Ownership.h revision 7247c88d1e41514a41085f83ebf03dd5220e054a 
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 CXXCtorInitializer;
27  class CXXBaseSpecifier;
28  class Decl;
29  class Expr;
30  class ParsedTemplateArgument;
31  class QualType;
32  class Stmt;
33  class TemplateName;
34  class TemplateParameterList;
35
36  /// OpaquePtr - This is a very simple POD type that wraps a pointer that the
37  /// Parser doesn't know about but that Sema or another client does.  The UID
38  /// template argument is used to make sure that "Decl" pointers are not
39  /// compatible with "Type" pointers for example.
40  template <class PtrTy>
41  class OpaquePtr {
42    void *Ptr;
43    explicit OpaquePtr(void *Ptr) : Ptr(Ptr) {}
44
45    typedef llvm::PointerLikeTypeTraits<PtrTy> Traits;
46
47  public:
48    OpaquePtr() : Ptr(0) {}
49
50    static OpaquePtr make(PtrTy P) { OpaquePtr OP; OP.set(P); return OP; }
51
52    template <typename T> T* getAs() const {
53      return get();
54    }
55
56    template <typename T> T getAsVal() const {
57      return get();
58    }
59
60    PtrTy get() const {
61      return Traits::getFromVoidPointer(Ptr);
62    }
63
64    void set(PtrTy P) {
65      Ptr = Traits::getAsVoidPointer(P);
66    }
67
68    LLVM_EXPLICIT operator bool() const { return Ptr != 0; }
69
70    void *getAsOpaquePtr() const { return Ptr; }
71    static OpaquePtr getFromOpaquePtr(void *P) { return OpaquePtr(P); }
72  };
73
74  /// UnionOpaquePtr - A version of OpaquePtr suitable for membership
75  /// in a union.
76  template <class T> struct UnionOpaquePtr {
77    void *Ptr;
78
79    static UnionOpaquePtr make(OpaquePtr<T> P) {
80      UnionOpaquePtr OP = { P.getAsOpaquePtr() };
81      return OP;
82    }
83
84    OpaquePtr<T> get() const { return OpaquePtr<T>::getFromOpaquePtr(Ptr); }
85    operator OpaquePtr<T>() const { return get(); }
86
87    UnionOpaquePtr &operator=(OpaquePtr<T> P) {
88      Ptr = P.getAsOpaquePtr();
89      return *this;
90    }
91  };
92}
93
94namespace llvm {
95  template <class T>
96  class PointerLikeTypeTraits<clang::OpaquePtr<T> > {
97  public:
98    static inline void *getAsVoidPointer(clang::OpaquePtr<T> P) {
99      // FIXME: Doesn't work? return P.getAs< void >();
100      return P.getAsOpaquePtr();
101    }
102    static inline clang::OpaquePtr<T> getFromVoidPointer(void *P) {
103      return clang::OpaquePtr<T>::getFromOpaquePtr(P);
104    }
105    enum { NumLowBitsAvailable = 0 };
106  };
107
108  template <class T>
109  struct isPodLike<clang::OpaquePtr<T> > { static const bool value = true; };
110}
111
112namespace clang {
113  // Basic
114  class DiagnosticBuilder;
115
116  // Determines whether the low bit of the result pointer for the
117  // given UID is always zero. If so, ActionResult will use that bit
118  // for it's "invalid" flag.
119  template<class Ptr>
120  struct IsResultPtrLowBitFree {
121    static const bool value = false;
122  };
123
124  /// ActionResult - This structure is used while parsing/acting on
125  /// expressions, stmts, etc.  It encapsulates both the object returned by
126  /// the action, plus a sense of whether or not it is valid.
127  /// When CompressInvalid is true, the "invalid" flag will be
128  /// stored in the low bit of the Val pointer.
129  template<class PtrTy,
130           bool CompressInvalid = IsResultPtrLowBitFree<PtrTy>::value>
131  class ActionResult {
132    PtrTy Val;
133    bool Invalid;
134
135  public:
136    ActionResult(bool Invalid = false)
137      : Val(PtrTy()), Invalid(Invalid) {}
138    ActionResult(PtrTy val) : Val(val), Invalid(false) {}
139    ActionResult(const DiagnosticBuilder &) : Val(PtrTy()), Invalid(true) {}
140
141    // These two overloads prevent void* -> bool conversions.
142    ActionResult(const void *);
143    ActionResult(volatile void *);
144
145    bool isInvalid() const { return Invalid; }
146    bool isUsable() const { return !Invalid && Val; }
147
148    PtrTy get() const { return Val; }
149    // FIXME: Replace with get.
150    PtrTy release() const { return Val; }
151    PtrTy take() const { return Val; }
152    template <typename T> T *takeAs() { return static_cast<T*>(get()); }
153
154    void set(PtrTy V) { Val = V; }
155
156    const ActionResult &operator=(PtrTy RHS) {
157      Val = RHS;
158      Invalid = false;
159      return *this;
160    }
161  };
162
163  // This ActionResult partial specialization places the "invalid"
164  // flag into the low bit of the pointer.
