org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/JavaElementDeltaBuilder.java - gerrit/aspectj/org.aspectj.shadows - Git at Google

 /*******************************************************************************
  * Copyright (c) 2000, 2004 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.jdt.internal.core;

 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.Map;

 import org.eclipse.jdt.core.IJavaElement;
 import org.eclipse.jdt.core.IJavaElementDelta;
 import org.eclipse.jdt.core.IParent;
 import org.eclipse.jdt.core.JavaModelException;
 import org.eclipse.jdt.core.compiler.CharOperation;

 /**
  * A java element delta biulder creates a java element delta on
  * a java element between the version of the java element
  * at the time the comparator was created and the current version
  * of the java element.
  *
  * It performs this operation by locally caching the contents of
  * the java element when it is created. When the method
  * createDeltas() is called, it creates a delta over the cached
  * contents and the new contents.
  */
 public class JavaElementDeltaBuilder {
 	/**
 	 * The java element handle
 	 */
 	IJavaElement javaElement;

 	/**
 	 * The maximum depth in the java element children we should look into
 	 */
 	int maxDepth = Integer.MAX_VALUE;

 	/**
 	 * The old handle to info relationships
 	 */
 	Map infos;

 	/**
 	 * The old position info
 	 */
 	Map oldPositions;

 	/**
 	 * The new position info
 	 */
 	Map newPositions;

 	/**
 	 * Change delta
 	 */
 	JavaElementDelta delta;

 	/**
 	 * List of added elements
 	 */
 	ArrayList added;

 	/**
 	 * List of removed elements
 	 */
 	ArrayList removed;

 	/**
 	 * Doubly linked list item
 	 */
 	class ListItem {
 		public IJavaElement previous;
 		public IJavaElement next;

 		public ListItem(IJavaElement previous, IJavaElement next) {
 			this.previous = previous;
 			this.next = next;
 		}
 	}
 /**
  * Creates a java element comparator on a java element
  * looking as deep as necessary.
  */
 public JavaElementDeltaBuilder(IJavaElement javaElement) {
 	this.javaElement = javaElement;
 	this.initialize();
 	this.recordElementInfo(
 		javaElement,
 		(JavaModel)this.javaElement.getJavaModel(),
 		0);
 }
 /**
  * Creates a java element comparator on a java element
  * looking only 'maxDepth' levels deep.
  */
 public JavaElementDeltaBuilder(IJavaElement javaElement, int maxDepth) {
 	this.javaElement = javaElement;
 	this.maxDepth = maxDepth;
 	this.initialize();
 	this.recordElementInfo(
 		javaElement,
 		(JavaModel)this.javaElement.getJavaModel(),
 		0);
 }
 /**
  * Repairs the positioning information
  * after an element has been added
  */
 private void added(IJavaElement element) {
 	this.added.add(element);
 	ListItem current = this.getNewPosition(element);
 	ListItem previous = null, next = null;
 	if (current.previous != null)
 		previous = this.getNewPosition(current.previous);
 	if (current.next != null)
 		next = this.getNewPosition(current.next);
 	if (previous != null)
 		previous.next = current.next;
 	if (next != null)
 		next.previous = current.previous;
 }
 /**
  * Builds the java element deltas between the old content of the compilation
  * unit and its new content.
  */
 public void buildDeltas() {
 	this.recordNewPositions(this.javaElement, 0);
 	this.findAdditions(this.javaElement, 0);
 	this.findDeletions();
 	this.findChangesInPositioning(this.javaElement, 0);
 	this.trimDelta(this.delta);
 	if (this.delta.getAffectedChildren().length == 0) {
 		// this is a fine grained but not children affected -> mark as content changed
 		this.delta.contentChanged();
 	}
 }
 private boolean equals(char[][][] first, char[][][] second) {
 	if (first == second)
 		return true;
 	if (first == null || second == null)
 		return false;
 	if (first.length != second.length)
 		return false;

 	for (int i = first.length; --i >= 0;)
 		if (!CharOperation.equals(first[i], second[i]))
 			return false;
 	return true;
 }
 /**
  * Finds elements which have been added or changed.
  */
 private void findAdditions(IJavaElement newElement, int depth) {
 	JavaElementInfo oldInfo = this.getElementInfo(newElement);
 	if (oldInfo == null && depth < this.maxDepth) {
 		this.delta.added(newElement);
 		added(newElement);
 	} else {
 		this.removeElementInfo(newElement);
 	}

 	if (depth >= this.maxDepth) {
 		// mark element as changed
 		this.delta.changed(newElement, IJavaElementDelta.F_CONTENT);
 		return;
 	}

