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	* DO NOT REMOVE OR ALTER!
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	/*
	* 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 com.sun.org.apache.xpath.internal.compiler;

	import javax.xml.transform.ErrorListener;
	import javax.xml.transform.SourceLocator;
	import javax.xml.transform.TransformerException;

	import com.sun.org.apache.xalan.internal.res.XSLMessages;
	import com.sun.org.apache.xml.internal.dtm.Axis;
	import com.sun.org.apache.xml.internal.dtm.DTMFilter;
	import com.sun.org.apache.xml.internal.dtm.DTMIterator;
	import com.sun.org.apache.xml.internal.utils.PrefixResolver;
	import com.sun.org.apache.xml.internal.utils.QName;
	import com.sun.org.apache.xml.internal.utils.SAXSourceLocator;
	import com.sun.org.apache.xpath.internal.Expression;
	import com.sun.org.apache.xpath.internal.axes.UnionPathIterator;
	import com.sun.org.apache.xpath.internal.axes.WalkerFactory;
	import com.sun.org.apache.xpath.internal.functions.FuncExtFunction;
	import com.sun.org.apache.xpath.internal.functions.FuncExtFunctionAvailable;
	import com.sun.org.apache.xpath.internal.functions.Function;
	import com.sun.org.apache.xpath.internal.functions.WrongNumberArgsException;
	import com.sun.org.apache.xpath.internal.objects.XNumber;
	import com.sun.org.apache.xpath.internal.objects.XString;
	import com.sun.org.apache.xpath.internal.operations.And;
	import com.sun.org.apache.xpath.internal.operations.Div;
	import com.sun.org.apache.xpath.internal.operations.Equals;
	import com.sun.org.apache.xpath.internal.operations.Gt;
	import com.sun.org.apache.xpath.internal.operations.Gte;
	import com.sun.org.apache.xpath.internal.operations.Lt;
	import com.sun.org.apache.xpath.internal.operations.Lte;
	import com.sun.org.apache.xpath.internal.operations.Minus;
	import com.sun.org.apache.xpath.internal.operations.Mod;
	import com.sun.org.apache.xpath.internal.operations.Mult;
	import com.sun.org.apache.xpath.internal.operations.Neg;
	import com.sun.org.apache.xpath.internal.operations.NotEquals;
	import com.sun.org.apache.xpath.internal.operations.Operation;
	import com.sun.org.apache.xpath.internal.operations.Or;
	import com.sun.org.apache.xpath.internal.operations.Plus;
	import com.sun.org.apache.xpath.internal.operations.UnaryOperation;
	import com.sun.org.apache.xpath.internal.operations.Variable;
	import com.sun.org.apache.xpath.internal.patterns.FunctionPattern;
	import com.sun.org.apache.xpath.internal.patterns.NodeTest;
	import com.sun.org.apache.xpath.internal.patterns.StepPattern;
	import com.sun.org.apache.xpath.internal.patterns.UnionPattern;
	import com.sun.org.apache.xpath.internal.res.XPATHErrorResources;

	/**
	* An instance of this class compiles an XPath string expression into
	* a Expression object. This class compiles the string into a sequence
	* of operation codes (op map) and then builds from that into an Expression
	* tree.
	* @xsl.usage advanced
	*/
	public class Compiler extends OpMap
	{

	/**
	* Construct a Compiler object with a specific ErrorListener and
	* SourceLocator where the expression is located.
	*
	* @param errorHandler Error listener where messages will be sent, or null
	* if messages should be sent to System err.
	* @param locator The location object where the expression lives, which
	* may be null, but which, if not null, must be valid over
	* the long haul, in other words, it will not be cloned.
	* @param fTable The FunctionTable object where the xpath build-in
	* functions are stored.
	*/
	public Compiler(ErrorListener errorHandler, SourceLocator locator,
	FunctionTable fTable)
	{
	m_errorHandler = errorHandler;
	m_locator = locator;
	m_functionTable = fTable;
	}

	/**
	* Construct a Compiler instance that has a null error listener and a
	* null source locator.
	*/
	public Compiler()
	{
	m_errorHandler = null;
	m_locator = null;
	}

