text: /*
   * Copyright (C) 2015 Red Hat, Inc. and/or its affiliates.
   *
   * 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.jboss.errai.jpa.client.local;
  
  import javax.persistence.Parameter;
  import javax.persistence.TypedQuery;
  
  import org.jboss.errai.common.client.api.Assert;
  
  import com.google.common.collect.ImmutableBiMap;
  
  /**
   * Factory class for creating TypedQuery instances. Used internally by
   * EntityManager's <i>createXXXQuery</i> methods.
   *
   * @author Jonathan Fuerth <jfuerth@gmail.com>
   */
  public abstract class TypedQueryFactory {
    protected final Class<?> actualResultType;
    protected final ImmutableBiMap<String, Parameter<?>> parameters;
  
  
    public TypedQueryFactory(
            Class<?> actualResultType,
            ErraiParameter<?>[] parameters) {
      this.actualResultType = Assert.notNull(actualResultType);
  
      ImmutableBiMap.Builder<String, Parameter<?>> pb = ImmutableBiMap.builder();
      for (Parameter<?> p : parameters) {
        pb.put(p.getName(), p);
      }
      this.parameters = pb.build();
    }
  
    /**
     * Creates an instance of the TypedQuery associated with this factory if its
     * result type is assignable to the given type.
     *
     * @param resultType
     *          The expected result type
     * @param entityManager
     *          the EntityManager the query will be executed in. Must not be null.
     * @param <T>
     *          The result type of the queries produced by this factory
     * @return A new instance of TypedQuery, whose result type is assignable to
     *         {@code resultType}.
     * @throws IllegalArgumentException
     *           if the query's result type is not assignable to the given type.
     */
    public <T> TypedQuery<T> createIfCompatible(Class<T> resultType, ErraiEntityManager entityManager) {
      Class<?> resultSupertype = actualResultType;
      while (resultSupertype != null) {
        if (resultType == resultSupertype) {
          return createQuery(entityManager);
        }
        resultSupertype = resultSupertype.getSuperclass();
      }
      throw new IllegalArgumentException("Expected return type " + resultType + " is not assignable from actual return type " + actualResultType);
    }
  
    /**
     * Subclasses must implement this method by returning a new instance of
     * ErraiTypedQuery that implements the query logic for the JPA query handled
     * by this factory.
     *
     * @param the
     *          EntityManager the query will be executed in. Must not be null.
     * @return a new instance of ErraiTypedQuery.
     */
    protected abstract <T> TypedQuery<T> createQuery(ErraiEntityManager entityManager);
  
  }
  