/*
* Copyright 2010-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file 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 com.amazonaws.util;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
/**
* An immutable map that could be built by convenient constructors.
* <p>
* Example of using map Builder:
*
* <pre>
* {
* @code
* Map<String, AttibuteValue> item =
* new ImmutableMapParameter.Builder<String, AttibuteValue>()
* .put("one", new AttibuteValue("1"))
* .put("two", new AttibuteValue("2"))
* .put("three", new AttibuteValue("3"))
* .build();
* }
* </pre>
*
* For <i>small</i> immutable maps (up to five entries), the
* {@code ImmutableMapParamter.of()} methods are preferred:
*
* <pre>
* {@code
* Map<String, AttibuteValue> item =
* ImmutableMapParameter
* .of("one", new AttributeValue("1"),
* "two", new AttributeValue("2"),
* "three", new AttributeValue("3"),
* }
* </pre>
*
* @param <K> Class of the key for the map.
* @param <V> Class of the value for the map.
*/
public class ImmutableMapParameter<K, V> implements Map<K, V> {
private static final String UNMODIFIABLE_MESSAGE = "This is an immutable map.";
private static final String DUPLICATED_KEY_MESSAGE = "Duplicate keys are provided.";
private final Map<K, V> map;
private ImmutableMapParameter(Map<K, V> map) {
this.map = map;
}
/**
* Returns a new MapParameterBuilder instance.
*/
public static <K, V> Builder<K, V> builder() {
return new Builder<K, V>();
}
/**
* Returns an ImmutableMapParameter instance containing a single entry.
*
* @param k0 Key of the single entry.
* @param v0 Value of the single entry.
*/
public static <K, V> ImmutableMapParameter<K, V> of(K k0, V v0) {
Map<K, V> map = Collections.singletonMap(k0, v0);
return new ImmutableMapParameter<K, V>(map);
}
/**
* Returns an ImmutableMapParameter instance containing two entries.
*
* @param k0 Key of the first entry.
* @param v0 Value of the first entry.
* @param k1 Key of the second entry.
* @param v1 Value of the second entry.
*/
public static <K, V> ImmutableMapParameter<K, V> of(K k0, V v0, K k1, V v1) {
Map<K, V> map = new HashMap<K, V>();
putAndWarnDuplicateKeys(map, k0, v0);
putAndWarnDuplicateKeys(map, k1, v1);
return new ImmutableMapParameter<K, V>(map);
}
/**
* Returns an ImmutableMapParameter instance containing three entries.
*
* @param k0 Key of the first entry.
* @param v0 Value of the first entry.
* @param k1 Key of the second entry.
* @param v1 Value of the second entry.
* @param k2 Key of the third entry.
* @param v2 Value of the third entry.
*/
public static <K, V> ImmutableMapParameter<K, V> of(K k0, V v0, K k1, V v1, K k2, V v2) {
Map<K, V> map = new HashMap<K, V>();
putAndWarnDuplicateKeys(map, k0, v0);
putAndWarnDuplicateKeys(map, k1, v1);
putAndWarnDuplicateKeys(map, k2, v2);
return new ImmutableMapParameter<K, V>(map);
}
/**
* Returns an ImmutableMapParameter instance containing four entries.
*
* @param k0 Key of the first entry.
* @param v0 Value of the first entry.
* @param k1 Key of the second entry.
* @param v1 Value of the second entry.
* @param k2 Key of the third entry.
* @param v2 Value of the third entry.
* @param k3 Key of the fourth entry.
* @param v3 Value of the fourth entry.
*/
public static <K, V> ImmutableMapParameter<K, V> of(K k0, V v0, K k1, V v1, K k2, V v2, K k3,
V v3) {
Map<K, V> map = new HashMap<K, V>();
putAndWarnDuplicateKeys(map, k0, v0);
putAndWarnDuplicateKeys(map, k1, v1);
putAndWarnDuplicateKeys(map, k2, v2);
putAndWarnDuplicateKeys(map, k3, v3);
return new ImmutableMapParameter<K, V>(map);
}
/**
* Returns an ImmutableMapParameter instance containing five entries.
*
* @param k0 Key of the first entry.
* @param v0 Value of the first entry.
* @param k1 Key of the second entry.
* @param v1 Value of the second entry.
* @param k2 Key of the third entry.
* @param v2 Value of the third entry.
* @param k3 Key of the fourth entry.
* @param v3 Value of the fourth entry.
* @param k4 Key of the fifth entry.
* @param v4 Value of the fifth entry.
*/
public static <K, V> ImmutableMapParameter<K, V> of(K k0, V v0, K k1, V v1, K k2, V v2, K k3,
V v3, K k4, V v4) {
Map<K, V> map = new HashMap<K, V>();
putAndWarnDuplicateKeys(map, k0, v0);
putAndWarnDuplicateKeys(map, k1, v1);
putAndWarnDuplicateKeys(map, k2, v2);
putAndWarnDuplicateKeys(map, k3, v3);
putAndWarnDuplicateKeys(map, k4, v4);
return new ImmutableMapParameter<K, V>(map);
}
/** Inherited methods **/
@Override
public boolean containsKey(Object key) {
return map.containsKey(key);
}
@Override
public boolean containsValue(Object value) {
return map.containsValue(value);
}
@Override
public Set<Entry<K, V>> entrySet() {
return map.entrySet();
}
@Override
public V get(Object key) {
return map.get(key);
}
@Override
public boolean isEmpty() {
return map.isEmpty();
}
@Override
public Set<K> keySet() {
return map.keySet();
}
@Override
public int size() {
return map.size();
}
@Override
public Collection<V> values() {
return map.values();
}
/** Unsupported methods **/
@Override
public void clear() {
throw new UnsupportedOperationException(UNMODIFIABLE_MESSAGE);
}
@Override
public V put(K key, V value) {
throw new UnsupportedOperationException(UNMODIFIABLE_MESSAGE);
}
@Override
public void putAll(Map<? extends K, ? extends V> map) {
throw new UnsupportedOperationException(UNMODIFIABLE_MESSAGE);
}
@Override
public V remove(Object key) {
throw new UnsupportedOperationException(UNMODIFIABLE_MESSAGE);
}
private static <K, V> void putAndWarnDuplicateKeys(Map<K, V> map, K key, V value) {
if (map.containsKey(key))
throw new IllegalArgumentException(DUPLICATED_KEY_MESSAGE);
map.put(key, value);
}
/**
* A convenient builder for creating ImmutableMapParameter instances.
*/
public static class Builder<K, V> {
private final Map<K, V> entries;
public Builder() {
this.entries = new HashMap<K, V>();
}
/**
* Add a key-value pair into the built map. The method will throw
* IllegalArgumentException immediately when duplicate keys are
* provided.
*
* @return Returns a reference to this object so that method calls can
* be chained together.
*/
public Builder<K, V> put(K key, V value) {
putAndWarnDuplicateKeys(entries, key, value);
return this;
}
/**
* Generates and returns a new ImmutableMapParameter instance which
* contains all the entries added into the Builder by {@code put()}
* method.
*/
public ImmutableMapParameter<K, V> build() {
HashMap<K, V> builtMap = new HashMap<K, V>();
builtMap.putAll(entries);
return new ImmutableMapParameter<K, V>(builtMap);
}
}
}