clang  8.0.0svn
RewriteRope.h
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1 //===- RewriteRope.h - Rope specialized for rewriter ------------*- 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 defines the RewriteRope class, which is a powerful string class.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_CLANG_REWRITE_CORE_REWRITEROPE_H
15 #define LLVM_CLANG_REWRITE_CORE_REWRITEROPE_H
16 
17 #include "llvm/ADT/IntrusiveRefCntPtr.h"
18 #include "llvm/ADT/StringRef.h"
19 #include <cassert>
20 #include <cstddef>
21 #include <iterator>
22 #include <utility>
23 
24 namespace clang {
25 
26  //===--------------------------------------------------------------------===//
27  // RopeRefCountString Class
28  //===--------------------------------------------------------------------===//
29 
30  /// RopeRefCountString - This struct is allocated with 'new char[]' from the
31  /// heap, and represents a reference counted chunk of string data. When its
32  /// ref count drops to zero, it is delete[]'d. This is primarily managed
33  /// through the RopePiece class below.
35  unsigned RefCount;
36  char Data[1]; // Variable sized.
37 
38  void Retain() { ++RefCount; }
39 
40  void Release() {
41  assert(RefCount > 0 && "Reference count is already zero.");
42  if (--RefCount == 0)
43  delete [] (char*)this;
44  }
45  };
46 
47  //===--------------------------------------------------------------------===//
48  // RopePiece Class
49  //===--------------------------------------------------------------------===//
50 
51  /// RopePiece - This class represents a view into a RopeRefCountString object.
52  /// This allows references to string data to be efficiently chopped up and
53  /// moved around without having to push around the string data itself.
54  ///
55  /// For example, we could have a 1M RopePiece and want to insert something
56  /// into the middle of it. To do this, we split it into two RopePiece objects
57  /// that both refer to the same underlying RopeRefCountString (just with
58  /// different offsets) which is a nice constant time operation.
59  struct RopePiece {
61  unsigned StartOffs = 0;
62  unsigned EndOffs = 0;
63 
64  RopePiece() = default;
66  unsigned End)
67  : StrData(std::move(Str)), StartOffs(Start), EndOffs(End) {}
68 
69  const char &operator[](unsigned Offset) const {
70  return StrData->Data[Offset+StartOffs];
71  }
72  char &operator[](unsigned Offset) {
73  return StrData->Data[Offset+StartOffs];
74  }
75 
76  unsigned size() const { return EndOffs-StartOffs; }
77  };
78 
79  //===--------------------------------------------------------------------===//
80  // RopePieceBTreeIterator Class
81  //===--------------------------------------------------------------------===//
82 
83  /// RopePieceBTreeIterator - This class provides read-only forward iteration
84  /// over bytes that are in a RopePieceBTree. This first iterates over bytes
85  /// in a RopePiece, then iterates over RopePiece's in a RopePieceBTreeLeaf,
86  /// then iterates over RopePieceBTreeLeaf's in a RopePieceBTree.
88  public std::iterator<std::forward_iterator_tag, const char, ptrdiff_t> {
89  /// CurNode - The current B+Tree node that we are inspecting.
90  const void /*RopePieceBTreeLeaf*/ *CurNode = nullptr;
91 
92  /// CurPiece - The current RopePiece in the B+Tree node that we're
93  /// inspecting.
94  const RopePiece *CurPiece = nullptr;
95 
96  /// CurChar - The current byte in the RopePiece we are pointing to.
97  unsigned CurChar = 0;
98 
99  public:
100  RopePieceBTreeIterator() = default;
101  RopePieceBTreeIterator(const void /*RopePieceBTreeNode*/ *N);
102 
103  char operator*() const {
104  return (*CurPiece)[CurChar];
105  }
106 
107  bool operator==(const RopePieceBTreeIterator &RHS) const {
108  return CurPiece == RHS.CurPiece && CurChar == RHS.CurChar;
109  }
110  bool operator!=(const RopePieceBTreeIterator &RHS) const {
111  return !operator==(RHS);
112  }
113 
114  RopePieceBTreeIterator& operator++() { // Preincrement
115  if (CurChar+1 < CurPiece->size())
116  ++CurChar;
117  else
118  MoveToNextPiece();
119  return *this;
120  }
121 
122  RopePieceBTreeIterator operator++(int) { // Postincrement
123  RopePieceBTreeIterator tmp = *this; ++*this; return tmp;
124  }
125 
126  llvm::StringRef piece() const {
127  return llvm::StringRef(&(*CurPiece)[0], CurPiece->size());
128  }
129 
130  void MoveToNextPiece();
131  };
132 
133  //===--------------------------------------------------------------------===//
134  // RopePieceBTree Class
135  //===--------------------------------------------------------------------===//
136 
138  void /*RopePieceBTreeNode*/ *Root;
139 
140  public:
141  RopePieceBTree();
142  RopePieceBTree(const RopePieceBTree &RHS);
143  RopePieceBTree &operator=(const RopePieceBTree &) = delete;
144  ~RopePieceBTree();
145 
147 
148  iterator begin() const { return iterator(Root); }
149  iterator end() const { return iterator(); }
150  unsigned size() const;
151  unsigned empty() const { return size() == 0; }
152 
153  void clear();
154 
155  void insert(unsigned Offset, const RopePiece &R);
156 
157  void erase(unsigned Offset, unsigned NumBytes);
158  };
159 
160  //===--------------------------------------------------------------------===//
161  // RewriteRope Class
162  //===--------------------------------------------------------------------===//
163 
164 /// RewriteRope - A powerful string class. This class supports extremely
165 /// efficient insertions and deletions into the middle of it, even for
166 /// ridiculously long strings.
