Java example source code file (ExsltDynamic.java)
The ExsltDynamic.java Java example source code
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/*
* Copyright 1999-2004 The Apache Software Foundation.
*
* 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,
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* See the License for the specific language governing permissions and
* limitations under the License.
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/*
* $Id: ExsltDynamic.java,v 1.1.2.1 2005/08/01 02:08:51 jeffsuttor Exp $
*/
package com.sun.org.apache.xalan.internal.lib;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.TransformerException;
import com.sun.org.apache.xalan.internal.extensions.ExpressionContext;
import com.sun.org.apache.xalan.internal.res.XSLMessages;
import com.sun.org.apache.xalan.internal.res.XSLTErrorResources;
import com.sun.org.apache.xpath.internal.NodeSet;
import com.sun.org.apache.xpath.internal.NodeSetDTM;
import com.sun.org.apache.xpath.internal.XPath;
import com.sun.org.apache.xpath.internal.XPathContext;
import com.sun.org.apache.xpath.internal.objects.XBoolean;
import com.sun.org.apache.xpath.internal.objects.XNodeSet;
import com.sun.org.apache.xpath.internal.objects.XNumber;
import com.sun.org.apache.xpath.internal.objects.XObject;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.Text;
import org.xml.sax.SAXNotSupportedException;
/**
* This class contains EXSLT dynamic extension functions.
*
* It is accessed by specifying a namespace URI as follows:
* <pre>
* xmlns:dyn="http://exslt.org/dynamic"
* </pre>
* The documentation for each function has been copied from the relevant
* EXSLT Implementer page.
*
* @see <a href="http://www.exslt.org/">EXSLT
* @xsl.usage general
*/
public class ExsltDynamic extends ExsltBase
{
public static final String EXSL_URI = "http://exslt.org/common";
/**
* The dyn:max function calculates the maximum value for the nodes passed as
* the first argument, where the value of each node is calculated dynamically
* using an XPath expression passed as a string as the second argument.
* <p>
* The expressions are evaluated relative to the nodes passed as the first argument.
* In other words, the value for each node is calculated by evaluating the XPath
* expression with all context information being the same as that for the call to
* the dyn:max function itself, except for the following:
* <p>
* <ul>
* <li>the context node is the node whose value is being calculated.
* <li>the context position is the position of the node within the node set passed as
* the first argument to the dyn:max function, arranged in document order.</li>
* <li>the context size is the number of nodes passed as the first argument to the
* dyn:max function.</li>
* </ul>
* <p>
* The dyn:max function returns the maximum of these values, calculated in exactly
* the same way as for math:max.
* <p>
* If the expression string passed as the second argument is an invalid XPath
* expression (including an empty string), this function returns NaN.
* <p>
* This function must take a second argument. To calculate the maximum of a set of
* nodes based on their string values, you should use the math:max function.
*
* @param myContext The ExpressionContext passed by the extension processor
* @param nl The node set
* @param expr The expression string
*
* @return The maximum evaluation value
*/
public static double max(ExpressionContext myContext, NodeList nl, String expr)
throws SAXNotSupportedException
{
XPathContext xctxt = null;
if (myContext instanceof XPathContext.XPathExpressionContext)
xctxt = ((XPathContext.XPathExpressionContext) myContext).getXPathContext();
else
throw new SAXNotSupportedException(XSLMessages.createMessage(XSLTErrorResources.ER_INVALID_CONTEXT_PASSED, new Object[]{myContext }));
if (expr == null || expr.length() == 0)
return Double.NaN;
NodeSetDTM contextNodes = new NodeSetDTM(nl, xctxt);
xctxt.pushContextNodeList(contextNodes);
double maxValue = - Double.MAX_VALUE;
for (int i = 0; i < contextNodes.getLength(); i++)
{
int contextNode = contextNodes.item(i);
xctxt.pushCurrentNode(contextNode);
double result = 0;
try
{
XPath dynamicXPath = new XPath(expr, xctxt.getSAXLocator(),
xctxt.getNamespaceContext(),
XPath.SELECT);
result = dynamicXPath.execute(xctxt, contextNode, xctxt.getNamespaceContext()).num();
}
catch (TransformerException e)
{
xctxt.popCurrentNode();
xctxt.popContextNodeList();
return Double.NaN;
}
xctxt.popCurrentNode();
if (result > maxValue)
maxValue = result;
}
xctxt.popContextNodeList();
return maxValue;
}
/**
* The dyn:min function calculates the minimum value for the nodes passed as the
* first argument, where the value of each node is calculated dynamically using
* an XPath expression passed as a string as the second argument.