 	JavaElementInfo newInfo = null;
 	try {
 		newInfo = (JavaElementInfo)((JavaElement)newElement).getElementInfo();
 	} catch (JavaModelException npe) {
 		return;
 	}

 	this.findContentChange(oldInfo, newInfo, newElement);

 	if (oldInfo != null && newElement instanceof IParent) {

 		IJavaElement[] children = newInfo.getChildren();
 		if (children != null) {
 			int length = children.length;
 			for(int i = 0; i < length; i++) {
 				this.findAdditions(children[i], depth + 1);
 			}
 		}
 	}
 }
 /**
  * Looks for changed positioning of elements.
  */
 private void findChangesInPositioning(IJavaElement element, int depth) {
 	if (depth >= this.maxDepth || this.added.contains(element) || this.removed.contains(element))
 		return;

 	if (!isPositionedCorrectly(element)) {
 		this.delta.changed(element, IJavaElementDelta.F_REORDER);
 	}

 	if (element instanceof IParent) {
 		JavaElementInfo info = null;
 		try {
 			info = (JavaElementInfo)((JavaElement)element).getElementInfo();
 		} catch (JavaModelException npe) {
 			return;
 		}

 		IJavaElement[] children = info.getChildren();
 		if (children != null) {
 			int length = children.length;
 			for(int i = 0; i < length; i++) {
 				this.findChangesInPositioning(children[i], depth + 1);
 			}
 		}
 	}
 }
 /**
  * The elements are equivalent, but might have content changes.
  */
 private void findContentChange(JavaElementInfo oldInfo, JavaElementInfo newInfo, IJavaElement newElement) {
 	if (oldInfo instanceof MemberElementInfo && newInfo instanceof MemberElementInfo) {
 		if (((MemberElementInfo)oldInfo).getModifiers() != ((MemberElementInfo)newInfo).getModifiers()) {
 			this.delta.changed(newElement, IJavaElementDelta.F_MODIFIERS);
 		} else if (oldInfo instanceof SourceMethodElementInfo && newInfo instanceof SourceMethodElementInfo) {
 			SourceMethodElementInfo oldSourceMethodInfo = (SourceMethodElementInfo)oldInfo;
 			SourceMethodElementInfo newSourceMethodInfo = (SourceMethodElementInfo)newInfo;
 			if (!CharOperation.equals(oldSourceMethodInfo.getReturnTypeName(), newSourceMethodInfo.getReturnTypeName())
 					|| !CharOperation.equals(oldSourceMethodInfo.getTypeParameterNames(), newSourceMethodInfo.getTypeParameterNames())
 					|| !equals(oldSourceMethodInfo.getTypeParameterBounds(), newSourceMethodInfo.getTypeParameterBounds())) {
 				this.delta.changed(newElement, IJavaElementDelta.F_CONTENT);
 			}
 		} else if (oldInfo instanceof SourceFieldElementInfo && newInfo instanceof SourceFieldElementInfo) {
 			if (!CharOperation.equals(
 					((SourceFieldElementInfo)oldInfo).getTypeName(),
 					((SourceFieldElementInfo)newInfo).getTypeName())) {
 				this.delta.changed(newElement, IJavaElementDelta.F_CONTENT);
 			}
 		}
 	}
 	if (oldInfo instanceof SourceTypeElementInfo && newInfo instanceof SourceTypeElementInfo) {
 		SourceTypeElementInfo oldSourceTypeInfo = (SourceTypeElementInfo)oldInfo;
 		SourceTypeElementInfo newSourceTypeInfo = (SourceTypeElementInfo)newInfo;
 		if (!CharOperation.equals(oldSourceTypeInfo.getSuperclassName(), newSourceTypeInfo.getSuperclassName())
 				|| !CharOperation.equals(oldSourceTypeInfo.getInterfaceNames(), newSourceTypeInfo.getInterfaceNames())) {
 			this.delta.changed(newElement, IJavaElementDelta.F_SUPER_TYPES);
 		}
 		if (!CharOperation.equals(oldSourceTypeInfo.getTypeParameterNames(), newSourceTypeInfo.getTypeParameterNames())
 				|| !equals(oldSourceTypeInfo.getTypeParameterBounds(), newSourceTypeInfo.getTypeParameterBounds())) {
 			this.delta.changed(newElement, IJavaElementDelta.F_CONTENT);
 		}
 	}
 }
 /**
  * Adds removed deltas for any handles left in the table
  */
 private void findDeletions() {
 	Iterator iter = this.infos.keySet().iterator();
 	while(iter.hasNext()) {
 		IJavaElement element = (IJavaElement)iter.next();
 		this.delta.removed(element);
 		this.removed(element);
 	}
 }
 private JavaElementInfo getElementInfo(IJavaElement element) {
 	return (JavaElementInfo)this.infos.get(element);
 }
 private ListItem getNewPosition(IJavaElement element) {
 	return (ListItem)this.newPositions.get(element);
 }
 private ListItem getOldPosition(IJavaElement element) {
 	return (ListItem)this.oldPositions.get(element);
 }
 private void initialize() {
 	this.infos = new HashMap(20);
 	this.oldPositions = new HashMap(20);
 	this.newPositions = new HashMap(20);
 	this.putOldPosition(this.javaElement, new ListItem(null, null));
 	this.putNewPosition(this.javaElement, new ListItem(null, null));
 	this.delta = new JavaElementDelta(javaElement);

