src/org/apache/xalan/xsltc/compiler/Whitespace.java - xalan-j - Git at Google

 /*
  * @(#)$Id$
  *
  * The Apache Software License, Version 1.1
  *
  *
  * Copyright (c) 2001-2003 The Apache Software Foundation.  All rights
  * reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  *
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in
  *    the documentation and/or other materials provided with the
  *    distribution.
  *
  * 3. The end-user documentation included with the redistribution,
  *    if any, must include the following acknowledgment:
  *       "This product includes software developed by the
  *        Apache Software Foundation (http://www.apache.org/)."
  *    Alternately, this acknowledgment may appear in the software itself,
  *    if and wherever such third-party acknowledgments normally appear.
  *
  * 4. The names "Xalan" and "Apache Software Foundation" must
  *    not be used to endorse or promote products derived from this
  *    software without prior written permission. For written
  *    permission, please contact apache@apache.org.
  *
  * 5. Products derived from this software may not be called "Apache",
  *    nor may "Apache" appear in their name, without prior written
  *    permission of the Apache Software Foundation.
  *
  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  * ====================================================================
  *
  * This software consists of voluntary contributions made by many
  * individuals on behalf of the Apache Software Foundation and was
  * originally based on software copyright (c) 2001, Sun
  * Microsystems., http://www.sun.com.  For more
  * information on the Apache Software Foundation, please see
  * <http://www.apache.org/>.
  *
  * @author Morten Jorgensen
  *
  */

 package org.apache.xalan.xsltc.compiler;

 import java.util.Vector;
 import java.util.StringTokenizer;

 import org.apache.xalan.xsltc.compiler.util.Type;
 import org.apache.xalan.xsltc.compiler.util.ReferenceType;

 import org.apache.bcel.classfile.JavaClass;
 import org.apache.bcel.classfile.Field;
 import org.apache.bcel.classfile.Method;
 import org.apache.bcel.generic.*;

 import org.apache.xalan.xsltc.dom.*;
 import org.apache.xalan.xsltc.compiler.util.*;

 final class Whitespace extends TopLevelElement {
     // Three possible actions for the translet:
     public static final int USE_PREDICATE  = 0;
     public static final int STRIP_SPACE    = 1;
     public static final int PRESERVE_SPACE = 2;

     // The 3 different categories of strip/preserve rules (order important)
     public static final int RULE_NONE      = 0;
     public static final int RULE_ELEMENT   = 1; // priority 0
     public static final int RULE_NAMESPACE = 2; // priority -1/4
     public static final int RULE_ALL       = 3; // priority -1/2

     private String _elementList;
     private int    _action;
     private int    _importPrecedence;

     /**
      * Auxillary class for encapsulating a single strip/preserve rule
      */
     private final static class WhitespaceRule {
 	private final int _action;
 	private String _namespace; // Should be replaced by NS type (int)
 	private String _element;   // Should be replaced by node type (int)
 	private int    _type;
 	private int    _priority;

 	/**
 	 * Strip/preserve rule constructor
 	 */
 	public WhitespaceRule(int action, String element, int precedence) {
  	    // Determine the action (strip or preserve) for this rule
 	    _action = action;

 	    // Get the namespace and element name for this rule
 	    final int colon = element.indexOf(':');
 	    if (colon >= 0) {
 		_namespace = element.substring(0,colon);
 		_element = element.substring(colon+1,element.length());
 	    }
 	    else {
 		_namespace = Constants.EMPTYSTRING;
 		_element = element;
 	    }

 	    // Determine the initial priority for this rule
 	    _priority = precedence << 2;

 	    // Get the strip/preserve type; either "NS:EL", "NS:*" or "*"
 	    if (_element.equals("*")) {
 		if (_namespace == Constants.EMPTYSTRING) {
 		    _type = RULE_ALL;       // Strip/preserve _all_ elements
 		    _priority += 2;         // Lowest priority
 		}
 		else {
 		    _type = RULE_NAMESPACE; // Strip/reserve elements within NS
 		    _priority += 1;         // Medium priority
 		}
 	    }
 	    else {
 		_type = RULE_ELEMENT;       // Strip/preserve single element
 	    }
 	}

 	/**
 	 * For sorting rules depending on priority
 	 */
 	public int compareTo(WhitespaceRule other) {
 	    return _priority < other._priority
 		? -1
 		: _priority > other._priority ? 1 : 0;
 	}

 	public int getAction() { return _action; }
 	public int getStrength() { return _type; }
 	public int getPriority() { return _priority; }
 	public String getElement() { return _element; }
 	public String getNamespace() { return _namespace; }
     }

