| //===--- RewriteRope.cpp - Rope specialized for rewriter --------*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements the RewriteRope class, which is a powerful string. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "clang/Rewrite/Core/RewriteRope.h" |
| #include "clang/Basic/LLVM.h" |
| #include <algorithm> |
| using namespace clang; |
| |
| /// RewriteRope is a "strong" string class, designed to make insertions and |
| /// deletions in the middle of the string nearly constant time (really, they are |
| /// O(log N), but with a very low constant factor). |
| /// |
| /// The implementation of this datastructure is a conceptual linear sequence of |
| /// RopePiece elements. Each RopePiece represents a view on a separately |
| /// allocated and reference counted string. This means that splitting a very |
| /// long string can be done in constant time by splitting a RopePiece that |
| /// references the whole string into two rope pieces that reference each half. |
| /// Once split, another string can be inserted in between the two halves by |
| /// inserting a RopePiece in between the two others. All of this is very |
| /// inexpensive: it takes time proportional to the number of RopePieces, not the |
| /// length of the strings they represent. |
| /// |
| /// While a linear sequences of RopePieces is the conceptual model, the actual |
| /// implementation captures them in an adapted B+ Tree. Using a B+ tree (which |
| /// is a tree that keeps the values in the leaves and has where each node |
| /// contains a reasonable number of pointers to children/values) allows us to |
| /// maintain efficient operation when the RewriteRope contains a *huge* number |
| /// of RopePieces. The basic idea of the B+ Tree is that it allows us to find |
| /// the RopePiece corresponding to some offset very efficiently, and it |
| /// automatically balances itself on insertions of RopePieces (which can happen |
| /// for both insertions and erases of string ranges). |
| /// |
| /// The one wrinkle on the theory is that we don't attempt to keep the tree |
| /// properly balanced when erases happen. Erases of string data can both insert |
| /// new RopePieces (e.g. when the middle of some other rope piece is deleted, |
| /// which results in two rope pieces, which is just like an insert) or it can |
| /// reduce the number of RopePieces maintained by the B+Tree. In the case when |
| /// the number of RopePieces is reduced, we don't attempt to maintain the |
| /// standard 'invariant' that each node in the tree contains at least |
| /// 'WidthFactor' children/values. For our use cases, this doesn't seem to |
| /// matter. |
| /// |
| /// The implementation below is primarily implemented in terms of three classes: |
| /// RopePieceBTreeNode - Common base class for: |
| /// |
| /// RopePieceBTreeLeaf - Directly manages up to '2*WidthFactor' RopePiece |
| /// nodes. This directly represents a chunk of the string with those |
| /// RopePieces contatenated. |
| /// RopePieceBTreeInterior - An interior node in the B+ Tree, which manages |
| /// up to '2*WidthFactor' other nodes in the tree. |
| |
| |
| //===----------------------------------------------------------------------===// |
| // RopePieceBTreeNode Class |
| //===----------------------------------------------------------------------===// |
| |
| namespace { |
| /// RopePieceBTreeNode - Common base class of RopePieceBTreeLeaf and |
| /// RopePieceBTreeInterior. This provides some 'virtual' dispatching methods |
| /// and a flag that determines which subclass the instance is. Also |
| /// important, this node knows the full extend of the node, including any |
| /// children that it has. This allows efficient skipping over entire subtrees |
| /// when looking for an offset in the BTree. |
| class RopePieceBTreeNode { |
| protected: |
