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Diffstat (limited to '')
-rw-r--r-- | sca-java-2.x/tags/2.0-Beta1-RC2/modules/common-xml/src/main/java/org/apache/tuscany/sca/common/xml/xpath/XPathHelper.java | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/sca-java-2.x/tags/2.0-Beta1-RC2/modules/common-xml/src/main/java/org/apache/tuscany/sca/common/xml/xpath/XPathHelper.java b/sca-java-2.x/tags/2.0-Beta1-RC2/modules/common-xml/src/main/java/org/apache/tuscany/sca/common/xml/xpath/XPathHelper.java new file mode 100644 index 0000000000..d364aa199f --- /dev/null +++ b/sca-java-2.x/tags/2.0-Beta1-RC2/modules/common-xml/src/main/java/org/apache/tuscany/sca/common/xml/xpath/XPathHelper.java @@ -0,0 +1,169 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + */ + +package org.apache.tuscany.sca.common.xml.xpath; + +import java.util.Collection; +import java.util.HashSet; +import java.util.regex.Matcher; +import java.util.regex.Pattern; + +import javax.xml.XMLConstants; +import javax.xml.namespace.NamespaceContext; +import javax.xml.xpath.XPath; +import javax.xml.xpath.XPathExpression; +import javax.xml.xpath.XPathExpressionException; +import javax.xml.xpath.XPathFactory; + +import org.apache.tuscany.sca.common.xml.stax.reader.NamespaceContextImpl; +import org.apache.tuscany.sca.core.ExtensionPointRegistry; +import org.apache.tuscany.sca.core.FactoryExtensionPoint; +import org.apache.tuscany.sca.core.UtilityExtensionPoint; + +/** + * Helper for XPath operations + */ +public class XPathHelper { + private XPathFactory factory; + + /** + * @param factory + */ + public XPathHelper(XPathFactory factory) { + super(); + this.factory = factory; + } + + public XPathHelper(ExtensionPointRegistry registry) { + FactoryExtensionPoint factories = registry.getExtensionPoint(FactoryExtensionPoint.class); + this.factory = factories.getFactory(XPathFactory.class); + } + + public static XPathHelper getInstance(ExtensionPointRegistry registry) { + UtilityExtensionPoint utilities = registry.getExtensionPoint(UtilityExtensionPoint.class); + return utilities.getUtility(XPathHelper.class); + } + + public XPath newXPath() { + return factory.newXPath(); + } + + public XPathExpression compile(NamespaceContext context, String expression) throws XPathExpressionException { + XPath path = newXPath(); + context = getNamespaceContext(expression, context); + return compile(path, context, expression); + } + + public XPathExpression compile(XPath path, NamespaceContext context, String expression) + throws XPathExpressionException { + path.setNamespaceContext(context); + return path.compile(expression); + } + + /** + * Take a snapshot of the given namespace context based on the prefixes found in the expression. + * In StAX, the prefix/namespace mapping in the namespace context can change as the event moves + * @param expression + * @param context + * @return + */ + public NamespaceContext getNamespaceContext(String expression, NamespaceContext context) { + NamespaceContextImpl nsContext = new NamespaceContextImpl(null); + + boolean found = false; + for (String prefix : getPrefixes(expression)) { + String namespace = context.getNamespaceURI(prefix); + if (namespace != null && !XMLConstants.NULL_NS_URI.equals(namespace)) { + nsContext.register(prefix, namespace); + if ( (namespace.equals("http://docs.oasis-open.org/ns/opencsa/sca/200912")) && !prefix.equals(XMLConstants.DEFAULT_NS_PREFIX)) + found = true; + } + } + + if(!found) { + nsContext.register("__sca", "http://docs.oasis-open.org/ns/opencsa/sca/200912"); + } + return nsContext; + } + + /** + * Registers a prefix in an existing NamespaceContext + * @param prefix + * @param namespace + * @param context + */ + public void registerPrefix(String prefix, String namespace, NamespaceContext context) { + NamespaceContextImpl nsContext = (NamespaceContextImpl) context; + nsContext.register(prefix, namespace); + } + + /** + * Parse the XPath expression to collect all the prefixes for namespaces + * @param expression + * @return A collection of prefixes + */ + private Collection<String> getPrefixes(String expression) { + Collection<String> prefixes = new HashSet<String>(); + prefixes.add(XMLConstants.DEFAULT_NS_PREFIX); + Pattern pattern = Pattern.compile("([a-zA-Z.]+):([a-zA-Z.]+)"); + Matcher matcher = pattern.matcher(expression); + while (matcher.find()) { + String prefix = extractNCName(matcher.group(1), true); + String local = extractNCName(matcher.group(2), false); + if (prefix != null && local != null) { + prefixes.add(prefix); + } + } + return prefixes; + } + + private String extractNCName(String str, boolean reverse) { + if (str.length() < 1) { + return null; + } + if (!reverse) { + if (!XMLCharHelper.isNCNameStart(str.charAt(0))) { + return null; + } + int i = 0, j = str.length(); + // Find the last non-NCName char + for (; i < j; i++) { + if (!XMLCharHelper.isNCName(str.charAt(i))) { + break; + } + } + return str.substring(0, i); + } else { + int j = str.length() - 1; + // Find the first non-NCName char + for (; j >= 0; j--) { + if (!XMLCharHelper.isNCName(str.charAt(j))) { + break; + } + } + // j is before the first char of the prefix + if (j != (str.length() - 1) && XMLCharHelper.isNCNameStart(str.charAt(j + 1))) { + return str.substring(j + 1); + } else { + return null; + } + } + } + +} |