	/**
	* Execute the XPath object from a given opcode position.
	* @param opPos The current position in the xpath.m_opMap array.
	* @return The result of the XPath.
	*
	* @throws TransformerException if there is a syntax or other error.
	* @xsl.usage advanced
	*/
	public Expression compile(int opPos) throws TransformerException
	{

	int op = getOp(opPos);

	Expression expr = null;
	// System.out.println(getPatternString()+"op: "+op);
	switch (op)
	{
	case OpCodes.OP_XPATH :
	expr = compile(opPos + 2); break;
	case OpCodes.OP_OR :
	expr = or(opPos); break;
	case OpCodes.OP_AND :
	expr = and(opPos); break;
	case OpCodes.OP_NOTEQUALS :
	expr = notequals(opPos); break;
	case OpCodes.OP_EQUALS :
	expr = equals(opPos); break;
	case OpCodes.OP_LTE :
	expr = lte(opPos); break;
	case OpCodes.OP_LT :
	expr = lt(opPos); break;
	case OpCodes.OP_GTE :
	expr = gte(opPos); break;
	case OpCodes.OP_GT :
	expr = gt(opPos); break;
	case OpCodes.OP_PLUS :
	expr = plus(opPos); break;
	case OpCodes.OP_MINUS :
	expr = minus(opPos); break;
	case OpCodes.OP_MULT :
	expr = mult(opPos); break;
	case OpCodes.OP_DIV :
	expr = div(opPos); break;
	case OpCodes.OP_MOD :
	expr = mod(opPos); break;
	// case OpCodes.OP_QUO :
	// expr = quo(opPos); break;
	case OpCodes.OP_NEG :
	expr = neg(opPos); break;
	case OpCodes.OP_STRING :
	expr = string(opPos); break;
	case OpCodes.OP_BOOL :
	expr = bool(opPos); break;
	case OpCodes.OP_NUMBER :
	expr = number(opPos); break;
	case OpCodes.OP_UNION :
	expr = union(opPos); break;
	case OpCodes.OP_LITERAL :
	expr = literal(opPos); break;
	case OpCodes.OP_VARIABLE :
	expr = variable(opPos); break;
	case OpCodes.OP_GROUP :
	expr = group(opPos); break;
	case OpCodes.OP_NUMBERLIT :
	expr = numberlit(opPos); break;
	case OpCodes.OP_ARGUMENT :
	expr = arg(opPos); break;
	case OpCodes.OP_EXTFUNCTION :
	expr = compileExtension(opPos); break;
	case OpCodes.OP_FUNCTION :
	expr = compileFunction(opPos); break;
	case OpCodes.OP_LOCATIONPATH :
	expr = locationPath(opPos); break;
	case OpCodes.OP_PREDICATE :
	expr = null; break; // should never hit this here.
	case OpCodes.OP_MATCHPATTERN :
	expr = matchPattern(opPos + 2); break;
	case OpCodes.OP_LOCATIONPATHPATTERN :
	expr = locationPathPattern(opPos); break;
	case OpCodes.OP_QUO:
	error(XPATHErrorResources.ER_UNKNOWN_OPCODE,
	new Object[]{ "quo" }); //"ERROR! Unknown op code: "+m_opMap[opPos]);
	break;
	default :
	error(XPATHErrorResources.ER_UNKNOWN_OPCODE,
	new Object[]{ Integer.toString(getOp(opPos)) }); //"ERROR! Unknown op code: "+m_opMap[opPos]);
	}
	// if(null != expr)
	// expr.setSourceLocator(m_locator);

	return expr;
	}

	/**
	* Bottle-neck compilation of an operation with left and right operands.
	*
	* @param operation non-null reference to parent operation.
	* @param opPos The op map position of the parent operation.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.operations.Operation} instance.
	*
	* @throws TransformerException if there is a syntax or other error.
	*/
	private Expression compileOperation(Operation operation, int opPos)
	throws TransformerException
	{

	int leftPos = getFirstChildPos(opPos);
	int rightPos = getNextOpPos(leftPos);