* <p>
* The expressions are evaluated relative to the nodes passed as the first argument.
* In other words, the value for each node is calculated by evaluating the XPath
* expression with all context information being the same as that for the call to
* the dyn:min function itself, except for the following:
* <p>
* <ul>
* <li>the context node is the node whose value is being calculated.
* <li>the context position is the position of the node within the node set passed
* as the first argument to the dyn:min function, arranged in document order.</li>
* <li>the context size is the number of nodes passed as the first argument to the
* dyn:min function.</li>
* </ul>
* <p>
* The dyn:min function returns the minimum of these values, calculated in exactly
* the same way as for math:min.
* <p>
* If the expression string passed as the second argument is an invalid XPath expression
* (including an empty string), this function returns NaN.
* <p>
* This function must take a second argument. To calculate the minimum of a set of
* nodes based on their string values, you should use the math:min function.
*
* @param myContext The ExpressionContext passed by the extension processor
* @param nl The node set
* @param expr The expression string
*
* @return The minimum evaluation value
*/
public static double min(ExpressionContext myContext, NodeList nl, String expr)
throws SAXNotSupportedException
{
XPathContext xctxt = null;
if (myContext instanceof XPathContext.XPathExpressionContext)
xctxt = ((XPathContext.XPathExpressionContext) myContext).getXPathContext();
else
throw new SAXNotSupportedException(XSLMessages.createMessage(XSLTErrorResources.ER_INVALID_CONTEXT_PASSED, new Object[]{myContext }));
if (expr == null || expr.length() == 0)
return Double.NaN;
NodeSetDTM contextNodes = new NodeSetDTM(nl, xctxt);
xctxt.pushContextNodeList(contextNodes);
double minValue = Double.MAX_VALUE;
for (int i = 0; i < nl.getLength(); i++)
{
int contextNode = contextNodes.item(i);
xctxt.pushCurrentNode(contextNode);
double result = 0;
try
{
XPath dynamicXPath = new XPath(expr, xctxt.getSAXLocator(),
xctxt.getNamespaceContext(),
XPath.SELECT);
result = dynamicXPath.execute(xctxt, contextNode, xctxt.getNamespaceContext()).num();
}
catch (TransformerException e)
{
xctxt.popCurrentNode();
xctxt.popContextNodeList();
return Double.NaN;
}
xctxt.popCurrentNode();
if (result < minValue)
minValue = result;
}
xctxt.popContextNodeList();
return minValue;
}
/**
* The dyn:sum function calculates the sum for the nodes passed as the first argument,
* where the value of each node is calculated dynamically using an XPath expression
* passed as a string as the second argument.
* <p>
* The expressions are evaluated relative to the nodes passed as the first argument.
* In other words, the value for each node is calculated by evaluating the XPath
* expression with all context information being the same as that for the call to
* the dyn:sum function itself, except for the following:
* <p>
* <ul>
* <li>the context node is the node whose value is being calculated.
* <li>the context position is the position of the node within the node set passed as
* the first argument to the dyn:sum function, arranged in document order.</li>
* <li>the context size is the number of nodes passed as the first argument to the
* dyn:sum function.</li>
* </ul>
* <p>
* The dyn:sum function returns the sumimum of these values, calculated in exactly
* the same way as for sum.
* <p>
* If the expression string passed as the second argument is an invalid XPath
* expression (including an empty string), this function returns NaN.
