clang  3.7.0
RewriteRope.cpp
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1 //===--- RewriteRope.cpp - 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 implements the RewriteRope class, which is a powerful string.
11 //
12 //===----------------------------------------------------------------------===//
13 
15 #include "clang/Basic/LLVM.h"
16 #include <algorithm>
17 using namespace clang;
18 
19 /// RewriteRope is a "strong" string class, designed to make insertions and
20 /// deletions in the middle of the string nearly constant time (really, they are
21 /// O(log N), but with a very low constant factor).
22 ///
23 /// The implementation of this datastructure is a conceptual linear sequence of
24 /// RopePiece elements. Each RopePiece represents a view on a separately
25 /// allocated and reference counted string. This means that splitting a very
26 /// long string can be done in constant time by splitting a RopePiece that
27 /// references the whole string into two rope pieces that reference each half.
28 /// Once split, another string can be inserted in between the two halves by
29 /// inserting a RopePiece in between the two others. All of this is very
30 /// inexpensive: it takes time proportional to the number of RopePieces, not the
31 /// length of the strings they represent.
32 ///
33 /// While a linear sequences of RopePieces is the conceptual model, the actual
34 /// implementation captures them in an adapted B+ Tree. Using a B+ tree (which
35 /// is a tree that keeps the values in the leaves and has where each node
36 /// contains a reasonable number of pointers to children/values) allows us to
37 /// maintain efficient operation when the RewriteRope contains a *huge* number
38 /// of RopePieces. The basic idea of the B+ Tree is that it allows us to find
39 /// the RopePiece corresponding to some offset very efficiently, and it
40 /// automatically balances itself on insertions of RopePieces (which can happen
41 /// for both insertions and erases of string ranges).
42 ///
43 /// The one wrinkle on the theory is that we don't attempt to keep the tree
44 /// properly balanced when erases happen. Erases of string data can both insert
45 /// new RopePieces (e.g. when the middle of some other rope piece is deleted,
46 /// which results in two rope pieces, which is just like an insert) or it can
47 /// reduce the number of RopePieces maintained by the B+Tree. In the case when
48 /// the number of RopePieces is reduced, we don't attempt to maintain the
49 /// standard 'invariant' that each node in the tree contains at least
50 /// 'WidthFactor' children/values. For our use cases, this doesn't seem to
51 /// matter.
52 ///
53 /// The implementation below is primarily implemented in terms of three classes:
54 /// RopePieceBTreeNode - Common base class for:
55 ///
56 /// RopePieceBTreeLeaf - Directly manages up to '2*WidthFactor' RopePiece
57 /// nodes. This directly represents a chunk of the string with those
58 /// RopePieces contatenated.
59 /// RopePieceBTreeInterior - An interior node in the B+ Tree, which manages
60 /// up to '2*WidthFactor' other nodes in the tree.
61 
62 
63 //===----------------------------------------------------------------------===//
64 // RopePieceBTreeNode Class
65 //===----------------------------------------------------------------------===//
66 
67 namespace {
68  /// RopePieceBTreeNode - Common base class of RopePieceBTreeLeaf and
69  /// RopePieceBTreeInterior. This provides some 'virtual' dispatching methods
70  /// and a flag that determines which subclass the instance is. Also
71  /// important, this node knows the full extend of the node, including any
72  /// children that it has. This allows efficient skipping over entire subtrees
73  /// when looking for an offset in the BTree.
74  class RopePieceBTreeNode {
75  protected:
76  /// WidthFactor - This controls the number of K/V slots held in the BTree:
77  /// how wide it is. Each level of the BTree is guaranteed to have at least
78  /// 'WidthFactor' elements in it (either ropepieces or children), (except
79  /// the root, which may have less) and may have at most 2*WidthFactor
80  /// elements.
81  enum { WidthFactor = 8 };
82 
83  /// Size - This is the number of bytes of file this node (including any
84  /// potential children) covers.
85  unsigned Size;
86 
87  /// IsLeaf - True if this is an instance of RopePieceBTreeLeaf, false if it
88  /// is an instance of RopePieceBTreeInterior.