     /**
      * Parse the attributes of the xsl:strip/preserve-space element.
      * The element should have not contents (ignored if any).
      */
     public void parseContents(Parser parser) {
 	// Determine if this is an xsl:strip- or preserve-space element
 	_action = _qname.getLocalPart().endsWith("strip-space")
 	    ? STRIP_SPACE : PRESERVE_SPACE;

 	// Determine the import precedence
 	_importPrecedence = parser.getCurrentImportPrecedence();

 	// Get the list of elements to strip/preserve
 	_elementList = getAttribute("elements");
 	if (_elementList == null || _elementList.length() == 0) {
 	    reportError(this, parser, ErrorMsg.REQUIRED_ATTR_ERR, "elements");
 	    return;
 	}

 	final SymbolTable stable = parser.getSymbolTable();
 	StringTokenizer list = new StringTokenizer(_elementList);
 	StringBuffer elements = new StringBuffer(Constants.EMPTYSTRING);

 	while (list.hasMoreElements()) {
 	    String token = list.nextToken();
 	    String prefix;
 	    String namespace;
 	    int col;

 	    if ((col = token.indexOf(':')) != -1) {
 		prefix  = token.substring(0,col);
 	    }
 	    else {
 		prefix = Constants.EMPTYSTRING;
 	    }

 	    namespace = lookupNamespace(prefix);
 	    if (namespace != null)
 		elements.append(namespace+":"+
 				token.substring(col+1,token.length()));
 	    else
 		elements.append(token);

 	    if (list.hasMoreElements())
 		elements.append(" ");
 	}
 	_elementList = elements.toString();
     }


     /**
      * De-tokenize the elements listed in the 'elements' attribute and
      * instanciate a set of strip/preserve rules.
      */
     public Vector getRules() {
 	final Vector rules = new Vector();
 	// Go through each element and instanciate strip/preserve-object
 	final StringTokenizer list = new StringTokenizer(_elementList);
 	while (list.hasMoreElements()) {
 	    rules.add(new WhitespaceRule(_action,
 					 list.nextToken(),
 					 _importPrecedence));
 	}
 	return rules;
     }


     /**
      * Scans through the rules vector and looks for a rule of higher
      * priority that contradicts the current rule.
      */
     private static WhitespaceRule findContradictingRule(Vector rules,
 							WhitespaceRule rule) {
 	for (int i = 0; i < rules.size(); i++) {
 	    // Get the next rule in the prioritized list
 	    WhitespaceRule currentRule = (WhitespaceRule)rules.elementAt(i);
 	    // We only consider rules with higher priority
 	    if (currentRule == rule) {
 		return null;
 	    }

 	    /*
 	     * See if there is a contradicting rule with higher priority.
 	     * If the rules has the same action then this rule is redundant,
 	     * if they have different action then this rule will never win.
 	     */
 	    switch (currentRule.getStrength()) {
 	    case RULE_ALL:
 		return currentRule;

 	    case RULE_ELEMENT:
 		if (!rule.getElement().equals(currentRule.getElement())) {
 		    break;
 		}
 		// intentional fall-through
 	    case RULE_NAMESPACE:
 		if (rule.getNamespace().equals(currentRule.getNamespace())) {
 		    return currentRule;
 		}
 		break;
 	    }
 	}
 	return null;
     }


     /**
      * Orders a set or rules by priority, removes redundant rules and rules
      * that are shadowed by stronger, contradicting rules.
      */
     private static int prioritizeRules(Vector rules) {
 	WhitespaceRule currentRule;
 	int defaultAction = PRESERVE_SPACE;

 	// Sort all rules with regard to priority
 	quicksort(rules, 0, rules.size()-1);

 	// Check if there are any "xsl:strip-space" elements at all.
 	// If there are no xsl:strip elements we can ignore all xsl:preserve
 	// elements and signal that all whitespaces should be preserved
 	boolean strip = false;
 	for (int i = 0; i < rules.size(); i++) {
 	    currentRule = (WhitespaceRule)rules.elementAt(i);
 	    if (currentRule.getAction() == STRIP_SPACE) {
 		strip = true;
 	    }
 	}
 	// Return with default action: PRESERVE_SPACE
 	if (!strip) {
 	    rules.removeAllElements();
 	    return PRESERVE_SPACE;
 	}

 	// Remove all rules that are contradicted by rules with higher priority
 	for (int idx = 0; idx < rules.size(); ) {
 	    currentRule = (WhitespaceRule)rules.elementAt(idx);

