/*
* Copyright (c) 2010, IETR/INSA of Rennes
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * 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.
* * Neither the name of the IETR/INSA of Rennes nor the names of its
* contributors may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS 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 COPYRIGHT OWNER OR 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
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*/
package net.sf.orcc.tools.merger.pattern;
import java.util.Iterator;
import java.util.List;
import net.sf.orcc.df.Action;
import net.sf.orcc.moc.Invocation;
/**
* This class defines a pattern. A pattern is the invocation of one or more
* patterns. A pattern can invoke one action (simple pattern), a series of other
* patterns (sequential pattern), or a loop of one pattern (loop pattern).
*
* @author Matthieu Wipliez
*
*/
public class PatternLoopRecognizer {
public PatternLoopRecognizer() {
}
/**
* If there are more than one iteration of the given pattern, adds a loop
* pattern with the given number of iterations to the sequential pattern.
* Otherwise just add the pattern to the sequential pattern.
*
* @param seq
* a sequential pattern
* @param iterations
* number of iterations <code>pattern</code> is repeated
* @param pattern
* a pattern
*/
private void addPattern(PatternSequential seq, int iterations,
PatternExecution pattern) {
if (iterations > 1) {
seq.add(new PatternLoop(iterations, pattern));
} else {
seq.add(pattern);
}
}
private PatternSequential createSequential(List<Invocation> invocations) {
PatternSequential pattern = new PatternSequential();
for (Invocation invocation : invocations) {
Action action = invocation.getAction();
PatternSimple simple = new PatternSimple(action);
pattern.add(simple);
}
return pattern;
}
/**
* Finds a loop pattern in the given sequential pattern.
*
* @param pattern
* a sequential pattern
* @return a sequential pattern (possibly the same)
*/
private PatternSequential findHigherOrderLoopPattern(
PatternSequential pattern, int length, PatternSequential look) {
PatternSequential newPattern = new PatternSequential();
PatternSequential sub = null;
int iterations = 0;
int maxIndex = pattern.size() - length - 1;
int i = 0;
while (i < maxIndex) {
sub = pattern.getSubPattern(i, length);
if (sub.equals(look)) {
iterations++;
i += length;
} else {
// add iterations of sub-pattern accumulated so far
if (iterations > 0) {
addPattern(newPattern, iterations, sub);
}
// add current element
newPattern.add(pattern.get(i));
iterations = 0;
i++;
}
}
// adds remaining iterations of sub-pattern
if (iterations > 0) {
addPattern(newPattern, iterations, sub);
}
// adds remaining non-recognized patterns
while (i < pattern.size()) {
newPattern.add(pattern.get(i));
i++;
}
return newPattern;
}
/**
* Finds a higher-order pattern in the given sequential pattern.
*
* @param pattern
* a sequential pattern
* @return a sequential pattern (possibly the same)
*/
private PatternSequential findHigherOrderPattern(PatternSequential pattern) {
PatternSequential best = pattern;
int maxPatternSize = pattern.size() / 2;
for (int i = 2; i < maxPatternSize; i++) {
PatternSequential newPattern = findHigherOrderPattern(pattern, i);
if (newPattern.cost() < best.cost()) {
best = newPattern;
}
}
return best;
}
/**
* Finds a higher-order pattern in the given sequential pattern, whose
* length is given.
*
* @param pattern
* a sequential pattern
* @return a sequential pattern (possibly the same)
*/
private PatternSequential findHigherOrderPattern(PatternSequential pattern,
int length) {
PatternSequential best = pattern;
int maxIndex = pattern.size() - length - 1;
for (int i = 0; i < maxIndex; i++) {
PatternSequential look = pattern.getSubPattern(i, length);
PatternSequential newPattern = findHigherOrderLoopPattern(pattern,
length, look);
if (newPattern.cost() < best.cost()) {
best = newPattern;
}
}
return best;
}
/**
* Finds a loop pattern in the given sequential pattern.
*
* @param oldPattern
* a sequential pattern
* @return a sequential pattern (possibly the same)
*/
private PatternSequential findLoopPattern(PatternSequential oldPattern) {
Iterator<PatternExecution> it = oldPattern.iterator();
if (it.hasNext()) {
PatternSequential newPattern = new PatternSequential();
PatternExecution previous = it.next();
int iterations = 1;
while (it.hasNext()) {
PatternExecution next = it.next();
if (previous.equals(next)) {
iterations++;
} else {
addPattern(newPattern, iterations, previous);
previous = next;
iterations = 1;
}
}
if (iterations > 0) {
addPattern(newPattern, iterations, previous);
}
return newPattern;
} else {
return oldPattern;
}
}
/**
* Finds a pattern in the given sequential pattern.
*
* @param pattern
* a sequential pattern
* @return a sequential pattern (possibly the same)
*/
private PatternSequential findPattern(PatternSequential pattern) {
PatternSequential oldPattern;
do {
oldPattern = pattern;
pattern = findLoopPattern(oldPattern);
} while (!pattern.equals(oldPattern));
do {
oldPattern = pattern;
pattern = findHigherOrderPattern(oldPattern);
} while (!pattern.equals(oldPattern));
return pattern;
}
/**
* Returns an execution pattern that matches the given list of actions.
*
* @param actions
* a list of actions
* @return an execution pattern that matches the given list of actions
*/
public PatternExecution getPattern(List<Invocation> invocations) {
PatternSequential oldPattern;
PatternSequential newPattern = createSequential(invocations);
do {
oldPattern = newPattern;
newPattern = findPattern(oldPattern);
} while (!newPattern.equals(oldPattern));
return newPattern;
}
}