	operation.setLeftRight(compile(leftPos), compile(rightPos));

	return operation;
	}

	/**
	* Bottle-neck compilation of a unary operation.
	*
	* @param unary The parent unary operation.
	* @param opPos The position in the op map of the parent operation.
	*
	* @return The unary argument.
	*
	* @throws TransformerException if syntax or other error occurs.
	*/
	private Expression compileUnary(UnaryOperation unary, int opPos)
	throws TransformerException
	{

	int rightPos = getFirstChildPos(opPos);

	unary.setRight(compile(rightPos));

	return unary;
	}

	/**
	* Compile an 'or' operation.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.operations.Or} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression or(int opPos) throws TransformerException
	{
	return compileOperation(new Or(), opPos);
	}

	/**
	* Compile an 'and' operation.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.operations.And} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression and(int opPos) throws TransformerException
	{
	return compileOperation(new And(), opPos);
	}

	/**
	* Compile a '!=' operation.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.operations.NotEquals} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression notequals(int opPos) throws TransformerException
	{
	return compileOperation(new NotEquals(), opPos);
	}

	/**
	* Compile a '=' operation.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.operations.Equals} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression equals(int opPos) throws TransformerException
	{
	return compileOperation(new Equals(), opPos);
	}

	/**
	* Compile a '<=' operation.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.operations.Lte} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression lte(int opPos) throws TransformerException
	{
	return compileOperation(new Lte(), opPos);
	}

	/**
	* Compile a '<' operation.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.operations.Lt} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression lt(int opPos) throws TransformerException
	{
	return compileOperation(new Lt(), opPos);
	}

	/**
	* Compile a '>=' operation.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.operations.Gte} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression gte(int opPos) throws TransformerException
	{
	return compileOperation(new Gte(), opPos);
	}

	/**
	* Compile a '>' operation.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.operations.Gt} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression gt(int opPos) throws TransformerException
	{
	return compileOperation(new Gt(), opPos);
	}

	/**
	* Compile a '+' operation.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.operations.Plus} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression plus(int opPos) throws TransformerException
	{
	return compileOperation(new Plus(), opPos);
	}

	/**
	* Compile a '-' operation.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.operations.Minus} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression minus(int opPos) throws TransformerException
	{
	return compileOperation(new Minus(), opPos);
	}

	/**
	* Compile a '*' operation.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.operations.Mult} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression mult(int opPos) throws TransformerException
	{
	return compileOperation(new Mult(), opPos);
	}

	/**
	* Compile a 'div' operation.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.operations.Div} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression div(int opPos) throws TransformerException
	{
	return compileOperation(new Div(), opPos);
	}

	/**
	* Compile a 'mod' operation.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.operations.Mod} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression mod(int opPos) throws TransformerException
	{
	return compileOperation(new Mod(), opPos);
	}

	/*
	* Compile a 'quo' operation.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.operations.Quo} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	// protected Expression quo(int opPos) throws TransformerException
	// {
	// return compileOperation(new Quo(), opPos);
	// }

	/**
	* Compile a unary '-' operation.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.operations.Neg} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression neg(int opPos) throws TransformerException
	{
	return compileUnary(new Neg(), opPos);
	}

	/**
	* Compile a 'string(...)' operation.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.operations.String} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression string(int opPos) throws TransformerException
	{
	return compileUnary(new com.sun.org.apache.xpath.internal.operations.String(), opPos);
	}

	/**
	* Compile a 'boolean(...)' operation.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.operations.Bool} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression bool(int opPos) throws TransformerException
	{
	return compileUnary(new com.sun.org.apache.xpath.internal.operations.Bool(), opPos);
	}

	/**
	* Compile a 'number(...)' operation.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.operations.Number} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression number(int opPos) throws TransformerException
	{
	return compileUnary(new com.sun.org.apache.xpath.internal.operations.Number(), opPos);
	}