 	    // Remove this single rule if it has no purpose
 	    if (findContradictingRule(rules,currentRule) != null) {
 		rules.remove(idx);
 	    }
 	    else {
 		// Remove all following rules if this one overrides all
 		if (currentRule.getStrength() == RULE_ALL) {
 		    defaultAction = currentRule.getAction();
 		    for (int i = idx; i < rules.size(); i++) {
 			rules.removeElementAt(i);
 		    }
 		}
 		// Skip to next rule (there might not be any)...
 		idx++;
 	    }
 	}

 	// The rules vector could be empty if first rule has strength RULE_ALL
 	if (rules.size() == 0) {
 	    return defaultAction;
 	}

 	// Now work backwards and strip away all rules that have the same
 	// action as the default rule (no reason the check them at the end).
 	do {
 	    currentRule = (WhitespaceRule)rules.lastElement();
 	    if (currentRule.getAction() == defaultAction) {
 		rules.removeElementAt(rules.size() - 1);
 	    }
 	    else {
 		break;
 	    }
 	} while (rules.size() > 0);

 	// Signal that whitespace detection predicate must be used.
 	return defaultAction;
     }

     public static void compileStripSpace(BranchHandle strip[],
 					 int sCount,
 					 InstructionList il) {
 	final InstructionHandle target = il.append(ICONST_1);
 	il.append(IRETURN);
 	for (int i = 0; i < sCount; i++) {
 	    strip[i].setTarget(target);
 	}
     }

     public static void compilePreserveSpace(BranchHandle preserve[],
 					    int pCount,
 					    InstructionList il) {
 	final InstructionHandle target = il.append(ICONST_0);
 	il.append(IRETURN);
 	for (int i = 0; i < pCount; i++) {
 	    preserve[i].setTarget(target);
 	}
     }

     /*
     private static void compileDebug(ClassGenerator classGen,
 				     InstructionList il) {
 	final ConstantPoolGen cpg = classGen.getConstantPool();
 	final int prt = cpg.addMethodref("java/lang/System/out",
 					 "println",
 					 "(Ljava/lang/String;)V");
 	il.append(DUP);
 	il.append(new INVOKESTATIC(prt));
     }
     */

     /**
      * Compiles the predicate method
      */
     private static void compilePredicate(Vector rules,
 					 int defaultAction,
 					 ClassGenerator classGen) {
 	final ConstantPoolGen cpg = classGen.getConstantPool();
 	final InstructionList il = new InstructionList();
 	final XSLTC xsltc = classGen.getParser().getXSLTC();

 	// private boolean Translet.stripSpace(int type) - cannot be static
 	final MethodGenerator stripSpace =
 	    new MethodGenerator(ACC_PUBLIC | ACC_FINAL ,
 			org.apache.bcel.generic.Type.BOOLEAN,
 			new org.apache.bcel.generic.Type[] {
 			    Util.getJCRefType(DOM_INTF_SIG),
 			    org.apache.bcel.generic.Type.INT,
 			    org.apache.bcel.generic.Type.INT
 			},
 			new String[] { "dom","node","type" },
 			"stripSpace",classGen.getClassName(),il,cpg);

 	classGen.addInterface("org/apache/xalan/xsltc/StripFilter");

 	final int paramDom = stripSpace.getLocalIndex("dom");
 	final int paramCurrent = stripSpace.getLocalIndex("node");
 	final int paramType = stripSpace.getLocalIndex("type");

 	BranchHandle strip[] = new BranchHandle[rules.size()];
 	BranchHandle preserve[] = new BranchHandle[rules.size()];
 	int sCount = 0;
 	int pCount = 0;

 	// Traverse all strip/preserve rules
 	for (int i = 0; i<rules.size(); i++) {
 	    // Get the next rule in the prioritised list
 	    WhitespaceRule rule = (WhitespaceRule)rules.elementAt(i);

 	    // Returns the namespace for a node in the DOM
 	    final int gns = cpg.addInterfaceMethodref(DOM_INTF,
 						      "getNamespaceName",
 						      "(I)Ljava/lang/String;");

 	    final int strcmp = cpg.addMethodref("java/lang/String",
 						"compareTo",
 						"(Ljava/lang/String;)I");

 	    // Handle elements="ns:*" type rule
 	    if (rule.getStrength() == RULE_NAMESPACE) {
 		il.append(new ALOAD(paramDom));
 		il.append(new ILOAD(paramCurrent));
 		il.append(new INVOKEINTERFACE(gns,2));
 		il.append(new PUSH(cpg, rule.getNamespace()));
 		il.append(new INVOKEVIRTUAL(strcmp));
 		il.append(ICONST_0);

 		if (rule.getAction() == STRIP_SPACE) {
 		    strip[sCount++] = il.append(new IF_ICMPEQ(null));
 		}
 		else {
 		    preserve[pCount++] = il.append(new IF_ICMPEQ(null));
 		}
 	    }
 	    // Handle elements="ns:el" type rule
 	    else if (rule.getStrength() == RULE_ELEMENT) {
 		// Create the QName for the element
 		final Parser parser = classGen.getParser();
 		QName qname;
 		if (rule.getNamespace() != Constants.EMPTYSTRING )
 		    qname = parser.getQName(rule.getNamespace(), null,
 					    rule.getElement());
 		else
 		    qname = parser.getQName(rule.getElement());

