ImmutableReplicator.java

/*
 * Copyright 2007 The Apache Software Foundation.
 *
 * 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 net.sf.beanlib.provider.replicator;

import net.jcip.annotations.ThreadSafe;
import net.sf.beanlib.spi.BeanTransformerSpi;
import net.sf.beanlib.spi.replicator.ImmutableReplicatorSpi;

/**
 * Default implementation of {@link net.sf.beanlib.spi.replicator.ImmutableReplicatorSpi}.
 * 
 * @author Joe D. Velopar
 */
public class ImmutableReplicator implements ImmutableReplicatorSpi {
    public static final Factory factory = new Factory();

    /**
     * Factory for {@link ImmutableReplicator}
     * 
     * @author Joe D. Velopar
     */
    @ThreadSafe
    private static class Factory implements ImmutableReplicatorSpi.Factory {
        private Factory() {}

        @Override
        public ImmutableReplicator newImmutableReplicatable(BeanTransformerSpi beanTransformer) {
            return new ImmutableReplicator();
        }
    }

    public static ImmutableReplicator newImmutableReplicatable(BeanTransformerSpi beanTransformer) {
        return factory.newImmutableReplicatable(beanTransformer);
    }

    protected ImmutableReplicator() {}

    @Override
    public <V, T> T replicateImmutable(V immutableFrom, Class<T> toClass) {
        if (toClass.isPrimitive()) {
            if (sameType(toClass, immutableFrom.getClass())) {
                @SuppressWarnings("unchecked")
                T ret = (T) immutableFrom;
                return ret;
            }
            // from & to are of totally different types
            return getDefaultPrimitiveValue(toClass);
        }
        // toClass is not primitive.
        // immutableFrom is not null, but could be a primitive.
        Class<?> fromClass = immutableFrom.getClass();

        if (fromClass.isPrimitive()) {
            if (sameType(fromClass, toClass)) {
                @SuppressWarnings("unchecked")
                T ret = (T) immutableFrom;
                return ret;
            }
            return getDefaultPrimitiveValue(toClass);
        }
        // from and to are both not primitives.
        return toClass.isAssignableFrom(immutableFrom.getClass()) ? toClass.cast(immutableFrom) : null;
    }

    @SuppressWarnings("unchecked")
    public static <T> T getDefaultPrimitiveValue(Class<T> primitiveClass) {
        return (T) (primitiveClass == boolean.class ? Boolean.FALSE : new Byte((byte) 0));
    }

    private static boolean sameType(Class<?> lhs, Class<?> rhs) {
        return lhs == boolean.class && rhs == Boolean.class || lhs == byte.class && rhs == Byte.class || lhs == char.class && rhs == Character.class
                || lhs == short.class && rhs == Short.class || lhs == int.class && rhs == Integer.class || lhs == long.class && rhs == Long.class
                || lhs == float.class && rhs == Float.class || lhs == double.class && rhs == Double.class;
    }
}