89  bool IsLeaf;
90 
91  RopePieceBTreeNode(bool isLeaf) : Size(0), IsLeaf(isLeaf) {}
92  ~RopePieceBTreeNode() = default;
93 
94  public:
95  bool isLeaf() const { return IsLeaf; }
96  unsigned size() const { return Size; }
97 
98  void Destroy();
99 
100  /// split - Split the range containing the specified offset so that we are
101  /// guaranteed that there is a place to do an insertion at the specified
102  /// offset. The offset is relative, so "0" is the start of the node.
103  ///
104  /// If there is no space in this subtree for the extra piece, the extra tree
105  /// node is returned and must be inserted into a parent.
106  RopePieceBTreeNode *split(unsigned Offset);
107 
108  /// insert - Insert the specified ropepiece into this tree node at the
109  /// specified offset. The offset is relative, so "0" is the start of the
110  /// node.
111  ///
112  /// If there is no space in this subtree for the extra piece, the extra tree
113  /// node is returned and must be inserted into a parent.
114  RopePieceBTreeNode *insert(unsigned Offset, const RopePiece &R);
115 
116  /// erase - Remove NumBytes from this node at the specified offset. We are
117  /// guaranteed that there is a split at Offset.
118  void erase(unsigned Offset, unsigned NumBytes);
119 
120  };
121 } // end anonymous namespace
122 
123 //===----------------------------------------------------------------------===//
124 // RopePieceBTreeLeaf Class
125 //===----------------------------------------------------------------------===//
126 
127 namespace {
128  /// RopePieceBTreeLeaf - Directly manages up to '2*WidthFactor' RopePiece
129  /// nodes. This directly represents a chunk of the string with those
130  /// RopePieces contatenated. Since this is a B+Tree, all values (in this case
131  /// instances of RopePiece) are stored in leaves like this. To make iteration
132  /// over the leaves efficient, they maintain a singly linked list through the
133  /// NextLeaf field. This allows the B+Tree forward iterator to be constant
134  /// time for all increments.
135  class RopePieceBTreeLeaf : public RopePieceBTreeNode {
136  /// NumPieces - This holds the number of rope pieces currently active in the
137  /// Pieces array.
138  unsigned char NumPieces;
139 
140  /// Pieces - This tracks the file chunks currently in this leaf.
141  ///
142  RopePiece Pieces[2*WidthFactor];
143 
144  /// NextLeaf - This is a pointer to the next leaf in the tree, allowing
145  /// efficient in-order forward iteration of the tree without traversal.
146  RopePieceBTreeLeaf **PrevLeaf, *NextLeaf;
147  public:
148  RopePieceBTreeLeaf() : RopePieceBTreeNode(true), NumPieces(0),
149  PrevLeaf(nullptr), NextLeaf(nullptr) {}
150  ~RopePieceBTreeLeaf() {
151  if (PrevLeaf || NextLeaf)
152  removeFromLeafInOrder();
153  clear();
154  }
155 
156  bool isFull() const { return NumPieces == 2*WidthFactor; }
157 
158  /// clear - Remove all rope pieces from this leaf.
159  void clear() {
160  while (NumPieces)
161  Pieces[--NumPieces] = RopePiece();
162  Size = 0;
163  }
164 
165  unsigned getNumPieces() const { return NumPieces; }
166 
167  const RopePiece &getPiece(unsigned i) const {
168  assert(i < getNumPieces() && "Invalid piece ID");
169  return Pieces[i];
170  }
171 
172  const RopePieceBTreeLeaf *getNextLeafInOrder() const { return NextLeaf; }
173  void insertAfterLeafInOrder(RopePieceBTreeLeaf *Node) {
174  assert(!PrevLeaf && !NextLeaf && "Already in ordering");
175 
176  NextLeaf = Node->NextLeaf;
177  if (NextLeaf)
178  NextLeaf->PrevLeaf = &NextLeaf;
179  PrevLeaf = &Node->NextLeaf;
180  Node->NextLeaf = this;
181  }
182 
183  void removeFromLeafInOrder() {
184  if (PrevLeaf) {
185  *PrevLeaf = NextLeaf;
186  if (NextLeaf)
187  NextLeaf->PrevLeaf = PrevLeaf;
188  } else if (NextLeaf) {
189  NextLeaf->PrevLeaf = nullptr;
190  }
191  }
192 
193  /// FullRecomputeSizeLocally - This method recomputes the 'Size' field by
194  /// summing the size of all RopePieces.