 		// Register the element.
 		final int elementType = xsltc.registerElement(qname);
 		il.append(new ILOAD(paramType));
 		il.append(new PUSH(cpg, elementType));

 		// Compare current node type with wanted element type
 		if (rule.getAction() == STRIP_SPACE)
 		    strip[sCount++] = il.append(new IF_ICMPEQ(null));
 		else
 		    preserve[pCount++] = il.append(new IF_ICMPEQ(null));
 	    }
 	}

 	if (defaultAction == STRIP_SPACE) {
 	    compileStripSpace(strip, sCount, il);
 	    compilePreserveSpace(preserve, pCount, il);
 	}
 	else {
 	    compilePreserveSpace(preserve, pCount, il);
 	    compileStripSpace(strip, sCount, il);
 	}

 	stripSpace.stripAttributes(true);
 	stripSpace.setMaxLocals();
 	stripSpace.setMaxStack();
 	stripSpace.removeNOPs();

 	classGen.addMethod(stripSpace.getMethod());
     }

     /**
      * Compiles the predicate method
      */
     private static void compileDefault(int defaultAction,
 				       ClassGenerator classGen) {
 	final ConstantPoolGen cpg = classGen.getConstantPool();
 	final InstructionList il = new InstructionList();
 	final XSLTC xsltc = classGen.getParser().getXSLTC();

 	// private boolean Translet.stripSpace(int type) - cannot be static
 	final MethodGenerator stripSpace =
 	    new MethodGenerator(ACC_PUBLIC | ACC_FINAL ,
 			org.apache.bcel.generic.Type.BOOLEAN,
 			new org.apache.bcel.generic.Type[] {
 			    Util.getJCRefType(DOM_INTF_SIG),
 			    org.apache.bcel.generic.Type.INT,
 			    org.apache.bcel.generic.Type.INT
 			},
 			new String[] { "dom","node","type" },
 			"stripSpace",classGen.getClassName(),il,cpg);

 	classGen.addInterface("org/apache/xalan/xsltc/StripFilter");

 	if (defaultAction == STRIP_SPACE)
 	    il.append(ICONST_1);
 	else
 	    il.append(ICONST_0);
 	il.append(IRETURN);

 	stripSpace.stripAttributes(true);
 	stripSpace.setMaxLocals();
 	stripSpace.setMaxStack();
 	stripSpace.removeNOPs();

 	classGen.addMethod(stripSpace.getMethod());
     }


     /**
      * Takes a vector of WhitespaceRule objects and generates a predicate
      * method. This method returns the translets default action for handling
      * whitespace text-nodes:
      *    - USE_PREDICATE  (run the method generated by this method)
      *    - STRIP_SPACE    (always strip whitespace text-nodes)
      *    - PRESERVE_SPACE (always preserve whitespace text-nodes)
      */
     public static int translateRules(Vector rules,
 				     ClassGenerator classGen) {
 	// Get the core rules in prioritized order
 	final int defaultAction = prioritizeRules(rules);
 	// The rules vector may be empty after prioritising
 	if (rules.size() == 0) {
 	    compileDefault(defaultAction,classGen);
 	    return defaultAction;
 	}
 	// Now - create a predicate method and sequence through rules...
 	compilePredicate(rules, defaultAction, classGen);
 	// Return with the translets required action (
 	return USE_PREDICATE;
     }

     /**
      * Sorts a range of rules with regard to PRIORITY only
      */
     private static void quicksort(Vector rules, int p, int r) {
 	while (p < r) {
 	    final int q = partition(rules, p, r);
 	    quicksort(rules, p, q);
 	    p = q + 1;
 	}
     }

     /**
      * Used with quicksort method above
      */
     private static int partition(Vector rules, int p, int r) {
 	final WhitespaceRule x = (WhitespaceRule)rules.elementAt((p+r) >>> 1);
 	int i = p - 1, j = r + 1;
 	while (true) {
 	    while (x.compareTo((WhitespaceRule)rules.elementAt(--j)) < 0) {
 	    }
 	    while (x.compareTo((WhitespaceRule)rules.elementAt(++i)) > 0) {
 	    }
 	    if (i < j) {
 		final WhitespaceRule tmp = (WhitespaceRule)rules.elementAt(i);
 		rules.setElementAt(rules.elementAt(j), i);
 		rules.setElementAt(tmp, j);
 	    }
 	    else {
 		return j;
 	    }
 	}
     }