	/**
	* Compile a literal string value.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.objects.XString} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression literal(int opPos)
	{

	opPos = getFirstChildPos(opPos);

	return (XString) getTokenQueue().elementAt(getOp(opPos));
	}

	/**
	* Compile a literal number value.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.objects.XNumber} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression numberlit(int opPos)
	{

	opPos = getFirstChildPos(opPos);

	return (XNumber) getTokenQueue().elementAt(getOp(opPos));
	}

	/**
	* Compile a variable reference.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.operations.Variable} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression variable(int opPos) throws TransformerException
	{

	Variable var = new Variable();

	opPos = getFirstChildPos(opPos);

	int nsPos = getOp(opPos);
	java.lang.String namespace
	= (OpCodes.EMPTY == nsPos) ? null
	: (java.lang.String) getTokenQueue().elementAt(nsPos);
	java.lang.String localname
	= (java.lang.String) getTokenQueue().elementAt(getOp(opPos+1));
	QName qname = new QName(namespace, localname);

	var.setQName(qname);

	return var;
	}

	/**
	* Compile an expression group.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to the contained expression.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression group(int opPos) throws TransformerException
	{

	// no-op
	return compile(opPos + 2);
	}

	/**
	* Compile a function argument.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to the argument expression.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression arg(int opPos) throws TransformerException
	{

	// no-op
	return compile(opPos + 2);
	}

	/**
	* Compile a location path union. The UnionPathIterator itself may create
	* {@link com.sun.org.apache.xpath.internal.axes.LocPathIterator} children.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.axes.LocPathIterator} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression union(int opPos) throws TransformerException
	{
	locPathDepth++;
	try
	{
	return UnionPathIterator.createUnionIterator(this, opPos);
	}
	finally
	{
	locPathDepth--;
	}
	}

	private int locPathDepth = -1;

	/**
	* Get the level of the location path or union being constructed.
	* @return 0 if it is a top-level path.
	*/
	public int getLocationPathDepth()
	{
	return locPathDepth;
	}

	/**
	* Get the function table
	*/
	FunctionTable getFunctionTable()
	{
	return m_functionTable;
	}

	/**
	* Compile a location path. The LocPathIterator itself may create
	* {@link com.sun.org.apache.xpath.internal.axes.AxesWalker} children.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.axes.LocPathIterator} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	public Expression locationPath(int opPos) throws TransformerException
	{
	locPathDepth++;
	try
	{
	DTMIterator iter = WalkerFactory.newDTMIterator(this, opPos, (locPathDepth == 0));
	return (Expression)iter; // cast OK, I guess.
	}
	finally
	{
	locPathDepth--;
	}
	}

	/**
	* Compile a location step predicate expression.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return the contained predicate expression.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	public Expression predicate(int opPos) throws TransformerException
	{
	return compile(opPos + 2);
	}

	/**
	* Compile an entire match pattern expression.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.patterns.UnionPattern} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected Expression matchPattern(int opPos) throws TransformerException
	{
	locPathDepth++;
	try
	{
	// First, count...
	int nextOpPos = opPos;
	int i;

	for (i = 0; getOp(nextOpPos) == OpCodes.OP_LOCATIONPATHPATTERN; i++)
	{
	nextOpPos = getNextOpPos(nextOpPos);
	}

	if (i == 1)
	return compile(opPos);

	UnionPattern up = new UnionPattern();
	StepPattern[] patterns = new StepPattern[i];

	for (i = 0; getOp(opPos) == OpCodes.OP_LOCATIONPATHPATTERN; i++)
	{
	nextOpPos = getNextOpPos(opPos);
	patterns[i] = (StepPattern) compile(opPos);
	opPos = nextOpPos;
	}

	up.setPatterns(patterns);

	return up;
	}
	finally
	{
	locPathDepth--;
	}
	}

	/**
	* Compile a location match pattern unit expression.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.patterns.StepPattern} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	public Expression locationPathPattern(int opPos)
	throws TransformerException
	{

	opPos = getFirstChildPos(opPos);

	return stepPattern(opPos, 0, null);
	}

	/**
	* Get a {@link org.w3c.dom.traversal.NodeFilter} bit set that tells what
	* to show for a given node test.
	*
	* @param opPos the op map position for the location step.
	*
	* @return {@link org.w3c.dom.traversal.NodeFilter} bit set that tells what
	* to show for a given node test.
	*/
	public int getWhatToShow(int opPos)
	{

	int axesType = getOp(opPos);
	int testType = getOp(opPos + 3);

