Check in LLVM r95781.
diff --git a/lib/Rewrite/DeltaTree.cpp b/lib/Rewrite/DeltaTree.cpp
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+//===--- DeltaTree.cpp - B-Tree for Rewrite Delta tracking ----------------===//
+//
+// 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 DeltaTree and related classes.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Rewrite/DeltaTree.h"
+#include "llvm/Support/Casting.h"
+#include <cstring>
+#include <cstdio>
+using namespace clang;
+using llvm::cast;
+using llvm::dyn_cast;
+
+/// The DeltaTree class is a multiway search tree (BTree) structure with some
+/// fancy features. B-Trees 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.
+
+namespace {
+ /// 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;
+ }
+ };
+
+ /// DeltaTreeNode - The common part of all nodes.
+ ///
+ class DeltaTreeNode {
+ public:
+ struct InsertResult {
+ DeltaTreeNode *LHS, *RHS;
+ SourceDelta Split;
+ };
+
+ private:
+ 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 (except the root) 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];
+ }
+
+ /// DoInsertion - Do an insertion of the specified FileIndex/Delta pair into
+ /// this node. If insertion is easy, do it and return false. Otherwise,
+ /// split the node, populate InsertRes with info about the split, and return
+ /// true.
+ bool DoInsertion(unsigned FileIndex, int Delta, InsertResult *InsertRes);
+
+ void DoSplit(InsertResult &InsertRes);
+
+
+ /// 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; }
+ };
+} // end anonymous namespace
+
+namespace {
+ /// 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;
+ }
+
+ DeltaTreeInteriorNode(const InsertResult &IR)
+ : DeltaTreeNode(false /*nonleaf*/) {
+ Children[0] = IR.LHS;
+ Children[1] = IR.RHS;
+ Values[0] = IR.Split;
+ FullDelta = IR.LHS->getFullDelta()+IR.RHS->getFullDelta()+IR.Split.Delta;
+ NumValuesUsed = 1;
+ }
+
+ 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(); }
+ };
+}
+
+
+/// Destroy - A 'virtual' destructor.
+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.
+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;
+}
+
+/// DoInsertion - Do an insertion of the specified FileIndex/Delta pair into
+/// this node. If insertion is easy, do it and return false. Otherwise,
+/// split the node, populate InsertRes with info about the split, and return
+/// true.
+bool DeltaTreeNode::DoInsertion(unsigned FileIndex, int Delta,
+ InsertResult *InsertRes) {
+ // 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 pre-existing record and finish early.
+ if (i != e && getValue(i).FileLoc == FileIndex) {
+ // NOTE: Delta could drop to zero here. This means that the delta entry is
+ // useless and could be removed. Supporting erases is more complex than
+ // leaving an entry with Delta=0, so we just leave an entry with Delta=0 in
+ // the tree.
+ Values[i].Delta += Delta;
+ return false;
+ }
+
+ // Otherwise, we found an insertion point, and we know that the value at the
+ // specified index is > FileIndex. Handle the leaf case first.
+ if (isLeaf()) {
+ if (!isFull()) {
+ // 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;
+ return false;
+ }
+
+ // Otherwise, if this is leaf is full, split the node at its median, insert
+ // the value into one of the children, and return the result.
+ assert(InsertRes && "No result location specified");
+ DoSplit(*InsertRes);
+
+ if (InsertRes->Split.FileLoc > FileIndex)
+ InsertRes->LHS->DoInsertion(FileIndex, Delta, 0 /*can't fail*/);
+ else
+ InsertRes->RHS->DoInsertion(FileIndex, Delta, 0 /*can't fail*/);
+ return true;
+ }
+
+ // Otherwise, this is an interior node. Send the request down the tree.
+ DeltaTreeInteriorNode *IN = cast<DeltaTreeInteriorNode>(this);
+ if (!IN->Children[i]->DoInsertion(FileIndex, Delta, InsertRes))
+ return false; // If there was space in the child, just return.
+
+ // Okay, this split the subtree, producing a new value and two children to
+ // insert here. If this node is non-full, we can just insert it directly.
+ if (!isFull()) {
+ // Now that we have two nodes and a new element, insert the perclated value
+ // into ourself by moving all the later values/children down, then inserting
+ // the new one.
+ if (i != e)
+ memmove(&IN->Children[i+2], &IN->Children[i+1],
+ (e-i)*sizeof(IN->Children[0]));
+ IN->Children[i] = InsertRes->LHS;
+ IN->Children[i+1] = InsertRes->RHS;
+
+ if (e != i)
+ memmove(&Values[i+1], &Values[i], (e-i)*sizeof(Values[0]));
+ Values[i] = InsertRes->Split;
+ ++NumValuesUsed;
+ return false;
+ }
+
+ // Finally, if this interior node was full and a node is percolated up, split
+ // ourself and return that up the chain. Start by saving all our info to
+ // avoid having the split clobber it.
+ IN->Children[i] = InsertRes->LHS;
+ DeltaTreeNode *SubRHS = InsertRes->RHS;
+ SourceDelta SubSplit = InsertRes->Split;
+
+ // Do the split.
+ DoSplit(*InsertRes);
+
+ // Figure out where to insert SubRHS/NewSplit.
