/*
* Copyright 1999-2012 Alibaba Group.
*
* Licensed 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.
*/
/**
* (created at 2011-1-19)
*/
package com.alibaba.cobar.parser.ast.expression.comparison;
import java.util.Map;
import com.alibaba.cobar.parser.ast.expression.BinaryOperatorExpression;
import com.alibaba.cobar.parser.ast.expression.Expression;
import com.alibaba.cobar.parser.ast.expression.ReplacableExpression;
import com.alibaba.cobar.parser.ast.expression.primary.literal.LiteralBoolean;
import com.alibaba.cobar.parser.util.ExprEvalUtils;
import com.alibaba.cobar.parser.util.Pair;
import com.alibaba.cobar.parser.visitor.SQLASTVisitor;
/**
* <code>higherPreExpr '<=>' higherPreExpr</code>
*
* @author <a href="mailto:shuo.qius@alibaba-inc.com">QIU Shuo</a>
*/
public class ComparisionNullSafeEqualsExpression extends BinaryOperatorExpression implements ReplacableExpression {
public ComparisionNullSafeEqualsExpression(Expression leftOprand, Expression rightOprand) {
super(leftOprand, rightOprand, PRECEDENCE_COMPARISION);
}
@Override
public String getOperator() {
return "<=>";
}
@Override
public Object evaluationInternal(Map<? extends Object, ? extends Object> parameters) {
Object left = leftOprand.evaluation(parameters);
Object right = rightOprand.evaluation(parameters);
if (left == UNEVALUATABLE || right == UNEVALUATABLE)
return UNEVALUATABLE;
if (left == null)
return right == null ? LiteralBoolean.TRUE : LiteralBoolean.FALSE;
if (right == null)
return LiteralBoolean.FALSE;
if (left instanceof Number || right instanceof Number) {
Pair<Number, Number> pair = ExprEvalUtils.convertNum2SameLevel(left, right);
left = pair.getKey();
right = pair.getValue();
}
return left.equals(right) ? LiteralBoolean.TRUE : LiteralBoolean.FALSE;
}
private Expression replaceExpr;
@Override
public void setReplaceExpr(Expression replaceExpr) {
this.replaceExpr = replaceExpr;
}
@Override
public void clearReplaceExpr() {
this.replaceExpr = null;
}
@Override
public void accept(SQLASTVisitor visitor) {
if (replaceExpr == null)
visitor.visit(this);
else
replaceExpr.accept(visitor);
}
}