	// System.out.println("testType: "+testType);
	switch (testType)
	{
	case OpCodes.NODETYPE_COMMENT :
	return DTMFilter.SHOW_COMMENT;
	case OpCodes.NODETYPE_TEXT :
	// return DTMFilter.SHOW_TEXT \| DTMFilter.SHOW_COMMENT;
	return DTMFilter.SHOW_TEXT \| DTMFilter.SHOW_CDATA_SECTION ;
	case OpCodes.NODETYPE_PI :
	return DTMFilter.SHOW_PROCESSING_INSTRUCTION;
	case OpCodes.NODETYPE_NODE :
	// return DTMFilter.SHOW_ALL;
	switch (axesType)
	{
	case OpCodes.FROM_NAMESPACE:
	return DTMFilter.SHOW_NAMESPACE;
	case OpCodes.FROM_ATTRIBUTES :
	case OpCodes.MATCH_ATTRIBUTE :
	return DTMFilter.SHOW_ATTRIBUTE;
	case OpCodes.FROM_SELF:
	case OpCodes.FROM_ANCESTORS_OR_SELF:
	case OpCodes.FROM_DESCENDANTS_OR_SELF:
	return DTMFilter.SHOW_ALL;
	default:
	if (getOp(0) == OpCodes.OP_MATCHPATTERN)
	return ~DTMFilter.SHOW_ATTRIBUTE
	& ~DTMFilter.SHOW_DOCUMENT
	& ~DTMFilter.SHOW_DOCUMENT_FRAGMENT;
	else
	return ~DTMFilter.SHOW_ATTRIBUTE;
	}
	case OpCodes.NODETYPE_ROOT :
	return DTMFilter.SHOW_DOCUMENT \| DTMFilter.SHOW_DOCUMENT_FRAGMENT;
	case OpCodes.NODETYPE_FUNCTEST :
	return NodeTest.SHOW_BYFUNCTION;
	case OpCodes.NODENAME :
	switch (axesType)
	{
	case OpCodes.FROM_NAMESPACE :
	return DTMFilter.SHOW_NAMESPACE;
	case OpCodes.FROM_ATTRIBUTES :
	case OpCodes.MATCH_ATTRIBUTE :
	return DTMFilter.SHOW_ATTRIBUTE;

	// break;
	case OpCodes.MATCH_ANY_ANCESTOR :
	case OpCodes.MATCH_IMMEDIATE_ANCESTOR :
	return DTMFilter.SHOW_ELEMENT;

	// break;
	default :
	return DTMFilter.SHOW_ELEMENT;
	}
	default :
	// System.err.println("We should never reach here.");
	return DTMFilter.SHOW_ALL;
	}
	}

	private static final boolean DEBUG = false;

	/**
	* Compile a step pattern unit expression, used for both location paths
	* and match patterns.
	*
	* @param opPos The current position in the m_opMap array.
	* @param stepCount The number of steps to expect.
	* @param ancestorPattern The owning StepPattern, which may be null.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.patterns.StepPattern} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	protected StepPattern stepPattern(
	int opPos, int stepCount, StepPattern ancestorPattern)
	throws TransformerException
	{

	int startOpPos = opPos;
	int stepType = getOp(opPos);

	if (OpCodes.ENDOP == stepType)
	{
	return null;
	}

	boolean addMagicSelf = true;

	int endStep = getNextOpPos(opPos);

	// int nextStepType = getOpMap()[endStep];
	StepPattern pattern;