+ DeltaTreeInteriorNode *InsertSide;
+ if (SubSplit.FileLoc < InsertRes->Split.FileLoc)
+ InsertSide = cast<DeltaTreeInteriorNode>(InsertRes->LHS);
+ else
+ InsertSide = cast<DeltaTreeInteriorNode>(InsertRes->RHS);
+
+ // We now have a non-empty interior node 'InsertSide' to insert
+ // SubRHS/SubSplit into. Find out where to insert SubSplit.
+
+ // Find the insertion point, the first delta whose index is >SubSplit.FileLoc.
+ i = 0; e = InsertSide->getNumValuesUsed();
+ while (i != e && SubSplit.FileLoc > InsertSide->getValue(i).FileLoc)
+ ++i;
+
+ // Now we know that i is the place to insert the split value into. Insert it
+ // and the child right after it.
+ if (i != e)
+ memmove(&InsertSide->Children[i+2], &InsertSide->Children[i+1],
+ (e-i)*sizeof(IN->Children[0]));
+ InsertSide->Children[i+1] = SubRHS;
+
+ if (e != i)
+ memmove(&InsertSide->Values[i+1], &InsertSide->Values[i],
+ (e-i)*sizeof(Values[0]));
+ InsertSide->Values[i] = SubSplit;
+ ++InsertSide->NumValuesUsed;
+ InsertSide->FullDelta += SubSplit.Delta + SubRHS->getFullDelta();
+ return true;
+}
+
+/// DoSplit - Split the currently full node (which has 2*WidthFactor-1 values)
+/// into two subtrees each with "WidthFactor-1" values and a pivot value.
+/// Return the pieces in InsertRes.
+void DeltaTreeNode::DoSplit(InsertResult &InsertRes) {
+ assert(isFull() && "Why split a non-full node?");
+
+ // Since this node is full, it contains 2*WidthFactor-1 values. We move
+ // the first 'WidthFactor-1' values to the LHS child (which we leave in this
+ // node), propagate one value up, and move the last 'WidthFactor-1' values
+ // into the RHS child.
+
+ // Create the new child node.
+ DeltaTreeNode *NewNode;
+ if (DeltaTreeInteriorNode *IN = dyn_cast<DeltaTreeInteriorNode>(this)) {
+ // If this is an interior node, also move over 'WidthFactor' children
+ // into the new node.
+ DeltaTreeInteriorNode *New = new DeltaTreeInteriorNode();
+ memcpy(&New->Children[0], &IN->Children[WidthFactor],
+ WidthFactor*sizeof(IN->Children[0]));
+ NewNode = New;
+ } else {
+ // Just create the new leaf node.
+ NewNode = new DeltaTreeNode();
+ }
+
+ // Move over the last 'WidthFactor-1' values from here to NewNode.
+ memcpy(&NewNode->Values[0], &Values[WidthFactor],
+ (WidthFactor-1)*sizeof(Values[0]));
+
+ // Decrease the number of values in the two nodes.
+ NewNode->NumValuesUsed = NumValuesUsed = WidthFactor-1;
+
+ // Recompute the two nodes' full delta.
+ NewNode->RecomputeFullDeltaLocally();
+ RecomputeFullDeltaLocally();
+
+ InsertRes.LHS = this;
+ InsertRes.RHS = NewNode;
+ InsertRes.Split = Values[WidthFactor-1];
+}
+
+
+
+//===----------------------------------------------------------------------===//
+// DeltaTree Implementation
+//===----------------------------------------------------------------------===//
+
+//#define VERIFY_TREE
+
+#ifdef VERIFY_TREE
+/// VerifyTree - Walk the btree performing assertions on various properties to
+/// verify consistency. This is useful for debugging new changes to the tree.
+static void VerifyTree(const DeltaTreeNode *N) {
+ 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());
+}
+#endif // VERIFY_TREE
+
+static DeltaTreeNode *getRoot(void *Root) {
+ return (DeltaTreeNode*)Root;
+}
+
+DeltaTree::DeltaTree() {
+ Root = new DeltaTreeNode();
+}
+DeltaTree::DeltaTree(const DeltaTree &RHS) {
+ // Currently we only support copying when the RHS is empty.
+ assert(getRoot(RHS.Root)->getNumValuesUsed() == 0 &&
+ "Can only copy empty tree");
+ Root = new DeltaTreeNode();
+}
+
+DeltaTree::~DeltaTree() {
+ getRoot(Root)->Destroy();
+}
+
+/// getDeltaAt - Return the accumulated delta at the specified file offset.
+/// This includes all insertions or delections that occurred *before* the
+/// specified file index.
+int DeltaTree::getDeltaAt(unsigned FileIndex) const {
+ const DeltaTreeNode *Node = getRoot(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+IN->getChild(NumValsGreater)->getFullDelta();
+
+ // 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 DeltaTree::AddDelta(unsigned FileIndex, int Delta) {
+ assert(Delta && "Adding a noop?");
+ DeltaTreeNode *MyRoot = getRoot(Root);
+
+ DeltaTreeNode::InsertResult InsertRes;
+ if (MyRoot->DoInsertion(FileIndex, Delta, &InsertRes)) {
+ Root = MyRoot = new DeltaTreeInteriorNode(InsertRes);
+ }
+
+#ifdef VERIFY_TREE
+ VerifyTree(MyRoot);
+#endif
+}
+