XPathImplUtil.java revision 692:b13f7d2000cf 
1/*
2 * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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24 */
25
26package com.sun.org.apache.xpath.internal.jaxp;
27
28import com.sun.org.apache.xalan.internal.res.XSLMessages;
29import com.sun.org.apache.xalan.internal.utils.FactoryImpl;
30import com.sun.org.apache.xalan.internal.utils.FeatureManager;
31import com.sun.org.apache.xml.internal.dtm.DTM;
32import com.sun.org.apache.xpath.internal.objects.XObject;
33import com.sun.org.apache.xpath.internal.res.XPATHErrorResources;
34import java.io.IOException;
35import javax.xml.namespace.QName;
36import javax.xml.parsers.DocumentBuilderFactory;
37import javax.xml.parsers.ParserConfigurationException;
38import javax.xml.transform.TransformerException;
39import javax.xml.xpath.XPathConstants;
40import javax.xml.xpath.XPathEvaluationResult;
41import javax.xml.xpath.XPathExpressionException;
42import javax.xml.xpath.XPathFunctionResolver;
43import javax.xml.xpath.XPathNodes;
44import javax.xml.xpath.XPathVariableResolver;
45import org.w3c.dom.Document;
46import org.w3c.dom.Node;
47import org.w3c.dom.traversal.NodeIterator;
48import org.xml.sax.InputSource;
49import org.xml.sax.SAXException;
50
51/**
52 * This class contains several utility methods used by XPathImpl and
53 * XPathExpressionImpl
54 */
55class XPathImplUtil {
56    XPathFunctionResolver functionResolver;
57    XPathVariableResolver variableResolver;
58    JAXPPrefixResolver prefixResolver;
59    boolean useServiceMechanism = true;
60    // By default Extension Functions are allowed in XPath Expressions. If
61    // Secure Processing Feature is set on XPathFactory then the invocation of
62    // extensions function need to throw XPathFunctionException
63    boolean featureSecureProcessing = false;
64    FeatureManager featureManager;
65
66    /**
67     * Evaluate an XPath context using the internal XPath engine
68     * @param contextItem The XPath context
69     * @param xpath The internal XPath engine
70     * @return an XObject
71     * @throws javax.xml.transform.TransformerException If the expression cannot be evaluated.
72     */
73    XObject eval(Object contextItem, com.sun.org.apache.xpath.internal.XPath xpath)
74            throws javax.xml.transform.TransformerException {
75        com.sun.org.apache.xpath.internal.XPathContext xpathSupport;
76        if (functionResolver != null) {
77            JAXPExtensionsProvider jep = new JAXPExtensionsProvider(
78                    functionResolver, featureSecureProcessing, featureManager);
79            xpathSupport = new com.sun.org.apache.xpath.internal.XPathContext(jep);
80        } else {
81            xpathSupport = new com.sun.org.apache.xpath.internal.XPathContext();
82        }
83
84        xpathSupport.setVarStack(new JAXPVariableStack(variableResolver));
85        XObject xobj;
86
87        Node contextNode = (Node)contextItem;
88        // We always need to have a ContextNode with Xalan XPath implementation
89        // To allow simple expression evaluation like 1+1 we are setting
90        // dummy Document as Context Node
91        if (contextNode == null) {
92            xobj = xpath.execute(xpathSupport, DTM.NULL, prefixResolver);
93        } else {
94            xobj = xpath.execute(xpathSupport, contextNode, prefixResolver);
95        }
96
97        return xobj;
98    }
99
100    /**
101     * Parse the input source and return a Document.
102     * @param source The {@code InputSource} of the document
103     * @return a DOM Document
104     * @throws XPathExpressionException if there is an error parsing the source.
105     */
106    Document getDocument(InputSource source)
107        throws XPathExpressionException {
108        requireNonNull(source, "Source");
109        try {
110            // we'd really like to cache those DocumentBuilders, but we can't because:
111            // 1. thread safety. parsers are not thread-safe, so at least
112            //    we need one instance per a thread.
113            // 2. parsers are non-reentrant, so now we are looking at having a
114            // pool of parsers.
115            // 3. then the class loading issue. The look-up procedure of
116            //    DocumentBuilderFactory.newInstance() depends on context class loader
117            //    and system properties, which may change during the execution of JVM.
118            //
119            // so we really have to create a fresh DocumentBuilder every time we need one
120            // - KK
121            DocumentBuilderFactory dbf = FactoryImpl.getDOMFactory(useServiceMechanism);
122            dbf.setNamespaceAware(true);
123            dbf.setValidating(false);
124            return dbf.newDocumentBuilder().parse(source);
125        } catch (ParserConfigurationException | SAXException | IOException e) {
126            throw new XPathExpressionException (e);
127        }
128    }
129
130    /**
131     * Get result depending on the QName type defined in XPathConstants
132     * @param resultObject the result of an evaluation
133     * @param returnType the return type
134     * @return result per the return type
135     * @throws TransformerException if the result can not be converted to
136     * the specified return type.