195  void FullRecomputeSizeLocally() {
196  Size = 0;
197  for (unsigned i = 0, e = getNumPieces(); i != e; ++i)
198  Size += getPiece(i).size();
199  }
200 
201  /// split - Split the range containing the specified offset so that we are
202  /// guaranteed that there is a place to do an insertion at the specified
203  /// offset. The offset is relative, so "0" is the start of the node.
204  ///
205  /// If there is no space in this subtree for the extra piece, the extra tree
206  /// node is returned and must be inserted into a parent.
207  RopePieceBTreeNode *split(unsigned Offset);
208 
209  /// insert - Insert the specified ropepiece into this tree node at the
210  /// specified offset. The offset is relative, so "0" is the start of the
211  /// node.
212  ///
213  /// If there is no space in this subtree for the extra piece, the extra tree
214  /// node is returned and must be inserted into a parent.
215  RopePieceBTreeNode *insert(unsigned Offset, const RopePiece &R);
216 
217 
218  /// erase - Remove NumBytes from this node at the specified offset. We are
219  /// guaranteed that there is a split at Offset.
220  void erase(unsigned Offset, unsigned NumBytes);
221 
222  static inline bool classof(const RopePieceBTreeNode *N) {
223  return N->isLeaf();
224  }
225  };
226 } // end anonymous namespace
227 
228 /// split - Split the range containing the specified offset so that we are
229 /// guaranteed that there is a place to do an insertion at the specified
230 /// offset. The offset is relative, so "0" is the start of the node.
231 ///
232 /// If there is no space in this subtree for the extra piece, the extra tree
233 /// node is returned and must be inserted into a parent.
234 RopePieceBTreeNode *RopePieceBTreeLeaf::split(unsigned Offset) {
235  // Find the insertion point. We are guaranteed that there is a split at the
236  // specified offset so find it.
237  if (Offset == 0 || Offset == size()) {
238  // Fastpath for a common case. There is already a splitpoint at the end.
239  return nullptr;
240  }
241 
242  // Find the piece that this offset lands in.
243  unsigned PieceOffs = 0;
244  unsigned i = 0;
245  while (Offset >= PieceOffs+Pieces[i].size()) {
246  PieceOffs += Pieces[i].size();
247  ++i;
248  }
249 
250  // If there is already a split point at the specified offset, just return
251  // success.
252  if (PieceOffs == Offset)
253  return nullptr;
254 
255  // Otherwise, we need to split piece 'i' at Offset-PieceOffs. Convert Offset
256  // to being Piece relative.
257  unsigned IntraPieceOffset = Offset-PieceOffs;
258 
259  // We do this by shrinking the RopePiece and then doing an insert of the tail.
260  RopePiece Tail(Pieces[i].StrData, Pieces[i].StartOffs+IntraPieceOffset,
261  Pieces[i].EndOffs);
262  Size -= Pieces[i].size();
263  Pieces[i].EndOffs = Pieces[i].StartOffs+IntraPieceOffset;
264  Size += Pieces[i].size();
265 
266  return insert(Offset, Tail);
267 }
268 
269 
270 /// insert - Insert the specified RopePiece into this tree node at the
271 /// specified offset. The offset is relative, so "0" is the start of the node.
272 ///
273 /// If there is no space in this subtree for the extra piece, the extra tree
274 /// node is returned and must be inserted into a parent.
275 RopePieceBTreeNode *RopePieceBTreeLeaf::insert(unsigned Offset,
276  const RopePiece &R) {
277  // If this node is not full, insert the piece.
278  if (!isFull()) {
279  // Find the insertion point. We are guaranteed that there is a split at the
280  // specified offset so find it.
281  unsigned i = 0, e = getNumPieces();
282  if (Offset == size()) {
283  // Fastpath for a common case.
284  i = e;
285  } else {
286  unsigned SlotOffs = 0;
287  for (; Offset > SlotOffs; ++i)
288  SlotOffs += getPiece(i).size();
289  assert(SlotOffs == Offset && "Split didn't occur before insertion!");
290  }
291 
292  // For an insertion into a non-full leaf node, just insert the value in
293  // its sorted position. This requires moving later values over.
294  for (; i != e; --e)
295  Pieces[e] = Pieces[e-1];
296  Pieces[i] = R;
297  ++NumPieces;
298  Size += R.size();
299  return nullptr;
300  }
301 
302  // Otherwise, if this is leaf is full, split it in two halves. Since this
303  // node is full, it contains 2*WidthFactor values. We move the first
304  // 'WidthFactor' values to the LHS child (which we leave in this node) and
305  // move the last 'WidthFactor' values into the RHS child.