	// boolean isSimple = ((OpCodes.ENDOP == nextStepType) && (stepCount == 0));
	int argLen;

	switch (stepType)
	{
	case OpCodes.OP_FUNCTION :
	if(DEBUG)
	System.out.println("MATCH_FUNCTION: "+m_currentPattern);
	addMagicSelf = false;
	argLen = getOp(opPos + OpMap.MAPINDEX_LENGTH);
	pattern = new FunctionPattern(compileFunction(opPos), Axis.PARENT, Axis.CHILD);
	break;
	case OpCodes.FROM_ROOT :
	if(DEBUG)
	System.out.println("FROM_ROOT, "+m_currentPattern);
	addMagicSelf = false;
	argLen = getArgLengthOfStep(opPos);
	opPos = getFirstChildPosOfStep(opPos);
	pattern = new StepPattern(DTMFilter.SHOW_DOCUMENT \|
	DTMFilter.SHOW_DOCUMENT_FRAGMENT,
	Axis.PARENT, Axis.CHILD);
	break;
	case OpCodes.MATCH_ATTRIBUTE :
	if(DEBUG)
	System.out.println("MATCH_ATTRIBUTE: "+getStepLocalName(startOpPos)+", "+m_currentPattern);
	argLen = getArgLengthOfStep(opPos);
	opPos = getFirstChildPosOfStep(opPos);
	pattern = new StepPattern(DTMFilter.SHOW_ATTRIBUTE,
	getStepNS(startOpPos),
	getStepLocalName(startOpPos),
	Axis.PARENT, Axis.ATTRIBUTE);
	break;
	case OpCodes.MATCH_ANY_ANCESTOR :
	if(DEBUG)
	System.out.println("MATCH_ANY_ANCESTOR: "+getStepLocalName(startOpPos)+", "+m_currentPattern);
	argLen = getArgLengthOfStep(opPos);
	opPos = getFirstChildPosOfStep(opPos);
	int what = getWhatToShow(startOpPos);
	// bit-o-hackery, but this code is due for the morgue anyway...
	if(0x00000500 == what)
	addMagicSelf = false;
	pattern = new StepPattern(getWhatToShow(startOpPos),
	getStepNS(startOpPos),
	getStepLocalName(startOpPos),
	Axis.ANCESTOR, Axis.CHILD);
	break;
	case OpCodes.MATCH_IMMEDIATE_ANCESTOR :
	if(DEBUG)
	System.out.println("MATCH_IMMEDIATE_ANCESTOR: "+getStepLocalName(startOpPos)+", "+m_currentPattern);
	argLen = getArgLengthOfStep(opPos);
	opPos = getFirstChildPosOfStep(opPos);
	pattern = new StepPattern(getWhatToShow(startOpPos),
	getStepNS(startOpPos),
	getStepLocalName(startOpPos),
	Axis.PARENT, Axis.CHILD);
	break;
	default :
	error(XPATHErrorResources.ER_UNKNOWN_MATCH_OPERATION, null); //"unknown match operation!");

	return null;
	}

	pattern.setPredicates(getCompiledPredicates(opPos + argLen));
	if(null == ancestorPattern)
	{
	// This is the magic and invisible "." at the head of every
	// match pattern, and corresponds to the current node in the context
	// list, from where predicates are counted.
	// So, in order to calculate "foo[3]", it has to count from the
	// current node in the context list, so, from that current node,
	// the full pattern is really "self::node()/child::foo[3]". If you
	// translate this to a select pattern from the node being tested,
	// which is really how we're treating match patterns, it works out to
	// self::foo/parent::node[child::foo[3]]", or close enough.
	/* if(addMagicSelf && pattern.getPredicateCount() > 0)
	{
	StepPattern selfPattern = new StepPattern(DTMFilter.SHOW_ALL,
	Axis.PARENT, Axis.CHILD);
	// We need to keep the new nodetest from affecting the score...
	XNumber score = pattern.getStaticScore();
	pattern.setRelativePathPattern(selfPattern);
	pattern.setStaticScore(score);
	selfPattern.setStaticScore(score);
	}*/
	}
	else
	{
	// System.out.println("Setting "+ancestorPattern+" as relative to "+pattern);
	pattern.setRelativePathPattern(ancestorPattern);
	}