 	// if building a delta on a compilation unit or below,
 	// it's a fine grained delta
 	if (javaElement.getElementType() >= IJavaElement.COMPILATION_UNIT) {
 		this.delta.fineGrained();
 	}

 	this.added = new ArrayList(5);
 	this.removed = new ArrayList(5);
 }
 /**
  * Inserts position information for the elements into the new or old positions table
  */
 private void insertPositions(IJavaElement[] elements, boolean isNew) {
 	int length = elements.length;
 	IJavaElement previous = null, current = null, next = (length > 0) ? elements[0] : null;
 	for(int i = 0; i < length; i++) {
 		previous = current;
 		current = next;
 		next = (i + 1 < length) ? elements[i + 1] : null;
 		if (isNew) {
 			this.putNewPosition(current, new ListItem(previous, next));
 		} else {
 			this.putOldPosition(current, new ListItem(previous, next));
 		}
 	}
 }
 /**
  * Returns whether the elements position has not changed.
  */
 private boolean isPositionedCorrectly(IJavaElement element) {
 	ListItem oldListItem = this.getOldPosition(element);
 	if (oldListItem == null) return false;

 	ListItem newListItem = this.getNewPosition(element);
 	if (newListItem == null) return false;

 	IJavaElement oldPrevious = oldListItem.previous;
 	IJavaElement newPrevious = newListItem.previous;
 	if (oldPrevious == null) {
 		return newPrevious == null;
 	} else {
 		return oldPrevious.equals(newPrevious);
 	}
 }
 private void putElementInfo(IJavaElement element, JavaElementInfo info) {
 	this.infos.put(element, info);
 }
 private void putNewPosition(IJavaElement element, ListItem position) {
 	this.newPositions.put(element, position);
 }
 private void putOldPosition(IJavaElement element, ListItem position) {
 	this.oldPositions.put(element, position);
 }
 /**
  * Records this elements info, and attempts
  * to record the info for the children.
  */
 private void recordElementInfo(IJavaElement element, JavaModel model, int depth) {
 	if (depth >= this.maxDepth) {
 		return;
 	}
 	JavaElementInfo info = (JavaElementInfo)JavaModelManager.getJavaModelManager().getInfo(element);
 	if (info == null) // no longer in the java model.
 		return;
 	this.putElementInfo(element, info);

 	if (element instanceof IParent) {
 		IJavaElement[] children = info.getChildren();
 		if (children != null) {
 			insertPositions(children, false);
 			for(int i = 0, length = children.length; i < length; i++)
 				recordElementInfo(children[i], model, depth + 1);
 		}
 	}
 }
 /**
  * Fills the newPositions hashtable with the new position information
  */
 private void recordNewPositions(IJavaElement newElement, int depth) {
 	if (depth < this.maxDepth && newElement instanceof IParent) {
 		JavaElementInfo info = null;
 		try {
 			info = (JavaElementInfo)((JavaElement)newElement).getElementInfo();
 		} catch (JavaModelException npe) {
 			return;
 		}

