src/share/classes/javax/swing/text/ElementIterator.java - toolchain/jdk/jdk9_jdk - Git at Google

 /*
  * Copyright (c) 1998, 2008, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this
  * particular file as subject to the "Classpath" exception as provided
  * by Oracle in the LICENSE file that accompanied this code.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */

 package javax.swing.text;

 import java.util.Stack;
 import java.util.Enumeration;

 /**
  * <p>
  * ElementIterator, as the name suggests, iteratates over the Element
  * tree.  The constructor can be invoked with either Document or an Element
  * as an argument.  If the constructor is invoked with a Document as an
  * argument then the root of the iteration is the return value of
  * document.getDefaultRootElement().
  *
  * The iteration happens in a depth-first manner.  In terms of how
  * boundary conditions are handled:
  * a) if next() is called before first() or current(), the
  *    root will be returned.
  * b) next() returns null to indicate the end of the list.
  * c) previous() returns null when the current element is the root
  *    or next() has returned null.
  *
  * The ElementIterator does no locking of the Element tree. This means
  * that it does not track any changes.  It is the responsibility of the
  * user of this class, to ensure that no changes happen during element
  * iteration.
  *
  * Simple usage example:
  *
  *    public void iterate() {
  *        ElementIterator it = new ElementIterator(root);
  *        Element elem;
  *        while (true) {
  *           if ((elem = next()) != null) {
  *               // process element
  *               System.out.println("elem: " + elem.getName());
  *           } else {
  *               break;
  *           }
  *        }
  *    }
  *
  * @author Sunita Mani
  *
  */

 public class ElementIterator implements Cloneable {


     private Element root;
     private Stack<StackItem> elementStack = null;

     /**
      * The StackItem class stores the element
      * as well as a child index.  If the
      * index is -1, then the element represented
      * on the stack is the element itself.
      * Otherwise, the index functions as as index
      * into the vector of children of the element.
      * In this case, the item on the stack
      * represents the "index"th child of the element
      *
      */
     private class StackItem implements Cloneable {
         Element item;
         int childIndex;

         private StackItem(Element elem) {
             /**
              * -1 index implies a self reference,
              * as opposed to an index into its
              * list of children.
              */
             this.item = elem;
             this.childIndex = -1;
         }

         private void incrementIndex() {
             childIndex++;
         }

         private Element getElement() {
             return item;
         }

         private int getIndex() {
             return childIndex;
         }

         protected Object clone() throws java.lang.CloneNotSupportedException {
             return super.clone();
         }
     }

     /**
      * Creates a new ElementIterator. The
      * root element is taken to get the
      * default root element of the document.
      *
      * @param document a Document.
      */
     public ElementIterator(Document document) {
         root = document.getDefaultRootElement();
     }


     /**
      * Creates a new ElementIterator.
      *
      * @param root the root Element.
      */
     public ElementIterator(Element root) {
         this.root = root;
     }


     /**
      * Clones the ElementIterator.
      *
      * @return a cloned ElementIterator Object.
      */
     public synchronized Object clone() {

         try {
             ElementIterator it = new ElementIterator(root);
             if (elementStack != null) {
                 it.elementStack = new Stack<StackItem>();
                 for (int i = 0; i < elementStack.size(); i++) {
                     StackItem item = elementStack.elementAt(i);
                     StackItem clonee = (StackItem)item.clone();
                     it.elementStack.push(clonee);
                 }
             }
             return it;
         } catch (CloneNotSupportedException e) {
             throw new InternalError();
         }
     }


     /**
      * Fetches the first element.
      *
      * @return an Element.
      */
     public Element first() {
         // just in case...
         if (root == null) {
             return null;
         }

         elementStack = new Stack<StackItem>();
         if (root.getElementCount() != 0) {
             elementStack.push(new StackItem(root));
         }
         return root;
     }

     /**
      * Fetches the current depth of element tree.
      *
      * @return the depth.
      */
     public int depth() {
         if (elementStack == null) {
             return 0;
         }
         return elementStack.size();
     }


