/*
* Copyright 2014 - 2017 Blazebit.
*
* 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.
*/
package com.blazebit.persistence.view;
import com.blazebit.persistence.RestrictionBuilder;
import com.blazebit.persistence.WhereBuilder;
/**
* An attribute filter provider is an object that applies restrictions on a {@link WhereBuilder}.
*
* Attribute filter providers must have a constructor that accepts either of the following parameter types
* <ul>
* <li>none</li>
* <li>{@linkplain Class}</li>
* <li>{@linkplain Object}</li>
* <li>{@linkplain Class}, {@linkplain Object}</li>
* </ul>
*
* The {@linkplain Class} argument refers to the expected type i.e. the attribute type. The object argument refers to the filter value.
*
* @author Christian Beikov
* @since 1.0.0
*/
public abstract class AttributeFilterProvider {
/**
* Applies restrictions for the given attributeExpression on the given where builder.
*
* @param <T> The actual type of the where builder
* @param whereBuilder The where builder on which the restrictions should be applied
* @param attributeExpression The expression for the attribute on which a restriction should be applied
* @return The object which the restriction builder returns on a terminal operation
*/
public <T extends WhereBuilder<T>> T apply(T whereBuilder, String attributeExpression) {
return apply(whereBuilder.where(attributeExpression));
}
/**
* Applies restrictions for the given subquery on the given where builder.
*
* @param <T> The actual type of the where builder
* @param whereBuilder The where builder on which the restrictions should be applied
* @param subqueryAlias The alias for the subquery which will be replaced by the actual subquery
* @param subqueryExpresion The expression which wraps a subquery
* @param provider The provider for the subquery
* @return The object which the restriction builder returns on a terminal operation
*/
public <T extends WhereBuilder<T>> T apply(T whereBuilder, String subqueryAlias, String subqueryExpresion, SubqueryProvider provider) {
if (subqueryAlias == null) {
return apply(provider.createSubquery(whereBuilder.whereSubquery()));
} else {
return apply(provider.createSubquery(whereBuilder.whereSubquery(subqueryAlias, subqueryExpresion)));
}
}
/**
* Applies a restriction on the given restriction builder.
*
* @param <T> The return type of terminal operations of the restriction builder
* @param restrictionBuilder The restriction builder
* @return The object which the restriction builder returns on a terminal operation
*/
protected <T> T apply(RestrictionBuilder<T> restrictionBuilder) {
throw new UnsupportedOperationException("Method not implemented!");
}
}