/* |
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* Licensed to the Apache Software Foundation (ASF) under one or more |
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* contributor license agreements. See the NOTICE file distributed with |
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* this work for additional information regarding copyright ownership. |
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* The ASF licenses this file to You under the Apache license, Version 2.0 |
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* (the "License"); you may not use this file except in compliance with |
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* the License. You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0 |
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the license for the specific language governing permissions and |
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* limitations under the license. |
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*/ |
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package org.apache.commons.text.lookup; |
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import java.util.Map; |
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import java.util.Objects; |
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import java.util.function.BiFunction; |
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/** |
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* A function-based lookup where the request for a lookup is answered by applying that function with a key. |
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* |
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* @param <R> A function's return type |
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* @param <P> A function's second input type |
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* |
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* @since 1.9 |
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*/ |
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final class BiFunctionStringLookup<P, R> implements BiStringLookup<P> { |
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/** |
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* Creates a new instance backed by a Function. |
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* |
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* @param <T> the function's input type |
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* @param biFunction the function, may be null. |
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* @return a new instance backed by the given function. |
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*/ |
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static <U, T> BiFunctionStringLookup<U, T> on(final BiFunction<String, U, T> biFunction) { |
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return new BiFunctionStringLookup<>(biFunction); |
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} |
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/** |
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* Creates a new instance backed by a Map. Used by the default lookup. |
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* |
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* @param <T> the map's value type. |
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* @param map the map of keys to values, may be null. |
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* @return a new instance backed by the given map. |
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*/ |
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static <U, T> BiFunctionStringLookup<U, T> on(final Map<String, T> map) { |
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return on((key, u) -> map.get(key)); |
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} |
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/** |
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* Function. |
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*/ |
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private final BiFunction<String, P, R> biFunction; |
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/** |
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* Creates a new instance backed by a Function. |
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* |
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* @param biFunction the function, may be null. |
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*/ |
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private BiFunctionStringLookup(final BiFunction<String, P, R> biFunction) { |
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this.biFunction = biFunction; |
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} |
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@Override |
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public String lookup(final String key) { |
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return lookup(key, null); |
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} |
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/** |
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* Looks up a String key by applying the function. |
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* <p> |
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* If the function is null, then null is returned. The function result object is converted to a string using |
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* toString(). |
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* </p> |
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* |
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* @param key the key to be looked up, may be null. |
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* @return The function result as a string, may be null. |
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*/ |
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@Override |
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public String lookup(final String key, final P object) { |
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if (biFunction == null) { |
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return null; |
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} |
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final R obj; |
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try { |
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obj = biFunction.apply(key, object); |
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} catch (final SecurityException | NullPointerException | IllegalArgumentException e) { |
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// Squelched. All lookup(String) will return null. |
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// Could be a ConcurrentHashMap and a null key request |
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return null; |
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} |
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return Objects.toString(obj, null); |
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} |
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@Override |
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public String toString() { |
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return super.toString() + " [function=" + biFunction + "]"; |
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} |
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} |