--- /dev/null
+//===--- DeltaTree.h - B-Tree for Rewrite Delta tracking --------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the DeltaTree class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef CLANG_REWRITE_DELTATREE_H
+#define CLANG_REWRITE_DELTATREE_H
+
+#include "llvm/Support/Casting.h"
+
+namespace clang {
+ using llvm::cast;
+ using llvm::dyn_cast;
+ class DeltaTreeInteriorNode;
+
+ /// SourceDelta - As code in the original input buffer is added and deleted,
+ /// SourceDelta records are used to keep track of how the input SourceLocation
+ /// object is mapped into the output buffer.
+ struct SourceDelta {
+ unsigned FileLoc;
+ int Delta;
+
+ static SourceDelta get(unsigned Loc, int D) {
+ SourceDelta Delta;
+ Delta.FileLoc = Loc;
+ Delta.Delta = D;
+ return Delta;
+ }
+ };
+
+ /// The DeltaTree class is a multiway search tree (BTree) structure with some
+ /// fancy features. B-Trees are are generally more memory and cache efficient
+ /// than binary trees, because they store multiple keys/values in each node.
+ ///
+ /// DeltaTree implements a key/value mapping from FileIndex to Delta, allowing
+ /// fast lookup by FileIndex. However, an added (important) bonus is that it
+ /// can also efficiently tell us the full accumulated delta for a specific
+ /// file offset as well, without traversing the whole tree.
+ ///
+ /// The nodes of the tree are made up of instances of two classes:
+ /// DeltaTreeNode and DeltaTreeInteriorNode. The later subclasses the
+ /// former and adds children pointers. Each node knows the full delta of all
+ /// entries (recursively) contained inside of it, which allows us to get the
+ /// full delta implied by a whole subtree in constant time.
+
+ /// DeltaTreeNode - The common part of all nodes.
+ ///
+ class DeltaTreeNode {
+ friend class DeltaTreeInteriorNode;
+
+ /// 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-1 K/V pairs (unless the whole tree is less full than that)
+ /// and may have at most 2*WidthFactor-1 K/V pairs.
+ enum { WidthFactor = 8 };
+
+ /// Values - This tracks the SourceDelta's currently in this node.
+ ///
+ SourceDelta Values[2*WidthFactor-1];
+
+ /// NumValuesUsed - This tracks the number of values this node currently
+ /// holds.
+ unsigned char NumValuesUsed;
+
+ /// IsLeaf - This is true if this is a leaf of the btree. If false, this is
+ /// an interior node, and is actually an instance of DeltaTreeInteriorNode.
+ bool IsLeaf;
+
+ /// FullDelta - This is the full delta of all the values in this node and
+ /// all children nodes.
+ int FullDelta;
+ public:
+ DeltaTreeNode(bool isLeaf = true)
+ : NumValuesUsed(0), IsLeaf(isLeaf), FullDelta(0) {}
+
+ bool isLeaf() const { return IsLeaf; }
+ int getFullDelta() const { return FullDelta; }
+ bool isFull() const { return NumValuesUsed == 2*WidthFactor-1; }
+
+ unsigned getNumValuesUsed() const { return NumValuesUsed; }
+ const SourceDelta &getValue(unsigned i) const {
+ assert(i < NumValuesUsed && "Invalid value #");
+ return Values[i];
+ }
+ SourceDelta &getValue(unsigned i) {
+ assert(i < NumValuesUsed && "Invalid value #");
+ return Values[i];
+ }
+
+ /// AddDeltaNonFull - Add a delta to this tree and/or it's children, knowing
+ /// that this node is not currently full.
+ void AddDeltaNonFull(unsigned FileIndex, int Delta);
+
+ /// RecomputeFullDeltaLocally - Recompute the FullDelta field by doing a
+ /// local walk over our contained deltas.
+ void RecomputeFullDeltaLocally();
+
+ void Destroy();
+
+ static inline bool classof(const DeltaTreeNode *) { return true; }
+ };
+
+ /// DeltaTreeInteriorNode - When isLeaf = false, a node has child pointers.
+ /// This class tracks them.
