1 //===- RewriteRope.h - Rope specialized for rewriter ------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file defines the RewriteRope class, which is a powerful string class.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_CLANG_REWRITE_CORE_REWRITEROPE_H
15 #define LLVM_CLANG_REWRITE_CORE_REWRITEROPE_H
17 #include "llvm/ADT/IntrusiveRefCntPtr.h"
18 #include "llvm/ADT/StringRef.h"
26 //===--------------------------------------------------------------------===//
27 // RopeRefCountString Class
28 //===--------------------------------------------------------------------===//
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.
34 struct RopeRefCountString {
36 char Data[1]; // Variable sized.
38 void Retain() { ++RefCount; }
41 assert(RefCount > 0 && "Reference count is already zero.");
43 delete [] (char*)this;
47 //===--------------------------------------------------------------------===//
49 //===--------------------------------------------------------------------===//
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.
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.
60 llvm::IntrusiveRefCntPtr<RopeRefCountString> StrData;
61 unsigned StartOffs = 0;
64 RopePiece() = default;
65 RopePiece(llvm::IntrusiveRefCntPtr<RopeRefCountString> Str, unsigned Start,
67 : StrData(std::move(Str)), StartOffs(Start), EndOffs(End) {}
69 const char &operator[](unsigned Offset) const {
70 return StrData->Data[Offset+StartOffs];
72 char &operator[](unsigned Offset) {
73 return StrData->Data[Offset+StartOffs];
76 unsigned size() const { return EndOffs-StartOffs; }
79 //===--------------------------------------------------------------------===//
80 // RopePieceBTreeIterator Class
81 //===--------------------------------------------------------------------===//
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.
87 class RopePieceBTreeIterator :
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;
92 /// CurPiece - The current RopePiece in the B+Tree node that we're
94 const RopePiece *CurPiece = nullptr;
96 /// CurChar - The current byte in the RopePiece we are pointing to.
100 RopePieceBTreeIterator() = default;
101 RopePieceBTreeIterator(const void /*RopePieceBTreeNode*/ *N);
103 char operator*() const {
104 return (*CurPiece)[CurChar];
107 bool operator==(const RopePieceBTreeIterator &RHS) const {
108 return CurPiece == RHS.CurPiece && CurChar == RHS.CurChar;
110 bool operator!=(const RopePieceBTreeIterator &RHS) const {
111 return !operator==(RHS);
114 RopePieceBTreeIterator& operator++() { // Preincrement
115 if (CurChar+1 < CurPiece->size())
122 RopePieceBTreeIterator operator++(int) { // Postincrement
123 RopePieceBTreeIterator tmp = *this; ++*this; return tmp;
126 llvm::StringRef piece() const {
127 return llvm::StringRef(&(*CurPiece)[0], CurPiece->size());
130 void MoveToNextPiece();
133 //===--------------------------------------------------------------------===//
134 // RopePieceBTree Class
135 //===--------------------------------------------------------------------===//
137 class RopePieceBTree {
138 void /*RopePieceBTreeNode*/ *Root;
142 RopePieceBTree(const RopePieceBTree &RHS);
143 RopePieceBTree &operator=(const RopePieceBTree &) = delete;
146 using iterator = RopePieceBTreeIterator;
148 iterator begin() const { return iterator(Root); }
149 iterator end() const { return iterator(); }
150 unsigned size() const;
151 unsigned empty() const { return size() == 0; }
155 void insert(unsigned Offset, const RopePiece &R);
157 void erase(unsigned Offset, unsigned NumBytes);
160 //===--------------------------------------------------------------------===//
162 //===--------------------------------------------------------------------===//
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.
168 RopePieceBTree Chunks;
170 /// We allocate space for string data out of a buffer of size AllocChunkSize.
171 /// This keeps track of how much space is left.
172 llvm::IntrusiveRefCntPtr<RopeRefCountString> AllocBuffer;
173 enum { AllocChunkSize = 4080 };
174 unsigned AllocOffs = AllocChunkSize;
177 RewriteRope() = default;
178 RewriteRope(const RewriteRope &RHS) : Chunks(RHS.Chunks) {}
180 using iterator = RopePieceBTree::iterator;
181 using const_iterator = RopePieceBTree::iterator;
183 iterator begin() const { return Chunks.begin(); }
184 iterator end() const { return Chunks.end(); }
185 unsigned size() const { return Chunks.size(); }
191 void assign(const char *Start, const char *End) {
194 Chunks.insert(0, MakeRopeString(Start, End));
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));
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);
210 RopePiece MakeRopeString(const char *Start, const char *End);
215 #endif // LLVM_CLANG_REWRITE_CORE_REWRITEROPE_H