 		IJavaElement[] children = info.getChildren();
 		if (children != null) {
 			insertPositions(children, true);
 			for(int i = 0, length = children.length; i < length; i++) {
 				recordNewPositions(children[i], depth + 1);
 			}
 		}
 	}
 }
 /**
  * Repairs the positioning information
  * after an element has been removed
  */
 private void removed(IJavaElement element) {
 	this.removed.add(element);
 	ListItem current = this.getOldPosition(element);
 	ListItem previous = null, next = null;
 	if (current.previous != null)
 		previous = this.getOldPosition(current.previous);
 	if (current.next != null)
 		next = this.getOldPosition(current.next);
 	if (previous != null)
 		previous.next = current.next;
 	if (next != null)
 		next.previous = current.previous;

 }
 private void removeElementInfo(IJavaElement element) {
 	this.infos.remove(element);
 }
 public String toString() {
 	StringBuffer buffer = new StringBuffer();
 	buffer.append("Built delta:\n"); //$NON-NLS-1$
 	buffer.append(this.delta.toString());
 	return buffer.toString();
 }
 /**
  * Trims deletion deltas to only report the highest level of deletion
  */
 private void trimDelta(JavaElementDelta elementDelta) {
 	if (elementDelta.getKind() == IJavaElementDelta.REMOVED) {
 		IJavaElementDelta[] children = elementDelta.getAffectedChildren();
 		for(int i = 0, length = children.length; i < length; i++) {
 			elementDelta.removeAffectedChild((JavaElementDelta)children[i]);
 		}
 	} else {
 		IJavaElementDelta[] children = elementDelta.getAffectedChildren();
 		for(int i = 0, length = children.length; i < length; i++) {
 			trimDelta((JavaElementDelta)children[i]);
 		}
 	}
 }
 }
	/*******************************************************************************
	* Copyright (c) 2000, 2004 IBM Corporation and others.
	* All rights reserved. This program and the accompanying materials
	* are made available under the terms of the Eclipse Public License v1.0
	* which accompanies this distribution, and is available at
	* http://www.eclipse.org/legal/epl-v10.html
	*
	* Contributors:
	* IBM Corporation - initial API and implementation
	*******************************************************************************/
	package org.eclipse.jdt.internal.core;

	import java.util.ArrayList;
	import java.util.HashMap;
	import java.util.Iterator;
	import java.util.Map;

	import org.eclipse.jdt.core.IJavaElement;
	import org.eclipse.jdt.core.IJavaElementDelta;
	import org.eclipse.jdt.core.IParent;
	import org.eclipse.jdt.core.JavaModelException;
	import org.eclipse.jdt.core.compiler.CharOperation;

	/**
	* A java element delta biulder creates a java element delta on
	* a java element between the version of the java element
	* at the time the comparator was created and the current version
	* of the java element.
	*
	* It performs this operation by locally caching the contents of
	* the java element when it is created. When the method
	* createDeltas() is called, it creates a delta over the cached
	* contents and the new contents.
	*/
	public class JavaElementDeltaBuilder {
	/**
	* The java element handle
	*/
	IJavaElement javaElement;

	/**
	* The maximum depth in the java element children we should look into
	*/
	int maxDepth = Integer.MAX_VALUE;

	/**
	* The old handle to info relationships
	*/
	Map infos;

	/**
	* The old position info
	*/
	Map oldPositions;

	/**
	* The new position info
	*/
	Map newPositions;

	/**
	* Change delta
	*/
	JavaElementDelta delta;

	/**
	* List of added elements
	*/
	ArrayList added;

	/**
	* List of removed elements
	*/
	ArrayList removed;

