org.apache.commons.text.lookup.BiFunctionStringLookup Maven / Gradle / Ivy
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache license, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License 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 org.apache.commons.text.lookup;
import java.util.Map;
import java.util.Objects;
import java.util.function.BiFunction;
/**
* A function-based lookup where the request for a lookup is answered by applying that function with a key.
*
* @param A function's return type
* @param A function's second input type
* @since 1.9
*/
final class BiFunctionStringLookup
implements BiStringLookup
{
/**
* Creates a new instance backed by a Function.
*
* @param the function's input type
* @param biFunction the function, may be null.
* @return a new instance backed by the given function.
*/
static BiFunctionStringLookup on(final BiFunction biFunction) {
return new BiFunctionStringLookup<>(biFunction);
}
/**
* Creates a new instance backed by a Map. Used by the default lookup.
*
* @param the map's value type.
* @param map the map of keys to values, may be null.
* @return a new instance backed by the given map.
*/
static BiFunctionStringLookup on(final Map map) {
return on((key, u) -> map.get(key));
}
/**
* Function.
*/
private final BiFunction biFunction;
/**
* Creates a new instance backed by a Function.
*
* @param biFunction the function, may be null.
*/
private BiFunctionStringLookup(final BiFunction biFunction) {
this.biFunction = biFunction;
}
@Override
public String lookup(final String key) {
return lookup(key, null);
}
/**
* Looks up a String key by applying the function.
*
* If the function is null, then null is returned. The function result object is converted to a string using
* toString().
*
*
* @param key the key to be looked up, may be null.
* @return The function result as a string, may be null.
*/
@Override
public String lookup(final String key, final P object) {
if (biFunction == null) {
return null;
}
final R obj;
try {
obj = biFunction.apply(key, object);
} catch (final SecurityException | NullPointerException | IllegalArgumentException e) {
// Squelched. All lookup(String) will return null.
// Could be a ConcurrentHashMap and a null key request
return null;
}
return Objects.toString(obj, null);
}
@Override
public String toString() {
return super.toString() + " [function=" + biFunction + "]";
}
}