core/runtime/src/main/java/org/qi4j/runtime/query/QueryImpl.java

/*
 * Copyright 2007 Niclas Hedhman.
 * Copyright 2008 Alin Dreghiciu.
 *
 * 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.qi4j.runtime.query;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import org.qi4j.api.composite.Composite;
import org.qi4j.api.property.Property;
import org.qi4j.api.query.Query;
import org.qi4j.api.query.QueryExecutionException;
import org.qi4j.api.query.QueryExpressions;
import org.qi4j.api.query.grammar.OrderBy;
import org.qi4j.functional.Iterables;
import org.qi4j.functional.Specification;
import org.qi4j.spi.query.QuerySource;

/**
 * Default implementation of {@link org.qi4j.api.query.Query}.
 */
/* package */ class QueryImpl<T>
    implements Query<T>
{
    private static final long serialVersionUID = 1L;

    /**
     * Type of queried entities.
     */
    private final Class<T> resultType;
    /**
     * Where clause.
     */
    private final Specification<Composite> whereClause;
    private QuerySource querySource;
    /**
     * Order by clause segments.
     */
    private Iterable<OrderBy> orderBySegments;
    /**
     * First result to be returned.
     */
    private Integer firstResult;
    /**
     * Maximum number of results to be returned.
     */
    private Integer maxResults;
    /**
     * Mapping between variable name and variable values.
     */
    private Map<String, Object> variables;

    /**
     * Constructor.
     *
     * @param resultType  type of queried entities; cannot be null
     * @param whereClause where clause
     */
    /* package */ QueryImpl( final Class<T> resultType,
               final Specification<Composite> whereClause,
               final QuerySource querySource
    )
    {
        this.resultType = resultType;
        this.whereClause = whereClause;
        this.querySource = querySource;
    }

    /**
     * @see org.qi4j.api.query.Query#orderBy(org.qi4j.api.query.grammar.OrderBy[])
     */
    @Override
    public Query<T> orderBy( final OrderBy... segments )
    {
        orderBySegments = Iterables.iterable( segments );
        return this;
    }

    /**
     * @see org.qi4j.api.query.Query#orderBy(org.qi4j.api.property.Property, org.qi4j.api.query.grammar.OrderBy.Order)
     */
    @Override
    public Query<T> orderBy( Property<?> property, OrderBy.Order order )
    {
        if( orderBySegments == null )
        {
            orderBySegments = Iterables.iterable( new OrderBy( QueryExpressions.property( property ), order ) );
        }
        else
        {
            orderBySegments = Iterables.append( new OrderBy( QueryExpressions.property( property ), order ), orderBySegments );
        }
        return this;
    }

    /**
     * @see org.qi4j.api.query.Query#orderBy(org.qi4j.api.property.Property)
     */
    @Override
    public Query<T> orderBy( Property<?> property )
    {
        orderBy( property, OrderBy.Order.ASCENDING );
        return this;
    }

    /**
     * @see org.qi4j.api.query.Query#firstResult(int)
     */
    @Override
    public Query<T> firstResult( int firstResult )
    {
        this.firstResult = firstResult;
        return this;
    }

    /**
     * @see org.qi4j.api.query.Query#maxResults(int)
     */
    @Override
    public Query<T> maxResults( int maxResults )
    {
        this.maxResults = maxResults;
        return this;
    }

    /**
     * @see org.qi4j.api.query.Query#setVariable(String, Object)
     */
    @SuppressWarnings( "unchecked" )
    @Override
    public Query<T> setVariable( final String name, final Object value )
    {
        if( variables == null )
        {
            variables = new HashMap<String, Object>();
        }
        variables.put( name, value );

        return this;
    }

    /**
     * @see org.qi4j.api.query.Query#getVariable(String)
     */
    @SuppressWarnings( "unchecked" )
    @Override
    public <V> V getVariable( final String name )
    {
        if( variables == null )
        {
            return null;
        }
        else
        {
            return (V) variables.get( name );
        }
    }

    @Override
    public Class<T> resultType()
    {
        return resultType;
    }

    @Override
    public T find()
        throws QueryExecutionException
    {
        return querySource.find( resultType, whereClause, orderBySegments, firstResult, maxResults, variables );
    }

    @Override
    public long count()
        throws QueryExecutionException
    {
        return querySource.count( resultType, whereClause, orderBySegments, firstResult, maxResults, variables );
    }

    @Override
    public Iterator<T> iterator()
    {
        return querySource.iterator( resultType, whereClause, orderBySegments, firstResult, maxResults, variables );
    }

    @Override
    public String toString()
    {
        return "Query{" +
               " FROM " + querySource +
               " WHERE " + whereClause +
               ( orderBySegments != null ? " ORDER BY " + orderBySegments : "" ) +
               ( firstResult != null ? " FIRST " + firstResult : "" ) +
               ( maxResults != null ? " MAX " + maxResults : "" ) +
               " EXPECT " + resultType +
               ( variables != null ? " WITH VARIABLES " + variables : "" ) +
               '}';
    }
}