* <p>
* This function must take a second argument. To calculate the sumimum of a set of
* nodes based on their string values, you should use the sum function.
*
* @param myContext The ExpressionContext passed by the extension processor
* @param nl The node set
* @param expr The expression string
*
* @return The sum of the evaluation value on each node
*/
public static double sum(ExpressionContext myContext, NodeList nl, String expr)
throws SAXNotSupportedException
{
XPathContext xctxt = null;
if (myContext instanceof XPathContext.XPathExpressionContext)
xctxt = ((XPathContext.XPathExpressionContext) myContext).getXPathContext();
else
throw new SAXNotSupportedException(XSLMessages.createMessage(XSLTErrorResources.ER_INVALID_CONTEXT_PASSED, new Object[]{myContext }));
if (expr == null || expr.length() == 0)
return Double.NaN;
NodeSetDTM contextNodes = new NodeSetDTM(nl, xctxt);
xctxt.pushContextNodeList(contextNodes);
double sum = 0;
for (int i = 0; i < nl.getLength(); i++)
{
int contextNode = contextNodes.item(i);
xctxt.pushCurrentNode(contextNode);
double result = 0;
try
{
XPath dynamicXPath = new XPath(expr, xctxt.getSAXLocator(),
xctxt.getNamespaceContext(),
XPath.SELECT);
result = dynamicXPath.execute(xctxt, contextNode, xctxt.getNamespaceContext()).num();
}
catch (TransformerException e)
{
xctxt.popCurrentNode();
xctxt.popContextNodeList();
return Double.NaN;
}
xctxt.popCurrentNode();
sum = sum + result;
}
xctxt.popContextNodeList();
return sum;
}
/**
* The dyn:map function evaluates the expression passed as the second argument for
* each of the nodes passed as the first argument, and returns a node set of those values.
* <p>
* The expressions are evaluated relative to the nodes passed as the first argument.
* In other words, the value for each node is calculated by evaluating the XPath
* expression with all context information being the same as that for the call to
* the dyn:map function itself, except for the following:
* <p>
* <ul>
* <li>The context node is the node whose value is being calculated.
* <li>the context position is the position of the node within the node set passed
* as the first argument to the dyn:map function, arranged in document order.</li>
* <li>the context size is the number of nodes passed as the first argument to the
* dyn:map function.</li>
* </ul>
* <p>
* If the expression string passed as the second argument is an invalid XPath
* expression (including an empty string), this function returns an empty node set.
* <p>
* If the XPath expression evaluates as a node set, the dyn:map function returns
* the union of the node sets returned by evaluating the expression for each of the
* nodes in the first argument. Note that this may mean that the node set resulting
* from the call to the dyn:map function contains a different number of nodes from
* the number in the node set passed as the first argument to the function.
* <p>
* If the XPath expression evaluates as a number, the dyn:map function returns a
* node set containing one exsl:number element (namespace http://exslt.org/common)
* for each node in the node set passed as the first argument to the dyn:map function,
* in document order. The string value of each exsl:number element is the same as
* the result of converting the number resulting from evaluating the expression to
* a string as with the number function, with the exception that Infinity results
* in an exsl:number holding the highest number the implementation can store, and
* -Infinity results in an exsl:number holding the lowest number the implementation
* can store.
* <p>
* If the XPath expression evaluates as a boolean, the dyn:map function returns a
* node set containing one exsl:boolean element (namespace http://exslt.org/common)
* for each node in the node set passed as the first argument to the dyn:map function,
* in document order. The string value of each exsl:boolean element is 'true' if the
* expression evaluates as true for the node, and '' if the expression evaluates as
* false.
* <p>
* Otherwise, the dyn:map function returns a node set containing one exsl:string
* element (namespace http://exslt.org/common) for each node in the node set passed
* as the first argument to the dyn:map function, in document order. The string
* value of each exsl:string element is the same as the result of converting the
* result of evaluating the expression for the relevant node to a string as with
* the string function.
