001/*
002 * Copyright (c) 2004 World Wide Web Consortium,
003 *
004 * (Massachusetts Institute of Technology, European Research Consortium for
005 * Informatics and Mathematics, Keio University). All Rights Reserved. This
006 * work is distributed under the W3C(r) Software License [1] in the hope that
007 * it will be useful, but WITHOUT ANY WARRANTY; without even the implied
008 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
009 *
010 * [1] http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231
011 */
012
013package org.w3c.dom.xpath;
014
015import org.w3c.dom.Node;
016import org.w3c.dom.DOMException;
017
018/**
019 * The <code>XPathResult</code> interface represents the result of the 
020 * evaluation of an XPath 1.0 expression within the context of a particular 
021 * node. Since evaluation of an XPath expression can result in various 
022 * result types, this object makes it possible to discover and manipulate 
023 * the type and value of the result.
024 * <p>See also the <a href='http://www.w3.org/TR/2004/NOTE-DOM-Level-3-XPath-20040226'>Document Object Model (DOM) Level 3 XPath Specification</a>.
025 */
026public interface XPathResult {
027    // XPathResultType
028    /**
029     * This code does not represent a specific type. An evaluation of an XPath 
030     * expression will never produce this type. If this type is requested, 
031     * then the evaluation returns whatever type naturally results from 
032     * evaluation of the expression. 
033     * <br>If the natural result is a node set when <code>ANY_TYPE</code> was 
034     * requested, then <code>UNORDERED_NODE_ITERATOR_TYPE</code> is always 
035     * the resulting type. Any other representation of a node set must be 
036     * explicitly requested.
037     */
038    public static final short ANY_TYPE                  = 0;
039    /**
040     * The result is a <a href='http://www.w3.org/TR/1999/REC-xpath-19991116#numbers'>number</a> as defined by [<a href='http://www.w3.org/TR/1999/REC-xpath-19991116'>XPath 1.0</a>]. 
041     * Document modification does not invalidate the number, but may mean 
042     * that reevaluation would not yield the same number.
043     */
044    public static final short NUMBER_TYPE               = 1;
045    /**
046     * The result is a <a href='http://www.w3.org/TR/1999/REC-xpath-19991116#strings'>string</a> as defined by [<a href='http://www.w3.org/TR/1999/REC-xpath-19991116'>XPath 1.0</a>]. 
047     * Document modification does not invalidate the string, but may mean 
048     * that the string no longer corresponds to the current document.
049     */
050    public static final short STRING_TYPE               = 2;
051    /**
052     * The result is a <a href='http://www.w3.org/TR/1999/REC-xpath-19991116#booleans'>boolean</a> as defined by [<a href='http://www.w3.org/TR/1999/REC-xpath-19991116'>XPath 1.0</a>]. 
053     * Document modification does not invalidate the boolean, but may mean 
054     * that reevaluation would not yield the same boolean.
055     */
056    public static final short BOOLEAN_TYPE              = 3;
057    /**
058     * The result is a <a href='http://www.w3.org/TR/1999/REC-xpath-19991116#node-sets'>node set</a> as defined by [<a href='http://www.w3.org/TR/1999/REC-xpath-19991116'>XPath 1.0</a>] that 
059     * will be accessed iteratively, which may not produce nodes in a 
060     * particular order. Document modification invalidates the iteration.
061     * <br>This is the default type returned if the result is a node set and 
062     * <code>ANY_TYPE</code> is requested.
063     */
064    public static final short UNORDERED_NODE_ITERATOR_TYPE = 4;
065    /**
066     * The result is a node set as defined by [<a href='http://www.w3.org/TR/1999/REC-xpath-19991116'>XPath 1.0</a>] that 
067     * will be accessed iteratively, which will produce document-ordered 
068     * nodes. Document modification invalidates the iteration.
069     */
070    public static final short ORDERED_NODE_ITERATOR_TYPE = 5;
071    /**
072     * The result is a <a href='http://www.w3.org/TR/1999/REC-xpath-19991116#node-sets'>node set</a> as defined by [<a href='http://www.w3.org/TR/1999/REC-xpath-19991116'>XPath 1.0</a>] that 
073     * will be accessed as a snapshot list of nodes that may not be in a 
074     * particular order. Document modification does not invalidate the 
075     * snapshot but may mean that reevaluation would not yield the same 
076     * snapshot and nodes in the snapshot may have been altered, moved, or 
077     * removed from the document.
078     */
079    public static final short UNORDERED_NODE_SNAPSHOT_TYPE = 6;
080    /**
081     * The result is a <a href='http://www.w3.org/TR/1999/REC-xpath-19991116#node-sets'>node set</a> as defined by [<a href='http://www.w3.org/TR/1999/REC-xpath-19991116'>XPath 1.0</a>] that 
082     * will be accessed as a snapshot list of nodes that will be in original 
083     * document order. Document modification does not invalidate the 
084     * snapshot but may mean that reevaluation would not yield the same 
085     * snapshot and nodes in the snapshot may have been altered, moved, or 
086     * removed from the document.
