/*		 
 * Copyright (C) 2002-2014 Sebastiano Vigna 
 *
 * 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 PACKAGE;

import it.unimi.dsi.fastutil.Function;

/** A type-specific {@link Function}; provides some additional methods that use polymorphism to avoid (un)boxing.
 *
 * <P>Type-specific versions of <code>get()</code>, <code>put()</code> and
 * <code>remove()</code> cannot rely on <code>null</code> to denote absence of
 * a key.  Rather, they return a {@linkplain #defaultReturnValue() default
 * return value}, which is set to 0 cast to the return type (<code>false</code>
 * for booleans) at creation, but can be changed using the
 * <code>defaultReturnValue()</code> method. 
 *
 * <P>For uniformity reasons, even maps returning objects implement the default
 * return value (of course, in this case the default return value is
 * initialized to <code>null</code>).
 *
 * <P><strong>Warning:</strong> to fall in line as much as possible with the
 * {@linkplain java.util.Map standard map interface}, it is strongly suggested
 * that standard versions of <code>get()</code>, <code>put()</code> and
 * <code>remove()</code> for maps with primitive-type values <em>return
 * <code>null</code> to denote missing keys</em> rather than wrap the default
 * return value in an object (of course, for maps with object keys and values
 * this is not possible, as there is no type-specific version).
 *
 * @see Function
 */

public interface FUNCTION KEY_VALUE_GENERIC extends Function<KEY_GENERIC_CLASS, VALUE_GENERIC_CLASS> {

#if #keys(primitive) || #values(primitive)

	/** Adds a pair to the map.
	 *
	 * @param key the key.
	 * @param value the value.
	 * @return the old value, or the {@linkplain #defaultReturnValue() default return value} if no value was present for the given key.
	 * @see Function#put(Object,Object)
	 */

	VALUE_GENERIC_TYPE put( KEY_GENERIC_TYPE key, VALUE_GENERIC_TYPE value );

	/** Returns the value to which the given key is mapped.
	 *
	 * @param key the key.
	 * @return the corresponding value, or the {@linkplain #defaultReturnValue() default return value} if no value was present for the given key.
	 * @see Function#get(Object)
	 */

	VALUE_GENERIC_TYPE GET_VALUE( KEY_TYPE key );

	/** Removes the mapping with the given key.
	 * @param key the key.
	 * @return the old value, or the {@linkplain #defaultReturnValue() default return value} if no value was present for the given key.
	 * @see Function#remove(Object)
	 */

	VALUE_GENERIC_TYPE REMOVE_VALUE( KEY_TYPE key );
#endif

#if #keys(primitive)

	/**
	 * @see Function#containsKey(Object)
	 */

	boolean containsKey( KEY_TYPE key );

#endif	 

	/** Sets the default return value. 
	 *
	 * This value must be returned by type-specific versions of
	 * <code>get()</code>, <code>put()</code> and <code>remove()</code> to
	 * denote that the map does not contain the specified key. It must be
	 * 0/<code>false</code>/<code>null</code> by default.
	 *
	 * @param rv the new default return value.
	 * @see #defaultReturnValue()
	 */

	void defaultReturnValue( VALUE_GENERIC_TYPE rv );

	 
	/** Gets the default return value.
	 *
	 * @return the current default return value.
	 */

	VALUE_GENERIC_TYPE defaultReturnValue();

}