| /// WidthFactor - This controls the number of K/V slots held in the BTree: |
| /// how wide it is. Each level of the BTree is guaranteed to have at least |
| /// 'WidthFactor' elements in it (either ropepieces or children), (except |
| /// the root, which may have less) and may have at most 2*WidthFactor |
| /// elements. |
| enum { WidthFactor = 8 }; |
| |
| /// Size - This is the number of bytes of file this node (including any |
| /// potential children) covers. |
| unsigned Size; |
| |
| /// IsLeaf - True if this is an instance of RopePieceBTreeLeaf, false if it |
| /// is an instance of RopePieceBTreeInterior. |
| bool IsLeaf; |
| |
| RopePieceBTreeNode(bool isLeaf) : Size(0), IsLeaf(isLeaf) {} |
| ~RopePieceBTreeNode() = default; |
| |
| public: |
| bool isLeaf() const { return IsLeaf; } |
| unsigned size() const { return Size; } |
| |
| void Destroy(); |
| |
| /// split - Split the range containing the specified offset so that we are |
| /// guaranteed that there is a place to do an insertion at the specified |
| /// offset. The offset is relative, so "0" is the start of the node. |
| /// |
| /// If there is no space in this subtree for the extra piece, the extra tree |
| /// node is returned and must be inserted into a parent. |
| RopePieceBTreeNode *split(unsigned Offset); |
| |
| /// insert - Insert the specified ropepiece into this tree node at the |
| /// specified offset. The offset is relative, so "0" is the start of the |
| /// node. |
| /// |
| /// If there is no space in this subtree for the extra piece, the extra tree |
| /// node is returned and must be inserted into a parent. |
| RopePieceBTreeNode *insert(unsigned Offset, const RopePiece &R); |
| |
| /// erase - Remove NumBytes from this node at the specified offset. We are |
| /// guaranteed that there is a split at Offset. |
| void erase(unsigned Offset, unsigned NumBytes); |
| |
| }; |
| } // end anonymous namespace |
| |
| //===----------------------------------------------------------------------===// |
| // RopePieceBTreeLeaf Class |
| //===----------------------------------------------------------------------===// |
| |
| namespace { |
| /// RopePieceBTreeLeaf - Directly manages up to '2*WidthFactor' RopePiece |
| /// nodes. This directly represents a chunk of the string with those |
| /// RopePieces contatenated. Since this is a B+Tree, all values (in this case |
| /// instances of RopePiece) are stored in leaves like this. To make iteration |
| /// over the leaves efficient, they maintain a singly linked list through the |
| /// NextLeaf field. This allows the B+Tree forward iterator to be constant |
| /// time for all increments. |
| class RopePieceBTreeLeaf : public RopePieceBTreeNode { |
| /// NumPieces - This holds the number of rope pieces currently active in the |
| /// Pieces array. |
| unsigned char NumPieces; |
| |
| /// Pieces - This tracks the file chunks currently in this leaf. |
| /// |
| RopePiece Pieces[2*WidthFactor]; |
| |
| /// NextLeaf - This is a pointer to the next leaf in the tree, allowing |
| /// efficient in-order forward iteration of the tree without traversal. |
| RopePieceBTreeLeaf **PrevLeaf, *NextLeaf; |
| public: |
| RopePieceBTreeLeaf() : RopePieceBTreeNode(true), NumPieces(0), |
| PrevLeaf(nullptr), NextLeaf(nullptr) {} |
| ~RopePieceBTreeLeaf() { |
| if (PrevLeaf || NextLeaf) |
| removeFromLeafInOrder(); |
| clear(); |
| } |
| |
| bool isFull() const { return NumPieces == 2*WidthFactor; } |
| |
| /// clear - Remove all rope pieces from this leaf. |
| void clear() { |
| while (NumPieces) |
| Pieces[--NumPieces] = RopePiece(); |
| Size = 0; |
| } |
| |
| unsigned getNumPieces() const { return NumPieces; } |
| |
| const RopePiece &getPiece(unsigned i) const { |
| assert(i < getNumPieces() && "Invalid piece ID"); |
| return Pieces[i]; |
| } |
| |
| const RopePieceBTreeLeaf *getNextLeafInOrder() const { return NextLeaf; } |