087     */
088    public static final short ORDERED_NODE_SNAPSHOT_TYPE = 7;
089    /**
090     * The result is a <a href='http://www.w3.org/TR/1999/REC-xpath-19991116#node-sets'>node set</a> as defined by [<a href='http://www.w3.org/TR/1999/REC-xpath-19991116'>XPath 1.0</a>] and 
091     * will be accessed as a single node, which may be <code>null</code>if 
092     * the node set is empty. Document modification does not invalidate the 
093     * node, but may mean that the result node no longer corresponds to the 
094     * current document. This is a convenience that permits optimization 
095     * since the implementation can stop once any node in the resulting set 
096     * has been found.
097     * <br>If there is more than one node in the actual result, the single 
098     * node returned might not be the first in document order.
099     */
100    public static final short ANY_UNORDERED_NODE_TYPE   = 8;
101    /**
102     * The result is a <a href='http://www.w3.org/TR/1999/REC-xpath-19991116#node-sets'>node set</a> as defined by [<a href='http://www.w3.org/TR/1999/REC-xpath-19991116'>XPath 1.0</a>] and 
103     * will be accessed as a single node, which may be <code>null</code> if 
104     * the node set is empty. Document modification does not invalidate the 
105     * node, but may mean that the result node no longer corresponds to the 
106     * current document. This is a convenience that permits optimization 
107     * since the implementation can stop once the first node in document 
108     * order of the resulting set has been found.
109     * <br>If there are more than one node in the actual result, the single 
110     * node returned will be the first in document order.
111     */
112    public static final short FIRST_ORDERED_NODE_TYPE   = 9;
113
114    /**
115     * A code representing the type of this result, as defined by the type 
116     * constants.
117     */
118    public short getResultType();
119
120    /**
121     * The value of this number result. If the native double type of the DOM 
122     * binding does not directly support the exact IEEE 754 result of the 
123     * XPath expression, then it is up to the definition of the binding to 
124     * specify how the XPath number is converted to the native binding 
125     * number.
126     * @exception XPathException
127     *   TYPE_ERR: raised if <code>resultType</code> is not 
128     *   <code>NUMBER_TYPE</code>.
129     */
130    public double getNumberValue()
131                             throws XPathException;
132
133    /**
134     * The value of this string result.
135     * @exception XPathException
136     *   TYPE_ERR: raised if <code>resultType</code> is not 
137     *   <code>STRING_TYPE</code>.
138     */
139    public String getStringValue()
140                             throws XPathException;
141
142    /**
143     * The value of this boolean result.
144     * @exception XPathException
145     *   TYPE_ERR: raised if <code>resultType</code> is not 
146     *   <code>BOOLEAN_TYPE</code>.
147     */
148    public boolean getBooleanValue()
149                             throws XPathException;
150
151    /**
152     * The value of this single node result, which may be <code>null</code>.
153     * @exception XPathException
154     *   TYPE_ERR: raised if <code>resultType</code> is not 
155     *   <code>ANY_UNORDERED_NODE_TYPE</code> or 
156     *   <code>FIRST_ORDERED_NODE_TYPE</code>.
157     */
158    public Node getSingleNodeValue()
159                             throws XPathException;
160
161    /**
162     * Signifies that the iterator has become invalid. True if 
163     * <code>resultType</code> is <code>UNORDERED_NODE_ITERATOR_TYPE</code> 
164     * or <code>ORDERED_NODE_ITERATOR_TYPE</code> and the document has been 
165     * modified since this result was returned.
166     */
167    public boolean getInvalidIteratorState();
168
169    /**
170     * The number of nodes in the result snapshot. Valid values for 
171     * snapshotItem indices are <code>0</code> to 
172     * <code>snapshotLength-1</code> inclusive.
173     * @exception XPathException
174     *   TYPE_ERR: raised if <code>resultType</code> is not 
175     *   <code>UNORDERED_NODE_SNAPSHOT_TYPE</code> or 
176     *   <code>ORDERED_NODE_SNAPSHOT_TYPE</code>.
177     */
178    public int getSnapshotLength()
179                             throws XPathException;
180
181    /**
182     * Iterates and returns the next node from the node set or 
183     * <code>null</code>if there are no more nodes.
184     * @return Returns the next node.
185     * @exception XPathException
186     *   TYPE_ERR: raised if <code>resultType</code> is not 
187     *   <code>UNORDERED_NODE_ITERATOR_TYPE</code> or 
188     *   <code>ORDERED_NODE_ITERATOR_TYPE</code>.
189     * @exception DOMException
190     *   INVALID_STATE_ERR: The document has been mutated since the result was 
191     *   returned.
192     */
193    public Node iterateNext()
194                            throws XPathException, DOMException;
195
196    /**
197     * Returns the <code>index</code>th item in the snapshot collection. If 
198     * <code>index</code> is greater than or equal to the number of nodes in 
199     * the list, this method returns <code>null</code>. Unlike the iterator 
200     * result, the snapshot does not become invalid, but may not correspond 
201     * to the current document if it is mutated.
202     * @param index Index into the snapshot collection.
203     * @return The node at the <code>index</code>th position in the 
204     *   <code>NodeList</code>, or <code>null</code> if that is not a valid 
205     *   index.
206     * @exception XPathException
207     *   TYPE_ERR: raised if <code>resultType</code> is not 
208     *   <code>UNORDERED_NODE_SNAPSHOT_TYPE</code> or 
209     *   <code>ORDERED_NODE_SNAPSHOT_TYPE</code>.
210     */
211    public Node snapshotItem(int index)
212                             throws XPathException;
213
214}