org.apache.activemq.artemis.selector.filter.LogicExpression Maven / Gradle / Ivy
/*
* 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.activemq.artemis.selector.filter;
import java.util.ArrayList;
import java.util.List;
/**
* A sequence of expressions, to be combined with OR or AND conjunctions.
*
*/
public abstract class LogicExpression implements BooleanExpression {
protected final List expressions = new ArrayList<>(2);
private LogicExpression(BooleanExpression lvalue, BooleanExpression rvalue) {
expressions.add(lvalue);
expressions.add(rvalue);
}
protected void addExpression(BooleanExpression expression) {
expressions.add(expression);
}
public BooleanExpression getLeft() {
if (expressions.size() == 2) {
return expressions.get(0);
}
throw new IllegalStateException("This expression is not binary: " + this);
}
public BooleanExpression getRight() {
if (expressions.size() == 2) {
return expressions.get(1);
}
throw new IllegalStateException("This expression is not binary: " + this);
}
/**
* Returns the symbol that represents this binary expression. For example, addition is
* represented by "+"
*
* @return
*/
public abstract String getExpressionSymbol();
@Override
public String toString() {
if (expressions.size() == 2) {
return "( " + expressions.get(0) + " " + getExpressionSymbol() + " " + expressions.get(1) + " )";
}
StringBuilder result = new StringBuilder("(");
int count = 0;
for (BooleanExpression expression : expressions) {
if (count++ > 0) {
result.append(" " + getExpressionSymbol() + " ");
}
result.append(expression.toString());
}
result.append(")");
return result.toString();
}
public static BooleanExpression createOR(BooleanExpression lvalue, BooleanExpression rvalue) {
if (lvalue instanceof ORExpression) {
ORExpression orExpression = (ORExpression) lvalue;
orExpression.addExpression(rvalue);
return orExpression;
} else {
return new ORExpression(lvalue, rvalue);
}
}
public static BooleanExpression createAND(BooleanExpression lvalue, BooleanExpression rvalue) {
if (lvalue instanceof ANDExpression) {
ANDExpression orExpression = (ANDExpression) lvalue;
orExpression.addExpression(rvalue);
return orExpression;
} else {
return new ANDExpression(lvalue, rvalue);
}
}
@Override
public abstract Object evaluate(Filterable message) throws FilterException;
@Override
public abstract boolean matches(Filterable message) throws FilterException;
private static class ORExpression extends LogicExpression {
ORExpression(BooleanExpression lvalue, BooleanExpression rvalue) {
super(lvalue, rvalue);
}
@Override
public Object evaluate(Filterable message) throws FilterException {
boolean someNulls = false;
for (BooleanExpression expression : expressions) {
Boolean lv = (Boolean)expression.evaluate(message);
if (lv != null && lv.booleanValue()) {
return Boolean.TRUE;
}
if (lv == null) {
someNulls = true;
}
}
if (someNulls) {
return null;
}
return Boolean.FALSE;
}
@Override
public boolean matches(Filterable message) throws FilterException {
for (BooleanExpression expression : expressions) {
boolean lv = expression.matches(message);
if (lv) {
return true;
}
}
return false;
}
@Override
public String getExpressionSymbol() {
return "OR";
}
}
private static class ANDExpression extends LogicExpression {
ANDExpression(BooleanExpression lvalue, BooleanExpression rvalue) {
super(lvalue, rvalue);
}
@Override
public Object evaluate(Filterable message) throws FilterException {
boolean someNulls = false;
for (BooleanExpression expression : expressions) {
Boolean lv = (Boolean)expression.evaluate(message);
if (lv != null && !lv.booleanValue()) {
return Boolean.FALSE;
}
if (lv == null) {
someNulls = true;
}
}
if (someNulls) {
return null;
}
return Boolean.TRUE;
}
@Override
public boolean matches(Filterable message) throws FilterException {
for (BooleanExpression expression : expressions) {
boolean lv = expression.matches(message);
if (!lv) {
return false;
}
}
return true;
}
@Override
public String getExpressionSymbol() {
return "AND";
}
}
}