| void insertAfterLeafInOrder(RopePieceBTreeLeaf *Node) { |
| assert(!PrevLeaf && !NextLeaf && "Already in ordering"); |
| |
| NextLeaf = Node->NextLeaf; |
| if (NextLeaf) |
| NextLeaf->PrevLeaf = &NextLeaf; |
| PrevLeaf = &Node->NextLeaf; |
| Node->NextLeaf = this; |
| } |
| |
| void removeFromLeafInOrder() { |
| if (PrevLeaf) { |
| *PrevLeaf = NextLeaf; |
| if (NextLeaf) |
| NextLeaf->PrevLeaf = PrevLeaf; |
| } else if (NextLeaf) { |
| NextLeaf->PrevLeaf = nullptr; |
| } |
| } |
| |
| /// FullRecomputeSizeLocally - This method recomputes the 'Size' field by |
| /// summing the size of all RopePieces. |
| void FullRecomputeSizeLocally() { |
| Size = 0; |
| for (unsigned i = 0, e = getNumPieces(); i != e; ++i) |
| Size += getPiece(i).size(); |
| } |
| |
| /// split - Split the range containing the specified offset so that we are |
| /// guaranteed that there is a place to do an insertion at the specified |
| /// offset. The offset is relative, so "0" is the start of the node. |
| /// |
| /// If there is no space in this subtree for the extra piece, the extra tree |
| /// node is returned and must be inserted into a parent. |
| RopePieceBTreeNode *split(unsigned Offset); |
| |
| /// insert - Insert the specified ropepiece into this tree node at the |
| /// specified offset. The offset is relative, so "0" is the start of the |
| /// node. |
| /// |
| /// If there is no space in this subtree for the extra piece, the extra tree |
| /// node is returned and must be inserted into a parent. |
| RopePieceBTreeNode *insert(unsigned Offset, const RopePiece &R); |
| |
| |
| /// erase - Remove NumBytes from this node at the specified offset. We are |
| /// guaranteed that there is a split at Offset. |
| void erase(unsigned Offset, unsigned NumBytes); |
| |
| static inline bool classof(const RopePieceBTreeNode *N) { |
| return N->isLeaf(); |
| } |
| }; |
| } // end anonymous namespace |
| |
| /// split - Split the range containing the specified offset so that we are |
| /// guaranteed that there is a place to do an insertion at the specified |
| /// offset. The offset is relative, so "0" is the start of the node. |
| /// |
| /// If there is no space in this subtree for the extra piece, the extra tree |
| /// node is returned and must be inserted into a parent. |
| RopePieceBTreeNode *RopePieceBTreeLeaf::split(unsigned Offset) { |
| // Find the insertion point. We are guaranteed that there is a split at the |
| // specified offset so find it. |
| if (Offset == 0 || Offset == size()) { |
| // Fastpath for a common case. There is already a splitpoint at the end. |
| return nullptr; |
| } |
| |
| // Find the piece that this offset lands in. |
| unsigned PieceOffs = 0; |
| unsigned i = 0; |
| while (Offset >= PieceOffs+Pieces[i].size()) { |
| PieceOffs += Pieces[i].size(); |
| ++i; |
| } |
| |
| // If there is already a split point at the specified offset, just return |
| // success. |
| if (PieceOffs == Offset) |
| return nullptr; |
| |
| // Otherwise, we need to split piece 'i' at Offset-PieceOffs. Convert Offset |
| // to being Piece relative. |
| unsigned IntraPieceOffset = Offset-PieceOffs; |
| |
| // We do this by shrinking the RopePiece and then doing an insert of the tail. |
| RopePiece Tail(Pieces[i].StrData, Pieces[i].StartOffs+IntraPieceOffset, |
| Pieces[i].EndOffs); |
| Size -= Pieces[i].size(); |
| Pieces[i].EndOffs = Pieces[i].StartOffs+IntraPieceOffset; |
| Size += Pieces[i].size(); |
| |
| return insert(Offset, Tail); |
| } |
| |
| |
| /// insert - Insert the specified RopePiece into this tree node at the |
| /// specified offset. The offset is relative, so "0" is the start of the node. |
| /// |
| /// If there is no space in this subtree for the extra piece, the extra tree |
| /// node is returned and must be inserted into a parent. |
| RopePieceBTreeNode *RopePieceBTreeLeaf::insert(unsigned Offset, |