137     */
138    Object getResultAsType(XObject resultObject, QName returnType)
139        throws TransformerException {
140        // XPathConstants.STRING
141        if (returnType.equals(XPathConstants.STRING)) {
142            return resultObject.str();
143        }
144        // XPathConstants.NUMBER
145        if (returnType.equals(XPathConstants.NUMBER)) {
146            return resultObject.num();
147        }
148        // XPathConstants.BOOLEAN
149        if (returnType.equals(XPathConstants.BOOLEAN)) {
150            return resultObject.bool();
151        }
152        // XPathConstants.NODESET ---ORdered, UNOrdered???
153        if (returnType.equals(XPathConstants.NODESET)) {
154            return resultObject.nodelist();
155        }
156        // XPathConstants.NODE
157        if (returnType.equals(XPathConstants.NODE)) {
158            NodeIterator ni = resultObject.nodeset();
159            //Return the first node, or null
160            return ni.nextNode();
161        }
162        // If isSupported check is already done then the execution path
163        // shouldn't come here. Being defensive
164        String fmsg = XSLMessages.createXPATHMessage(
165                XPATHErrorResources.ER_UNSUPPORTED_RETURN_TYPE,
166                new Object[] { returnType.toString()});
167        throw new IllegalArgumentException (fmsg);
168    }
169
170    /**
171     * Construct an XPathExpressionResult object based on the result of the
172     * evaluation and cast to the specified class type.
173     * @param <T> The class type
174     * @param resultObject the result of an evaluation
175     * @param type The class type expected to be returned by the XPath expression.
176     * @return an instance of the specified type or null if the XObject returned
177     * an UNKNOWN object type.
178     * @throws TransformerException if there is an error converting the result
179     * to the specified type. It's unlikely to happen. This is mostly needed
180     * by the internal XPath engine.
181     */
182    <T> T getXPathResult(XObject resultObject, Class<T> type)
183            throws TransformerException {
184        int resultType = resultObject.getType();
185
186        switch (resultType) {
187            case XObject.CLASS_BOOLEAN :
188                return type.cast(new XPathResultImpl<>(resultObject, Boolean.class));
189            case XObject.CLASS_NUMBER :
190                return type.cast(new XPathResultImpl<>(resultObject, Double.class));
191            case XObject.CLASS_STRING :
192                return type.cast(new XPathResultImpl<>(resultObject, String.class));
193            case XObject.CLASS_NODESET :
194                return type.cast(new XPathResultImpl<>(resultObject, XPathNodes.class));
195            case XObject.CLASS_RTREEFRAG :  //NODE
196                return type.cast(new XPathResultImpl<>(resultObject, Node.class));
197        }
198
199        return null;
200    }
201
202    /**
203     * Check whether or not the specified type is supported
204     * @param <T> The class type
205     * @param type The type to be checked
206     * @throws IllegalArgumentException if the type is not supported
207     */
208    <T> void isSupportedClassType(Class<T> type) {
209        requireNonNull(type, "The class type");
210        if (type.isAssignableFrom(Boolean.class) ||
211                type.isAssignableFrom(Double.class) ||
212                type.isAssignableFrom(Integer.class) ||
213                type.isAssignableFrom(Long.class) ||
214                type.isAssignableFrom(String.class) ||
215                type.isAssignableFrom(XPathNodes.class) ||
216                type.isAssignableFrom(Node.class) ||
217                type.isAssignableFrom(XPathEvaluationResult.class)) {
218            return;
219        }
220        String fmsg = XSLMessages.createXPATHMessage(
221                XPATHErrorResources.ER_UNSUPPORTED_RETURN_TYPE,
222                new Object[] { type.toString() });
223        throw new IllegalArgumentException (fmsg);
224    }
225
226    /**
227     * Check if the requested returnType is supported.
228     * @param returnType the return type
229     * @throws IllegalArgumentException if the return type is not supported
230     */
231    void isSupported(QName returnType) {
232        requireNonNull(returnType, "returnType");
233        if (returnType.equals(XPathConstants.STRING) ||
234                returnType.equals(XPathConstants.NUMBER) ||
235                returnType.equals(XPathConstants.BOOLEAN) ||
236                returnType.equals(XPathConstants.NODE) ||
237                returnType.equals(XPathConstants.NODESET)) {
238            return;
239        }
240        String fmsg = XSLMessages.createXPATHMessage(
241                XPATHErrorResources.ER_UNSUPPORTED_RETURN_TYPE,
242                new Object[] { returnType.toString() });
243        throw new IllegalArgumentException (fmsg);
244     }
245
246    /**
247     * Checks that the specified parameter is not {@code null}.
248     *
249     * @param <T> the type of the reference
250     * @param param the parameter to check for nullity
251     * @param paramName the parameter name
252     * @throws NullPointerException if {@code param} is {@code null}
253     */
254    <T> void requireNonNull(T param, String paramName) {
255        if (param == null) {
256            String fmsg = XSLMessages.createXPATHMessage(
257                    XPATHErrorResources.ER_ARG_CANNOT_BE_NULL,
258                    new Object[] {paramName});
259            throw new NullPointerException (fmsg);
260        }
261    }
262}
263