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org.htmlunit.xpath.compiler.OpMap Maven / Gradle / Ivy
/*
* 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 org.htmlunit.xpath.compiler;
import java.util.ArrayList;
import javax.xml.transform.TransformerException;
import org.htmlunit.xpath.patterns.NodeTest;
import org.htmlunit.xpath.res.XPATHErrorResources;
import org.htmlunit.xpath.res.XPATHMessages;
/** 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;
/** {@inheritDoc} */
@Override
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 starting size of the token queue. */
static final int MAXTOKENQUEUESIZE = 500;
/*
* Amount to grow token queue when it becomes full
*/
static final int BLOCKTOKENQUEUESIZE = 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.
*/
final ArrayList m_tokenQueue = new ArrayList<>();
/**
* Get the XPath as a list of tokens.
*
* @return ObjectVector of tokens.
*/
public ArrayList getTokenQueue() {
return m_tokenQueue;
}
/**
* Get size of the token queue.
*
* @return The size of the token queue.
*/
public int getTokenQueueSize() {
return m_tokenQueue.size();
}
/**
* 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.
*/
OpMapVector m_opMap = null;
// 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 n = m_opMap.elementAt(MAPINDEX_LENGTH);
m_opMap.setToSize(n + 4);
m_opMap.setElementAt(0, n);
m_opMap.setElementAt(0, n + 1);
m_opMap.setElementAt(0, n + 2);
n = m_tokenQueue.size();
m_tokenQueue.add(null);
m_tokenQueue.add(null);
m_tokenQueue.add(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.elementAt(opPos);
}
/**
* Set the op at index to the given int.
*
* @param opPos index into op map.
* @param value Value to set
*/
public void setOp(int opPos, int value) {
m_opMap.setElementAt(value, 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.elementAt(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(
XPATHMessages.createXPATHMessage(
XPATHErrorResources.ER_UNKNOWN_STEP, new Object[] {String.valueOf(stepType)}));
}
}
/**
* 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) throws javax.xml.transform.TransformerException {
int stepType = m_opMap.elementAt(opPos);
if ((stepType >= OpCodes.AXES_START_TYPES) && (stepType <= OpCodes.AXES_END_TYPES)) {
return opPos + m_opMap.elementAt(opPos + 2);
} else if ((stepType >= OpCodes.FIRST_NODESET_OP) && (stepType <= OpCodes.LAST_NODESET_OP)) {
return opPos + m_opMap.elementAt(opPos + 1);
} else if (-2 == stepType) {
return -2;
} else {
error(
org.htmlunit.xpath.res.XPATHErrorResources.ER_UNKNOWN_OPCODE,
new Object[] {String.valueOf(stepType)});
return -1;
}
}
/**
* 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
* org.htmlunit.xpath.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 javax.xml.transform.TransformerException {
java.lang.String fmsg = XPATHMessages.createXPATHMessage(msg, args);
throw new javax.xml.transform.TransformerException(fmsg);
}
/**
* 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;
}
/**
* 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.elementAt(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.elementAt(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.elementAt(opPosOfStep + 4);
if (index >= 0) return (String) m_tokenQueue.get(index);
else if (OpCodes.ELEMWILDCARD == index) return NodeTest.WILD;
else return null;
}
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.elementAt(opPosOfStep + 4);
break;
case 3:
index = m_opMap.elementAt(opPosOfStep + 5);
break;
default:
index = OpCodes.EMPTY;
break; // Should assert error
}
if (index >= 0) return m_tokenQueue.get(index).toString();
else if (OpCodes.ELEMWILDCARD == index) return NodeTest.WILD;
else return null;
}
}
