/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
*/
package org.apache.ambari.server.api.predicate.expressions;
import java.util.List;
import org.apache.ambari.server.api.predicate.InvalidQueryException;
import org.apache.ambari.server.api.predicate.operators.Operator;
import org.apache.ambari.server.controller.spi.Predicate;
/**
* Expression representation.
* There are two types of expressions, relational and logical.
* Each expression has an operator and either 2 operands for binary
* expressions or 1 operand for unary expressions.
*/
public interface Expression<T> {
/**
* Merge expression with surrounding expressions.
*
* @param left the preceding expression
* @param right the following expression
* @param precedence the precedence level being merged. Only expressions at this precedence level
* should be merged. Others should simply return the left expression, themselves and
* the right expression in that order.
*
* @return a list of expressions after merging. Do not return any null elements.
*/
List<Expression> merge(Expression left, Expression right, int precedence);
/**
* Get the predicate representation of the expression.
* @return a predicate instance for the expression
*/
Predicate toPredicate() throws InvalidQueryException;
/**
* Set the expressions left operand.
*
* @param left the left operand
*/
void setLeftOperand(T left);
/**
* Set the expressions right operand.
*
* @param right the right operand
*/
void setRightOperand(T right);
/**
* Get the left operand expression.
*
* @return the left operand
*/
T getLeftOperand();
/**
* Get the right operand expression.
*
* @return the right operand.
*/
T getRightOperand();
/**
* Get the expression operator.
*
* @return the logical operator for the expression
*/
Operator getOperator();
}