+ class DeltaTreeInteriorNode : public DeltaTreeNode {
+ DeltaTreeNode *Children[2*WidthFactor];
+ ~DeltaTreeInteriorNode() {
+ for (unsigned i = 0, e = NumValuesUsed+1; i != e; ++i)
+ Children[i]->Destroy();
+ }
+ friend class DeltaTreeNode;
+ public:
+ DeltaTreeInteriorNode() : DeltaTreeNode(false /*nonleaf*/) {}
+
+ DeltaTreeInteriorNode(DeltaTreeNode *FirstChild)
+ : DeltaTreeNode(false /*nonleaf*/) {
+ FullDelta = FirstChild->FullDelta;
+ Children[0] = FirstChild;
+ }
+
+ const DeltaTreeNode *getChild(unsigned i) const {
+ assert(i < getNumValuesUsed()+1 && "Invalid child");
+ return Children[i];
+ }
+ DeltaTreeNode *getChild(unsigned i) {
+ assert(i < getNumValuesUsed()+1 && "Invalid child");
+ return Children[i];
+ }
+
+ static inline bool classof(const DeltaTreeInteriorNode *) { return true; }
+ static inline bool classof(const DeltaTreeNode *N) { return !N->isLeaf(); }
+ private:
+ void SplitChild(unsigned ChildNo);
+ };
+
+ /// Destroy - A 'virtual' destructor.
+ inline void DeltaTreeNode::Destroy() {
+ if (isLeaf())
+ delete this;
+ else
+ delete cast<DeltaTreeInteriorNode>(this);
+ }
+
+ /// RecomputeFullDeltaLocally - Recompute the FullDelta field by doing a
+ /// local walk over our contained deltas.
+ inline void DeltaTreeNode::RecomputeFullDeltaLocally() {
+ int NewFullDelta = 0;
+ for (unsigned i = 0, e = getNumValuesUsed(); i != e; ++i)
+ NewFullDelta += Values[i].Delta;
+ if (DeltaTreeInteriorNode *IN = dyn_cast<DeltaTreeInteriorNode>(this))
+ for (unsigned i = 0, e = getNumValuesUsed()+1; i != e; ++i)
+ NewFullDelta += IN->getChild(i)->getFullDelta();
+ FullDelta = NewFullDelta;
+ }
+
+
+ /// AddDeltaNonFull - Add a delta to this tree and/or it's children, knowing
+ /// that this node is not currently full.
+ inline void DeltaTreeNode::AddDeltaNonFull(unsigned FileIndex, int Delta) {
+ assert(!isFull() && "AddDeltaNonFull on a full tree?");
+
+ // Maintain full delta for this node.
+ FullDelta += Delta;
+
+ // Find the insertion point, the first delta whose index is >= FileIndex.
+ unsigned i = 0, e = getNumValuesUsed();
+ while (i != e && FileIndex > getValue(i).FileLoc)
+ ++i;
+
+ // If we found an a record for exactly this file index, just merge this
+ // value into the preexisting record and finish early.
+ if (i != e && getValue(i).FileLoc == FileIndex) {
+ // NOTE: Delta could drop to zero here. This means that the next delta
+ // entry is useless and could be removed. Supporting erases is
+ // significantly more complex though, so we just leave an entry with
+ // Delta=0 in the tree.
+ Values[i].Delta += Delta;
+ return;
+ }
+
+ if (DeltaTreeInteriorNode *IN = dyn_cast<DeltaTreeInteriorNode>(this)) {
+ // Insertion into an interior node propagates the value down to a child.
+ DeltaTreeNode *Child = IN->getChild(i);
+
+ // If the child tree is full, split it, pulling an element up into our
+ // node.
+ if (Child->isFull()) {
+ IN->SplitChild(i);
+ SourceDelta &MedianVal = getValue(i);
+
+ // If the median value we pulled up is exactly our insert position, add
+ // the delta and return.
+ if (MedianVal.FileLoc == FileIndex) {
+ MedianVal.Delta += Delta;
+ return;
+ }
+
+ // If the median value pulled up is less than our current search point,
+ // include those deltas and search down the RHS now.
+ if (MedianVal.FileLoc < FileIndex)
+ Child = IN->getChild(i+1);
+ }
+
+ Child->AddDeltaNonFull(FileIndex, Delta);
+ } else {
+ // For an insertion into a non-full leaf node, just insert the value in
+ // its sorted position. This requires moving later values over.