| const RopePiece &R) { |
| // If this node is not full, insert the piece. |
| if (!isFull()) { |
| // Find the insertion point. We are guaranteed that there is a split at the |
| // specified offset so find it. |
| unsigned i = 0, e = getNumPieces(); |
| if (Offset == size()) { |
| // Fastpath for a common case. |
| i = e; |
| } else { |
| unsigned SlotOffs = 0; |
| for (; Offset > SlotOffs; ++i) |
| SlotOffs += getPiece(i).size(); |
| assert(SlotOffs == Offset && "Split didn't occur before insertion!"); |
| } |
| |
| // For an insertion into a non-full leaf node, just insert the value in |
| // its sorted position. This requires moving later values over. |
| for (; i != e; --e) |
| Pieces[e] = Pieces[e-1]; |
| Pieces[i] = R; |
| ++NumPieces; |
| Size += R.size(); |
| return nullptr; |
| } |
| |
| // Otherwise, if this is leaf is full, split it in two halves. Since this |
| // node is full, it contains 2*WidthFactor values. We move the first |
| // 'WidthFactor' values to the LHS child (which we leave in this node) and |
| // move the last 'WidthFactor' values into the RHS child. |
| |
| // Create the new node. |
| RopePieceBTreeLeaf *NewNode = new RopePieceBTreeLeaf(); |
| |
| // Move over the last 'WidthFactor' values from here to NewNode. |
| std::copy(&Pieces[WidthFactor], &Pieces[2*WidthFactor], |
| &NewNode->Pieces[0]); |
| // Replace old pieces with null RopePieces to drop refcounts. |
| std::fill(&Pieces[WidthFactor], &Pieces[2*WidthFactor], RopePiece()); |
| |
| // Decrease the number of values in the two nodes. |
| NewNode->NumPieces = NumPieces = WidthFactor; |
| |
| // Recompute the two nodes' size. |
| NewNode->FullRecomputeSizeLocally(); |
| FullRecomputeSizeLocally(); |
| |
| // Update the list of leaves. |
| NewNode->insertAfterLeafInOrder(this); |
| |
| // These insertions can't fail. |
| if (this->size() >= Offset) |
| this->insert(Offset, R); |
| else |
| NewNode->insert(Offset - this->size(), R); |
| return NewNode; |
| } |
| |
| /// erase - Remove NumBytes from this node at the specified offset. We are |
| /// guaranteed that there is a split at Offset. |
| void RopePieceBTreeLeaf::erase(unsigned Offset, unsigned NumBytes) { |
| // Since we are guaranteed that there is a split at Offset, we start by |
| // finding the Piece that starts there. |
| unsigned PieceOffs = 0; |
| unsigned i = 0; |
| for (; Offset > PieceOffs; ++i) |
| PieceOffs += getPiece(i).size(); |
| assert(PieceOffs == Offset && "Split didn't occur before erase!"); |
| |
| unsigned StartPiece = i; |
| |
| // Figure out how many pieces completely cover 'NumBytes'. We want to remove |
| // all of them. |
| for (; Offset+NumBytes > PieceOffs+getPiece(i).size(); ++i) |
| PieceOffs += getPiece(i).size(); |
| |
| // If we exactly include the last one, include it in the region to delete. |
| if (Offset+NumBytes == PieceOffs+getPiece(i).size()) { |
| PieceOffs += getPiece(i).size(); |
| ++i; |
| } |
| |
| // If we completely cover some RopePieces, erase them now. |
| if (i != StartPiece) { |
| unsigned NumDeleted = i-StartPiece; |
| for (; i != getNumPieces(); ++i) |
| Pieces[i-NumDeleted] = Pieces[i]; |
| |
| // Drop references to dead rope pieces. |
| std::fill(&Pieces[getNumPieces()-NumDeleted], &Pieces[getNumPieces()], |
| RopePiece()); |
| NumPieces -= NumDeleted; |
| |
| unsigned CoverBytes = PieceOffs-Offset; |
| NumBytes -= CoverBytes; |
| Size -= CoverBytes; |
| } |
| |
| // If we completely removed some stuff, we could be done. |
| if (NumBytes == 0) return; |
| |
| // Okay, now might be erasing part of some Piece. If this is the case, then |
| // move the start point of the piece. |
| assert(getPiece(StartPiece).size() > NumBytes); |
| Pieces[StartPiece].StartOffs += NumBytes; |
| |
| // The size of this node just shrunk by NumBytes. |
| Size -= NumBytes; |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // RopePieceBTreeInterior Class |
