/*
* 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 3 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.
* You should have received a copy of the GNU General Public License along with this program;
* if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
package com.meidusa.amoeba.parser.expression;
import com.meidusa.amoeba.sqljep.function.Comparative;
/**
* 可比较表达式
* @author <a href=mailto:piratebase@sina.com>Struct chen</a>
*
*/
public class ComparisonExpression extends Expression {
private int comparison;
private Expression expression;
@SuppressWarnings("unchecked")
@Override
public Comparable evaluate(Object[] parameters) {
if(expression != null){
Comparable<?> comparable = expression.evaluate(parameters);
if(comparable != null){
return new Comparative(comparison,comparable);
}else{
return null;
}
}else{
return null;
}
}
public Expression reverse(){
this.setComparison(Comparative.reverseComparison(this.getComparison()));
return this;
}
public int getComparison() {
return comparison;
}
public void setComparison(int function) {
this.comparison = function;
}
public boolean isRealtime(){
return expression!= null?expression.isRealtime():false;
}
public Expression getExpression() {
return expression;
}
public void setExpression(Expression expression) {
this.expression = expression;
}
@Override
protected void toString(StringBuilder builder) {
if(expression instanceof ConstantExpression){
ConstantExpression cos = (ConstantExpression)expression;
if(cos.evaluate(null) == null){
builder.append(comparison == Comparative.NotEquivalent?" is not null":" is null");
return;
}
}
builder.append(" ");
builder.append(Comparative.getComparisonName(comparison));
builder.append(" ");
if(expression != null){
expression.toString(builder);
}
}
}