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/*
* Copyright 2000-2014 JetBrains s.r.o.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.intellij.util.diff;
import com.intellij.openapi.util.Ref;
import com.intellij.util.ThreeState;
import java.util.ArrayList;
import java.util.List;
/**
* @author max
*/
public class DiffTree<OT, NT> {
private static final int CHANGE_PARENT_VERSUS_CHILDREN_THRESHOLD = 20;
private final FlyweightCapableTreeStructure<OT> myOldTree;
private final FlyweightCapableTreeStructure<NT> myNewTree;
private final ShallowNodeComparator<OT, NT> myComparator;
private final DiffTreeChangeBuilder<OT, NT> myConsumer;
private final List<Ref<OT[]>> myOldChildrenLists = new ArrayList<Ref<OT[]>>();
private final List<Ref<NT[]>> myNewChildrenLists = new ArrayList<Ref<NT[]>>();
private DiffTree(final FlyweightCapableTreeStructure<OT> oldTree,
final FlyweightCapableTreeStructure<NT> newTree,
final ShallowNodeComparator<OT, NT> comparator,
final DiffTreeChangeBuilder<OT, NT> consumer) {
myOldTree = oldTree;
myNewTree = newTree;
myComparator = comparator;
myConsumer = consumer;
}
public static <OT, NT> void diff(final FlyweightCapableTreeStructure<OT> oldTree,
final FlyweightCapableTreeStructure<NT> newTree,
final ShallowNodeComparator<OT, NT> comparator,
final DiffTreeChangeBuilder<OT, NT> consumer) {
new DiffTree<OT, NT>(oldTree, newTree, comparator, consumer).build(oldTree.getRoot(), newTree.getRoot(), 0);
}
private enum CompareResult {
EQUAL, // 100% equal
DRILL_DOWN_NEEDED, // element types are equal, but elements are composite
TYPE_ONLY, // only element types are equal
NOT_EQUAL, // 100% different
}
private void build(OT oldN, NT newN, int level) {
OT oldNode = myOldTree.prepareForGetChildren(oldN);
NT newNode = myNewTree.prepareForGetChildren(newN);
if (level >= myNewChildrenLists.size()) {
myNewChildrenLists.add(new Ref<NT[]>());
myOldChildrenLists.add(new Ref<OT[]>());
}
final Ref<OT[]> oldChildrenR = myOldChildrenLists.get(level);
int oldSize = myOldTree.getChildren(oldNode, oldChildrenR);
final OT[] oldChildren = oldChildrenR.get();
final Ref<NT[]> newChildrenR = myNewChildrenLists.get(level);
int newSize = myNewTree.getChildren(newNode, newChildrenR);
final NT[] newChildren = newChildrenR.get();
compareLevel(level, oldNode, oldSize, oldChildren, newNode, newSize, newChildren);
disposeLevel(oldChildren, oldSize, newChildren, newSize);
}
private void compareLevel(int level, OT oldNode, int oldSize, OT[] oldChildren, NT newNode, int newSize, NT[] newChildren) {
if (Math.abs(oldSize - newSize) > CHANGE_PARENT_VERSUS_CHILDREN_THRESHOLD) {
myConsumer.nodeReplaced(oldNode, newNode);
return;
}
final ShallowNodeComparator<OT, NT> comparator = myComparator;
if (oldSize == 0 && newSize == 0) {
if (!comparator.hashCodesEqual(oldNode, newNode) || !comparator.typesEqual(oldNode, newNode)) {
myConsumer.nodeReplaced(oldNode, newNode);
}
return;
}
while (oldSize > 0 && newSize > 0) {
OT oldChild1 = oldChildren[oldSize-1];
NT newChild1 = newChildren[newSize-1];