*
* @param myContext The ExpressionContext passed by the extension processor
* @param nl The node set
* @param expr The expression string
*
* @return The node set after evaluation
*/
public static NodeList map(ExpressionContext myContext, NodeList nl, String expr)
throws SAXNotSupportedException
{
XPathContext xctxt = null;
Document lDoc = null;
if (myContext instanceof XPathContext.XPathExpressionContext)
xctxt = ((XPathContext.XPathExpressionContext) myContext).getXPathContext();
else
throw new SAXNotSupportedException(XSLMessages.createMessage(XSLTErrorResources.ER_INVALID_CONTEXT_PASSED, new Object[]{myContext }));
if (expr == null || expr.length() == 0)
return new NodeSet();
NodeSetDTM contextNodes = new NodeSetDTM(nl, xctxt);
xctxt.pushContextNodeList(contextNodes);
NodeSet resultSet = new NodeSet();
resultSet.setShouldCacheNodes(true);
for (int i = 0; i < nl.getLength(); i++)
{
int contextNode = contextNodes.item(i);
xctxt.pushCurrentNode(contextNode);
XObject object = null;
try
{
XPath dynamicXPath = new XPath(expr, xctxt.getSAXLocator(),
xctxt.getNamespaceContext(),
XPath.SELECT);
object = dynamicXPath.execute(xctxt, contextNode, xctxt.getNamespaceContext());
if (object instanceof XNodeSet)
{
NodeList nodelist = null;
nodelist = ((XNodeSet)object).nodelist();
for (int k = 0; k < nodelist.getLength(); k++)
{
Node n = nodelist.item(k);
if (!resultSet.contains(n))
resultSet.addNode(n);
}
}
else
{
if (lDoc == null)
{
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
dbf.setNamespaceAware(true);
DocumentBuilder db = dbf.newDocumentBuilder();
lDoc = db.newDocument();
}
Element element = null;
if (object instanceof XNumber)
element = lDoc.createElementNS(EXSL_URI, "exsl:number");
else if (object instanceof XBoolean)
element = lDoc.createElementNS(EXSL_URI, "exsl:boolean");
else
element = lDoc.createElementNS(EXSL_URI, "exsl:string");
Text textNode = lDoc.createTextNode(object.str());
element.appendChild(textNode);
resultSet.addNode(element);
}
}
catch (Exception e)
{
xctxt.popCurrentNode();
xctxt.popContextNodeList();
return new NodeSet();
}
xctxt.popCurrentNode();
}
xctxt.popContextNodeList();
return resultSet;
}
/**
* The dyn:evaluate function evaluates a string as an XPath expression and returns
* the resulting value, which might be a boolean, number, string, node set, result
* tree fragment or external object. The sole argument is the string to be evaluated.
* <p>
* If the expression string passed as the second argument is an invalid XPath
* expression (including an empty string), this function returns an empty node set.
* <p>
* You should only use this function if the expression must be constructed dynamically,
* otherwise it is much more efficient to use the expression literally.
*
* @param myContext The ExpressionContext passed by the extension processor
* @param xpathExpr The XPath expression string
*
* @return The evaluation result
*/
public static XObject evaluate(ExpressionContext myContext, String xpathExpr)
throws SAXNotSupportedException
{
if (myContext instanceof XPathContext.XPathExpressionContext)
{
XPathContext xctxt = null;
try
{
xctxt = ((XPathContext.XPathExpressionContext) myContext).getXPathContext();
XPath dynamicXPath = new XPath(xpathExpr, xctxt.getSAXLocator(),
xctxt.getNamespaceContext(),
XPath.SELECT);
return dynamicXPath.execute(xctxt, myContext.getContextNode(),
xctxt.getNamespaceContext());
}
catch (TransformerException e)
{
return new XNodeSet(xctxt.getDTMManager());
}
}
else
throw new SAXNotSupportedException(XSLMessages.createMessage(XSLTErrorResources.ER_INVALID_CONTEXT_PASSED, new Object[]{myContext })); //"Invalid context passed to evaluate "
}
/**
* The dyn:closure function creates a node set resulting from transitive closure of
* evaluating the expression passed as the second argument on each of the nodes passed
* as the first argument, then on the node set resulting from that and so on until no
* more nodes are found. For example:
* <pre>
* dyn:closure(., '*')
* </pre>
* returns all the descendant elements of the node (its element children, their
* children, their children's children and so on).