     /**
      * Type-check contents/attributes - nothing to do...
      */
     public Type typeCheck(SymbolTable stable) throws TypeCheckError {
 	return Type.Void; // We don't return anything.
     }

     /**
      * This method should not produce any code
      */
     public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
     }
 }
	/*
	* @(#)$Id$
	*
	* The Apache Software License, Version 1.1
	*
	*
	* Copyright (c) 2001-2003 The Apache Software Foundation. All rights
	* reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	*
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	*
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in
	* the documentation and/or other materials provided with the
	* distribution.
	*
	* 3. The end-user documentation included with the redistribution,
	* if any, must include the following acknowledgment:
	* "This product includes software developed by the
	* Apache Software Foundation (http://www.apache.org/)."
	* Alternately, this acknowledgment may appear in the software itself,
	* if and wherever such third-party acknowledgments normally appear.
	*
	* 4. The names "Xalan" and "Apache Software Foundation" must
	* not be used to endorse or promote products derived from this
	* software without prior written permission. For written
	* permission, please contact apache@apache.org.
	*
	* 5. Products derived from this software may not be called "Apache",
	* nor may "Apache" appear in their name, without prior written
	* permission of the Apache Software Foundation.
	*
	* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
	* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
	* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
	* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
	* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
	* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
	* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
	* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	* SUCH DAMAGE.
	* ====================================================================
	*
	* This software consists of voluntary contributions made by many
	* individuals on behalf of the Apache Software Foundation and was
	* originally based on software copyright (c) 2001, Sun
	* Microsystems., http://www.sun.com. For more
	* information on the Apache Software Foundation, please see
	* <http://www.apache.org/>.
	*
	* @author Morten Jorgensen
	*
	*/

	package org.apache.xalan.xsltc.compiler;

	import java.util.Vector;
	import java.util.StringTokenizer;

	import org.apache.xalan.xsltc.compiler.util.Type;
	import org.apache.xalan.xsltc.compiler.util.ReferenceType;

	import org.apache.bcel.classfile.JavaClass;
	import org.apache.bcel.classfile.Field;
	import org.apache.bcel.classfile.Method;
	import org.apache.bcel.generic.*;

	import org.apache.xalan.xsltc.dom.*;
	import org.apache.xalan.xsltc.compiler.util.*;

	final class Whitespace extends TopLevelElement {
	// Three possible actions for the translet:
	public static final int USE_PREDICATE = 0;
	public static final int STRIP_SPACE = 1;
	public static final int PRESERVE_SPACE = 2;

	// The 3 different categories of strip/preserve rules (order important)
	public static final int RULE_NONE = 0;
	public static final int RULE_ELEMENT = 1; // priority 0
	public static final int RULE_NAMESPACE = 2; // priority -1/4
	public static final int RULE_ALL = 3; // priority -1/2

	private String _elementList;
	private int _action;
	private int _importPrecedence;

	/**
	* Auxillary class for encapsulating a single strip/preserve rule
	*/
	private final static class WhitespaceRule {
	private final int _action;
	private String _namespace; // Should be replaced by NS type (int)
	private String _element; // Should be replaced by node type (int)
	private int _type;
	private int _priority;

	/**
	* Strip/preserve rule constructor
	*/
	public WhitespaceRule(int action, String element, int precedence) {
	// Determine the action (strip or preserve) for this rule
	_action = action;

	// Get the namespace and element name for this rule
	final int colon = element.indexOf(':');
	if (colon >= 0) {
	_namespace = element.substring(0,colon);
	_element = element.substring(colon+1,element.length());
	}
	else {
	_namespace = Constants.EMPTYSTRING;
	_element = element;
	}

	// Determine the initial priority for this rule
	_priority = precedence << 2;

	// Get the strip/preserve type; either "NS:EL", "NS:" or ""
	if (_element.equals("*")) {
	if (_namespace == Constants.EMPTYSTRING) {
	_type = RULE_ALL; // Strip/preserve _all_ elements
	_priority += 2; // Lowest priority
	}
	else {
	_type = RULE_NAMESPACE; // Strip/reserve elements within NS
	_priority += 1; // Medium priority
	}
	}
	else {
	_type = RULE_ELEMENT; // Strip/preserve single element
	}
	}

