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/*

 * This file is available under and governed by the GNU General Public

 * License version 2 only, as published by the Free Software Foundation.

 * However, the following notice accompanied the original version of this

 * file and, per its terms, should not be removed:

 *

 * Copyright (c) 2002 World Wide Web Consortium,

 * (Massachusetts Institute of Technology, Institut National de

 * Recherche en Informatique et en Automatique, Keio University). All

 * Rights Reserved. This program is distributed under the W3C's Software

 * Intellectual Property License. This program 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 W3C License http://www.w3.org/Consortium/Legal/ for more details.

 */

package org.w3c.dom.xpath;

import org.w3c.dom.Node;

import org.w3c.dom.DOMException;

/**

 * The <code>XPathResult</code> interface represents the result of the

 * evaluation of an XPath 1.0 expression within the context of a particular

 * node. Since evaluation of an XPath expression can result in various

 * result types, this object makes it possible to discover and manipulate

 * the type and value of the result.

 */

public interface XPathResult {

    // XPathResultType

    /**

     * This code does not represent a specific type. An evaluation of an XPath

     * expression will never produce this type. If this type is requested,

     * then the evaluation returns whatever type naturally results from

     * evaluation of the expression.

     * <br>If the natural result is a node set when <code>ANY_TYPE</code> was

     * requested, then <code>UNORDERED_NODE_ITERATOR_TYPE</code> is always

     * the resulting type. Any other representation of a node set must be

     * explicitly requested.

     */

    public static final short ANY_TYPE                  = 0;

    /**

     * The result is a number as defined by . Document modification does not

     * invalidate the number, but may mean that reevaluation would not yield

     * the same number.

     */

    public static final short NUMBER_TYPE               = 1;

    /**

     * The result is a string as defined by . Document modification does not

     * invalidate the string, but may mean that the string no longer

     * corresponds to the current document.

     */

    public static final short STRING_TYPE               = 2;

    /**

     * The result is a boolean as defined by . Document modification does not

     * invalidate the boolean, but may mean that reevaluation would not

     * yield the same boolean.

     */

    public static final short BOOLEAN_TYPE              = 3;

    /**

     * The result is a node set as defined by  that will be accessed

     * iteratively, which may not produce nodes in a particular order.

     * Document modification invalidates the iteration.

     * <br>This is the default type returned if the result is a node set and

     * <code>ANY_TYPE</code> is requested.

     */

    public static final short UNORDERED_NODE_ITERATOR_TYPE = 4;

    /**

     * The result is a node set as defined by  that will be accessed

     * iteratively, which will produce document-ordered nodes. Document

     * modification invalidates the iteration.

     */

    public static final short ORDERED_NODE_ITERATOR_TYPE = 5;

    /**

     * The result is a node set as defined by  that will be accessed as a

     * snapshot list of nodes that may not be in a particular order.

     * Document modification does not invalidate the snapshot but may mean

     * that reevaluation would not yield the same snapshot and nodes in the

     * snapshot may have been altered, moved, or removed from the document.

     */

    public static final short UNORDERED_NODE_SNAPSHOT_TYPE = 6;

    /**

     * The result is a node set as defined by  that will be accessed as a

     * snapshot list of nodes that will be in original document order.

     * Document modification does not invalidate the snapshot but may mean

     * that reevaluation would not yield the same snapshot and nodes in the

     * snapshot may have been altered, moved, or removed from the document.

     */

    public static final short ORDERED_NODE_SNAPSHOT_TYPE = 7;

    /**

     * The result is a node set as defined by  and will be accessed as a

     * single node, which may be <code>null</code>if the node set is empty.

     * Document modification does not invalidate the node, but may mean that

     * the result node no longer corresponds to the current document. This

     * is a convenience that permits optimization since the implementation

     * can stop once any node in the in the resulting set has been found.

     * <br>If there are more than one node in the actual result, the single

     * node returned might not be the first in document order.

     */

    public static final short ANY_UNORDERED_NODE_TYPE   = 8;

    /**

     * The result is a node set as defined by  and will be accessed as a

     * single node, which may be <code>null</code> if the node set is empty.