     /**
      * Fetches the current Element.
      *
      * @return element on top of the stack or
      *          <code>null</code> if the root element is <code>null</code>
      */
     public Element current() {

         if (elementStack == null) {
             return first();
         }

         /*
           get a handle to the element on top of the stack.
         */
         if (! elementStack.empty()) {
             StackItem item = elementStack.peek();
             Element elem = item.getElement();
             int index = item.getIndex();
             // self reference
             if (index == -1) {
                 return elem;
             }
             // return the child at location "index".
             return elem.getElement(index);
         }
         return null;
     }


     /**
      * Fetches the next Element. The strategy
      * used to locate the next element is
      * a depth-first search.
      *
      * @return the next element or <code>null</code>
      *          at the end of the list.
      */
     public Element next() {

         /* if current() has not been invoked
            and next is invoked, the very first
            element will be returned. */
         if (elementStack == null) {
             return first();
         }

         // no more elements
         if (elementStack.isEmpty()) {
             return null;
         }

         // get a handle to the element on top of the stack

         StackItem item = elementStack.peek();
         Element elem = item.getElement();
         int index = item.getIndex();

         if (index+1 < elem.getElementCount()) {
             Element child = elem.getElement(index+1);
             if (child.isLeaf()) {
                 /* In this case we merely want to increment
                    the child index of the item on top of the
                    stack.*/
                 item.incrementIndex();
             } else {
                 /* In this case we need to push the child(branch)
                    on the stack so that we can iterate over its
                    children. */
                 elementStack.push(new StackItem(child));
             }
             return child;
         } else {
             /* No more children for the item on top of the
                stack therefore pop the stack. */
             elementStack.pop();
             if (!elementStack.isEmpty()) {
                 /* Increment the child index for the item that
                    is now on top of the stack. */
                 StackItem top = elementStack.peek();
                 top.incrementIndex();
                 /* We now want to return its next child, therefore
                    call next() recursively. */
                 return next();
             }
         }
         return null;
     }


     /**
      * Fetches the previous Element. If howver the current
      * element is the last element, or the current element
      * is null, then null is returned.
      *
      * @return previous <code>Element</code> if available
      *
      */
     public Element previous() {

         int stackSize;
         if (elementStack == null || (stackSize = elementStack.size()) == 0) {
             return null;
         }

         // get a handle to the element on top of the stack
         //
         StackItem item = elementStack.peek();
         Element elem = item.getElement();
         int index = item.getIndex();

         if (index > 0) {
             /* return child at previous index. */
             return getDeepestLeaf(elem.getElement(--index));
         } else if (index == 0) {
             /* this implies that current is the element's
                first child, therefore previous is the
                element itself. */
             return elem;
         } else if (index == -1) {
             if (stackSize == 1) {
                 // current is the root, nothing before it.
                 return null;
             }
             /* We need to return either the item
                below the top item or one of the
                former's children. */
             StackItem top = elementStack.pop();
             item = elementStack.peek();

             // restore the top item.
             elementStack.push(top);
             elem = item.getElement();
             index = item.getIndex();
             return ((index == -1) ? elem : getDeepestLeaf(elem.getElement
                                                           (index)));
         }
         // should never get here.
         return null;
     }

     /**
      * Returns the last child of <code>parent</code> that is a leaf. If the
      * last child is a not a leaf, this method is called with the last child.
      */
     private Element getDeepestLeaf(Element parent) {
         if (parent.isLeaf()) {
             return parent;
         }
         int childCount = parent.getElementCount();
         if (childCount == 0) {
             return parent;
         }
         return getDeepestLeaf(parent.getElement(childCount - 1));
     }

     /*
       Iterates through the element tree and prints
       out each element and its attributes.
     */
     private void dumpTree() {

         Element elem;
         while (true) {
             if ((elem = next()) != null) {
                 System.out.println("elem: " + elem.getName());
                 AttributeSet attr = elem.getAttributes();
                 String s = "";
                 Enumeration names = attr.getAttributeNames();
                 while (names.hasMoreElements()) {
                     Object key = names.nextElement();
                     Object value = attr.getAttribute(key);
                     if (value instanceof AttributeSet) {
                         // don't go recursive
                         s = s + key + "=**AttributeSet** ";
                     } else {
                         s = s + key + "=" + value + " ";
                     }
                 }
                 System.out.println("attributes: " + s);
             } else {
                 break;
             }
         }
     }
 }
	/*
	* Copyright (c) 1998, 2008, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package javax.swing.text;

	import java.util.Stack;
	import java.util.Enumeration;

