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/* ExpressionToString.java
* =========================================================================
* This file is part of the GrInvIn project - http://www.grinvin.org
*
* Copyright (C) 2005-2008 Universiteit Gent
*
* This program 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 2 of the License, or (at
* your option) any later version.
*
* This program is 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.
*
* A copy of the GNU General Public License can be found in the file
* LICENSE.txt provided with the source distribution of this program (see
* the META-INF directory in the source jar). This license can also be
* found on the GNU website at http://www.gnu.org/licenses/gpl.html.
*
* If you did not receive a copy of the GNU General Public License along
* with this program, contact the lead developer, or write to the Free
* Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
package org.grinvin.expr;
import org.grinvin.invariants.Invariant;
/**
* Visitor which converts an expression to a string.<p>
* <b>Note:</b> This class is not thread safe.
*/
public class ExpressionToString implements Expression.Visitor {
//
private String result;
//
@SuppressWarnings("PMD.SingularField")
private ExpressionToString childVisitor;
/**
* Get a visitor for visiting children of expressions.
*/
private ExpressionToString getChildVisitor () {
if (childVisitor == null)
childVisitor = new ExpressionToString ();
return childVisitor;
}
/**
* Return the resulting string.
*/
public String getString () {
return this.result;
}
//
private int strength;
/**
* Return the strength of the resulting string. (Used to determine
* whether parentheses are needed.)
*/
public int getStrength () {
return this.strength;
}
public void visitInvariant(Invariant invariant) {
this.result = invariant.getName();
this.strength = Integer.MAX_VALUE;
}
public void visitIntegerLiteral(IntegerLiteral literal) {
this.result = literal.toString();
this.strength = Integer.MAX_VALUE;
}
public void visitCompound(Compound compound) {
Operator operator = compound.getOperator();
ExpressionToString childVisitor = getChildVisitor ();
int numberOfArguments = compound.getNumberOfChildren();
this.strength = operator.getStrength();
if (numberOfArguments == 1) {
// unary operator
compound.getChild(0).accept (childVisitor);
String str = childVisitor.getString();
if (this.strength >= childVisitor.getStrength())
str = "(" + str + ")";
this.result = operator.getSymbol() + " " + str;
} else if (numberOfArguments == 2) {
// binary operator (assumed left associative)
compound.getChild(0).accept (childVisitor);
String str1 = childVisitor.getString();
if (this.strength > childVisitor.getStrength())
str1 = "(" + str1 + ")";
compound.getChild(1).accept (childVisitor);
String str2 = childVisitor.getString();
if (this.strength >= childVisitor.getStrength())
str2 = "(" + str2 + ")";
this.result = str1 + " " + operator.getSymbol() + " " + str2;
} else {
assert false;
}
}
}
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