306 
307  // Create the new node.
308  RopePieceBTreeLeaf *NewNode = new RopePieceBTreeLeaf();
309 
310  // Move over the last 'WidthFactor' values from here to NewNode.
311  std::copy(&Pieces[WidthFactor], &Pieces[2*WidthFactor],
312  &NewNode->Pieces[0]);
313  // Replace old pieces with null RopePieces to drop refcounts.
314  std::fill(&Pieces[WidthFactor], &Pieces[2*WidthFactor], RopePiece());
315 
316  // Decrease the number of values in the two nodes.
317  NewNode->NumPieces = NumPieces = WidthFactor;
318 
319  // Recompute the two nodes' size.
320  NewNode->FullRecomputeSizeLocally();
321  FullRecomputeSizeLocally();
322 
323  // Update the list of leaves.
324  NewNode->insertAfterLeafInOrder(this);
325 
326  // These insertions can't fail.
327  if (this->size() >= Offset)
328  this->insert(Offset, R);
329  else
330  NewNode->insert(Offset - this->size(), R);
331  return NewNode;
332 }
333 
334 /// erase - Remove NumBytes from this node at the specified offset. We are
335 /// guaranteed that there is a split at Offset.
336 void RopePieceBTreeLeaf::erase(unsigned Offset, unsigned NumBytes) {
337  // Since we are guaranteed that there is a split at Offset, we start by
338  // finding the Piece that starts there.
339  unsigned PieceOffs = 0;
340  unsigned i = 0;
341  for (; Offset > PieceOffs; ++i)
342  PieceOffs += getPiece(i).size();
343  assert(PieceOffs == Offset && "Split didn't occur before erase!");
344 
345  unsigned StartPiece = i;
346 
347  // Figure out how many pieces completely cover 'NumBytes'. We want to remove
348  // all of them.
349  for (; Offset+NumBytes > PieceOffs+getPiece(i).size(); ++i)
350  PieceOffs += getPiece(i).size();
351 
352  // If we exactly include the last one, include it in the region to delete.
353  if (Offset+NumBytes == PieceOffs+getPiece(i).size())
354  PieceOffs += getPiece(i).size(), ++i;
355 
356  // If we completely cover some RopePieces, erase them now.
357  if (i != StartPiece) {
358  unsigned NumDeleted = i-StartPiece;
359  for (; i != getNumPieces(); ++i)
360  Pieces[i-NumDeleted] = Pieces[i];
361 
362  // Drop references to dead rope pieces.
363  std::fill(&Pieces[getNumPieces()-NumDeleted], &Pieces[getNumPieces()],
364  RopePiece());
365  NumPieces -= NumDeleted;
366 
367  unsigned CoverBytes = PieceOffs-Offset;
368  NumBytes -= CoverBytes;
369  Size -= CoverBytes;
370  }
371 
372  // If we completely removed some stuff, we could be done.
373  if (NumBytes == 0) return;
374 
375  // Okay, now might be erasing part of some Piece. If this is the case, then
376  // move the start point of the piece.
377  assert(getPiece(StartPiece).size() > NumBytes);
378  Pieces[StartPiece].StartOffs += NumBytes;
379 
380  // The size of this node just shrunk by NumBytes.
381  Size -= NumBytes;
382 }
383 
384 //===----------------------------------------------------------------------===//
385 // RopePieceBTreeInterior Class
386 //===----------------------------------------------------------------------===//
387 
388 namespace {
389  /// RopePieceBTreeInterior - This represents an interior node in the B+Tree,
390  /// which holds up to 2*WidthFactor pointers to child nodes.
391  class RopePieceBTreeInterior : public RopePieceBTreeNode {
392  /// NumChildren - This holds the number of children currently active in the
393  /// Children array.