	/**
	* For sorting rules depending on priority
	*/
	public int compareTo(WhitespaceRule other) {
	return _priority < other._priority
	? -1
	: _priority > other._priority ? 1 : 0;
	}

	public int getAction() { return _action; }
	public int getStrength() { return _type; }
	public int getPriority() { return _priority; }
	public String getElement() { return _element; }
	public String getNamespace() { return _namespace; }
	}

	/**
	* Parse the attributes of the xsl:strip/preserve-space element.
	* The element should have not contents (ignored if any).
	*/
	public void parseContents(Parser parser) {
	// Determine if this is an xsl:strip- or preserve-space element
	_action = _qname.getLocalPart().endsWith("strip-space")
	? STRIP_SPACE : PRESERVE_SPACE;

	// Determine the import precedence
	_importPrecedence = parser.getCurrentImportPrecedence();

	// Get the list of elements to strip/preserve
	_elementList = getAttribute("elements");
	if (_elementList == null \|\| _elementList.length() == 0) {
	reportError(this, parser, ErrorMsg.REQUIRED_ATTR_ERR, "elements");
	return;
	}

	final SymbolTable stable = parser.getSymbolTable();
	StringTokenizer list = new StringTokenizer(_elementList);
	StringBuffer elements = new StringBuffer(Constants.EMPTYSTRING);

	while (list.hasMoreElements()) {
	String token = list.nextToken();
	String prefix;
	String namespace;
	int col;

	if ((col = token.indexOf(':')) != -1) {
	prefix = token.substring(0,col);
	}
	else {
	prefix = Constants.EMPTYSTRING;
	}

	namespace = lookupNamespace(prefix);
	if (namespace != null)
	elements.append(namespace+":"+
	token.substring(col+1,token.length()));
	else
	elements.append(token);

	if (list.hasMoreElements())
	elements.append(" ");
	}
	_elementList = elements.toString();
	}


	/**
	* De-tokenize the elements listed in the 'elements' attribute and
	* instanciate a set of strip/preserve rules.
	*/
	public Vector getRules() {
	final Vector rules = new Vector();
	// Go through each element and instanciate strip/preserve-object
	final StringTokenizer list = new StringTokenizer(_elementList);
	while (list.hasMoreElements()) {
	rules.add(new WhitespaceRule(_action,
	list.nextToken(),
	_importPrecedence));
	}
	return rules;
	}


	/**
	* Scans through the rules vector and looks for a rule of higher
	* priority that contradicts the current rule.
	*/
	private static WhitespaceRule findContradictingRule(Vector rules,
	WhitespaceRule rule) {
	for (int i = 0; i < rules.size(); i++) {
	// Get the next rule in the prioritized list
	WhitespaceRule currentRule = (WhitespaceRule)rules.elementAt(i);
	// We only consider rules with higher priority
	if (currentRule == rule) {
	return null;
	}

	/*
	* See if there is a contradicting rule with higher priority.
	* If the rules has the same action then this rule is redundant,
	* if they have different action then this rule will never win.
	*/
	switch (currentRule.getStrength()) {
	case RULE_ALL:
	return currentRule;

	case RULE_ELEMENT:
	if (!rule.getElement().equals(currentRule.getElement())) {
	break;
	}
	// intentional fall-through
	case RULE_NAMESPACE:
	if (rule.getNamespace().equals(currentRule.getNamespace())) {
	return currentRule;
	}
	break;
	}
	}
	return null;
	}


	/**
	* Orders a set or rules by priority, removes redundant rules and rules
	* that are shadowed by stronger, contradicting rules.
	*/
	private static int prioritizeRules(Vector rules) {
	WhitespaceRule currentRule;
	int defaultAction = PRESERVE_SPACE;

	// Sort all rules with regard to priority
	quicksort(rules, 0, rules.size()-1);

	// Check if there are any "xsl:strip-space" elements at all.
	// If there are no xsl:strip elements we can ignore all xsl:preserve
	// elements and signal that all whitespaces should be preserved
	boolean strip = false;
	for (int i = 0; i < rules.size(); i++) {
	currentRule = (WhitespaceRule)rules.elementAt(i);
	if (currentRule.getAction() == STRIP_SPACE) {
	strip = true;
	}
	}
	// Return with default action: PRESERVE_SPACE
	if (!strip) {
	rules.removeAllElements();
	return PRESERVE_SPACE;
	}

	// Remove all rules that are contradicted by rules with higher priority
	for (int idx = 0; idx < rules.size(); ) {
	currentRule = (WhitespaceRule)rules.elementAt(idx);