CompareResult c11 = looksEqual(comparator, oldChild1, newChild1);
if (c11 != CompareResult.EQUAL && c11 != CompareResult.DRILL_DOWN_NEEDED) {
break;
}
if (c11 == CompareResult.DRILL_DOWN_NEEDED) {
build(oldChild1, newChild1, level + 1);
}
oldSize--;
newSize--;
}
int oldIndex = 0;
int newIndex = 0;
while (oldIndex < oldSize || newIndex < newSize) {
OT oldChild1 = oldIndex < oldSize ? oldChildren[oldIndex] : null;
OT oldChild2 = oldIndex < oldSize-1 ? oldChildren[oldIndex+1] : null;
NT newChild1 = newIndex < newSize ? newChildren[newIndex] : null;
NT newChild2 = newIndex < newSize-1 ? newChildren[newIndex+1] : null;
CompareResult c11 = looksEqual(comparator, oldChild1, newChild1);
if (c11 == CompareResult.EQUAL || c11 == CompareResult.DRILL_DOWN_NEEDED) {
if (c11 == CompareResult.DRILL_DOWN_NEEDED) {
build(oldChild1, newChild1, level+1);
}
oldIndex++;
newIndex++;
continue;
}
if (c11 == CompareResult.TYPE_ONLY) {
CompareResult c21 = looksEqual(comparator, oldChild2, newChild1);
if (c21 == CompareResult.EQUAL || c21 == CompareResult.DRILL_DOWN_NEEDED) {
myConsumer.nodeDeleted(oldNode, oldChild1);
oldIndex++;
continue;
}
CompareResult c12 = looksEqual(comparator, oldChild1, newChild2);
if (c12 == CompareResult.EQUAL || c12 == CompareResult.DRILL_DOWN_NEEDED) {
myConsumer.nodeInserted(oldNode, newChild1, newIndex);
newIndex++;
continue;
}
myConsumer.nodeReplaced(oldChild1, newChild1);
oldIndex++;
newIndex++;
continue;
}
CompareResult c12 = looksEqual(comparator, oldChild1, newChild2);
if (c12 == CompareResult.EQUAL || c12 == CompareResult.DRILL_DOWN_NEEDED || c12 == CompareResult.TYPE_ONLY) {
myConsumer.nodeInserted(oldNode, newChild1, newIndex);
newIndex++;
continue;
}
CompareResult c21 = looksEqual(comparator, oldChild2, newChild1);
if (c21 == CompareResult.EQUAL || c21 == CompareResult.DRILL_DOWN_NEEDED || c21 == CompareResult.TYPE_ONLY) {
myConsumer.nodeDeleted(oldNode, oldChild1);
oldIndex++;
continue;
}
if (oldChild1 == null) {
myConsumer.nodeInserted(oldNode, newChild1, newIndex);
newIndex++;
continue;
}
if (newChild1 == null) {
myConsumer.nodeDeleted(oldNode, oldChild1);
oldIndex++;
continue;
}
myConsumer.nodeReplaced(oldChild1, newChild1);
oldIndex++;
newIndex++;
}
}
private CompareResult looksEqual(ShallowNodeComparator<OT, NT> comparator, OT oldChild1, NT newChild1) {
if (oldChild1 == null || newChild1 == null) {
return oldChild1 == newChild1 ? CompareResult.EQUAL : CompareResult.NOT_EQUAL;
}
if (!comparator.typesEqual(oldChild1, newChild1)) return CompareResult.NOT_EQUAL;
ThreeState ret = comparator.deepEqual(oldChild1, newChild1);
if (ret == ThreeState.YES) return CompareResult.EQUAL;
if (ret == ThreeState.UNSURE) return CompareResult.DRILL_DOWN_NEEDED;
return CompareResult.TYPE_ONLY;
}
private void disposeLevel(final OT[] oldChildren, final int oldSize, final NT[] newChildren, final int newSize) {
myOldTree.disposeChildren(oldChildren, oldSize);
myNewTree.disposeChildren(newChildren, newSize);
}
}
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