| //===----------------------------------------------------------------------===// |
| |
| namespace { |
| /// RopePieceBTreeInterior - This represents an interior node in the B+Tree, |
| /// which holds up to 2*WidthFactor pointers to child nodes. |
| class RopePieceBTreeInterior : public RopePieceBTreeNode { |
| /// NumChildren - This holds the number of children currently active in the |
| /// Children array. |
| unsigned char NumChildren; |
| RopePieceBTreeNode *Children[2*WidthFactor]; |
| public: |
| RopePieceBTreeInterior() : RopePieceBTreeNode(false), NumChildren(0) {} |
| |
| RopePieceBTreeInterior(RopePieceBTreeNode *LHS, RopePieceBTreeNode *RHS) |
| : RopePieceBTreeNode(false) { |
| Children[0] = LHS; |
| Children[1] = RHS; |
| NumChildren = 2; |
| Size = LHS->size() + RHS->size(); |
| } |
| |
| ~RopePieceBTreeInterior() { |
| for (unsigned i = 0, e = getNumChildren(); i != e; ++i) |
| Children[i]->Destroy(); |
| } |
| |
| bool isFull() const { return NumChildren == 2*WidthFactor; } |
| |
| unsigned getNumChildren() const { return NumChildren; } |
| const RopePieceBTreeNode *getChild(unsigned i) const { |
| assert(i < NumChildren && "invalid child #"); |
| return Children[i]; |
| } |
| RopePieceBTreeNode *getChild(unsigned i) { |
| assert(i < NumChildren && "invalid child #"); |
| return Children[i]; |
| } |
| |
| /// FullRecomputeSizeLocally - Recompute the Size field of this node by |
| /// summing up the sizes of the child nodes. |
| void FullRecomputeSizeLocally() { |
| Size = 0; |
| for (unsigned i = 0, e = getNumChildren(); i != e; ++i) |
| Size += getChild(i)->size(); |
| } |
| |
| |
| /// split - Split the range containing the specified offset so that we are |
| /// guaranteed that there is a place to do an insertion at the specified |
| /// offset. The offset is relative, so "0" is the start of the node. |
| /// |
| /// If there is no space in this subtree for the extra piece, the extra tree |
| /// node is returned and must be inserted into a parent. |
| RopePieceBTreeNode *split(unsigned Offset); |
| |
| |
| /// insert - Insert the specified ropepiece into this tree node at the |
| /// specified offset. The offset is relative, so "0" is the start of the |
| /// node. |
| /// |
| /// If there is no space in this subtree for the extra piece, the extra tree |
| /// node is returned and must be inserted into a parent. |
| RopePieceBTreeNode *insert(unsigned Offset, const RopePiece &R); |
| |
| /// HandleChildPiece - A child propagated an insertion result up to us. |
| /// Insert the new child, and/or propagate the result further up the tree. |
| RopePieceBTreeNode *HandleChildPiece(unsigned i, RopePieceBTreeNode *RHS); |
| |
| /// erase - Remove NumBytes from this node at the specified offset. We are |
| /// guaranteed that there is a split at Offset. |
| void erase(unsigned Offset, unsigned NumBytes); |
| |
| static inline bool classof(const RopePieceBTreeNode *N) { |
| return !N->isLeaf(); |
| } |
| }; |
| } // end anonymous namespace |
| |
| /// split - Split the range containing the specified offset so that we are |
| /// guaranteed that there is a place to do an insertion at the specified |
| /// offset. The offset is relative, so "0" is the start of the node. |
| /// |
| /// If there is no space in this subtree for the extra piece, the extra tree |
| /// node is returned and must be inserted into a parent. |
| RopePieceBTreeNode *RopePieceBTreeInterior::split(unsigned Offset) { |
| // Figure out which child to split. |
| if (Offset == 0 || Offset == size()) |
| return nullptr; // If we have an exact offset, we're already split. |
| |
| unsigned ChildOffset = 0; |
| unsigned i = 0; |
| for (; Offset >= ChildOffset+getChild(i)->size(); ++i) |
| ChildOffset += getChild(i)->size(); |
| |
| // If already split there, we're done. |
| if (ChildOffset == Offset) |
