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Optional XML functionality for Teiid.
/*
* Copyright Red Hat, Inc. and/or its affiliates
* and other contributors as indicated by the @author tags and
* the COPYRIGHT.txt file distributed with this work.
*
* Licensed 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.teiid.xquery.saxon;
import java.io.IOException;
import javax.xml.XMLConstants;
import javax.xml.transform.Source;
import org.teiid.core.TeiidProcessingException;
import org.teiid.core.TeiidRuntimeException;
import org.teiid.core.util.PropertiesUtils;
import org.teiid.query.function.source.XMLSystemFunctions;
import org.teiid.util.CharsetUtils;
import org.teiid.util.WSUtil;
import net.sf.saxon.om.Item;
import net.sf.saxon.om.NameChecker;
import net.sf.saxon.om.NodeInfo;
import net.sf.saxon.om.QNameException;
import net.sf.saxon.sxpath.XPathDynamicContext;
import net.sf.saxon.sxpath.XPathEvaluator;
import net.sf.saxon.sxpath.XPathExpression;
import net.sf.saxon.trans.XPathException;
public class XMLFunctions {
private static final boolean USE_X_ESCAPE = PropertiesUtils.getHierarchicalProperty("org.teiid.useXMLxEscape", true, Boolean.class); //$NON-NLS-1$
public static String xpathValue(Object doc, String xpath) throws XPathException, TeiidProcessingException {
Source s = null;
try {
s = XMLSystemFunctions.convertToSource(doc);
XPathEvaluator eval = new XPathEvaluator();
// Wrap the string() function to force a string return
XPathExpression expr = eval.createExpression(xpath);
XPathDynamicContext context = expr.createDynamicContext(eval.getConfiguration().buildDocumentTree(s).getRootNode());
Object o = expr.evaluateSingle(context);
if(o == null) {
return null;
}
// Return string value of node type
if(o instanceof Item) {
Item i = (Item)o;
if (isNull(i)) {
return null;
}
return i.getStringValue();
}
// Return string representation of non-node value
return o.toString();
} finally {
WSUtil.closeSource(s);
}
}
/**
* Validate whether the XPath is a valid XPath. If not valid, an XPathExpressionException will be thrown.
* @param xpath An xpath expression, for example: a/b/c/getText()
*/
public static void validateXpath(String xpath) throws TeiidProcessingException {
if(xpath == null) {
return;
}
XPathEvaluator eval = new XPathEvaluator();
try {
eval.createExpression(xpath);
} catch (XPathException e) {
throw new TeiidProcessingException(e);
}
}
public static String[] validateQName(String name) throws TeiidProcessingException {
try {
return NameChecker.getQNameParts(name);
} catch (QNameException e) {
throw new TeiidProcessingException(e);
}
}
public static boolean isValidNCName(String prefix) {
return NameChecker.isValidNCName(prefix);
}
public static boolean isNull(Item i) {
if (i instanceof NodeInfo) {
NodeInfo ni = (NodeInfo)i;
return ni.getNodeKind() == net.sf.saxon.type.Type.ELEMENT && !ni.hasChildNodes() && Boolean.valueOf(ni.getAttributeValue(XMLConstants.W3C_XML_SCHEMA_INSTANCE_NS_URI, "nil")); //$NON-NLS-1$
/* ideally we'd be able to check for nilled, but that doesn't work without validation
if (ni.isNilled()) {
tuple.add(null);
continue;
}*/
}
return false;
}
public static String escapeName(String name, boolean fully) {
StringBuilder sb = new StringBuilder();
char[] chars = name.toCharArray();
int i = 0;
boolean surrogatePair = false;
if (fully && name.regionMatches(true, 0, "xml", 0, 3)) { //$NON-NLS-1$
escapeChar(sb, name.charAt(0));
sb.append(chars, 1, 2);
i = 3;
}
for (; i < chars.length; i++) {
char chr = chars[i];
switch (chr) {
case ':':
if (fully || i == 0) {
escapeChar(sb, chr);
continue;
}
break;
case '_':
if (chars.length > i+1 && chars[i+1] == 'x') {
escapeChar(sb, chr);
continue;
}
break;
default:
int codepoint = chr;
if (i+1 < chars.length && Character.isSurrogatePair(chr, chars[i+1])) {
i++;
codepoint = Character.toCodePoint(chr, chars[i]);
surrogatePair = true;
}
if (i == (surrogatePair?1:0)) {
if (!NameChecker.isNCNameStartChar(codepoint)) {
escapeChar(sb, codepoint);
continue;
}
} else if (!NameChecker.isNCNameChar(codepoint)) {
escapeChar(sb, codepoint);
continue;
}
break;
}
sb.append(chr);
if (surrogatePair) {
sb.append(chars[i]);
}
}
return sb.toString();
}
private static void escapeChar(StringBuilder sb, int chr) {
boolean bmp = Character.isBmpCodePoint(chr);
if (USE_X_ESCAPE) {
sb.append("_x"); //$NON-NLS-1$
} else {
sb.append("_u"); //$NON-NLS-1$
}
try {
if (!bmp) {
byte high = (byte)(chr >> 16);
CharsetUtils.toHex(sb, high);
}
CharsetUtils.toHex(sb, (byte)(chr >> 8));
CharsetUtils.toHex(sb, (byte)chr);
} catch (IOException e) {
throw new TeiidRuntimeException(e);
}
sb.append("_"); //$NON-NLS-1$
}
}