org.atlasapi.persistence.content.query.QuerySplitter.java Source code

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Here is the source code for org.atlasapi.persistence.content.query.QuerySplitter.java

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/* Copyright 2010 Meta Broadcast Ltd
    
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 org.atlasapi.persistence.content.query;

import java.util.List;
import java.util.Set;

import org.atlasapi.content.criteria.AtomicQuery;
import org.atlasapi.content.criteria.AttributeQuery;
import org.atlasapi.content.criteria.BooleanAttributeQuery;
import org.atlasapi.content.criteria.ContentQuery;
import org.atlasapi.content.criteria.DateTimeAttributeQuery;
import org.atlasapi.content.criteria.EnumAttributeQuery;
import org.atlasapi.content.criteria.IntegerAttributeQuery;
import org.atlasapi.content.criteria.MatchesNothing;
import org.atlasapi.content.criteria.QueryVisitor;
import org.atlasapi.content.criteria.StringAttributeQuery;
import org.atlasapi.media.entity.Identified;

import com.google.common.collect.Iterables;
import com.metabroadcast.common.base.Maybe;

public class QuerySplitter {

    public Maybe<ContentQuery> retain(ContentQuery query, Set<Class<? extends Identified>> allowedTypes) {
        return split(query, allowedTypes, true);
    }

    public Maybe<ContentQuery> discard(ContentQuery query, Set<Class<? extends Identified>> allowedTypes) {
        return split(query, allowedTypes, false);
    }

    private Maybe<ContentQuery> split(ContentQuery query, final Set<Class<? extends Identified>> allowedTypes,
            final boolean retain) {

        List<Maybe<AtomicQuery>> extracted = query.accept(new QueryVisitor<Maybe<AtomicQuery>>() {

            @Override
            public Maybe<AtomicQuery> visit(IntegerAttributeQuery query) {
                return allowed(query);
            }

            @Override
            public Maybe<AtomicQuery> visit(StringAttributeQuery query) {
                return allowed(query);
            }

            @Override
            public Maybe<AtomicQuery> visit(BooleanAttributeQuery query) {
                return allowed(query);
            }

            @Override
            public Maybe<AtomicQuery> visit(EnumAttributeQuery<?> query) {
                return allowed(query);
            }

            @Override
            public Maybe<AtomicQuery> visit(DateTimeAttributeQuery query) {
                return allowed(query);
            }

            @Override
            public Maybe<AtomicQuery> visit(MatchesNothing noOp) {
                return Maybe.nothing();
            }

            private Maybe<AtomicQuery> allowed(AttributeQuery<?> query) {
                if (allowedTypes.contains(query.getAttribute().target())) {
                    return retain ? Maybe.<AtomicQuery>just(query) : Maybe.<AtomicQuery>nothing();
                } else {
                    return retain ? Maybe.<AtomicQuery>nothing() : Maybe.<AtomicQuery>just(query);
                }
            }
        });

        Iterable<AtomicQuery> operands = Maybe.filterValues(extracted);
        if (Iterables.isEmpty(operands)) {
            return Maybe.nothing();
        } else {
            return Maybe.just(query.copyWithOperands(operands));
        }

    }
}