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Collections and collection utilities for Neo4j.
/*
* Copyright (c) "Neo4j"
* Neo4j Sweden AB [https://neo4j.com]
*
* This file is part of Neo4j.
*
* Neo4j is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see type of keys
* @param type of values
* @return a Map with the entries supplied by {@code objects}.
*/
public static Map genericMap(Object... objects) {
return genericMap(new HashMap<>(), objects);
}
/**
* A short-hand method for adding key/value pairs into a {@link Map}.
*
* @param targetMap the {@link Map} to put the objects into.
* @param objects alternating key and value.
* @param type of keys
* @param type of values
* @return a Map with the entries supplied by {@code objects}.
*/
@SuppressWarnings("unchecked")
public static Map genericMap(Map targetMap, Object... objects) {
int i = 0;
while (i < objects.length) {
targetMap.put((K) objects[i++], (V) objects[i++]);
}
return targetMap;
}
/**
* A short-hand method for creating a {@link Map} of key/value pairs where
* both keys and values are {@link String}s.
*
* @param strings alternating key and value.
* @return a Map with the entries supplied by {@code strings}.
*/
public static Map stringMap(String... strings) {
return genericMap((Object[]) strings);
}
/**
* A short-hand method for creating a {@link Map} of key/value pairs where
* both keys and values are {@link String}s.
*
* @param targetMap the {@link Map} to put the objects into.
* @param strings alternating key and value.
* @return a Map with the entries supplied by {@code strings}.
*/
public static Map stringMap(Map targetMap, String... strings) {
return genericMap(targetMap, (Object[]) strings);
}
/**
* A short-hand method for creating a {@link Map} of key/value pairs where
* keys are {@link String}s and values are {@link Object}s.
*
* @param objects alternating key and value.
* @return a Map with the entries supplied by {@code objects}.
*/
public static Map map(Object... objects) {
return genericMap(objects);
}
/**
* A short-hand method for creating a {@link Map} of key/value pairs where
* keys are {@link String}s and values are {@link Object}s.
*
* @param targetMap the {@link Map} to put the objects into.
* @param objects alternating key and value.
* @return a Map with the entries supplied by {@code objects}.
*/
public static Map map(Map targetMap, Object... objects) {
return genericMap(targetMap, objects);
}
/**
* Loads a {@link Map} from an {@link InputStream} assuming strings as keys
* and values.
*
* @param stream the {@link InputStream} containing a
* {@link Properties}-like layout of keys and values.
* @return the read data as a {@link Map}.
* @throws IOException if the {@code stream} throws {@link IOException}.
*/
public static Map load(InputStream stream) throws IOException {
Properties props = new Properties();
props.load(stream);
Map result = new HashMap<>();
for (Map.Entry entry : props.entrySet()) {
// Properties does not trim whitespace from the right side of values
result.put((String) entry.getKey(), ((String) entry.getValue()).trim());
}
return result;
}
/**
* Stores the data in {@code config} into {@code file} in a standard java
* {@link Properties} format.
* @param config the data to store in the properties file.
* @param file the file to store the properties in.
* @throws IOException IO error.
*/
public static void store(Map config, Path file) throws IOException {
try (OutputStream stream = new BufferedOutputStream(Files.newOutputStream(file))) {
store(config, stream);
}
}
/**
* Stores the data in {@code config} into {@code stream} in a standard java
* {@link Properties} format.
* @param config the data to store in the properties file.
* @param stream the {@link OutputStream} to store the properties in.
* @throws IOException IO error.
*/
public static void store(Map config, OutputStream stream) throws IOException {
Properties properties = new Properties();
for (Map.Entry property : config.entrySet()) {
properties.setProperty(property.getKey(), property.getValue());
}
properties.store(stream, null);
}
/**
* Stores the data in {@code config} into {@code writer} in a standard java
* {@link Properties} format.
*
* @param config the data to store in the properties file.
* @param writer the {@link Writer} to store the properties in.
* @throws IOException IO error.
*/
public static void store(Map config, Writer writer) throws IOException {
Properties properties = new Properties();
properties.putAll(config);
properties.store(writer, null);
}
/**
* Mutates the input map by removing entries which do not have keys in the new backing data, as extracted with
* the keyExtractor.
* @param map the map to mutate.
* @param newBackingData the backing data to retain.
* @param keyExtractor the function to extract keys from the backing data.
* @param type of the key in the input map.
* @param type of the values in the input map.
* @param type of the keys in the new baking data.
*/
public static void trimToList(Map map, List newBackingData, Function keyExtractor) {
Set retainedKeys = newBackingData.stream().map(keyExtractor).collect(Collectors.toSet());
trimToList(map, retainedKeys);
}
/**
* Mutates the input map by removing entries which are not in the retained set of keys.
* @param map the map to mutate.
* @param retainedKeys the keys to retain.
* @param type of the key.
* @param type of the values.
*/
public static void trimToList(Map map, Set retainedKeys) {
Set keysToRemove = new HashSet<>(map.keySet());
keysToRemove.removeAll(retainedKeys);
keysToRemove.forEach(map::remove);
}
}