	/**
	* Doubly linked list item
	*/
	class ListItem {
	public IJavaElement previous;
	public IJavaElement next;

	public ListItem(IJavaElement previous, IJavaElement next) {
	this.previous = previous;
	this.next = next;
	}
	}
	/**
	* Creates a java element comparator on a java element
	* looking as deep as necessary.
	*/
	public JavaElementDeltaBuilder(IJavaElement javaElement) {
	this.javaElement = javaElement;
	this.initialize();
	this.recordElementInfo(
	javaElement,
	(JavaModel)this.javaElement.getJavaModel(),
	0);
	}
	/**
	* Creates a java element comparator on a java element
	* looking only 'maxDepth' levels deep.
	*/
	public JavaElementDeltaBuilder(IJavaElement javaElement, int maxDepth) {
	this.javaElement = javaElement;
	this.maxDepth = maxDepth;
	this.initialize();
	this.recordElementInfo(
	javaElement,
	(JavaModel)this.javaElement.getJavaModel(),
	0);
	}
	/**
	* Repairs the positioning information
	* after an element has been added
	*/
	private void added(IJavaElement element) {
	this.added.add(element);
	ListItem current = this.getNewPosition(element);
	ListItem previous = null, next = null;
	if (current.previous != null)
	previous = this.getNewPosition(current.previous);
	if (current.next != null)
	next = this.getNewPosition(current.next);
	if (previous != null)
	previous.next = current.next;
	if (next != null)
	next.previous = current.previous;
	}
	/**
	* Builds the java element deltas between the old content of the compilation
	* unit and its new content.
	*/
	public void buildDeltas() {
	this.recordNewPositions(this.javaElement, 0);
	this.findAdditions(this.javaElement, 0);
	this.findDeletions();
	this.findChangesInPositioning(this.javaElement, 0);
	this.trimDelta(this.delta);
	if (this.delta.getAffectedChildren().length == 0) {
	// this is a fine grained but not children affected -> mark as content changed
	this.delta.contentChanged();
	}
	}
	private boolean equals(char[][][] first, char[][][] second) {
	if (first == second)
	return true;
	if (first == null \|\| second == null)
	return false;
	if (first.length != second.length)
	return false;

	for (int i = first.length; --i >= 0;)
	if (!CharOperation.equals(first[i], second[i]))
	return false;
	return true;
	}
	/**
	* Finds elements which have been added or changed.
	*/
	private void findAdditions(IJavaElement newElement, int depth) {
	JavaElementInfo oldInfo = this.getElementInfo(newElement);
	if (oldInfo == null && depth < this.maxDepth) {
	this.delta.added(newElement);
	added(newElement);
	} else {
	this.removeElementInfo(newElement);
	}

	if (depth >= this.maxDepth) {
	// mark element as changed
	this.delta.changed(newElement, IJavaElementDelta.F_CONTENT);
	return;
	}

	JavaElementInfo newInfo = null;
	try {
	newInfo = (JavaElementInfo)((JavaElement)newElement).getElementInfo();
	} catch (JavaModelException npe) {
	return;
	}

	this.findContentChange(oldInfo, newInfo, newElement);

	if (oldInfo != null && newElement instanceof IParent) {

	IJavaElement[] children = newInfo.getChildren();
	if (children != null) {
	int length = children.length;
	for(int i = 0; i < length; i++) {
	this.findAdditions(children[i], depth + 1);
	}
	}
	}
	}
	/**
	* Looks for changed positioning of elements.
	*/
	private void findChangesInPositioning(IJavaElement element, int depth) {
	if (depth >= this.maxDepth \|\| this.added.contains(element) \|\| this.removed.contains(element))
	return;

	if (!isPositionedCorrectly(element)) {
	this.delta.changed(element, IJavaElementDelta.F_REORDER);
	}

	if (element instanceof IParent) {
	JavaElementInfo info = null;
	try {
	info = (JavaElementInfo)((JavaElement)element).getElementInfo();
	} catch (JavaModelException npe) {
	return;
	}

