org.javimmutable.collections.JImmutableListMap Maven / Gradle / Ivy
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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>>,
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 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 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 map contains no values
*/
boolean isEmpty();
/**
* @return true only if map contains values
*/
default boolean isNonEmpty()
{
return !isEmpty();
}
/**
* @return an equivalent collection with no values
*/
@Nonnull
JImmutableListMap deleteAll();
/**
* 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();
/**
* Processes every key/list pair in this map using the provided function.
*/
default void forEach(@Nonnull Proc2> proc)
{
for (JImmutableMap.Entry> e : this) {
proc.apply(e.getKey(), e.getValue());
}
}
/**
* Processes every key/list pair in this map using the provided function.
*/
default void forEachThrows(@Nonnull Proc2Throws, E> proc)
throws E
{
for (JImmutableMap.Entry> e : this) {
proc.apply(e.getKey(), e.getValue());
}
}
/**
* 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()));
}
}
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