TypeLocBuilder.h revision 360784 
1//===--- TypeLocBuilder.h - Type Source Info collector ----------*- 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 TypeLocBuilder, a class for building TypeLocs
10//  bottom-up.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_CLANG_LIB_SEMA_TYPELOCBUILDER_H
15#define LLVM_CLANG_LIB_SEMA_TYPELOCBUILDER_H
16
17#include "clang/AST/ASTContext.h"
18#include "clang/AST/TypeLoc.h"
19
20namespace clang {
21
22class TypeLocBuilder {
23  enum { InlineCapacity = 8 * sizeof(SourceLocation) };
24
25  /// The underlying location-data buffer.  Data grows from the end
26  /// of the buffer backwards.
27  char *Buffer;
28
29  /// The capacity of the current buffer.
30  size_t Capacity;
31
32  /// The index of the first occupied byte in the buffer.
33  size_t Index;
34
35#ifndef NDEBUG
36  /// The last type pushed on this builder.
37  QualType LastTy;
38#endif
39
40  /// The inline buffer.
41  enum { BufferMaxAlignment = alignof(void *) };
42  alignas(BufferMaxAlignment) char InlineBuffer[InlineCapacity];
43  unsigned NumBytesAtAlign4, NumBytesAtAlign8;
44
45public:
46  TypeLocBuilder()
47      : Buffer(InlineBuffer), Capacity(InlineCapacity), Index(InlineCapacity),
48        NumBytesAtAlign4(0), NumBytesAtAlign8(0) {}
49
50  ~TypeLocBuilder() {
51    if (Buffer != InlineBuffer)
52      delete[] Buffer;
53  }
54
55  /// Ensures that this buffer has at least as much capacity as described.
56  void reserve(size_t Requested) {
57    if (Requested > Capacity)
58      // For now, match the request exactly.
59      grow(Requested);
60  }
61
62  /// Pushes a copy of the given TypeLoc onto this builder.  The builder
63  /// must be empty for this to work.
64  void pushFullCopy(TypeLoc L);
65
66  /// Pushes space for a typespec TypeLoc.  Invalidates any TypeLocs
67  /// previously retrieved from this builder.
68  TypeSpecTypeLoc pushTypeSpec(QualType T) {
69    size_t LocalSize = TypeSpecTypeLoc::LocalDataSize;
70    unsigned LocalAlign = TypeSpecTypeLoc::LocalDataAlignment;
71    return pushImpl(T, LocalSize, LocalAlign).castAs<TypeSpecTypeLoc>();
72  }
73
74  /// Resets this builder to the newly-initialized state.
75  void clear() {
76#ifndef NDEBUG
77    LastTy = QualType();
78#endif
79    Index = Capacity;
80    NumBytesAtAlign4 = NumBytesAtAlign8 = 0;
81  }
82
83  /// Tell the TypeLocBuilder that the type it is storing has been
84  /// modified in some safe way that doesn't affect type-location information.
85  void TypeWasModifiedSafely(QualType T) {
86#ifndef NDEBUG
87    LastTy = T;
88#endif
89  }
90
91  /// Pushes space for a new TypeLoc of the given type.  Invalidates
92  /// any TypeLocs previously retrieved from this builder.
93  template <class TyLocType> TyLocType push(QualType T) {
94    TyLocType Loc = TypeLoc(T, nullptr).castAs<TyLocType>();
95    size_t LocalSize = Loc.getLocalDataSize();
96    unsigned LocalAlign = Loc.getLocalDataAlignment();
97    return pushImpl(T, LocalSize, LocalAlign).castAs<TyLocType>();
98  }
99
100  /// Creates a TypeSourceInfo for the given type.
101  TypeSourceInfo *getTypeSourceInfo(ASTContext& Context, QualType T) {
102#ifndef NDEBUG
103    assert(T == LastTy && "type doesn't match last type pushed!");
104#endif
105
106    size_t FullDataSize = Capacity - Index;
107    TypeSourceInfo *DI = Context.CreateTypeSourceInfo(T, FullDataSize);
108    memcpy(DI->getTypeLoc().getOpaqueData(), &Buffer[Index], FullDataSize);
109    return DI;
110  }
111
112  /// Copies the type-location information to the given AST context and
113  /// returns a \c TypeLoc referring into the AST context.
114  TypeLoc getTypeLocInContext(ASTContext &Context, QualType T) {
115#ifndef NDEBUG
116    assert(T == LastTy && "type doesn't match last type pushed!");
117#endif
118
119    size_t FullDataSize = Capacity - Index;
120    void *Mem = Context.Allocate(FullDataSize);
121    memcpy(Mem, &Buffer[Index], FullDataSize);
122    return TypeLoc(T, Mem);
123  }
124
125private:
126
127  TypeLoc pushImpl(QualType T, size_t LocalSize, unsigned LocalAlignment);
128
129  /// Grow to the given capacity.
130  void grow(size_t NewCapacity);
131
132  /// Retrieve a temporary TypeLoc that refers into this \c TypeLocBuilder
133  /// object.
134  ///
135  /// The resulting \c TypeLoc should only be used so long as the
136  /// \c TypeLocBuilder is active and has not had more type information
137  /// pushed into it.
138  TypeLoc getTemporaryTypeLoc(QualType T) {
139#ifndef NDEBUG
140    assert(LastTy == T && "type doesn't match last type pushed!");
141#endif
142    return TypeLoc(T, &Buffer[Index]);
143  }
144};
145
146}
147
148#endif
149