165  template<typename PtrTy>
166  class ActionResult<PtrTy, true> {
167    // A pointer whose low bit is 1 if this result is invalid, 0
168    // otherwise.
169    uintptr_t PtrWithInvalid;
170    typedef llvm::PointerLikeTypeTraits<PtrTy> PtrTraits;
171  public:
172    ActionResult(bool Invalid = false)
173      : PtrWithInvalid(static_cast<uintptr_t>(Invalid)) { }
174
175    ActionResult(PtrTy V) {
176      void *VP = PtrTraits::getAsVoidPointer(V);
177      PtrWithInvalid = reinterpret_cast<uintptr_t>(VP);
178      assert((PtrWithInvalid & 0x01) == 0 && "Badly aligned pointer");
179    }
180    ActionResult(const DiagnosticBuilder &) : PtrWithInvalid(0x01) { }
181
182    // These two overloads prevent void* -> bool conversions.
183    ActionResult(const void *);
184    ActionResult(volatile void *);
185
186    bool isInvalid() const { return PtrWithInvalid & 0x01; }
187    bool isUsable() const { return PtrWithInvalid > 0x01; }
188
189    PtrTy get() const {
190      void *VP = reinterpret_cast<void *>(PtrWithInvalid & ~0x01);
191      return PtrTraits::getFromVoidPointer(VP);
192    }
193    // FIXME: Replace with get.
194    PtrTy take() const { return get(); }
195    PtrTy release() const { return get(); }
196    template <typename T> T *takeAs() { return static_cast<T*>(get()); }
197
198    void set(PtrTy V) {
199      void *VP = PtrTraits::getAsVoidPointer(V);
200      PtrWithInvalid = reinterpret_cast<uintptr_t>(VP);
201      assert((PtrWithInvalid & 0x01) == 0 && "Badly aligned pointer");
202    }
203
204    const ActionResult &operator=(PtrTy RHS) {
205      void *VP = PtrTraits::getAsVoidPointer(RHS);
206      PtrWithInvalid = reinterpret_cast<uintptr_t>(VP);
207      assert((PtrWithInvalid & 0x01) == 0 && "Badly aligned pointer");
208      return *this;
209    }
210
211    // For types where we can fit a flag in with the pointer, provide
212    // conversions to/from pointer type.
213    static ActionResult getFromOpaquePointer(void *P) {
214      ActionResult Result;
215      Result.PtrWithInvalid = (uintptr_t)P;
216      return Result;
217    }
218    void *getAsOpaquePointer() const { return (void*)PtrWithInvalid; }
219  };
220
221  /// An opaque type for threading parsed type information through the
222  /// parser.
223  typedef OpaquePtr<QualType> ParsedType;
224  typedef UnionOpaquePtr<QualType> UnionParsedType;
225
226  // We can re-use the low bit of expression, statement, base, and
227  // member-initializer pointers for the "invalid" flag of
228  // ActionResult.
229  template<> struct IsResultPtrLowBitFree<Expr*> {
230    static const bool value = true;
231  };
232  template<> struct IsResultPtrLowBitFree<Stmt*> {
233    static const bool value = true;
234  };
235  template<> struct IsResultPtrLowBitFree<CXXBaseSpecifier*> {
236    static const bool value = true;
237  };
238  template<> struct IsResultPtrLowBitFree<CXXCtorInitializer*> {
239    static const bool value = true;
240  };
241
242  typedef ActionResult<Expr*> ExprResult;
243  typedef ActionResult<Stmt*> StmtResult;
244  typedef ActionResult<ParsedType> TypeResult;
245  typedef ActionResult<CXXBaseSpecifier*> BaseResult;
246  typedef ActionResult<CXXCtorInitializer*> MemInitResult;
247
248  typedef ActionResult<Decl*> DeclResult;
249  typedef OpaquePtr<TemplateName> ParsedTemplateTy;
250
251  typedef llvm::MutableArrayRef<Expr*> MultiExprArg;
252  typedef llvm::MutableArrayRef<Stmt*> MultiStmtArg;
253  typedef llvm::MutableArrayRef<ParsedTemplateArgument> ASTTemplateArgsPtr;
254  typedef llvm::MutableArrayRef<ParsedType> MultiTypeArg;
255  typedef llvm::MutableArrayRef<TemplateParameterList*> MultiTemplateParamsArg;
256
257  inline ExprResult ExprError() { return ExprResult(true); }
258  inline StmtResult StmtError() { return StmtResult(true); }
259
260  inline ExprResult ExprError(const DiagnosticBuilder&) { return ExprError(); }
261  inline StmtResult StmtError(const DiagnosticBuilder&) { return StmtError(); }
262
263  inline ExprResult ExprEmpty() { return ExprResult(false); }
264  inline StmtResult StmtEmpty() { return StmtResult(false); }
265
266  inline Expr *AssertSuccess(ExprResult R) {
267    assert(!R.isInvalid() && "operation was asserted to never fail!");
268    return R.get();
269  }
270
271  inline Stmt *AssertSuccess(StmtResult R) {
272    assert(!R.isInvalid() && "operation was asserted to never fail!");
273    return R.get();
274  }
275}
276
277#endif
278