/**
* 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.controller.utilities;
import java.util.LinkedList;
import java.util.List;
import org.apache.ambari.server.controller.predicate.AndPredicate;
import org.apache.ambari.server.controller.predicate.EqualsPredicate;
import org.apache.ambari.server.controller.predicate.GreaterEqualsPredicate;
import org.apache.ambari.server.controller.predicate.GreaterPredicate;
import org.apache.ambari.server.controller.predicate.LessEqualsPredicate;
import org.apache.ambari.server.controller.predicate.LessPredicate;
import org.apache.ambari.server.controller.predicate.NotPredicate;
import org.apache.ambari.server.controller.predicate.OrPredicate;
import org.apache.ambari.server.controller.spi.Predicate;
/**
* Builder for predicates.
*/
public class PredicateBuilder {
private String propertyId;
private List<Predicate> predicates = new LinkedList<>();
private Operator operator = null;
private final PredicateBuilder outer;
private boolean done = false;
private boolean not = false;
public PredicateBuilder() {
this.outer = null;
}
private PredicateBuilder(PredicateBuilder outer) {
this.outer = outer;
}
/**
* Allow for chaining of already constructed predicates
*/
public PredicateBuilder(Predicate predicate) {
this.outer = null;
this.addPredicate(predicate);
}
private enum Operator {
And,
Or
}
public PredicateBuilderWithProperty property(String id) {
checkDone();
propertyId = id;
return new PredicateBuilderWithProperty();
}
public PredicateBuilder not() {
not = true;
return this;
}
public PredicateBuilder begin() {
checkDone();
return new PredicateBuilder(this);
}
public Predicate toPredicate() {
return getPredicate();
}
private void checkDone() {
if (done) {
throw new IllegalStateException("Can't reuse a predicate builder.");
}
}
private PredicateBuilderWithPredicate getPredicateBuilderWithPredicate() {
return new PredicateBuilderWithPredicate();
}
private void addPredicate(Predicate predicate) {
predicates.add(predicate);
}
private void handleComparator() {
if (operator == null) {
return;
}
if (predicates.size() == 0) {
throw new IllegalStateException("No left operand.");
}
Predicate predicate;
switch (operator) {
case And:
predicate = new AndPredicate(predicates.toArray(new Predicate[predicates.size()]));
break;
case Or:
predicate = new OrPredicate(predicates.toArray(new Predicate[predicates.size()]));
break;
default:
throw new IllegalStateException("Unknown operator " + this.operator);
}
predicates.clear();
addPredicate(predicate);
}
private Predicate getPredicate() {
handleComparator();
if (predicates.size() == 1) {
Predicate predicate = predicates.get(0);
if (not) {
predicate = new NotPredicate(predicate);
not = false;
}
return predicate;
}
throw new IllegalStateException("Can't return a predicate.");
}
public class PredicateBuilderWithProperty {
// ----- Equals -----
public <T>PredicateBuilderWithPredicate equals(Comparable<T> value) {
if (propertyId == null) {
throw new IllegalStateException("No property.");
}
addPredicate(new EqualsPredicate<>(propertyId, value));
return new PredicateBuilderWithPredicate();
}
// ----- Greater than -----
public <T>PredicateBuilderWithPredicate greaterThan(Comparable<T> value) {
if (propertyId == null) {
throw new IllegalStateException("No property.");
}
addPredicate(new GreaterPredicate<>(propertyId, value));
return new PredicateBuilderWithPredicate();
}
// ----- Greater than equal to -----
public <T>PredicateBuilderWithPredicate greaterThanEqualTo(Comparable<T> value) {
if (propertyId == null) {
throw new IllegalStateException("No property.");
}
addPredicate(new GreaterEqualsPredicate<>(propertyId, value));
return new PredicateBuilderWithPredicate();
}
// ----- Less than -----
public <T>PredicateBuilderWithPredicate lessThan(Comparable<T> value) {
if (propertyId == null) {
throw new IllegalStateException("No property.");
}
addPredicate(new LessPredicate<>(propertyId, value));
return new PredicateBuilderWithPredicate();
}
// ----- Less than equal to -----
public <T>PredicateBuilderWithPredicate lessThanEqualTo(Comparable<T> value) {
if (propertyId == null) {
throw new IllegalStateException("No property.");
}
addPredicate(new LessEqualsPredicate<>(propertyId, value));
return new PredicateBuilderWithPredicate();
}
}
public class PredicateBuilderWithPredicate {
public PredicateBuilder and() {
if (operator != Operator.And) {
handleComparator();
operator = Operator.And;
}
return PredicateBuilder.this;
}
public PredicateBuilder or() {
if (operator != Operator.Or) {
handleComparator();
operator = Operator.Or;
}
return PredicateBuilder.this;
}
public Predicate toPredicate() {
if (outer != null) {
throw new IllegalStateException("Unbalanced block - missing end.");
}
done = true;
return getPredicate();
}
public PredicateBuilderWithPredicate end() {
if (outer == null) {
throw new IllegalStateException("Unbalanced block - missing begin.");
}
outer.addPredicate(getPredicate());
return outer.getPredicateBuilderWithPredicate();
}
}
}