Back to index...

	/*
	* Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.
	*/
	/*
	* 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.
	*/
	/*
	* $Id: TestSeq.java,v 1.2.4.1 2005/09/12 11:31:38 pvedula Exp $
	*/

	package com.sun.org.apache.xalan.internal.xsltc.compiler;

	import com.sun.org.apache.bcel.internal.generic.GOTO_W;
	import com.sun.org.apache.bcel.internal.generic.InstructionHandle;
	import com.sun.org.apache.bcel.internal.generic.InstructionList;
	import com.sun.org.apache.xalan.internal.xsltc.compiler.util.ClassGenerator;
	import com.sun.org.apache.xalan.internal.xsltc.compiler.util.MethodGenerator;
	import java.util.ArrayList;
	import java.util.List;
	import java.util.Map;

	/**
	* A test sequence is a sequence of patterns that
	*
	* (1) occured in templates in the same mode
	* (2) share the same kernel node type (e.g. A/B and C/C/B)
	* (3) may also contain patterns matching "*" and "node()"
	* (element sequence only) or matching "@*" (attribute
	* sequence only).
	*
	* A test sequence may have a default template, which will be
	* instantiated if none of the other patterns match.
	* @author Jacek Ambroziak
	* @author Santiago Pericas-Geertsen
	* @author Erwin Bolwidt <ejb@klomp.org>
	* @author Morten Jorgensen
	* @LastModified: Nov 2017
	*/
	final class TestSeq {

	/**
	* Integer code for the kernel type of this test sequence
	*/
	private int _kernelType;

	/**
	* ArrayList of all patterns in the test sequence. May include
	* patterns with "", "@" or "node()" kernel.
	*/
	private List<LocationPathPattern> _patterns = null;

	/**
	* A reference to the Mode object.
	*/
	private Mode _mode = null;

	/**
	* Default template for this test sequence
	*/
	private Template _default = null;

	/**
	* Instruction list representing this test sequence.
	*/
	private InstructionList _instructionList;

	/**
	* Cached handle to avoid compiling more than once.
	*/
	private InstructionHandle _start = null;

	/**
	* Creates a new test sequence given a set of patterns and a mode.
	*/
	public TestSeq(List<LocationPathPattern> patterns, Mode mode) {
	this(patterns, -2, mode);
	}

	public TestSeq(List<LocationPathPattern> patterns, int kernelType, Mode mode) {
	_patterns = patterns;
	_kernelType = kernelType;
	_mode = mode;
	}

	/**
	* Returns a string representation of this test sequence. Notice
	* that test sequences are mutable, so the value returned by this
	* method is different before and after calling reduce().
	*/
	public String toString() {
	final int count = _patterns.size();
	final StringBuffer result = new StringBuffer();

	for (int i = 0; i < count; i++) {
	final LocationPathPattern pattern = _patterns.get(i);

	if (i == 0) {
	result.append("Testseq for kernel ").append(_kernelType)
	.append('\n');
	}
	result.append(" pattern ").append(i).append(": ")
	.append(pattern.toString())
	.append('\n');
	}
	return result.toString();
	}

	/**
	* Returns the instruction list for this test sequence
	*/
	public InstructionList getInstructionList() {
	return _instructionList;
	}

	/**
	* Return the highest priority for a pattern in this test
	* sequence. This is either the priority of the first or
	* of the default pattern.
	*/
	public double getPriority() {
	final Template template = (_patterns.isEmpty()) ? _default
	: ((Pattern) _patterns.get(0)).getTemplate();
	return template.getPriority();
	}

	/**
	* Returns the position of the highest priority pattern in
	* this test sequence.
	*/
	public int getPosition() {
	final Template template = (_patterns.isEmpty()) ? _default
	: ((Pattern) _patterns.get(0)).getTemplate();
	return template.getPosition();
	}

	/**
	* Reduce the patterns in this test sequence. Creates a new
	* vector of patterns and sets the default pattern if it
	* finds a patterns that is fully reduced.
	*/
	public void reduce() {
	final List<LocationPathPattern> newPatterns = new ArrayList<>();

	for (LocationPathPattern pattern : _patterns) {
	// Reduce this pattern
	pattern.reduceKernelPattern();

	// Is this pattern fully reduced?
	if (pattern.isWildcard()) {
	_default = pattern.getTemplate();
	break; // Ignore following patterns
	}
	else {
	newPatterns.add(pattern);
	}
	}
	_patterns = newPatterns;
	}

	/**
	* Returns, by reference, the templates that are included in
	* this test sequence. Note that a single template can occur
	* in several test sequences if its pattern is a union.
	*/
	public void findTemplates(Map<Template, Object> templates) {
	if (_default != null) {
	templates.put(_default, this);
	}
	for (LocationPathPattern pattern : _patterns) {
	templates.put(pattern.getTemplate(), this);
	}
	}

	/**
	* Get the instruction handle to a template's code. This is
	* used when a single template occurs in several test
	* sequences; that is, if its pattern is a union of patterns
	* (e.g. match="A/B \| A/C").
	*/
	private InstructionHandle getTemplateHandle(Template template) {
	return _mode.getTemplateInstructionHandle(template);
	}

	/**
	* Returns pattern n in this test sequence
	*/
	private LocationPathPattern getPattern(int n) {
	return _patterns.get(n);
	}

	/**
	* Compile the code for this test sequence. Compile patterns
	* from highest to lowest priority. Note that since patterns
	* can be share by multiple test sequences, instruction lists
	* must be copied before backpatching.
	*/
	public InstructionHandle compile(ClassGenerator classGen,
	MethodGenerator methodGen,
	InstructionHandle continuation)
	{
	// Returned cached value if already compiled
	if (_start != null) {
	return _start;
	}

	// If not patterns, then return handle for default template
	final int count = _patterns.size();
	if (count == 0) {
	return (_start = getTemplateHandle(_default));
	}

	// Init handle to jump when all patterns failed
	InstructionHandle fail = (_default == null) ? continuation
	: getTemplateHandle(_default);

	// Compile all patterns in reverse order
	for (int n = count - 1; n >= 0; n--) {
	final LocationPathPattern pattern = getPattern(n);
	final Template template = pattern.getTemplate();
	final InstructionList il = new InstructionList();

	// Patterns expect current node on top of stack
	il.append(methodGen.loadCurrentNode());

	// Apply the test-code compiled for the pattern
	InstructionList ilist = methodGen.getInstructionList(pattern);
	if (ilist == null) {
	ilist = pattern.compile(classGen, methodGen);
	methodGen.addInstructionList(pattern, ilist);
	}

	// Make a copy of the instruction list for backpatching
	InstructionList copyOfilist = ilist.copy();

	FlowList trueList = pattern.getTrueList();
	if (trueList != null) {
	trueList = trueList.copyAndRedirect(ilist, copyOfilist);
	}
	FlowList falseList = pattern.getFalseList();
	if (falseList != null) {
	falseList = falseList.copyAndRedirect(ilist, copyOfilist);
	}

	il.append(copyOfilist);

	// On success branch to the template code
	final InstructionHandle gtmpl = getTemplateHandle(template);
	final InstructionHandle success = il.append(new GOTO_W(gtmpl));

	if (trueList != null) {
	trueList.backPatch(success);
	}
	if (falseList != null) {
	falseList.backPatch(fail);
	}

	// Next pattern's 'fail' target is this pattern's first instruction
	fail = il.getStart();

	// Append existing instruction list to the end of this one
	if (_instructionList != null) {
	il.append(_instructionList);
	}

	// Set current instruction list to be this one
	_instructionList = il;
	}
	return (_start = fail);
	}
	}

Back to index...