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Add MapBuilder, re #64 
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‎src/main/java/org/libj/util/MapBuilder.java

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/* Copyright (c) 2024 LibJ
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* You should have received a copy of The MIT License (MIT) along with this
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* program. If not, see <http://opensource.org/licenses/MIT/>.
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*/
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package org.libj.util;
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import java.util.Map;
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/**
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* Class providing the builder pattern for the population of key/value pairs into arbitrary {@link Map}s.
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*
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* @param <K> The type of keys maintained by the map.
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* @param <V> The type of mapped values in the map.
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* @param <M> The type of the map.
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*/
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public class MapBuilder<K,V,M extends Map<K,V>> {
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/**
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* Associates the specified value with the specified key in the target map, and returns the target map.
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*
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* @param <K> The type of keys maintained by the map.
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* @param <V> The type of mapped values in the map.
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* @param <M> The type of the map.
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* @param map The target {@link Map}.
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* @param key Key with which the specified value is to be associated in the target map of this {@link MapBuilder}.
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* @param value Value to be associated with the specified key in the target map of this {@link MapBuilder}.
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* @return The target {@link Map}.
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* @throws UnsupportedOperationException if the {@link Map#put} operation is not supported by the target map of this
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* {@link MapBuilder}.
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* @throws ClassCastException If the class of the specified key or value prevents it from being stored in the target map of this
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* {@link MapBuilder}.
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* @throws NullPointerException If the specified key or value is null and the target map of this {@link MapBuilder} does not permit
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* null keys or values.
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* @throws IllegalArgumentException If some property of the specified key or value prevents it from being stored in the target map
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* of this {@link MapBuilder}.
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* @throws NullPointerException If the target map of this {@link MapBuilder} is null.
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* @see Map#put(Object,Object)
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*/
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public static <K,V,M extends Map<K,V>> M put(final M map, final K key, final V value) {
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map.put(key, value);
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return map;
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}
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/**
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* Associates the specified variable array of alternating key and value arguments in the target map, and returns the target map.
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*
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* @param <K> The type of keys maintained by the map.
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* @param <V> The type of mapped values in the map.
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* @param <M> The type of the map.
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* @param map The target {@link Map}.
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* @param keyValue Variable array of alternating key and value arguments.
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* @return The target {@link Map}.
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* @throws UnsupportedOperationException if the {@link Map#put} operation is not supported by the target map of this
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* {@link MapBuilder}.
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* @throws ClassCastException If the class of the specified key or value prevents it from being stored in the target map of this
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* {@link MapBuilder}.
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* @throws NullPointerException If the specified key or value is null and the target map of this {@link MapBuilder} does not permit
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* null keys or values.
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* @throws IllegalArgumentException If the number of provided key and value arguments is not even, or if some property of the
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* specified key or value prevents it from being stored in the target map of this {@link MapBuilder}.
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* @throws NullPointerException If the target map of this {@link MapBuilder} is null.
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* @see Map#put(Object,Object)
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*/
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@SuppressWarnings("unchecked")
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public static <K,V,M extends Map<K,V>> M put(final M map, final Object ... keyValue) {
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final Map m = map;
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final int len = keyValue.length;
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if (len % 2 != 0)
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throw new IllegalArgumentException("Expected an even number of alternating key and value arguments");
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for (int i = 0; i < len; m.put(keyValue[i++], keyValue[i++])); // [A]
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return map;
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}
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private final M map;
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/**
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* Creates a new {@link MapBuilder} with the provided {@link Map} as the target map of the builder pattern.
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*
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* @param map The target {@link Map} of the builder pattern.
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*/
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public MapBuilder(final M map) {
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this.map = map;
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}
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/**
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* Associates the specified value with the specified key in the target map of this {@link MapBuilder}, and returns {@code this}
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* {@link MapBuilder}.
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*
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* @param key Key with which the specified value is to be associated in the target map of this {@link MapBuilder}.
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* @param value Value to be associated with the specified key in the target map of this {@link MapBuilder}.
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* @return {@code this} {@link MapBuilder}.
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* @throws UnsupportedOperationException if the {@link Map#put} operation is not supported by the target map of this
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* {@link MapBuilder}.
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* @throws ClassCastException If the class of the specified key or value prevents it from being stored in the target map of this
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* {@link MapBuilder}.
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* @throws NullPointerException If the specified key or value is null and the target map of this {@link MapBuilder} does not permit
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* null keys or values.
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* @throws IllegalArgumentException If some property of the specified key or value prevents it from being stored in the target map
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* of this {@link MapBuilder}.
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* @throws NullPointerException If the target map of this {@link MapBuilder} is null.
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* @see Map#put(Object,Object)
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*/
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public MapBuilder<K,V,M> put(final K key, final V value) {
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map.put(key, value);
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return this;
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}
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/**
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* Copies all of the mappings from the specified map to the target map of this {@link MapBuilder}, and returns {@code this}
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* {@link MapBuilder}. The effect of this call is equivalent to that of calling {@link #put(Object,Object) put(k, v)} on this
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* {@link MapBuilder} once for each mapping from key {@code k} to value {@code v} in the specified map. The behavior of this
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* operation is undefined if the specified map is modified while the operation is in progress.
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*
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* @return {@code this} {@link MapBuilder}.
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* @param m Mappings to be stored in the target map of this {@link MapBuilder}.
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* @throws UnsupportedOperationException If the {@link Map#putAll} operation is not supported by the target map of this
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* {@link MapBuilder}.
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* @throws ClassCastException If the class of a key or value in the specified map prevents it from being stored in the target map of
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* this {@link MapBuilder}.
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* @throws NullPointerException If the specified map is null, or if the target map of this {@link MapBuilder} does not permit null
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* keys or values, and the specified map contains null keys or values.
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* @throws IllegalArgumentException If some property of a key or value in the specified map prevents it from being stored in the
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* target map of this {@link MapBuilder}.
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* @throws NullPointerException If the target map of this {@link MapBuilder} is null.
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* @see Map#putAll(Map)
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*/
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public MapBuilder<K,V,M> putAll(final Map<? extends K,? extends V> m) {
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map.putAll(m);
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return this;
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}
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/**
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* If the specified key is not already associated with a value in the target map of this {@link MapBuilder} (or is mapped to
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* {@code null}), this method associates the specified key with the given value, and returns {@code this} {@link MapBuilder}.
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*
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* @param key Key with which the specified value is to be associated in the target map of this {@link MapBuilder}.
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* @param value Value to be associated with the specified key in the target map of this {@link MapBuilder}.
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* @return {@code this} {@link MapBuilder}.
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* @throws UnsupportedOperationException If the {@link Map#put} operation is not supported by the target map of this
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* {@link MapBuilder}.
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* @throws ClassCastException If the key or value is of an inappropriate type for the target map of this {@link MapBuilder}.
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* @throws NullPointerException If the specified key or value is null, and the target map of this {@link MapBuilder} does not permit
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* null keys or values.
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* @throws IllegalArgumentException If some property of the specified key or value prevents it from being stored in the target map
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* of this {@link MapBuilder}.
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* @throws NullPointerException If the target map of this {@link MapBuilder} is null.
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* @see Map#putIfAbsent(Object,Object)
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*/
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public MapBuilder<K,V,M> putIfAbsent(final K key, final V value) {
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map.putIfAbsent(key, value);
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return this;
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}
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public M build() {
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return map;
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}
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}

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