	/**
	* <p>
	* ElementIterator, as the name suggests, iteratates over the Element
	* tree. The constructor can be invoked with either Document or an Element
	* as an argument. If the constructor is invoked with a Document as an
	* argument then the root of the iteration is the return value of
	* document.getDefaultRootElement().
	*
	* The iteration happens in a depth-first manner. In terms of how
	* boundary conditions are handled:
	* a) if next() is called before first() or current(), the
	* root will be returned.
	* b) next() returns null to indicate the end of the list.
	* c) previous() returns null when the current element is the root
	* or next() has returned null.
	*
	* The ElementIterator does no locking of the Element tree. This means
	* that it does not track any changes. It is the responsibility of the
	* user of this class, to ensure that no changes happen during element
	* iteration.
	*
	* Simple usage example:
	*
	* public void iterate() {
	* ElementIterator it = new ElementIterator(root);
	* Element elem;
	* while (true) {
	* if ((elem = next()) != null) {
	* // process element
	* System.out.println("elem: " + elem.getName());
	* } else {
	* break;
	* }
	* }
	* }
	*
	* @author Sunita Mani
	*
	*/

	public class ElementIterator implements Cloneable {


	private Element root;
	private Stack<StackItem> elementStack = null;

	/**
	* The StackItem class stores the element
	* as well as a child index. If the
	* index is -1, then the element represented
	* on the stack is the element itself.
	* Otherwise, the index functions as as index
	* into the vector of children of the element.
	* In this case, the item on the stack
	* represents the "index"th child of the element
	*
	*/
	private class StackItem implements Cloneable {
	Element item;
	int childIndex;

	private StackItem(Element elem) {
	/**
	* -1 index implies a self reference,
	* as opposed to an index into its
	* list of children.
	*/
	this.item = elem;
	this.childIndex = -1;
	}

	private void incrementIndex() {
	childIndex++;
	}

	private Element getElement() {
	return item;
	}

	private int getIndex() {
	return childIndex;
	}

	protected Object clone() throws java.lang.CloneNotSupportedException {
	return super.clone();
	}
	}

	/**
	* Creates a new ElementIterator. The
	* root element is taken to get the
	* default root element of the document.
	*
	* @param document a Document.
	*/
	public ElementIterator(Document document) {
	root = document.getDefaultRootElement();
	}


	/**
	* Creates a new ElementIterator.
	*
	* @param root the root Element.
	*/
	public ElementIterator(Element root) {
	this.root = root;
	}


	/**
	* Clones the ElementIterator.
	*
	* @return a cloned ElementIterator Object.
	*/
	public synchronized Object clone() {

	try {
	ElementIterator it = new ElementIterator(root);
	if (elementStack != null) {
	it.elementStack = new Stack<StackItem>();
	for (int i = 0; i < elementStack.size(); i++) {
	StackItem item = elementStack.elementAt(i);
	StackItem clonee = (StackItem)item.clone();
	it.elementStack.push(clonee);
	}
	}
	return it;
	} catch (CloneNotSupportedException e) {
	throw new InternalError();
	}
	}


	/**
	* Fetches the first element.
	*
	* @return an Element.
	*/
	public Element first() {
	// just in case...
	if (root == null) {
	return null;
	}

	elementStack = new Stack<StackItem>();
	if (root.getElementCount() != 0) {
	elementStack.push(new StackItem(root));
	}
	return root;
	}

	/**
	* Fetches the current depth of element tree.
	*
	* @return the depth.
	*/
	public int depth() {
	if (elementStack == null) {
	return 0;
	}
	return elementStack.size();
	}