| return nullptr; |
| |
| // Otherwise, recursively split the child. |
| if (RopePieceBTreeNode *RHS = getChild(i)->split(Offset-ChildOffset)) |
| return HandleChildPiece(i, RHS); |
| return nullptr; // Done! |
| } |
| |
| /// insert - Insert the specified ropepiece into this tree node at the |
| /// specified offset. The offset is relative, so "0" is the start of the |
| /// node. |
| /// |
| /// If there is no space in this subtree for the extra piece, the extra tree |
| /// node is returned and must be inserted into a parent. |
| RopePieceBTreeNode *RopePieceBTreeInterior::insert(unsigned Offset, |
| const RopePiece &R) { |
| // Find the insertion point. We are guaranteed that there is a split at the |
| // specified offset so find it. |
| unsigned i = 0, e = getNumChildren(); |
| |
| unsigned ChildOffs = 0; |
| if (Offset == size()) { |
| // Fastpath for a common case. Insert at end of last child. |
| i = e-1; |
| ChildOffs = size()-getChild(i)->size(); |
| } else { |
| for (; Offset > ChildOffs+getChild(i)->size(); ++i) |
| ChildOffs += getChild(i)->size(); |
| } |
| |
| Size += R.size(); |
| |
| // Insert at the end of this child. |
| if (RopePieceBTreeNode *RHS = getChild(i)->insert(Offset-ChildOffs, R)) |
| return HandleChildPiece(i, RHS); |
| |
| return nullptr; |
| } |
| |
| /// HandleChildPiece - A child propagated an insertion result up to us. |
| /// Insert the new child, and/or propagate the result further up the tree. |
| RopePieceBTreeNode * |
| RopePieceBTreeInterior::HandleChildPiece(unsigned i, RopePieceBTreeNode *RHS) { |
| // Otherwise the child propagated a subtree up to us as a new child. See if |
| // we have space for it here. |
| if (!isFull()) { |
| // Insert RHS after child 'i'. |
| if (i + 1 != getNumChildren()) |
| memmove(&Children[i+2], &Children[i+1], |
| (getNumChildren()-i-1)*sizeof(Children[0])); |
| Children[i+1] = RHS; |
| ++NumChildren; |
| return nullptr; |
| } |
| |
| // Okay, this node is full. Split it in half, moving WidthFactor children to |
| // a newly allocated interior node. |
| |
| // Create the new node. |
| RopePieceBTreeInterior *NewNode = new RopePieceBTreeInterior(); |
| |
| // Move over the last 'WidthFactor' values from here to NewNode. |
| memcpy(&NewNode->Children[0], &Children[WidthFactor], |
| WidthFactor*sizeof(Children[0])); |
| |
| // Decrease the number of values in the two nodes. |
| NewNode->NumChildren = NumChildren = WidthFactor; |
| |
| // Finally, insert the two new children in the side the can (now) hold them. |
| // These insertions can't fail. |
| if (i < WidthFactor) |
| this->HandleChildPiece(i, RHS); |
| else |
| NewNode->HandleChildPiece(i-WidthFactor, RHS); |
| |
| // Recompute the two nodes' size. |
| NewNode->FullRecomputeSizeLocally(); |
| FullRecomputeSizeLocally(); |
| return NewNode; |
| } |
| |
| /// erase - Remove NumBytes from this node at the specified offset. We are |
| /// guaranteed that there is a split at Offset. |
| void RopePieceBTreeInterior::erase(unsigned Offset, unsigned NumBytes) { |
| // This will shrink this node by NumBytes. |
| Size -= NumBytes; |
| |
| // Find the first child that overlaps with Offset. |
| unsigned i = 0; |
| for (; Offset >= getChild(i)->size(); ++i) |
| Offset -= getChild(i)->size(); |
| |
| // Propagate the delete request into overlapping children, or completely |
| // delete the children as appropriate. |
| while (NumBytes) { |
| RopePieceBTreeNode *CurChild = getChild(i); |
| |
| // If we are deleting something contained entirely in the child, pass on the |
| // request. |
| if (Offset+NumBytes < CurChild->size()) { |
| CurChild->erase(Offset, NumBytes); |
| return; |
| } |
| |
| // If this deletion request starts somewhere in the middle of the child, it |
| // must be deleting to the end of the child. |
| if (Offset) { |
| unsigned BytesFromChild = CurChild->size()-Offset; |