* <p>
* The expression is thus evaluated several times, each with a different node set
* acting as the context of the expression. The first time the expression is
* evaluated, the context node set is the first argument passed to the dyn:closure
* function. In other words, the node set for each node is calculated by evaluating
* the XPath expression with all context information being the same as that for
* the call to the dyn:closure function itself, except for the following:
* <p>
* <ul>
* <li>the context node is the node whose value is being calculated.
* <li>the context position is the position of the node within the node set passed
* as the first argument to the dyn:closure function, arranged in document order.</li>
* <li>the context size is the number of nodes passed as the first argument to the
* dyn:closure function.</li>
* <li>the current node is the node whose value is being calculated.
* </ul>
* <p>
* The result for a particular iteration is the union of the node sets resulting
* from evaluting the expression for each of the nodes in the source node set for
* that iteration. This result is then used as the source node set for the next
* iteration, and so on. The result of the function as a whole is the union of
* the node sets generated by each iteration.
* <p>
* If the expression string passed as the second argument is an invalid XPath
* expression (including an empty string) or an expression that does not return a
* node set, this function returns an empty node set.
*
* @param myContext The ExpressionContext passed by the extension processor
* @param nl The node set
* @param expr The expression string
*
* @return The node set after evaluation
*/
public static NodeList closure(ExpressionContext myContext, NodeList nl, String expr)
throws SAXNotSupportedException
{
XPathContext xctxt = null;
if (myContext instanceof XPathContext.XPathExpressionContext)
xctxt = ((XPathContext.XPathExpressionContext) myContext).getXPathContext();
else
throw new SAXNotSupportedException(XSLMessages.createMessage(XSLTErrorResources.ER_INVALID_CONTEXT_PASSED, new Object[]{myContext }));
if (expr == null || expr.length() == 0)
return new NodeSet();
NodeSet closureSet = new NodeSet();
closureSet.setShouldCacheNodes(true);
NodeList iterationList = nl;
do
{
NodeSet iterationSet = new NodeSet();
NodeSetDTM contextNodes = new NodeSetDTM(iterationList, xctxt);
xctxt.pushContextNodeList(contextNodes);
for (int i = 0; i < iterationList.getLength(); i++)
{
int contextNode = contextNodes.item(i);
xctxt.pushCurrentNode(contextNode);
XObject object = null;
try
{
XPath dynamicXPath = new XPath(expr, xctxt.getSAXLocator(),
xctxt.getNamespaceContext(),
XPath.SELECT);
object = dynamicXPath.execute(xctxt, contextNode, xctxt.getNamespaceContext());
if (object instanceof XNodeSet)
{
NodeList nodelist = null;
nodelist = ((XNodeSet)object).nodelist();
for (int k = 0; k < nodelist.getLength(); k++)
{
Node n = nodelist.item(k);
if (!iterationSet.contains(n))
iterationSet.addNode(n);
}
}
else
{
xctxt.popCurrentNode();
xctxt.popContextNodeList();
return new NodeSet();
}
}
catch (TransformerException e)
{
xctxt.popCurrentNode();
xctxt.popContextNodeList();
return new NodeSet();
}
xctxt.popCurrentNode();
}
xctxt.popContextNodeList();
iterationList = iterationSet;
for (int i = 0; i < iterationList.getLength(); i++)
{
Node n = iterationList.item(i);
if (!closureSet.contains(n))
closureSet.addNode(n);
}
} while(iterationList.getLength() > 0);
return closureSet;
}
}
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