	// Remove this single rule if it has no purpose
	if (findContradictingRule(rules,currentRule) != null) {
	rules.remove(idx);
	}
	else {
	// Remove all following rules if this one overrides all
	if (currentRule.getStrength() == RULE_ALL) {
	defaultAction = currentRule.getAction();
	for (int i = idx; i < rules.size(); i++) {
	rules.removeElementAt(i);
	}
	}
	// Skip to next rule (there might not be any)...
	idx++;
	}
	}

	// The rules vector could be empty if first rule has strength RULE_ALL
	if (rules.size() == 0) {
	return defaultAction;
	}

	// Now work backwards and strip away all rules that have the same
	// action as the default rule (no reason the check them at the end).
	do {
	currentRule = (WhitespaceRule)rules.lastElement();
	if (currentRule.getAction() == defaultAction) {
	rules.removeElementAt(rules.size() - 1);
	}
	else {
	break;
	}
	} while (rules.size() > 0);

	// Signal that whitespace detection predicate must be used.
	return defaultAction;
	}

	public static void compileStripSpace(BranchHandle strip[],
	int sCount,
	InstructionList il) {
	final InstructionHandle target = il.append(ICONST_1);
	il.append(IRETURN);
	for (int i = 0; i < sCount; i++) {
	strip[i].setTarget(target);
	}
	}

	public static void compilePreserveSpace(BranchHandle preserve[],
	int pCount,
	InstructionList il) {
	final InstructionHandle target = il.append(ICONST_0);
	il.append(IRETURN);
	for (int i = 0; i < pCount; i++) {
	preserve[i].setTarget(target);
	}
	}

	/*
	private static void compileDebug(ClassGenerator classGen,
	InstructionList il) {
	final ConstantPoolGen cpg = classGen.getConstantPool();
	final int prt = cpg.addMethodref("java/lang/System/out",
	"println",
	"(Ljava/lang/String;)V");
	il.append(DUP);
	il.append(new INVOKESTATIC(prt));
	}
	*/

	/**
	* Compiles the predicate method
	*/
	private static void compilePredicate(Vector rules,
	int defaultAction,
	ClassGenerator classGen) {
	final ConstantPoolGen cpg = classGen.getConstantPool();
	final InstructionList il = new InstructionList();
	final XSLTC xsltc = classGen.getParser().getXSLTC();

	// private boolean Translet.stripSpace(int type) - cannot be static
	final MethodGenerator stripSpace =
	new MethodGenerator(ACC_PUBLIC \| ACC_FINAL ,
	org.apache.bcel.generic.Type.BOOLEAN,
	new org.apache.bcel.generic.Type[] {
	Util.getJCRefType(DOM_INTF_SIG),
	org.apache.bcel.generic.Type.INT,
	org.apache.bcel.generic.Type.INT
	},
	new String[] { "dom","node","type" },
	"stripSpace",classGen.getClassName(),il,cpg);

	classGen.addInterface("org/apache/xalan/xsltc/StripFilter");

	final int paramDom = stripSpace.getLocalIndex("dom");
	final int paramCurrent = stripSpace.getLocalIndex("node");
	final int paramType = stripSpace.getLocalIndex("type");

	BranchHandle strip[] = new BranchHandle[rules.size()];
	BranchHandle preserve[] = new BranchHandle[rules.size()];
	int sCount = 0;
	int pCount = 0;

	// Traverse all strip/preserve rules
	for (int i = 0; i<rules.size(); i++) {
	// Get the next rule in the prioritised list
	WhitespaceRule rule = (WhitespaceRule)rules.elementAt(i);

	// Returns the namespace for a node in the DOM
	final int gns = cpg.addInterfaceMethodref(DOM_INTF,
	"getNamespaceName",
	"(I)Ljava/lang/String;");

	final int strcmp = cpg.addMethodref("java/lang/String",
	"compareTo",
	"(Ljava/lang/String;)I");

	// Handle elements="ns:*" type rule
	if (rule.getStrength() == RULE_NAMESPACE) {
	il.append(new ALOAD(paramDom));
	il.append(new ILOAD(paramCurrent));
	il.append(new INVOKEINTERFACE(gns,2));
	il.append(new PUSH(cpg, rule.getNamespace()));
	il.append(new INVOKEVIRTUAL(strcmp));
	il.append(ICONST_0);

	if (rule.getAction() == STRIP_SPACE) {
	strip[sCount++] = il.append(new IF_ICMPEQ(null));
	}
	else {
	preserve[pCount++] = il.append(new IF_ICMPEQ(null));
	}
	}
	// Handle elements="ns:el" type rule
	else if (rule.getStrength() == RULE_ELEMENT) {
	// Create the QName for the element
	final Parser parser = classGen.getParser();
	QName qname;
	if (rule.getNamespace() != Constants.EMPTYSTRING )
	qname = parser.getQName(rule.getNamespace(), null,
	rule.getElement());
	else
	qname = parser.getQName(rule.getElement());