     * Document modification does not invalidate the node, but may mean that

     * the result node no longer corresponds to the current document. This

     * is a convenience that permits optimization since the implementation

     * can stop once the first node in document order of the resulting set

     * has been found.

     * <br>If there are more than one node in the actual result, the single

     * node returned will be the first in document order.

     */

    public static final short FIRST_ORDERED_NODE_TYPE   = 9;

    /**

     * A code representing the type of this result, as defined by the type

     * constants.

     */

    public short getResultType();

    /**

     * The value of this number result. If the native double type of the DOM

     * binding does not directly support the exact IEEE 754 result of the

     * XPath expression, then it is up to the definition of the binding

     * binding to specify how the XPath number is converted to the native

     * binding number.

     * @exception XPathException

     *   TYPE_ERR: raised if <code>resultType</code> is not

     *   <code>NUMBER_TYPE</code>.

     */

    public double getNumberValue()

                             throws XPathException;

    /**

     * The value of this string result.

     * @exception XPathException

     *   TYPE_ERR: raised if <code>resultType</code> is not

     *   <code>STRING_TYPE</code>.

     */

    public String getStringValue()

                             throws XPathException;

    /**

     * The value of this boolean result.

     * @exception XPathException

     *   TYPE_ERR: raised if <code>resultType</code> is not

     *   <code>BOOLEAN_TYPE</code>.

     */

    public boolean getBooleanValue()

                             throws XPathException;

    /**

     * The value of this single node result, which may be <code>null</code>.

     * @exception XPathException

     *   TYPE_ERR: raised if <code>resultType</code> is not

     *   <code>ANY_UNORDERED_NODE_TYPE</code> or

     *   <code>FIRST_ORDERED_NODE_TYPE</code>.

     */

    public Node getSingleNodeValue()

                             throws XPathException;

    /**

     * Signifies that the iterator has become invalid. True if

     * <code>resultType</code> is <code>UNORDERED_NODE_ITERATOR_TYPE</code>

     * or <code>ORDERED_NODE_ITERATOR_TYPE</code> and the document has been

     * modified since this result was returned.

     */

    public boolean getInvalidIteratorState();

    /**

     * The number of nodes in the result snapshot. Valid values for

     * snapshotItem indices are <code>0</code> to

     * <code>snapshotLength-1</code> inclusive.

     * @exception XPathException

     *   TYPE_ERR: raised if <code>resultType</code> is not

     *   <code>UNORDERED_NODE_SNAPSHOT_TYPE</code> or

     *   <code>ORDERED_NODE_SNAPSHOT_TYPE</code>.

     */

    public int getSnapshotLength()

                             throws XPathException;

    /**

     * Iterates and returns the next node from the node set or

     * <code>null</code>if there are no more nodes.

     * @return Returns the next node.

     * @exception XPathException

     *   TYPE_ERR: raised if <code>resultType</code> is not

     *   <code>UNORDERED_NODE_ITERATOR_TYPE</code> or

     *   <code>ORDERED_NODE_ITERATOR_TYPE</code>.

     * @exception DOMException

     *   INVALID_STATE_ERR: The document has been mutated since the result was

     *   returned.

     */

    public Node iterateNext()

                            throws XPathException, DOMException;

    /**

     * Returns the <code>index</code>th item in the snapshot collection. If

     * <code>index</code> is greater than or equal to the number of nodes in

     * the list, this method returns <code>null</code>. Unlike the iterator

     * result, the snapshot does not become invalid, but may not correspond

     * to the current document if it is mutated.

     * @param index Index into the snapshot collection.

     * @return The node at the <code>index</code>th position in the

     *   <code>NodeList</code>, or <code>null</code> if that is not a valid

     *   index.

     * @exception XPathException

     *   TYPE_ERR: raised if <code>resultType</code> is not

     *   <code>UNORDERED_NODE_SNAPSHOT_TYPE</code> or

     *   <code>ORDERED_NODE_SNAPSHOT_TYPE</code>.

     */

    public Node snapshotItem(int index)

                             throws XPathException;

}