/*
 * Copyright (c) OSGi Alliance (2016). All Rights Reserved.
 *
 * 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.osgi.converter;

import java.lang.reflect.Type;

import org.osgi.annotation.versioning.ProviderType;

/**
 * This interface is used to specify the target that an object should be
 * converted to. A {@link Converting} instance can be obtained via the
 * {@link Converter} service by starting a conversion for a specific object.
 *
 * @author $Id$
 * @ThreadSafe
 */
@ProviderType
public interface Converting {
	/**
	 * The default value to use when the object cannot be converted or in case
	 * of conversion from a {@code null} value.
	 * 
	 * @param defVal The default value.
	 * @return The current {@code Converting} object so that additional calls
	 *         can be chained.
	 */
	Converting defaultValue(Object defVal);

	/**
	 * Specify the target object type for the conversion as a class object.
	 *
	 * @param cls The class to convert to.
	 * @return The converted object.
	 */
	<T> T to(Class<T> cls);

	/**
	 * Specify the target object type as a {@link TypeReference}. If the target
	 * class carries generics information a TypeReference should be used as this
	 * preserves the generic information whereas a Class object has this
	 * information erased. Example use:
	 *
	 * <pre>
	 * List&lt;String&gt; result = converter.convert(Arrays.asList(1, 2, 3))
	 * 		.to(new TypeReference&lt;List&lt;String&gt;&gt;() {});
	 * </pre>
	 *
	 * @param ref A type reference to the object being converted to.
	 * @return The converted object.
	 */
	<T> T to(TypeReference<T> ref);

	/**
	 * Specify the target object type as a Java Reflection Type object.
	 *
	 * @param type A Type object to represent the target type to be converted
	 *            to.
	 * @return The converted object.
	 */
	Object to(Type type);

	/**
	 * Same as {@code to(String.class)}.
	 * 
	 * @return The converted object.
	 */
	@Override
	String toString();
}

/*
 * Copyright (c) OSGi Alliance (2016). All Rights Reserved.
 *
 * 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.osgi.converter;

import java.lang.reflect.Type;

import org.osgi.annotation.versioning.ProviderType;

/**
 * This interface is used to specify the target that an object should be
 * converted to. A {@link Converting} instance can be obtained via the
 * {@link Converter} service by starting a conversion for a specific object.
 *
 * @author $Id$
 * @ThreadSafe
 */
@ProviderType
public interface Converting {
	/**
	 * Convert the source object based on rules for the class being passed in.
	 * This method can be used to disambiguate objects that would match multiple
	 * conversion rules.
	 * 
	 * @param type The type or class to be used as the source type for the
	 *            conversion
	 * @return The current {@code Converting} object so that additional calls
	 *         can be chained.
	 */
	Converting as(Class< ? > type);

	/**
	 * The default value to use when the object cannot be converted or in case
	 * of conversion from a {@code null} value.
	 *
	 * @param defVal The default value.
	 * @return The current {@code Converting} object so that additional calls
	 *         can be chained.
	 */
	Converting defaultValue(Object defVal);

	/**
	 * Specify the target object type for the conversion as a class object.
	 *
	 * @param cls The class to convert to.
	 * @return The converted object.
	 */
	<T> T to(Class<T> cls);

	/**
	 * Specify the target object type as a {@link TypeReference}. If the target
	 * class carries generics information a TypeReference should be used as this
	 * preserves the generic information whereas a Class object has this
	 * information erased. Example use:
	 *
	 * <pre>
	 * List&lt;String&gt; result = converter.convert(Arrays.asList(1, 2, 3))
	 * 		.to(new TypeReference&lt;List&lt;String&gt;&gt;() {});
	 * </pre>
	 *
	 * @param ref A type reference to the object being converted to.
	 * @return The converted object.
	 */
	<T> T to(TypeReference<T> ref);

	/**
	 * Specify the target object type as a Java Reflection Type object.
	 *
	 * @param type A Type object to represent the target type to be converted
	 *            to.
	 * @return The converted object.
	 */
	Object to(Type type);

	/**
	 * Same as {@code to(String.class)}.
	 *
	 * @return The converted object.
	 */
	@Override
	String toString();
}

Add as() to Converter API