+ if (i != e)
+ memmove(&Values[i+1], &Values[i], sizeof(Values[0])*(e-i));
+ Values[i] = SourceDelta::get(FileIndex, Delta);
+ ++NumValuesUsed;
+ }
+ }
+
+ /// SplitChild - At this point, we know that the current node is not full and
+ /// that the specified child of this node is. Split the child in half at its
+ /// median, propagating one value up into us. Child may be either an interior
+ /// or leaf node.
+ inline void DeltaTreeInteriorNode::SplitChild(unsigned ChildNo) {
+ //printf("SplitChild: %p %d\n", (void*)this, ChildNo);
+
+ DeltaTreeNode *Child = getChild(ChildNo);
+ assert(!isFull() && Child->isFull() && "Inconsistent constraints");
+
+ // Since the child is full, it contains 2*WidthFactor-1 values. We move
+ // the first 'WidthFactor-1' values to the LHS child (which we leave in the
+ // original child), propagate one value up into us, and move the last
+ // 'WidthFactor-1' values into thew RHS child.
+
+ // Create the new child node.
+ DeltaTreeNode *NewNode;
+ if (DeltaTreeInteriorNode *CIN = dyn_cast<DeltaTreeInteriorNode>(Child)) {
+ // If the child is an interior node, also move over 'WidthFactor' grand
+ // children into the new node.
+ NewNode = new DeltaTreeInteriorNode();
+ memcpy(&((DeltaTreeInteriorNode*)NewNode)->Children[0],
+ &CIN->Children[WidthFactor],
+ WidthFactor*sizeof(CIN->Children[0]));
+ } else {
+ // Just create the child node.
+ NewNode = new DeltaTreeNode();
+ }
+
+ // Move over the last 'WidthFactor-1' values from Child to NewNode.
+ memcpy(&NewNode->Values[0], &Child->Values[WidthFactor],
+ (WidthFactor-1)*sizeof(Child->Values[0]));
+
+ // Decrease the number of values in the two children.
+ NewNode->NumValuesUsed = Child->NumValuesUsed = WidthFactor-1;
+
+ // Recompute the two children's full delta. Our delta hasn't changed, but
+ // their delta has.
+ NewNode->RecomputeFullDeltaLocally();
+ Child->RecomputeFullDeltaLocally();
+
+ // Now that we have two nodes and a new element, insert the median value
+ // into ourself by moving all the later values/children down, then inserting
+ // the new one.
+ if (getNumValuesUsed() != ChildNo)
+ memmove(&Children[ChildNo+2], &Children[ChildNo+1],
+ (getNumValuesUsed()-ChildNo)*sizeof(Children[0]));
+ Children[ChildNo+1] = NewNode;
+
+ if (getNumValuesUsed() != ChildNo)
+ memmove(&Values[ChildNo+1], &Values[ChildNo],
+ (getNumValuesUsed()-ChildNo)*sizeof(Values[0]));
+ Values[ChildNo] = Child->Values[WidthFactor-1];
+ ++NumValuesUsed;
+ }
+
+
+
+ /// DeltaTree - a multiway search tree (BTree) structure with some fancy
+ /// features. B-Trees are are generally more memory and cache efficient than
+ /// binary trees, because they store multiple keys/values in each node. This
+ /// implements a key/value mapping from index to delta, and allows fast lookup
+ /// on index. However, an added (important) bonus is that it can also
+ /// efficiently tell us the full accumulated delta for a specific file offset
+ /// as well, without traversing the whole tree.
+ class DeltaTree {
+ DeltaTreeNode *Root;
+ void operator=(const DeltaTree&); // DO NOT IMPLEMENT
+ public:
+ DeltaTree() {
+ Root = new DeltaTreeNode();
+ }
+ DeltaTree(const DeltaTree &RHS) {
+ // Currently we only support copying when the RHS is empty.
+ assert(RHS.empty() && "Can only copy empty tree");
+ Root = new DeltaTreeNode();
+ }
+
+ ~DeltaTree() {
+ Root->Destroy();
+ }
+
+ bool empty() const {
+ return Root->getNumValuesUsed() == 0;
+ }
+
+ /// getDeltaAt - Return the accumulated delta at the specified file offset.
+ /// This includes all insertions or delections that occurred *before* the
+ /// specified file index.
