TypeSafeMultiMap.java

/*
 * *************************************************************************************************************************************************************
 *
 * TheseFoolishThings: Miscellaneous utilities
 * http://tidalwave.it/projects/thesefoolishthings
 *
 * Copyright (C) 2009 - 2025 by Tidalwave s.a.s. (http://tidalwave.it)
 *
 * *************************************************************************************************************************************************************
 *
 * 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.
 *
 * *************************************************************************************************************************************************************
 *
 * git clone https://bitbucket.org/tidalwave/thesefoolishthings-src
 * git clone https://github.com/tidalwave-it/thesefoolishthings-src
 *
 * *************************************************************************************************************************************************************
 */
package it.tidalwave.util;

// import javax.annotation.Nonnegative;
import jakarta.annotation.Nonnull;
import java.util.Collection;
import java.util.Collections;
import java.util.Map;
import java.util.Set;
import java.util.function.BiConsumer;
import it.tidalwave.util.impl.TypeSafeHashMultiMap;

/***************************************************************************************************************************************************************
 *
 * A map that is type safe, i.e. the pairs (key, value) are type-checked, and can contain multiple values, i.e. it's
 * associated to collections (key, collection of values). It's immutable.
 *
 * @author  Fabrizio Giudici
 *
 **************************************************************************************************************************************************************/
public interface TypeSafeMultiMap extends Iterable<Map.Entry<Key<?>, Collection<?>>>
  {
    /***********************************************************************************************************************************************************
     * Returns a value given its key.
     *
     * @param   <T>   the type
     * @param   key   the key
     * @return        the value as a {@link Collection}
     **********************************************************************************************************************************************************/
    @Nonnull
    public <T> Collection<T> get (@Nonnull Key<T> key);

    /***********************************************************************************************************************************************************
     * Checks whether a pair has been stored.
     *
     * @param   key   the key
     * @return        {@code true} if the pair is present
     **********************************************************************************************************************************************************/
    public boolean containsKey (@Nonnull Key<?> key);

    /***********************************************************************************************************************************************************
     * Returns a set of all the contained keys.
     *
     * @return        the keys as a mutable set
     **********************************************************************************************************************************************************/
    @Nonnull
    public Set<Key<?>> keySet();

    /***********************************************************************************************************************************************************
     * Returns a set of all the contained values.
     *
     * @return        the values as a mutable collection
     * @since         3.2-ALPHA-6
     **********************************************************************************************************************************************************/
    @Nonnull
    public Collection<Collection<?>> values();

    /***********************************************************************************************************************************************************
     * Returns a set of all the contained (key, value) pairs.
     *
     * @return        the pairs as a mutable collection
     * @since         3.2-ALPHA-6
     **********************************************************************************************************************************************************/
     @Nonnull
     public Set<Map.Entry<Key<?>, Collection<?>>> entrySet();

    /***********************************************************************************************************************************************************
     * Returns the size of this map.
     *
     * @return        the size
     **********************************************************************************************************************************************************/
    /* @Nonnegative */
    public int size();

    /***********************************************************************************************************************************************************
     * Performs the given action on all the pairs (key, value) contained in this map.
     *
     * @param action  the action
     * @param <T>     the value type
     * @since         3.2-ALPHA-10
     **********************************************************************************************************************************************************/
    public <T> void forEach (@Nonnull BiConsumer<? super Key<T>, ? super Collection<T>> action);

    /***********************************************************************************************************************************************************
     * Returns the contents as a plain {@link Map}.
     *
     * @return        the contents as a mutable map
     **********************************************************************************************************************************************************/
    @Nonnull
    public Map<Key<?>, Collection<?>> asMap();

    /***********************************************************************************************************************************************************
     * Creates a new instance with an additional pair (key, value).
     *
     * @param   <T>   the type
     * @param   key   the key
     * @param   value the value
     * @return        the new instance
     * @since         3.2-ALPHA-2
     **********************************************************************************************************************************************************/
    @Nonnull
    public <T> TypeSafeMultiMap with (@Nonnull final Key<T> key, @Nonnull final T value);

    /***********************************************************************************************************************************************************
     * Creates an instance cloning the given map.
     *
     * @param   map   the map to clone
     * @return        the new instance
     * @since         3.2-ALPHA-2
     **********************************************************************************************************************************************************/
    @Nonnull
    public static TypeSafeMultiMap ofCloned (@Nonnull final Map<? extends Key<?>, ? extends Collection<?>> map)
      {
        return new TypeSafeHashMultiMap(map);
      }

    /***********************************************************************************************************************************************************
     * Creates a new empty instance.
     *
     * @return        the new instance
     * @since         3.2-ALPHA-2
     **********************************************************************************************************************************************************/
    @Nonnull
    public static TypeSafeMultiMap newInstance()
      {
        return new TypeSafeHashMultiMap(Collections.emptyMap());
      }
  }