/*
* The Apache Software License, Version 1.1
*
*
* Copyright (c) 1999 The Apache Software Foundation. All rights
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* Apache Software Foundation (http://www.apache.org/)."
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* ====================================================================
*
* 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) 1999, Lotus
* Development Corporation., http://www.lotus.com. For more
* information on the Apache Software Foundation, please see
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*/
package org.apache.xpath.compiler;
import java.util.Vector;
import org.apache.xml.utils.QName;
import org.apache.xpath.patterns.NodeTest;
/**
* This class represents the data structure basics of the XPath
* object.
*/
public class OpMap
{
/**
* The current pattern string, for diagnostics purposes
*/
protected String m_currentPattern;
/**
* Return the expression as a string for diagnostics.
*
* @return The expression string.
*/
public String toString()
{
return m_currentPattern;
}
/**
* Return the expression as a string for diagnostics.
*
* @return The expression string.
*/
public String getPatternString()
{
return m_currentPattern;
}
/**
* The max size that the token queue can grow to.
*/
static final int MAXTOKENQUEUESIZE = 500;
/**
* TokenStack is the queue of used tokens. The current token is the token at the
* end of the m_tokenQueue. The idea is that the queue can be marked and a sequence
* of tokens can be reused.
*/
public Object[] m_tokenQueue = new Object[MAXTOKENQUEUESIZE];
/**
* Get the XPath as a list of tokens.
*
* @return an array of string tokens.
*/
public Object[] getTokenQueue()
{
return m_tokenQueue;
}
/**
* Get the XPath as a list of tokens.
*
* @param pos index into token queue.
*
* @return The token, normally a string.
*/
public Object getToken(int pos)
{
return m_tokenQueue[pos];
}
/**
* The current size of the token queue.
*/
public int m_tokenQueueSize = 0;
/**
* Get size of the token queue.
*
* @return The size of the token queue.
*/
public int getTokenQueueSize()
{
return m_tokenQueueSize;
}
/**
* An operations map is used instead of a proper parse tree. It contains
* operations codes and indexes into the m_tokenQueue.
* I use an array instead of a full parse tree in order to cut down
* on the number of objects created.
*/
public int m_opMap[] = null;
/**
* Get the opcode list that describes the XPath operations. It contains
* operations codes and indexes into the m_tokenQueue.
* I use an array instead of a full parse tree in order to cut down
* on the number of objects created.
*
* @return An array of integers that is the opcode list that describes the XPath operations.
*/
public int[] getOpMap()
{
return m_opMap;
}
// Position indexes
/**
* The length is always the opcode position + 1.
* Length is always expressed as the opcode+length bytes,
* so it is always 2 or greater.
*/
public static final int MAPINDEX_LENGTH = 1;
/**
* Replace the large arrays
* with a small array.
*/
void shrink()
{
int map[] = m_opMap;
int n = m_opMap[MAPINDEX_LENGTH];
;
m_opMap = new int[n + 4];
int i;
for (i = 0; i < n; i++)
{
m_opMap[i] = map[i];
}
m_opMap[i] = 0;
m_opMap[i + 1] = 0;
m_opMap[i + 2] = 0;
Object[] tokens = m_tokenQueue;
n = m_tokenQueueSize;
m_tokenQueue = new Object[n + 4];
for (i = 0; i < n; i++)
{
m_tokenQueue[i] = tokens[i];
}
m_tokenQueue[i] = null;
m_tokenQueue[i + 1] = null;
m_tokenQueue[i + 2] = null;
}
/**
* Given an operation position, return the current op.
*
* @param opPos index into op map.
* @return the op that corresponds to the opPos argument.
*/
public int getOp(int opPos)
{
return m_opMap[opPos];
}
/**
* Given an operation position, return the end position, i.e. the
* beginning of the next operation.
*
* @param opPos An op position of an operation for which there is a size
* entry following.
* @return position of next operation in m_opMap.
*/
public int getNextOpPos(int opPos)
{
return opPos + m_opMap[opPos + 1];
}
/**
* Given a location step position, return the end position, i.e. the
* beginning of the next step.
*
* @param opPos the position of a location step.
* @return the position of the next location step.
*/
public int getNextStepPos(int opPos)
{
int stepType = getOp(opPos);
if ((stepType >= OpCodes.AXES_START_TYPES)
&& (stepType <= OpCodes.AXES_END_TYPES))
{
return getNextOpPos(opPos);
}
else if ((stepType >= OpCodes.FIRST_NODESET_OP)
&& (stepType <= OpCodes.LAST_NODESET_OP))
{
int newOpPos = getNextOpPos(opPos);
while (OpCodes.OP_PREDICATE == getOp(newOpPos))
{
newOpPos = getNextOpPos(newOpPos);
}
stepType = getOp(newOpPos);
if (!((stepType >= OpCodes.AXES_START_TYPES)
&& (stepType <= OpCodes.AXES_END_TYPES)))
{
return OpCodes.ENDOP;
}
return newOpPos;
}
else
{
throw new RuntimeException(
"Programmer's assertion in getNextStepPos: unknown stepType: "
+ stepType);
}
}
/**
* Given an operation position, return the end position, i.e. the
* beginning of the next operation.