+ int getDeltaAt(unsigned FileIndex) const {
+ const DeltaTreeNode *Node = Root;
+
+ int Result = 0;
+
+ // Walk down the tree.
+ while (1) {
+ // For all nodes, include any local deltas before the specified file
+ // index by summing them up directly. Keep track of how many were
+ // included.
+ unsigned NumValsGreater = 0;
+ for (unsigned e = Node->getNumValuesUsed(); NumValsGreater != e;
+ ++NumValsGreater) {
+ const SourceDelta &Val = Node->getValue(NumValsGreater);
+
+ if (Val.FileLoc >= FileIndex)
+ break;
+ Result += Val.Delta;
+ }
+
+ // If we have an interior node, include information about children and
+ // recurse. Otherwise, if we have a leaf, we're done.
+ const DeltaTreeInteriorNode *IN = dyn_cast<DeltaTreeInteriorNode>(Node);
+ if (!IN) return Result;
+
+ // Include any children to the left of the values we skipped, all of
+ // their deltas should be included as well.
+ for (unsigned i = 0; i != NumValsGreater; ++i)
+ Result += IN->getChild(i)->getFullDelta();
+
+ // If we found exactly the value we were looking for, break off the
+ // search early. There is no need to search the RHS of the value for
+ // partial results.
+ if (NumValsGreater != Node->getNumValuesUsed() &&
+ Node->getValue(NumValsGreater).FileLoc == FileIndex)
+ return Result;
+
+ // Otherwise, traverse down the tree. The selected subtree may be
+ // partially included in the range.
+ Node = IN->getChild(NumValsGreater);
+ }
+ // NOT REACHED.
+ }
+
+
+ /// AddDelta - When a change is made that shifts around the text buffer,
+ /// this method is used to record that info. It inserts a delta of 'Delta'
+ /// into the current DeltaTree at offset FileIndex.
+ void AddDelta(unsigned FileIndex, int Delta) {
+ assert(Delta && "Adding a noop?");
+ //printf("Add: %d %d\n", FileIndex, Delta);
+ //if (FileIndex == 9251)
+ //printf("Here\n");
+
+ // If the root is full, create a new dummy (non-empty) interior node that
+ // points to it, allowing the old root to be split.
+ if (Root->isFull())
+ Root = new DeltaTreeInteriorNode(Root);
+
+ Root->AddDeltaNonFull(FileIndex, Delta);
+
+ //VerifyTree(Root);
+ }
+
+ void VerifyTree(const DeltaTreeNode *N) const {
+ const DeltaTreeInteriorNode *IN = dyn_cast<DeltaTreeInteriorNode>(N);
+ if (IN == 0) {
+ // Verify leaves, just ensure that FullDelta matches up and the elements
+ // are in proper order.
+ int FullDelta = 0;
+ for (unsigned i = 0, e = N->getNumValuesUsed(); i != e; ++i) {
+ if (i)
+ assert(N->getValue(i-1).FileLoc < N->getValue(i).FileLoc);
+ FullDelta += N->getValue(i).Delta;
+ }
+ assert(FullDelta == N->getFullDelta());
+ return;
+ }
+
+ // Verify interior nodes: Ensure that FullDelta matches up and the
+ // elements are in proper order and the children are in proper order.
+ int FullDelta = 0;
+ for (unsigned i = 0, e = IN->getNumValuesUsed(); i != e; ++i) {
+ const SourceDelta &IVal = N->getValue(i);
+ const DeltaTreeNode *IChild = IN->getChild(i);
+ if (i)
+ assert(IN->getValue(i-1).FileLoc < IVal.FileLoc);
+ FullDelta += IVal.Delta;
+ FullDelta += IChild->getFullDelta();
+
+ // The largest value in child #i should be smaller than FileLoc.
+ assert(IChild->getValue(IChild->getNumValuesUsed()-1).FileLoc <
+ IVal.FileLoc);
+
+ // The smallest value in child #i+1 should be larger than FileLoc.
+ assert(IN->getChild(i+1)->getValue(0).FileLoc > IVal.FileLoc);
+ VerifyTree(IChild);
+ }
+
+ FullDelta += IN->getChild(IN->getNumValuesUsed())->getFullDelta();
+
+ assert(FullDelta == N->getFullDelta());
+ }
+ };
+} // end namespace llvm
+
+#endif
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