| CurChild->erase(Offset, BytesFromChild); |
| NumBytes -= BytesFromChild; |
| // Start at the beginning of the next child. |
| Offset = 0; |
| ++i; |
| continue; |
| } |
| |
| // If the deletion request completely covers the child, delete it and move |
| // the rest down. |
| NumBytes -= CurChild->size(); |
| CurChild->Destroy(); |
| --NumChildren; |
| if (i != getNumChildren()) |
| memmove(&Children[i], &Children[i+1], |
| (getNumChildren()-i)*sizeof(Children[0])); |
| } |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // RopePieceBTreeNode Implementation |
| //===----------------------------------------------------------------------===// |
| |
| void RopePieceBTreeNode::Destroy() { |
| if (RopePieceBTreeLeaf *Leaf = dyn_cast<RopePieceBTreeLeaf>(this)) |
| delete Leaf; |
| else |
| delete cast<RopePieceBTreeInterior>(this); |
| } |
| |
| /// split - Split the range containing the specified offset so that we are |
| /// guaranteed that there is a place to do an insertion at the specified |
| /// offset. The offset is relative, so "0" is the start of the node. |
| /// |
| /// If there is no space in this subtree for the extra piece, the extra tree |
| /// node is returned and must be inserted into a parent. |
| RopePieceBTreeNode *RopePieceBTreeNode::split(unsigned Offset) { |
| assert(Offset <= size() && "Invalid offset to split!"); |
| if (RopePieceBTreeLeaf *Leaf = dyn_cast<RopePieceBTreeLeaf>(this)) |
| return Leaf->split(Offset); |
| return cast<RopePieceBTreeInterior>(this)->split(Offset); |
| } |
| |
| /// insert - Insert the specified ropepiece into this tree node at the |
| /// specified offset. The offset is relative, so "0" is the start of the |
| /// node. |
| /// |
| /// If there is no space in this subtree for the extra piece, the extra tree |
| /// node is returned and must be inserted into a parent. |
| RopePieceBTreeNode *RopePieceBTreeNode::insert(unsigned Offset, |
| const RopePiece &R) { |
| assert(Offset <= size() && "Invalid offset to insert!"); |
| if (RopePieceBTreeLeaf *Leaf = dyn_cast<RopePieceBTreeLeaf>(this)) |
| return Leaf->insert(Offset, R); |
| return cast<RopePieceBTreeInterior>(this)->insert(Offset, R); |
| } |
| |
| /// erase - Remove NumBytes from this node at the specified offset. We are |
| /// guaranteed that there is a split at Offset. |
| void RopePieceBTreeNode::erase(unsigned Offset, unsigned NumBytes) { |
| assert(Offset+NumBytes <= size() && "Invalid offset to erase!"); |
| if (RopePieceBTreeLeaf *Leaf = dyn_cast<RopePieceBTreeLeaf>(this)) |
| return Leaf->erase(Offset, NumBytes); |
| return cast<RopePieceBTreeInterior>(this)->erase(Offset, NumBytes); |
| } |
| |
| |
| //===----------------------------------------------------------------------===// |
| // RopePieceBTreeIterator Implementation |
| //===----------------------------------------------------------------------===// |
| |
| static const RopePieceBTreeLeaf *getCN(const void *P) { |
| return static_cast<const RopePieceBTreeLeaf*>(P); |
| } |
| |
| // begin iterator. |
| RopePieceBTreeIterator::RopePieceBTreeIterator(const void *n) { |
| const RopePieceBTreeNode *N = static_cast<const RopePieceBTreeNode*>(n); |
| |
| // Walk down the left side of the tree until we get to a leaf. |
| while (const RopePieceBTreeInterior *IN = dyn_cast<RopePieceBTreeInterior>(N)) |
| N = IN->getChild(0); |
| |
| // We must have at least one leaf. |
| CurNode = cast<RopePieceBTreeLeaf>(N); |
| |
| // If we found a leaf that happens to be empty, skip over it until we get |
| // to something full. |
| while (CurNode && getCN(CurNode)->getNumPieces() == 0) |
| CurNode = getCN(CurNode)->getNextLeafInOrder(); |
| |
| if (CurNode) |
| CurPiece = &getCN(CurNode)->getPiece(0); |
| else // Empty tree, this is an end() iterator. |
| CurPiece = nullptr; |
| CurChar = 0; |
| } |
| |
| void RopePieceBTreeIterator::MoveToNextPiece() { |