	/**
	* Fetches the current Element.
	*
	* @return element on top of the stack or
	* <code>null</code> if the root element is <code>null</code>
	*/
	public Element current() {

	if (elementStack == null) {
	return first();
	}

	/*
	get a handle to the element on top of the stack.
	*/
	if (! elementStack.empty()) {
	StackItem item = elementStack.peek();
	Element elem = item.getElement();
	int index = item.getIndex();
	// self reference
	if (index == -1) {
	return elem;
	}
	// return the child at location "index".
	return elem.getElement(index);
	}
	return null;
	}


	/**
	* Fetches the next Element. The strategy
	* used to locate the next element is
	* a depth-first search.
	*
	* @return the next element or <code>null</code>
	* at the end of the list.
	*/
	public Element next() {

	/* if current() has not been invoked
	and next is invoked, the very first
	element will be returned. */
	if (elementStack == null) {
	return first();
	}

	// no more elements
	if (elementStack.isEmpty()) {
	return null;
	}

	// get a handle to the element on top of the stack

	StackItem item = elementStack.peek();
	Element elem = item.getElement();
	int index = item.getIndex();

	if (index+1 < elem.getElementCount()) {
	Element child = elem.getElement(index+1);
	if (child.isLeaf()) {
	/* In this case we merely want to increment
	the child index of the item on top of the
	stack.*/
	item.incrementIndex();
	} else {
	/* In this case we need to push the child(branch)
	on the stack so that we can iterate over its
	children. */
	elementStack.push(new StackItem(child));
	}
	return child;
	} else {
	/* No more children for the item on top of the
	stack therefore pop the stack. */
	elementStack.pop();
	if (!elementStack.isEmpty()) {
	/* Increment the child index for the item that
	is now on top of the stack. */
	StackItem top = elementStack.peek();
	top.incrementIndex();
	/* We now want to return its next child, therefore
	call next() recursively. */
	return next();
	}
	}
	return null;
	}


	/**
	* Fetches the previous Element. If howver the current
	* element is the last element, or the current element
	* is null, then null is returned.
	*
	* @return previous <code>Element</code> if available
	*
	*/
	public Element previous() {

	int stackSize;
	if (elementStack == null \|\| (stackSize = elementStack.size()) == 0) {
	return null;
	}

	// get a handle to the element on top of the stack
	//
	StackItem item = elementStack.peek();
	Element elem = item.getElement();
	int index = item.getIndex();

	if (index > 0) {
	/* return child at previous index. */
	return getDeepestLeaf(elem.getElement(--index));
	} else if (index == 0) {
	/* this implies that current is the element's
	first child, therefore previous is the
	element itself. */
	return elem;
	} else if (index == -1) {
	if (stackSize == 1) {
	// current is the root, nothing before it.
	return null;
	}
	/* We need to return either the item
	below the top item or one of the
	former's children. */
	StackItem top = elementStack.pop();
	item = elementStack.peek();

	// restore the top item.
	elementStack.push(top);
	elem = item.getElement();
	index = item.getIndex();
	return ((index == -1) ? elem : getDeepestLeaf(elem.getElement
	(index)));
	}
	// should never get here.
	return null;
	}

	/**
	* Returns the last child of <code>parent</code> that is a leaf. If the
	* last child is a not a leaf, this method is called with the last child.
	*/
	private Element getDeepestLeaf(Element parent) {
	if (parent.isLeaf()) {
	return parent;
	}
	int childCount = parent.getElementCount();
	if (childCount == 0) {
	return parent;
	}
	return getDeepestLeaf(parent.getElement(childCount - 1));
	}

	/*
	Iterates through the element tree and prints
	out each element and its attributes.
	*/
	private void dumpTree() {

	Element elem;
	while (true) {
	if ((elem = next()) != null) {
	System.out.println("elem: " + elem.getName());
	AttributeSet attr = elem.getAttributes();
	String s = "";
	Enumeration names = attr.getAttributeNames();
	while (names.hasMoreElements()) {
	Object key = names.nextElement();
	Object value = attr.getAttribute(key);
	if (value instanceof AttributeSet) {
	// don't go recursive
	s = s + key + "=AttributeSet ";
	} else {
	s = s + key + "=" + value + " ";
	}
	}
	System.out.println("attributes: " + s);
	} else {
	break;
	}
	}
	}
	}