394  unsigned char NumChildren;
395  RopePieceBTreeNode *Children[2*WidthFactor];
396  public:
397  RopePieceBTreeInterior() : RopePieceBTreeNode(false), NumChildren(0) {}
398 
399  RopePieceBTreeInterior(RopePieceBTreeNode *LHS, RopePieceBTreeNode *RHS)
400  : RopePieceBTreeNode(false) {
401  Children[0] = LHS;
402  Children[1] = RHS;
403  NumChildren = 2;
404  Size = LHS->size() + RHS->size();
405  }
406 
407  ~RopePieceBTreeInterior() {
408  for (unsigned i = 0, e = getNumChildren(); i != e; ++i)
409  Children[i]->Destroy();
410  }
411 
412  bool isFull() const { return NumChildren == 2*WidthFactor; }
413 
414  unsigned getNumChildren() const { return NumChildren; }
415  const RopePieceBTreeNode *getChild(unsigned i) const {
416  assert(i < NumChildren && "invalid child #");
417  return Children[i];
418  }
419  RopePieceBTreeNode *getChild(unsigned i) {
420  assert(i < NumChildren && "invalid child #");
421  return Children[i];
422  }
423 
424  /// FullRecomputeSizeLocally - Recompute the Size field of this node by
425  /// summing up the sizes of the child nodes.
426  void FullRecomputeSizeLocally() {
427  Size = 0;
428  for (unsigned i = 0, e = getNumChildren(); i != e; ++i)
429  Size += getChild(i)->size();
430  }
431 
432 
433  /// split - Split the range containing the specified offset so that we are
434  /// guaranteed that there is a place to do an insertion at the specified
435  /// offset. The offset is relative, so "0" is the start of the node.
436  ///
437  /// If there is no space in this subtree for the extra piece, the extra tree
438  /// node is returned and must be inserted into a parent.
439  RopePieceBTreeNode *split(unsigned Offset);
440 
441 
442  /// insert - Insert the specified ropepiece into this tree node at the
443  /// specified offset. The offset is relative, so "0" is the start of the
444  /// node.
445  ///
446  /// If there is no space in this subtree for the extra piece, the extra tree
447  /// node is returned and must be inserted into a parent.
448  RopePieceBTreeNode *insert(unsigned Offset, const RopePiece &R);
449 
450  /// HandleChildPiece - A child propagated an insertion result up to us.
451  /// Insert the new child, and/or propagate the result further up the tree.
452  RopePieceBTreeNode *HandleChildPiece(unsigned i, RopePieceBTreeNode *RHS);
453 
454  /// erase - Remove NumBytes from this node at the specified offset. We are
455  /// guaranteed that there is a split at Offset.
456  void erase(unsigned Offset, unsigned NumBytes);
457 
458  static inline bool classof(const RopePieceBTreeNode *N) {
459  return !N->isLeaf();
460  }
461  };
462 } // end anonymous namespace
463 
464 /// split - Split the range containing the specified offset so that we are
465 /// guaranteed that there is a place to do an insertion at the specified
466 /// offset. The offset is relative, so "0" is the start of the node.
467 ///
468 /// If there is no space in this subtree for the extra piece, the extra tree
469 /// node is returned and must be inserted into a parent.
470 RopePieceBTreeNode *RopePieceBTreeInterior::split(unsigned Offset) {
471  // Figure out which child to split.
472  if (Offset == 0 || Offset == size())
473  return nullptr; // If we have an exact offset, we're already split.
474 
475  unsigned ChildOffset = 0;
476  unsigned i = 0;
477  for (; Offset >= ChildOffset+getChild(i)->size(); ++i)
478  ChildOffset += getChild(i)->size();
479 
480  // If already split there, we're done.
481  if (ChildOffset == Offset)
482  return nullptr;
483 
484  // Otherwise, recursively split the child.
485  if (RopePieceBTreeNode *RHS = getChild(i)->split(Offset-ChildOffset))
486  return HandleChildPiece(i, RHS);
487  return nullptr; // Done!
488 }
489 
490 /// insert - Insert the specified ropepiece into this tree node at the
491 /// specified offset. The offset is relative, so "0" is the start of the
492 /// node.
493 ///
494 /// If there is no space in this subtree for the extra piece, the extra tree
495 /// node is returned and must be inserted into a parent.
496 RopePieceBTreeNode *RopePieceBTreeInterior::insert(unsigned Offset,
497  const RopePiece &R) {
498  // Find the insertion point. We are guaranteed that there is a split at the
499  // specified offset so find it.
500  unsigned i = 0, e = getNumChildren();
501 
502  unsigned ChildOffs = 0;
503  if (Offset == size()) {
504  // Fastpath for a common case. Insert at end of last child.
