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Library providing immutable/persistent collection classes for
Java. While collections are immutable they provide methods for
adding and removing values by creating new modified copies of
themselves. Each copy shares almost all of its structure with
other copies to minimize memory consumption.
///###////////////////////////////////////////////////////////////////////////
//
// Burton Computer Corporation
// http://www.burton-computer.com
//
// Copyright (c) 2018, Burton Computer Corporation
// All rights reserved.
//
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// modification, are permitted provided that the following conditions are met:
//
// Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in
// the documentation and/or other materials provided with the
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// of its contributors may be used to endorse or promote products
// derived from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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package org.javimmutable.collections;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.annotation.concurrent.Immutable;
import java.util.Iterator;
import java.util.stream.Collector;
/**
* Interface for maps that map keys to lists of values.
*/
@Immutable
public interface JImmutableListMap
extends Insertable, JImmutableListMap>,
Mapped>,
IterableStreamable>>,
Cursorable>>,
InvariantCheckable
{
/**
* Return the list associated with key or an empty list if no list is associated.
*
* @param key identifies the value to retrieve
* @return list associated with key or an empty list if no value is associated
*/
@Nonnull
JImmutableList getList(@Nonnull K key);
/**
* Sets the list associated with a specific key. Key and value must be non-null.
* If the key already has a list in the map the old list is discarded
* and the new list is stored in its place. Returns a new JImmutableListMap reflecting
* any changes. The original map is always left unchanged.
*
* @param key non-null key
* @param value list of possibly null values to use for this key
* @return new map reflecting the change
*/
@Nonnull
JImmutableListMap assign(@Nonnull K key,
@Nonnull JImmutableList value);
/**
* Add key/value entry to the map, replacing any existing entry with same key.
*/
@Nonnull
@Override
JImmutableListMap insert(@Nonnull JImmutableMap.Entry value);
/**
* Add value to the list for the specified key. Note that this can create duplicate values
* in the list.
*/
@Nonnull
JImmutableListMap insert(@Nonnull K key,
@Nullable V value);
/**
* Adds all of the elements of the specified collection to the List for the specified key.
*/
@Nonnull
default JImmutableListMap insertAll(@Nonnull K key,
@Nonnull Iterable values)
{
return assign(key, getList(key).insertAll(values));
}
/**
* Adds all of the elements of the specified collection to the List for the specified key.
*/
@Nonnull
default JImmutableListMap insertAll(@Nonnull K key,
@Nonnull Cursor values)
{
return assign(key, getList(key).insertAll(values));
}
/**
* Adds all of the elements of the specified collection to the List for the specified key.
*/
@Nonnull
default JImmutableListMap insertAll(@Nonnull K key,
@Nonnull Iterator values)
{
return assign(key, getList(key).insertAll(values));
}
/**
* Deletes the entry for the specified key (if any). Returns a new map if the value
* was deleted or the current map if the key was not contained in the map.
*
* @param key non-null key
* @return same or different map depending on whether key was removed
*/
@Nonnull
JImmutableListMap delete(@Nonnull K key);
/**
* Deletes the list for every key in keys. Returns a new map if the keys were deleted or the
* current map if the keys were contained in the map.
*/
@Nonnull
default JImmutableListMap deleteAll(@Nonnull Iterable keys)
{
return deleteAll(keys.iterator());
}
/**
* Deletes the list for every key in keys. Returns a new map if the keys were deleted or the
* current map if the keys were contained in the map.
*/
@Nonnull
default JImmutableListMap deleteAll(@Nonnull Cursor keys)
{
JImmutableListMap map = this;
for (Cursor cursor = keys.start(); cursor.hasValue(); cursor = cursor.next()) {
map = map.delete(cursor.getValue());
}
return map;
}
/**
* Deletes the list for every key in keys. Returns a new map if the keys were deleted or the
* current map if the keys were contained in the map.
*/
@Nonnull
default JImmutableListMap deleteAll(@Nonnull Iterator keys)
{
JImmutableListMap map = this;
while (keys.hasNext()) {
map = map.delete(keys.next());
}
return map;
}
/**
* Apply the specified transform function to the List assigned to the specified key and assign the result
* to the key in this map. If no List is currently assigned to the key the transform function is called
* with an empty list.
*
* @param key key holding list to be updated
* @param transform function to update the list
* @return new map with update applied to list associated with key
*/
default JImmutableListMap transform(@Nonnull K key,
@Nonnull Func1, JImmutableList> transform)
{
final JImmutableList current = getList(key);
final JImmutableList transformed = transform.apply(current);
return (transformed == current) ? this : assign(key, transformed);
}
/**
* Apply the specified transform function to the List assigned to the specified key and assign the result
* to the key in this map. If no list is currently assigned to the key the transform function is never
* called and this map is returned unchanged.
*
* @param key key holding list to be updated
* @param transform function to update the list
* @return new map with update applied to list associated with key
*/
default JImmutableListMap transformIfPresent(@Nonnull K key,
@Nonnull Func1, JImmutableList> transform)
{
final JImmutableList current = get(key);
if (current != null) {
final JImmutableList transformed = transform.apply(current);
if (transformed != current) {
return assign(key, transformed);
}
}
return this;
}
/**
* Return the number of keys in the map.
*/
int size();
/**
* @return true only if list contains no values
*/
boolean isEmpty();
/**
* @return an equivalent collection with no values
*/
@Nonnull
JImmutableListMap deleteAll();
/**
* Creates a Cursor to access all of the Map's keys.
*/
@Nonnull
Cursor keysCursor();
/**
* Creates a Cursor to access all of the specified key's list.
* If no list exists for key an empty cursor is returned.
*
* @return a (possibly empty) cursor for traversing the values associated with key
*/
@Nonnull
Cursor valuesCursor(@Nonnull K key);
/**
* Creates a Streamable to access all of the Map's keys.
*/
@Nonnull
IterableStreamable keys();
/**
* Creates a Streamable to access all of the specified key's list.
* If no list exists for key an empty Streamable is returned.
*
* @return a (possibly empty) Streamable for traversing the values associated with key
*/
@Nonnull
IterableStreamable values(@Nonnull K key);
/**
* Creates a Streamable to access all of the Map's entries.
*/
@Nonnull
IterableStreamable> entries();
/**
* Returns a Collector that creates a listMap of the same type as this containing all
* of the collected values inserted over whatever starting values this already contained.
*/
@Nonnull
default Collector, ?, JImmutableListMap> listMapCollector()
{
return GenericCollector.ordered(this, deleteAll(), a -> a.isEmpty(), (a, v) -> a.insert(v), (a, b) -> a.insertAll(b.entries()));
}
}