const ActionResult &operator=(PtrTy RHS) {
160      Val = RHS;
161      Invalid = false;
162      return *this;
163    }
164  };
165
166  // This ActionResult partial specialization places the "invalid"
167  // flag into the low bit of the pointer.
168  template<typename PtrTy>
169  class ActionResult<PtrTy, true> {
170    // A pointer whose low bit is 1 if this result is invalid, 0
171    // otherwise.
172    uintptr_t PtrWithInvalid;
173    typedef llvm::PointerLikeTypeTraits<PtrTy> PtrTraits;
174  public:
175    ActionResult(bool Invalid = false)
176      : PtrWithInvalid(static_cast<uintptr_t>(Invalid)) { }
177
178    ActionResult(PtrTy V) {
179      void *VP = PtrTraits::getAsVoidPointer(V);
180      PtrWithInvalid = reinterpret_cast<uintptr_t>(VP);
181      assert((PtrWithInvalid & 0x01) == 0 && "Badly aligned pointer");
182    }
183    ActionResult(const DiagnosticBuilder &) : PtrWithInvalid(0x01) { }
184
185    // These two overloads prevent void* -> bool conversions.
186    ActionResult(const void *);
187    ActionResult(volatile void *);
188
189    bool isInvalid() const { return PtrWithInvalid & 0x01; }
190    bool isUsable() const { return PtrWithInvalid > 0x01; }
191
192    PtrTy get() const {
193      void *VP = reinterpret_cast<void *>(PtrWithInvalid & ~0x01);
194      return PtrTraits::getFromVoidPointer(VP);
195    }
196    // FIXME: Replace with get.
197    PtrTy take() const { return get(); }
198    PtrTy release() const { return get(); }
199    template <typename T> T *takeAs() { return static_cast<T*>(get()); }
200
201    void set(PtrTy V) {
202      void *VP = PtrTraits::getAsVoidPointer(V);
203      PtrWithInvalid = reinterpret_cast<uintptr_t>(VP);
204      assert((PtrWithInvalid & 0x01) == 0 && "Badly aligned pointer");
205    }
206
207    const ActionResult &operator=(PtrTy RHS) {
208      void *VP = PtrTraits::getAsVoidPointer(RHS);
209      PtrWithInvalid = reinterpret_cast<uintptr_t>(VP);
210      assert((PtrWithInvalid & 0x01) == 0 && "Badly aligned pointer");
211      return *this;
212    }
213  };
214
215  /// An opaque type for threading parsed type information through the
216  /// parser.
217  typedef OpaquePtr<QualType> ParsedType;
218  typedef UnionOpaquePtr<QualType> UnionParsedType;
219
220  // We can re-use the low bit of expression, statement, base, and
221  // member-initializer pointers for the "invalid" flag of
222  // ActionResult.
223  template<> struct IsResultPtrLowBitFree<Expr*> {
224    static const bool value = true;
225  };
226  template<> struct IsResultPtrLowBitFree<Stmt*> {
227    static const bool value = true;
228  };
229  template<> struct IsResultPtrLowBitFree<CXXBaseSpecifier*> {
230    static const bool value = true;
231  };
232  template<> struct IsResultPtrLowBitFree<CXXCtorInitializer*> {
233    static const bool value = true;
234  };
235
236  typedef ActionResult<Expr*> ExprResult;
237  typedef ActionResult<Stmt*> StmtResult;
238  typedef ActionResult<ParsedType> TypeResult;
239  typedef ActionResult<CXXBaseSpecifier*> BaseResult;
240  typedef ActionResult<CXXCtorInitializer*> MemInitResult;
241
242  typedef ActionResult<Decl*> DeclResult;
243  typedef OpaquePtr<TemplateName> ParsedTemplateTy;
244
245  typedef llvm::MutableArrayRef<Expr*> MultiExprArg;
246  typedef llvm::MutableArrayRef<Stmt*> MultiStmtArg;
247  typedef llvm::MutableArrayRef<ParsedTemplateArgument> ASTTemplateArgsPtr;
248  typedef llvm::MutableArrayRef<ParsedType> MultiTypeArg;
249  typedef llvm::MutableArrayRef<TemplateParameterList*> MultiTemplateParamsArg;
250
251  inline ExprResult ExprError() { return ExprResult(true); }
252  inline StmtResult StmtError() { return StmtResult(true); }
253
254  inline ExprResult ExprError(const DiagnosticBuilder&) { return ExprError(); }
255  inline StmtResult StmtError(const DiagnosticBuilder&) { return StmtError(); }
256
257  inline ExprResult ExprEmpty() { return ExprResult(false); }
258  inline StmtResult StmtEmpty() { return StmtResult(false); }
259
260  inline Expr *AssertSuccess(ExprResult R) {
261    assert(!R.isInvalid() && "operation was asserted to never fail!");
262    return R.get();
263  }
264
265  inline Stmt *AssertSuccess(StmtResult R) {
266    assert(!R.isInvalid() && "operation was asserted to never fail!");
267    return R.get();
268  }
269}
270
271#endif
272