505  i = e-1;
506  ChildOffs = size()-getChild(i)->size();
507  } else {
508  for (; Offset > ChildOffs+getChild(i)->size(); ++i)
509  ChildOffs += getChild(i)->size();
510  }
511 
512  Size += R.size();
513 
514  // Insert at the end of this child.
515  if (RopePieceBTreeNode *RHS = getChild(i)->insert(Offset-ChildOffs, R))
516  return HandleChildPiece(i, RHS);
517 
518  return nullptr;
519 }
520 
521 /// HandleChildPiece - A child propagated an insertion result up to us.
522 /// Insert the new child, and/or propagate the result further up the tree.
523 RopePieceBTreeNode *
524 RopePieceBTreeInterior::HandleChildPiece(unsigned i, RopePieceBTreeNode *RHS) {
525  // Otherwise the child propagated a subtree up to us as a new child. See if
526  // we have space for it here.
527  if (!isFull()) {
528  // Insert RHS after child 'i'.
529  if (i + 1 != getNumChildren())
530  memmove(&Children[i+2], &Children[i+1],
531  (getNumChildren()-i-1)*sizeof(Children[0]));
532  Children[i+1] = RHS;
533  ++NumChildren;
534  return nullptr;
535  }
536 
537  // Okay, this node is full. Split it in half, moving WidthFactor children to
538  // a newly allocated interior node.
539 
540  // Create the new node.
541  RopePieceBTreeInterior *NewNode = new RopePieceBTreeInterior();
542 
543  // Move over the last 'WidthFactor' values from here to NewNode.
544  memcpy(&NewNode->Children[0], &Children[WidthFactor],
545  WidthFactor*sizeof(Children[0]));
546 
547  // Decrease the number of values in the two nodes.
548  NewNode->NumChildren = NumChildren = WidthFactor;
549 
550  // Finally, insert the two new children in the side the can (now) hold them.
551  // These insertions can't fail.
552  if (i < WidthFactor)
553  this->HandleChildPiece(i, RHS);
554  else
555  NewNode->HandleChildPiece(i-WidthFactor, RHS);
556 
557  // Recompute the two nodes' size.
558  NewNode->FullRecomputeSizeLocally();
559  FullRecomputeSizeLocally();
560  return NewNode;
561 }
562 
563 /// erase - Remove NumBytes from this node at the specified offset. We are
564 /// guaranteed that there is a split at Offset.
565 void RopePieceBTreeInterior::erase(unsigned Offset, unsigned NumBytes) {
566  // This will shrink this node by NumBytes.
567  Size -= NumBytes;
568 
569  // Find the first child that overlaps with Offset.
570  unsigned i = 0;
571  for (; Offset >= getChild(i)->size(); ++i)
572  Offset -= getChild(i)->size();
573 
574  // Propagate the delete request into overlapping children, or completely
575  // delete the children as appropriate.
576  while (NumBytes) {
577  RopePieceBTreeNode *CurChild = getChild(i);
578 
579  // If we are deleting something contained entirely in the child, pass on the
580  // request.
581  if (Offset+NumBytes < CurChild->size()) {
582  CurChild->erase(Offset, NumBytes);
583  return;
584  }
585 
586  // If this deletion request starts somewhere in the middle of the child, it
587  // must be deleting to the end of the child.
588  if (Offset) {
589  unsigned BytesFromChild = CurChild->size()-Offset;
590  CurChild->erase(Offset, BytesFromChild);
591  NumBytes -= BytesFromChild;
592  // Start at the beginning of the next child.
593  Offset = 0;
594  ++i;
595  continue;
596  }
597 
598  // If the deletion request completely covers the child, delete it and move
599  // the rest down.
600  NumBytes -= CurChild->size();
601  CurChild->Destroy();
602  --NumChildren;
603  if (i != getNumChildren())
604  memmove(&Children[i], &Children[i+1],
605  (getNumChildren()-i)*sizeof(Children[0]));
606  }
607 }
608 
609 //===----------------------------------------------------------------------===//
610 // RopePieceBTreeNode Implementation
611 //===----------------------------------------------------------------------===//
612 
613 void RopePieceBTreeNode::Destroy() {
614  if (RopePieceBTreeLeaf *Leaf = dyn_cast<RopePieceBTreeLeaf>(this))
615  delete Leaf;
616  else
617  delete cast<RopePieceBTreeInterior>(this);
618 }
619 
620 /// split - Split the range containing the specified offset so that we are
621 /// guaranteed that there is a place to do an insertion at the specified
622 /// offset. The offset is relative, so "0" is the start of the node.