| if (CurPiece != &getCN(CurNode)->getPiece(getCN(CurNode)->getNumPieces()-1)) { |
| CurChar = 0; |
| ++CurPiece; |
| return; |
| } |
| |
| // Find the next non-empty leaf node. |
| do |
| CurNode = getCN(CurNode)->getNextLeafInOrder(); |
| while (CurNode && getCN(CurNode)->getNumPieces() == 0); |
| |
| if (CurNode) |
| CurPiece = &getCN(CurNode)->getPiece(0); |
| else // Hit end(). |
| CurPiece = nullptr; |
| CurChar = 0; |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // RopePieceBTree Implementation |
| //===----------------------------------------------------------------------===// |
| |
| static RopePieceBTreeNode *getRoot(void *P) { |
| return static_cast<RopePieceBTreeNode*>(P); |
| } |
| |
| RopePieceBTree::RopePieceBTree() { |
| Root = new RopePieceBTreeLeaf(); |
| } |
| RopePieceBTree::RopePieceBTree(const RopePieceBTree &RHS) { |
| assert(RHS.empty() && "Can't copy non-empty tree yet"); |
| Root = new RopePieceBTreeLeaf(); |
| } |
| RopePieceBTree::~RopePieceBTree() { |
| getRoot(Root)->Destroy(); |
| } |
| |
| unsigned RopePieceBTree::size() const { |
| return getRoot(Root)->size(); |
| } |
| |
| void RopePieceBTree::clear() { |
| if (RopePieceBTreeLeaf *Leaf = dyn_cast<RopePieceBTreeLeaf>(getRoot(Root))) |
| Leaf->clear(); |
| else { |
| getRoot(Root)->Destroy(); |
| Root = new RopePieceBTreeLeaf(); |
| } |
| } |
| |
| void RopePieceBTree::insert(unsigned Offset, const RopePiece &R) { |
| // #1. Split at Offset. |
| if (RopePieceBTreeNode *RHS = getRoot(Root)->split(Offset)) |
| Root = new RopePieceBTreeInterior(getRoot(Root), RHS); |
| |
| // #2. Do the insertion. |
| if (RopePieceBTreeNode *RHS = getRoot(Root)->insert(Offset, R)) |
| Root = new RopePieceBTreeInterior(getRoot(Root), RHS); |
| } |
| |
| void RopePieceBTree::erase(unsigned Offset, unsigned NumBytes) { |
| // #1. Split at Offset. |
| if (RopePieceBTreeNode *RHS = getRoot(Root)->split(Offset)) |
| Root = new RopePieceBTreeInterior(getRoot(Root), RHS); |
| |
| // #2. Do the erasing. |
| getRoot(Root)->erase(Offset, NumBytes); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // RewriteRope Implementation |
| //===----------------------------------------------------------------------===// |
| |
| /// MakeRopeString - This copies the specified byte range into some instance of |
| /// RopeRefCountString, and return a RopePiece that represents it. This uses |
| /// the AllocBuffer object to aggregate requests for small strings into one |
| /// allocation instead of doing tons of tiny allocations. |
| RopePiece RewriteRope::MakeRopeString(const char *Start, const char *End) { |
| unsigned Len = End-Start; |
| assert(Len && "Zero length RopePiece is invalid!"); |
| |
| // If we have space for this string in the current alloc buffer, use it. |
| if (AllocOffs+Len <= AllocChunkSize) { |
| memcpy(AllocBuffer->Data+AllocOffs, Start, Len); |
| AllocOffs += Len; |
| return RopePiece(AllocBuffer, AllocOffs-Len, AllocOffs); |
| } |
| |
| // If we don't have enough room because this specific allocation is huge, |
| // just allocate a new rope piece for it alone. |
| if (Len > AllocChunkSize) { |
| unsigned Size = End-Start+sizeof(RopeRefCountString)-1; |
| RopeRefCountString *Res = |
| reinterpret_cast<RopeRefCountString *>(new char[Size]); |
| Res->RefCount = 0; |
| memcpy(Res->Data, Start, End-Start); |
| return RopePiece(Res, 0, End-Start); |
| } |
| |
| // Otherwise, this was a small request but we just don't have space for it |
| // Make a new chunk and share it with later allocations. |
| |
| unsigned AllocSize = offsetof(RopeRefCountString, Data) + AllocChunkSize; |
| RopeRefCountString *Res = |
| reinterpret_cast<RopeRefCountString *>(new char[AllocSize]); |
| Res->RefCount = 0; |
| memcpy(Res->Data, Start, Len); |
| AllocBuffer = Res; |
| AllocOffs = Len; |
| |
| return RopePiece(AllocBuffer, 0, Len); |
| } |
| |
| |