clang-1/lib/Rewrite/RewriteRope.cpp

808 строки
30 KiB
C++
Исходник Обычный вид История

//===--- 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/RewriteRope.h"
#include "llvm/Support/Casting.h"
#include <algorithm>
using namespace clang;
using llvm::dyn_cast;
using llvm::cast;
/// 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() {}
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);
static inline bool classof(const RopePieceBTreeNode *) { return true; }
};
} // 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(0), NextLeaf(0) {}
~RopePieceBTreeLeaf() {
if (PrevLeaf || NextLeaf)
removeFromLeafInOrder();
}
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 == 0 && NextLeaf == 0 && "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 = 0;
}
}
/// 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 RopePieceBTreeLeaf *) { return true; }
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 0;
}
// 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 0;
// 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 0;
}
// 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();
}
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 RopePieceBTreeInterior *) { return true; }
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 0; // 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 0;
// Otherwise, recursively split the child.
if (RopePieceBTreeNode *RHS = getChild(i)->split(Offset-ChildOffset))
return HandleChildPiece(i, RHS);
return 0; // 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 0;
}
/// 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 false;
}
// 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 != 0)
CurPiece = &getCN(CurNode)->getPiece(0);
else // Empty tree, this is an end() iterator.
CurPiece = 0;
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 != 0)
CurPiece = &getCN(CurNode)->getPiece(0);
else // Hit end().
CurPiece = 0;
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.
// If we had an old allocation, drop our reference to it.
if (AllocBuffer && --AllocBuffer->RefCount == 0)
delete [] (char*)AllocBuffer;
unsigned AllocSize = offsetof(RopeRefCountString, Data) + AllocChunkSize;
AllocBuffer = reinterpret_cast<RopeRefCountString *>(new char[AllocSize]);
AllocBuffer->RefCount = 0;
memcpy(AllocBuffer->Data, Start, Len);
AllocOffs = Len;
// Start out the new allocation with a refcount of 1, since we have an
// internal reference to it.
AllocBuffer->addRef();
return RopePiece(AllocBuffer, 0, Len);
}