	StepPattern relativePathPattern = stepPattern(endStep, stepCount + 1,
	pattern);

	return (null != relativePathPattern) ? relativePathPattern : pattern;
	}

	/**
	* Compile a zero or more predicates for a given match pattern.
	*
	* @param opPos The position of the first predicate the m_opMap array.
	*
	* @return reference to array of {@link com.sun.org.apache.xpath.internal.Expression} instances.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	public Expression[] getCompiledPredicates(int opPos)
	throws TransformerException
	{

	int count = countPredicates(opPos);

	if (count > 0)
	{
	Expression[] predicates = new Expression[count];

	compilePredicates(opPos, predicates);

	return predicates;
	}

	return null;
	}

	/**
	* Count the number of predicates in the step.
	*
	* @param opPos The position of the first predicate the m_opMap array.
	*
	* @return The number of predicates for this step.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	public int countPredicates(int opPos) throws TransformerException
	{

	int count = 0;

	while (OpCodes.OP_PREDICATE == getOp(opPos))
	{
	count++;

	opPos = getNextOpPos(opPos);
	}

	return count;
	}

	/**
	* Compiles predicates in the step.
	*
	* @param opPos The position of the first predicate the m_opMap array.
	* @param predicates An empty pre-determined array of
	* {@link com.sun.org.apache.xpath.internal.Expression}s, that will be filled in.
	*
	* @throws TransformerException
	*/
	private void compilePredicates(int opPos, Expression[] predicates)
	throws TransformerException
	{

	for (int i = 0; OpCodes.OP_PREDICATE == getOp(opPos); i++)
	{
	predicates[i] = predicate(opPos);
	opPos = getNextOpPos(opPos);
	}
	}

	/**
	* Compile a built-in XPath function.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.functions.Function} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	Expression compileFunction(int opPos) throws TransformerException
	{

	int endFunc = opPos + getOp(opPos + 1) - 1;

	opPos = getFirstChildPos(opPos);

	int funcID = getOp(opPos);

	opPos++;

	if (-1 != funcID)
	{
	Function func = m_functionTable.getFunction(funcID);

	/**
	* It is a trick for function-available. Since the function table is an
	* instance field, insert this table at compilation time for later usage
	*/

	if (func instanceof FuncExtFunctionAvailable)
	((FuncExtFunctionAvailable) func).setFunctionTable(m_functionTable);

	func.postCompileStep(this);

	try
	{
	int i = 0;

	for (int p = opPos; p < endFunc; p = getNextOpPos(p), i++)
	{

	// System.out.println("argPos: "+ p);
	// System.out.println("argCode: "+ m_opMap[p]);
	func.setArg(compile(p), i);
	}

	func.checkNumberArgs(i);
	}
	catch (WrongNumberArgsException wnae)
	{
	java.lang.String name = m_functionTable.getFunctionName(funcID);

	m_errorHandler.fatalError( new TransformerException(
	XSLMessages.createXPATHMessage(XPATHErrorResources.ER_ONLY_ALLOWS,
	new Object[]{name, wnae.getMessage()}), m_locator));
	//"name + " only allows " + wnae.getMessage() + " arguments", m_locator));
	}

	return func;
	}
	else
	{
	error(XPATHErrorResources.ER_FUNCTION_TOKEN_NOT_FOUND, null); //"function token not found.");

	return null;
	}
	}

	// The current id for extension functions.
	private static long s_nextMethodId = 0;

	/**
	* Get the next available method id
	*/
	synchronized private long getNextMethodId()
	{
	if (s_nextMethodId == Long.MAX_VALUE)
	s_nextMethodId = 0;

	return s_nextMethodId++;
	}

	/**
	* Compile an extension function.
	*
	* @param opPos The current position in the m_opMap array.
	*
	* @return reference to {@link com.sun.org.apache.xpath.internal.functions.FuncExtFunction} instance.
	*
	* @throws TransformerException if a error occurs creating the Expression.
	*/
	private Expression compileExtension(int opPos)
	throws TransformerException
	{

	int endExtFunc = opPos + getOp(opPos + 1) - 1;

	opPos = getFirstChildPos(opPos);

	java.lang.String ns = (java.lang.String) getTokenQueue().elementAt(getOp(opPos));

	opPos++;

	java.lang.String funcName =
	(java.lang.String) getTokenQueue().elementAt(getOp(opPos));

	opPos++;

	// We create a method key to uniquely identify this function so that we
	// can cache the object needed to invoke it. This way, we only pay the
	// reflection overhead on the first call.