623 ///
624 /// If there is no space in this subtree for the extra piece, the extra tree
625 /// node is returned and must be inserted into a parent.
626 RopePieceBTreeNode *RopePieceBTreeNode::split(unsigned Offset) {
627  assert(Offset <= size() && "Invalid offset to split!");
628  if (RopePieceBTreeLeaf *Leaf = dyn_cast<RopePieceBTreeLeaf>(this))
629  return Leaf->split(Offset);
630  return cast<RopePieceBTreeInterior>(this)->split(Offset);
631 }
632 
633 /// insert - Insert the specified ropepiece into this tree node at the
634 /// specified offset. The offset is relative, so "0" is the start of the
635 /// node.
636 ///
637 /// If there is no space in this subtree for the extra piece, the extra tree
638 /// node is returned and must be inserted into a parent.
639 RopePieceBTreeNode *RopePieceBTreeNode::insert(unsigned Offset,
640  const RopePiece &R) {
641  assert(Offset <= size() && "Invalid offset to insert!");
642  if (RopePieceBTreeLeaf *Leaf = dyn_cast<RopePieceBTreeLeaf>(this))
643  return Leaf->insert(Offset, R);
644  return cast<RopePieceBTreeInterior>(this)->insert(Offset, R);
645 }
646 
647 /// erase - Remove NumBytes from this node at the specified offset. We are
648 /// guaranteed that there is a split at Offset.
649 void RopePieceBTreeNode::erase(unsigned Offset, unsigned NumBytes) {
650  assert(Offset+NumBytes <= size() && "Invalid offset to erase!");
651  if (RopePieceBTreeLeaf *Leaf = dyn_cast<RopePieceBTreeLeaf>(this))
652  return Leaf->erase(Offset, NumBytes);
653  return cast<RopePieceBTreeInterior>(this)->erase(Offset, NumBytes);
654 }
655 
656 
657 //===----------------------------------------------------------------------===//
658 // RopePieceBTreeIterator Implementation
659 //===----------------------------------------------------------------------===//
660 
661 static const RopePieceBTreeLeaf *getCN(const void *P) {
662  return static_cast<const RopePieceBTreeLeaf*>(P);
663 }
664 
665 // begin iterator.
667  const RopePieceBTreeNode *N = static_cast<const RopePieceBTreeNode*>(n);
668 
669  // Walk down the left side of the tree until we get to a leaf.
670  while (const RopePieceBTreeInterior *IN = dyn_cast<RopePieceBTreeInterior>(N))
671  N = IN->getChild(0);
672 
673  // We must have at least one leaf.
674  CurNode = cast<RopePieceBTreeLeaf>(N);
675 
676  // If we found a leaf that happens to be empty, skip over it until we get
677  // to something full.
678  while (CurNode && getCN(CurNode)->getNumPieces() == 0)
679  CurNode = getCN(CurNode)->getNextLeafInOrder();
680 
681  if (CurNode)
682  CurPiece = &getCN(CurNode)->getPiece(0);
683  else // Empty tree, this is an end() iterator.
684  CurPiece = nullptr;
685  CurChar = 0;
686 }
687 
689  if (CurPiece != &getCN(CurNode)->getPiece(getCN(CurNode)->getNumPieces()-1)) {
690  CurChar = 0;
691  ++CurPiece;
692  return;
693  }
694 
695  // Find the next non-empty leaf node.
696  do
697  CurNode = getCN(CurNode)->getNextLeafInOrder();
698  while (CurNode && getCN(CurNode)->getNumPieces() == 0);
699 
700  if (CurNode)
701  CurPiece = &getCN(CurNode)->getPiece(0);
702  else // Hit end().