167 class RewriteRope {
168  RopePieceBTree Chunks;
169 
170  /// We allocate space for string data out of a buffer of size AllocChunkSize.
171  /// This keeps track of how much space is left.
173  enum { AllocChunkSize = 4080 };
174  unsigned AllocOffs = AllocChunkSize;
175 
176 public:
177  RewriteRope() = default;
178  RewriteRope(const RewriteRope &RHS) : Chunks(RHS.Chunks) {}
179 
182 
183  iterator begin() const { return Chunks.begin(); }
184  iterator end() const { return Chunks.end(); }
185  unsigned size() const { return Chunks.size(); }
186 
187  void clear() {
188  Chunks.clear();
189  }
190 
191  void assign(const char *Start, const char *End) {
192  clear();
193  if (Start != End)
194  Chunks.insert(0, MakeRopeString(Start, End));
195  }
196 
197  void insert(unsigned Offset, const char *Start, const char *End) {
198  assert(Offset <= size() && "Invalid position to insert!");
199  if (Start == End) return;
200  Chunks.insert(Offset, MakeRopeString(Start, End));
201  }
202 
203  void erase(unsigned Offset, unsigned NumBytes) {
204  assert(Offset+NumBytes <= size() && "Invalid region to erase!");
205  if (NumBytes == 0) return;
206  Chunks.erase(Offset, NumBytes);
207  }
208 
209 private:
210  RopePiece MakeRopeString(const char *Start, const char *End);
211 };
212 
213 } // namespace clang
214 
215 #endif // LLVM_CLANG_REWRITE_CORE_REWRITEROPE_H
void insert(unsigned Offset, const char *Start, const char *End)
Definition: RewriteRope.h:197
bool operator==(CanQual< T > x, CanQual< U > y)
void insert(unsigned Offset, const RopePiece &R)
RewriteRope - A powerful string class.
Definition: RewriteRope.h:167
virtual void clear()
llvm::StringRef piece() const
Definition: RewriteRope.h:126
void erase(unsigned Offset, unsigned NumBytes)
Definition: RewriteRope.h:203
RopePieceBTreeIterator & operator++()
Definition: RewriteRope.h:114
RopeRefCountString - This struct is allocated with &#39;new char[]&#39; from the heap, and represents a refer...
Definition: RewriteRope.h:34
Definition: Format.h:2073
const char & operator[](unsigned Offset) const
Definition: RewriteRope.h:69
RopePiece - This class represents a view into a RopeRefCountString object.
Definition: RewriteRope.h:59
uint32_t Offset
Definition: CacheTokens.cpp:43
iterator end() const
Definition: RewriteRope.h:184
llvm::IntrusiveRefCntPtr< RopeRefCountString > StrData
Definition: RewriteRope.h:60
void erase(unsigned Offset, unsigned NumBytes)
iterator begin() const
Definition: RewriteRope.h:183
unsigned empty() const
Definition: RewriteRope.h:151
SourceLocation End
RewriteRope(const RewriteRope &RHS)
Definition: RewriteRope.h:178
unsigned size() const
Definition: RewriteRope.h:185
RopePieceBTreeIterator iterator
Definition: RewriteRope.h:146
unsigned size() const
Definition: RewriteRope.h:76
RopePiece(llvm::IntrusiveRefCntPtr< RopeRefCountString > Str, unsigned Start, unsigned End)
Definition: RewriteRope.h:65
Dataflow Directional Tag Classes.
RopePieceBTreeIterator - This class provides read-only forward iteration over bytes that are in a Rop...
Definition: RewriteRope.h:87
bool operator==(const RopePieceBTreeIterator &RHS) const
Definition: RewriteRope.h:107
void assign(const char *Start, const char *End)
Definition: RewriteRope.h:191
unsigned size() const
iterator begin() const
Definition: RewriteRope.h:148
iterator end() const
Definition: RewriteRope.h:149
char & operator[](unsigned Offset)
Definition: RewriteRope.h:72
RopePieceBTreeIterator operator++(int)
Definition: RewriteRope.h:122
bool operator!=(const RopePieceBTreeIterator &RHS) const
Definition: RewriteRope.h:110