plantuml/src/net/sourceforge/plantuml/regex/ShuntingYard.java

109 lines
3.7 KiB
Java

/* ========================================================================
* PlantUML : a free UML diagram generator
* ========================================================================
*
* (C) Copyright 2009-2020, Arnaud Roques
*
* Project Info: http://plantuml.com
*
* If you like this project or if you find it useful, you can support us at:
*
* http://plantuml.com/patreon (only 1$ per month!)
* http://plantuml.com/paypal
*
* This file is part of PlantUML.
*
* PlantUML is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* PlantUML distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
* License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*
*
* Original Author: Arnaud Roques
*
*
*/
package net.sourceforge.plantuml.regex;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Deque;
import java.util.Iterator;
import java.util.List;
public class ShuntingYard {
final private List<ReToken> ouputQueue = new ArrayList<>();
final private Deque<ReToken> operatorStack = new ArrayDeque<>();
public ShuntingYard(Iterator<ReToken> it) {
while (it.hasNext()) {
final ReToken token = it.next();
// System.err.println("token=" + token);
// System.err.println("ouputQueue=" + ouputQueue);
// System.err.println("operatorStack=" + operatorStack);
if (token.getType() == ReTokenType.SIMPLE_CHAR) {
ouputQueue.add(token);
} else if (token.getType() == ReTokenType.ESCAPED_CHAR) {
ouputQueue.add(token);
} else if (token.getType() == ReTokenType.GROUP) {
ouputQueue.add(token);
} else if (token.getType() == ReTokenType.CLASS) {
ouputQueue.add(token);
} else if (token.getType() == ReTokenType.ANCHOR) {
ouputQueue.add(token);
} else if (token.getType() == ReTokenType.QUANTIFIER) {
ouputQueue.add(token);
} else if (token.getType() == ReTokenType.CONCATENATION_IMPLICIT) {
// push it onto the operator stack.
operatorStack.addFirst(token);
} else if (token.getType() == ReTokenType.ALTERNATIVE) {
while (thereIsAConcatenationAtTheTopOfTheOperatorStack())
ouputQueue.add(operatorStack.removeFirst());
// push it onto the operator stack.
operatorStack.addFirst(token);
} else if (token.getType() == ReTokenType.PARENTHESIS_OPEN) {
operatorStack.addFirst(token);
} else if (token.getType() == ReTokenType.PARENTHESIS_CLOSE) {
while (operatorStack.peekFirst() != null
&& operatorStack.peekFirst().getType() != ReTokenType.PARENTHESIS_OPEN)
ouputQueue.add(operatorStack.removeFirst());
final ReToken first = operatorStack.removeFirst();
// ouputQueue.add(first);
} else {
throw new UnsupportedOperationException(token.toString());
}
}
while (operatorStack.isEmpty() == false) {
final ReToken token = operatorStack.removeFirst();
ouputQueue.add(token);
}
// System.err.println("ouputQueue=" + ouputQueue);
}
private boolean thereIsAConcatenationAtTheTopOfTheOperatorStack() {
final ReToken top = operatorStack.peekFirst();
return top != null && top.getType() == ReTokenType.CONCATENATION_IMPLICIT;
}
public final List<ReToken> getOuputQueue() {
return Collections.unmodifiableList(ouputQueue);
}
}