	// Register the element.
	final int elementType = xsltc.registerElement(qname);
	il.append(new ILOAD(paramType));
	il.append(new PUSH(cpg, elementType));

	// Compare current node type with wanted element type
	if (rule.getAction() == STRIP_SPACE)
	strip[sCount++] = il.append(new IF_ICMPEQ(null));
	else
	preserve[pCount++] = il.append(new IF_ICMPEQ(null));
	}
	}

	if (defaultAction == STRIP_SPACE) {
	compileStripSpace(strip, sCount, il);
	compilePreserveSpace(preserve, pCount, il);
	}
	else {
	compilePreserveSpace(preserve, pCount, il);
	compileStripSpace(strip, sCount, il);
	}

	stripSpace.stripAttributes(true);
	stripSpace.setMaxLocals();
	stripSpace.setMaxStack();
	stripSpace.removeNOPs();

	classGen.addMethod(stripSpace.getMethod());
	}

	/**
	* Compiles the predicate method
	*/
	private static void compileDefault(int defaultAction,
	ClassGenerator classGen) {
	final ConstantPoolGen cpg = classGen.getConstantPool();
	final InstructionList il = new InstructionList();
	final XSLTC xsltc = classGen.getParser().getXSLTC();

	// private boolean Translet.stripSpace(int type) - cannot be static
	final MethodGenerator stripSpace =
	new MethodGenerator(ACC_PUBLIC \| ACC_FINAL ,
	org.apache.bcel.generic.Type.BOOLEAN,
	new org.apache.bcel.generic.Type[] {
	Util.getJCRefType(DOM_INTF_SIG),
	org.apache.bcel.generic.Type.INT,
	org.apache.bcel.generic.Type.INT
	},
	new String[] { "dom","node","type" },
	"stripSpace",classGen.getClassName(),il,cpg);

	classGen.addInterface("org/apache/xalan/xsltc/StripFilter");

	if (defaultAction == STRIP_SPACE)
	il.append(ICONST_1);
	else
	il.append(ICONST_0);
	il.append(IRETURN);

	stripSpace.stripAttributes(true);
	stripSpace.setMaxLocals();
	stripSpace.setMaxStack();
	stripSpace.removeNOPs();

	classGen.addMethod(stripSpace.getMethod());
	}


	/**
	* Takes a vector of WhitespaceRule objects and generates a predicate
	* method. This method returns the translets default action for handling
	* whitespace text-nodes:
	* - USE_PREDICATE (run the method generated by this method)
	* - STRIP_SPACE (always strip whitespace text-nodes)
	* - PRESERVE_SPACE (always preserve whitespace text-nodes)
	*/
	public static int translateRules(Vector rules,
	ClassGenerator classGen) {
	// Get the core rules in prioritized order
	final int defaultAction = prioritizeRules(rules);
	// The rules vector may be empty after prioritising
	if (rules.size() == 0) {
	compileDefault(defaultAction,classGen);
	return defaultAction;
	}
	// Now - create a predicate method and sequence through rules...
	compilePredicate(rules, defaultAction, classGen);
	// Return with the translets required action (
	return USE_PREDICATE;
	}

	/**
	* Sorts a range of rules with regard to PRIORITY only
	*/
	private static void quicksort(Vector rules, int p, int r) {
	while (p < r) {
	final int q = partition(rules, p, r);
	quicksort(rules, p, q);
	p = q + 1;
	}
	}

	/**
	* Used with quicksort method above
	*/
	private static int partition(Vector rules, int p, int r) {
	final WhitespaceRule x = (WhitespaceRule)rules.elementAt((p+r) >>> 1);
	int i = p - 1, j = r + 1;
	while (true) {
	while (x.compareTo((WhitespaceRule)rules.elementAt(--j)) < 0) {
	}
	while (x.compareTo((WhitespaceRule)rules.elementAt(++i)) > 0) {
	}
	if (i < j) {
	final WhitespaceRule tmp = (WhitespaceRule)rules.elementAt(i);
	rules.setElementAt(rules.elementAt(j), i);
	rules.setElementAt(tmp, j);
	}
	else {
	return j;
	}
	}
	}

	/**
	* Type-check contents/attributes - nothing to do...
	*/
	public Type typeCheck(SymbolTable stable) throws TypeCheckError {
	return Type.Void; // We don't return anything.
	}

	/**
	* This method should not produce any code
	*/
	public void translate(ClassGenerator classGen, MethodGenerator methodGen) {
	}
	}