*
* @param opMap The operations map.
* @param opPos index to operation, for which there is a size entry following.
* @return position of next operation in m_opMap.
*/
public static int getNextOpPos(int[] opMap, int opPos)
{
return opPos + opMap[opPos + 1];
}
/**
* Given an FROM_stepType position, return the position of the
* first predicate, if there is one, or else this will point
* to the end of the FROM_stepType.
* Example:
* int posOfPredicate = xpath.getNextOpPos(stepPos);
* boolean hasPredicates =
* OpCodes.OP_PREDICATE == xpath.getOp(posOfPredicate);
*
* @param opPos position of FROM_stepType op.
* @return position of predicate in FROM_stepType structure.
*/
public int getFirstPredicateOpPos(int opPos)
{
int stepType = m_opMap[opPos];
if ((stepType >= OpCodes.AXES_START_TYPES)
&& (stepType <= OpCodes.AXES_END_TYPES))
{
return opPos + m_opMap[opPos + 2];
}
else if ((stepType >= OpCodes.FIRST_NODESET_OP)
&& (stepType <= OpCodes.LAST_NODESET_OP))
{
return opPos + m_opMap[opPos + 1];
}
else
{
throw new RuntimeException(
"Programmer's assertion in getNextStepPos: unknown stepType: "
+ stepType);
}
}
/**
* Go to the first child of a given operation.
*
* @param opPos position of operation.
*
* @return The position of the first child of the operation.
*/
public static int getFirstChildPos(int opPos)
{
return opPos + 2;
}
/**
* Get the length of an operation.
*
* @param opPos The position of the operation in the op map.
*
* @return The size of the operation.
*/
public int getArgLength(int opPos)
{
return m_opMap[opPos + MAPINDEX_LENGTH];
}
/**
* Given a location step, get the length of that step.
*
* @param opPos Position of location step in op map.
*
* @return The length of the step.
*/
public int getArgLengthOfStep(int opPos)
{
return m_opMap[opPos + MAPINDEX_LENGTH + 1] - 3;
}
/**
* Get the first child position of a given location step.
*
* @param opPos Position of location step in the location map.
*
* @return The first child position of the step.
*/
public static int getFirstChildPosOfStep(int opPos)
{
return opPos + 3;
}
/**
* Get the test type of the step, i.e. NODETYPE_XXX value.
*
* @param opPosOfStep The position of the FROM_XXX step.
*
* @return NODETYPE_XXX value.
*/
public int getStepTestType(int opPosOfStep)
{
return m_opMap[opPosOfStep + 3]; // skip past op, len, len without predicates
}
/**
* Get the namespace of the step.
*
* @param opPosOfStep The position of the FROM_XXX step.
*
* @return The step's namespace, NodeTest.WILD, or null for null namespace.
*/
public String getStepNS(int opPosOfStep)
{
int argLenOfStep = getArgLengthOfStep(opPosOfStep);
// System.out.println("getStepNS.argLenOfStep: "+argLenOfStep);
if (argLenOfStep == 3)
{
int index = m_opMap[opPosOfStep + 4];
if (index >= 0)
return (String) m_tokenQueue[index];
else if (OpCodes.ELEMWILDCARD == index)
return NodeTest.WILD;
else
return null;
}
else
return null;
}
/**
* Get the local name of the step.
* @param opPosOfStep The position of the FROM_XXX step.
*
* @return OpCodes.EMPTY, OpCodes.ELEMWILDCARD, or the local name.
*/
public String getStepLocalName(int opPosOfStep)
{
int argLenOfStep = getArgLengthOfStep(opPosOfStep);
// System.out.println("getStepLocalName.argLenOfStep: "+argLenOfStep);
int index;
switch (argLenOfStep)
{
case 0 :
index = OpCodes.EMPTY;
break;
case 1 :
index = OpCodes.ELEMWILDCARD;
break;
case 2 :
index = m_opMap[opPosOfStep + 4];
break;
case 3 :
index = m_opMap[opPosOfStep + 5];
break;
default :
index = OpCodes.EMPTY;
break; // Should assert error
}
// int index = (argLenOfStep == 3) ? m_opMap[opPosOfStep+5]
// : ((argLenOfStep == 1) ? -3 : -2);
if (index >= 0)
return (String) m_tokenQueue[index].toString();
else if (OpCodes.ELEMWILDCARD == index)
return NodeTest.WILD;
else
return null;
}
}