703  CurPiece = nullptr;
704  CurChar = 0;
705 }
706 
707 //===----------------------------------------------------------------------===//
708 // RopePieceBTree Implementation
709 //===----------------------------------------------------------------------===//
710 
711 static RopePieceBTreeNode *getRoot(void *P) {
712  return static_cast<RopePieceBTreeNode*>(P);
713 }
714 
716  Root = new RopePieceBTreeLeaf();
717 }
719  assert(RHS.empty() && "Can't copy non-empty tree yet");
720  Root = new RopePieceBTreeLeaf();
721 }
723  getRoot(Root)->Destroy();
724 }
725 
726 unsigned RopePieceBTree::size() const {
727  return getRoot(Root)->size();
728 }
729 
731  if (RopePieceBTreeLeaf *Leaf = dyn_cast<RopePieceBTreeLeaf>(getRoot(Root)))
732  Leaf->clear();
733  else {
734  getRoot(Root)->Destroy();
735  Root = new RopePieceBTreeLeaf();
736  }
737 }
738 
739 void RopePieceBTree::insert(unsigned Offset, const RopePiece &R) {
740  // #1. Split at Offset.
741  if (RopePieceBTreeNode *RHS = getRoot(Root)->split(Offset))
742  Root = new RopePieceBTreeInterior(getRoot(Root), RHS);
743 
744  // #2. Do the insertion.
745  if (RopePieceBTreeNode *RHS = getRoot(Root)->insert(Offset, R))
746  Root = new RopePieceBTreeInterior(getRoot(Root), RHS);
747 }
748 
749 void RopePieceBTree::erase(unsigned Offset, unsigned NumBytes) {
750  // #1. Split at Offset.
751  if (RopePieceBTreeNode *RHS = getRoot(Root)->split(Offset))
752  Root = new RopePieceBTreeInterior(getRoot(Root), RHS);
753 
754  // #2. Do the erasing.
755  getRoot(Root)->erase(Offset, NumBytes);
756 }
757 
758 //===----------------------------------------------------------------------===//
759 // RewriteRope Implementation
760 //===----------------------------------------------------------------------===//
761 
762 /// MakeRopeString - This copies the specified byte range into some instance of
763 /// RopeRefCountString, and return a RopePiece that represents it. This uses
764 /// the AllocBuffer object to aggregate requests for small strings into one
765 /// allocation instead of doing tons of tiny allocations.
766 RopePiece RewriteRope::MakeRopeString(const char *Start, const char *End) {
767  unsigned Len = End-Start;
768  assert(Len && "Zero length RopePiece is invalid!");
769 
770  // If we have space for this string in the current alloc buffer, use it.
771  if (AllocOffs+Len <= AllocChunkSize) {
772  memcpy(AllocBuffer->Data+AllocOffs, Start, Len);
773  AllocOffs += Len;
774  return RopePiece(AllocBuffer, AllocOffs-Len, AllocOffs);
775  }
776 
777  // If we don't have enough room because this specific allocation is huge,
778  // just allocate a new rope piece for it alone.
779  if (Len > AllocChunkSize) {
780  unsigned Size = End-Start+sizeof(RopeRefCountString)-1;
781  RopeRefCountString *Res =
782  reinterpret_cast<RopeRefCountString *>(new char[Size]);
783  Res->RefCount = 0;
784  memcpy(Res->Data, Start, End-Start);
785  return RopePiece(Res, 0, End-Start);
786  }
787 
788  // Otherwise, this was a small request but we just don't have space for it
789  // Make a new chunk and share it with later allocations.
790 
791  unsigned AllocSize = offsetof(RopeRefCountString, Data) + AllocChunkSize;
792  RopeRefCountString *Res =
793  reinterpret_cast<RopeRefCountString *>(new char[AllocSize]);
794  Res->RefCount = 0;
795  memcpy(Res->Data, Start, Len);
796  AllocBuffer = Res;
797  AllocOffs = Len;
798 
799  return RopePiece(AllocBuffer, 0, Len);
800 }
801 
802 
unsigned empty() const
Definition: RewriteRope.h:149
void insert(unsigned Offset, const RopePiece &R)
uint32_t Offset
Definition: CacheTokens.cpp:43
Forward-declares and imports various common LLVM datatypes that clang wants to use unqualified...
AnnotatingParser & P
void erase(unsigned Offset, unsigned NumBytes)
const SmallVectorImpl< AnnotatedLine * >::const_iterator End
unsigned size() const
#define offsetof(t, d)
Definition: stddef.h:120
#define false
Definition: stdbool.h:33
unsigned size() const
Definition: RewriteRope.h:77
virtual void clear()
static RopePieceBTreeNode * getRoot(void *P)
ast_type_traits::DynTypedNode Node
static bool classof(const OMPClause *T)
static const RopePieceBTreeLeaf * getCN(const void *P)
#define true
Definition: stdbool.h:32