	IJavaElement[] children = info.getChildren();
	if (children != null) {
	int length = children.length;
	for(int i = 0; i < length; i++) {
	this.findChangesInPositioning(children[i], depth + 1);
	}
	}
	}
	}
	/**
	* The elements are equivalent, but might have content changes.
	*/
	private void findContentChange(JavaElementInfo oldInfo, JavaElementInfo newInfo, IJavaElement newElement) {
	if (oldInfo instanceof MemberElementInfo && newInfo instanceof MemberElementInfo) {
	if (((MemberElementInfo)oldInfo).getModifiers() != ((MemberElementInfo)newInfo).getModifiers()) {
	this.delta.changed(newElement, IJavaElementDelta.F_MODIFIERS);
	} else if (oldInfo instanceof SourceMethodElementInfo && newInfo instanceof SourceMethodElementInfo) {
	SourceMethodElementInfo oldSourceMethodInfo = (SourceMethodElementInfo)oldInfo;
	SourceMethodElementInfo newSourceMethodInfo = (SourceMethodElementInfo)newInfo;
	if (!CharOperation.equals(oldSourceMethodInfo.getReturnTypeName(), newSourceMethodInfo.getReturnTypeName())
	\|\| !CharOperation.equals(oldSourceMethodInfo.getTypeParameterNames(), newSourceMethodInfo.getTypeParameterNames())
	\|\| !equals(oldSourceMethodInfo.getTypeParameterBounds(), newSourceMethodInfo.getTypeParameterBounds())) {
	this.delta.changed(newElement, IJavaElementDelta.F_CONTENT);
	}
	} else if (oldInfo instanceof SourceFieldElementInfo && newInfo instanceof SourceFieldElementInfo) {
	if (!CharOperation.equals(
	((SourceFieldElementInfo)oldInfo).getTypeName(),
	((SourceFieldElementInfo)newInfo).getTypeName())) {
	this.delta.changed(newElement, IJavaElementDelta.F_CONTENT);
	}
	}
	}
	if (oldInfo instanceof SourceTypeElementInfo && newInfo instanceof SourceTypeElementInfo) {
	SourceTypeElementInfo oldSourceTypeInfo = (SourceTypeElementInfo)oldInfo;
	SourceTypeElementInfo newSourceTypeInfo = (SourceTypeElementInfo)newInfo;
	if (!CharOperation.equals(oldSourceTypeInfo.getSuperclassName(), newSourceTypeInfo.getSuperclassName())
	\|\| !CharOperation.equals(oldSourceTypeInfo.getInterfaceNames(), newSourceTypeInfo.getInterfaceNames())) {
	this.delta.changed(newElement, IJavaElementDelta.F_SUPER_TYPES);
	}
	if (!CharOperation.equals(oldSourceTypeInfo.getTypeParameterNames(), newSourceTypeInfo.getTypeParameterNames())
	\|\| !equals(oldSourceTypeInfo.getTypeParameterBounds(), newSourceTypeInfo.getTypeParameterBounds())) {
	this.delta.changed(newElement, IJavaElementDelta.F_CONTENT);
	}
	}
	}
	/**
	* Adds removed deltas for any handles left in the table
	*/
	private void findDeletions() {
	Iterator iter = this.infos.keySet().iterator();
	while(iter.hasNext()) {
	IJavaElement element = (IJavaElement)iter.next();
	this.delta.removed(element);
	this.removed(element);
	}
	}
	private JavaElementInfo getElementInfo(IJavaElement element) {
	return (JavaElementInfo)this.infos.get(element);
	}
	private ListItem getNewPosition(IJavaElement element) {
	return (ListItem)this.newPositions.get(element);
	}
	private ListItem getOldPosition(IJavaElement element) {
	return (ListItem)this.oldPositions.get(element);
	}
	private void initialize() {
	this.infos = new HashMap(20);
	this.oldPositions = new HashMap(20);
	this.newPositions = new HashMap(20);
	this.putOldPosition(this.javaElement, new ListItem(null, null));
	this.putNewPosition(this.javaElement, new ListItem(null, null));
	this.delta = new JavaElementDelta(javaElement);