	Function extension = new FuncExtFunction(ns, funcName, String.valueOf(getNextMethodId()));

	try
	{
	int i = 0;

	while (opPos < endExtFunc)
	{
	int nextOpPos = getNextOpPos(opPos);

	extension.setArg(this.compile(opPos), i);

	opPos = nextOpPos;

	i++;
	}
	}
	catch (WrongNumberArgsException wnae)
	{
	; // should never happen
	}

	return extension;
	}

	/**
	* Warn the user of an problem.
	*
	* @param msg An error msgkey that corresponds to one of the constants found
	* in {@link com.sun.org.apache.xpath.internal.res.XPATHErrorResources}, which is
	* a key for a format string.
	* @param args An array of arguments represented in the format string, which
	* may be null.
	*
	* @throws TransformerException if the current ErrorListoner determines to
	* throw an exception.
	*/
	public void warn(String msg, Object[] args) throws TransformerException
	{

	java.lang.String fmsg = XSLMessages.createXPATHWarning(msg, args);

	if (null != m_errorHandler)
	{
	m_errorHandler.warning(new TransformerException(fmsg, m_locator));
	}
	else
	{
	System.out.println(fmsg
	+"; file "+m_locator.getSystemId()
	+"; line "+m_locator.getLineNumber()
	+"; column "+m_locator.getColumnNumber());
	}
	}

	/**
	* Tell the user of an assertion error, and probably throw an
	* exception.
	*
	* @param b If false, a runtime exception will be thrown.
	* @param msg The assertion message, which should be informative.
	*
	* @throws RuntimeException if the b argument is false.
	*/
	public void assertion(boolean b, java.lang.String msg)
	{

	if (!b)
	{
	java.lang.String fMsg = XSLMessages.createXPATHMessage(
	XPATHErrorResources.ER_INCORRECT_PROGRAMMER_ASSERTION,
	new Object[]{ msg });

	throw new RuntimeException(fMsg);
	}
	}

	/**
	* Tell the user of an error, and probably throw an
	* exception.
	*
	* @param msg An error msgkey that corresponds to one of the constants found
	* in {@link com.sun.org.apache.xpath.internal.res.XPATHErrorResources}, which is
	* a key for a format string.
	* @param args An array of arguments represented in the format string, which
	* may be null.
	*
	* @throws TransformerException if the current ErrorListoner determines to
	* throw an exception.
	*/
	public void error(String msg, Object[] args) throws TransformerException
	{

	java.lang.String fmsg = XSLMessages.createXPATHMessage(msg, args);


	if (null != m_errorHandler)
	{
	m_errorHandler.fatalError(new TransformerException(fmsg, m_locator));
	}
	else
	{

	// System.out.println(te.getMessage()
	// +"; file "+te.getSystemId()
	// +"; line "+te.getLineNumber()
	// +"; column "+te.getColumnNumber());
	throw new TransformerException(fmsg, (SAXSourceLocator)m_locator);
	}
	}

	/**
	* The current prefixResolver for the execution context.
	*/
	private PrefixResolver m_currentPrefixResolver = null;

	/**
	* Get the current namespace context for the xpath.
	*
	* @return The current prefix resolver, may be null, though hopefully not.
	*/
	public PrefixResolver getNamespaceContext()
	{
	return m_currentPrefixResolver;
	}

	/**
	* Set the current namespace context for the xpath.
	*
	* @param pr The resolver for prefixes in the XPath expression.
	*/
	public void setNamespaceContext(PrefixResolver pr)
	{
	m_currentPrefixResolver = pr;
	}

	/** The error listener where errors will be sent. If this is null, errors
	* and warnings will be sent to System.err. May be null. */
	ErrorListener m_errorHandler;

	/** The source locator for the expression being compiled. May be null. */
	SourceLocator m_locator;

	/**
	* The FunctionTable for all xpath build-in functions
	*/
	private FunctionTable m_functionTable;
	}

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