	// if building a delta on a compilation unit or below,
	// it's a fine grained delta
	if (javaElement.getElementType() >= IJavaElement.COMPILATION_UNIT) {
	this.delta.fineGrained();
	}

	this.added = new ArrayList(5);
	this.removed = new ArrayList(5);
	}
	/**
	* Inserts position information for the elements into the new or old positions table
	*/
	private void insertPositions(IJavaElement[] elements, boolean isNew) {
	int length = elements.length;
	IJavaElement previous = null, current = null, next = (length > 0) ? elements[0] : null;
	for(int i = 0; i < length; i++) {
	previous = current;
	current = next;
	next = (i + 1 < length) ? elements[i + 1] : null;
	if (isNew) {
	this.putNewPosition(current, new ListItem(previous, next));
	} else {
	this.putOldPosition(current, new ListItem(previous, next));
	}
	}
	}
	/**
	* Returns whether the elements position has not changed.
	*/
	private boolean isPositionedCorrectly(IJavaElement element) {
	ListItem oldListItem = this.getOldPosition(element);
	if (oldListItem == null) return false;

	ListItem newListItem = this.getNewPosition(element);
	if (newListItem == null) return false;

	IJavaElement oldPrevious = oldListItem.previous;
	IJavaElement newPrevious = newListItem.previous;
	if (oldPrevious == null) {
	return newPrevious == null;
	} else {
	return oldPrevious.equals(newPrevious);
	}
	}
	private void putElementInfo(IJavaElement element, JavaElementInfo info) {
	this.infos.put(element, info);
	}
	private void putNewPosition(IJavaElement element, ListItem position) {
	this.newPositions.put(element, position);
	}
	private void putOldPosition(IJavaElement element, ListItem position) {
	this.oldPositions.put(element, position);
	}
	/**
	* Records this elements info, and attempts
	* to record the info for the children.
	*/
	private void recordElementInfo(IJavaElement element, JavaModel model, int depth) {
	if (depth >= this.maxDepth) {
	return;
	}
	JavaElementInfo info = (JavaElementInfo)JavaModelManager.getJavaModelManager().getInfo(element);
	if (info == null) // no longer in the java model.
	return;
	this.putElementInfo(element, info);

	if (element instanceof IParent) {
	IJavaElement[] children = info.getChildren();
	if (children != null) {
	insertPositions(children, false);
	for(int i = 0, length = children.length; i < length; i++)
	recordElementInfo(children[i], model, depth + 1);
	}
	}
	}
	/**
	* Fills the newPositions hashtable with the new position information
	*/
	private void recordNewPositions(IJavaElement newElement, int depth) {
	if (depth < this.maxDepth && newElement instanceof IParent) {
	JavaElementInfo info = null;
	try {
	info = (JavaElementInfo)((JavaElement)newElement).getElementInfo();
	} catch (JavaModelException npe) {
	return;
	}

	IJavaElement[] children = info.getChildren();
	if (children != null) {
	insertPositions(children, true);
	for(int i = 0, length = children.length; i < length; i++) {
	recordNewPositions(children[i], depth + 1);
	}
	}
	}
	}
	/**
	* Repairs the positioning information
	* after an element has been removed
	*/
	private void removed(IJavaElement element) {
	this.removed.add(element);
	ListItem current = this.getOldPosition(element);
	ListItem previous = null, next = null;
	if (current.previous != null)
	previous = this.getOldPosition(current.previous);
	if (current.next != null)
	next = this.getOldPosition(current.next);
	if (previous != null)
	previous.next = current.next;
	if (next != null)
	next.previous = current.previous;

	}
	private void removeElementInfo(IJavaElement element) {
	this.infos.remove(element);
	}
	public String toString() {
	StringBuffer buffer = new StringBuffer();
	buffer.append("Built delta:\n"); //$NON-NLS-1$
	buffer.append(this.delta.toString());
	return buffer.toString();
	}
	/**
	* Trims deletion deltas to only report the highest level of deletion
	*/
	private void trimDelta(JavaElementDelta elementDelta) {
	if (elementDelta.getKind() == IJavaElementDelta.REMOVED) {
	IJavaElementDelta[] children = elementDelta.getAffectedChildren();
	for(int i = 0, length = children.length; i < length; i++) {
	elementDelta.removeAffectedChild((JavaElementDelta)children[i]);
	}
	} else {
	IJavaElementDelta[] children = elementDelta.getAffectedChildren();
	for(int i = 0, length = children.length; i < length; i++) {
	trimDelta((JavaElementDelta)children[i]);
	}
	}
	}
	}