77 lines
2.1 KiB
Java
77 lines
2.1 KiB
Java
/*
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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.el.stream;
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import javax.el.ELException;
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import javax.el.LambdaExpression;
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import org.apache.el.util.MessageFactory;
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public class Optional {
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private final Object obj;
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static final Optional EMPTY = new Optional(null);
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Optional(Object obj) {
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this.obj = obj;
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}
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public Object get() throws ELException {
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if (obj == null) {
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throw new ELException(MessageFactory.get("stream.optional.empty"));
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} else {
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return obj;
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}
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}
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public void ifPresent(LambdaExpression le) {
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if (obj != null) {
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le.invoke(obj);
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}
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}
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public Object orElse(Object other) {
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if (obj == null) {
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return other;
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} else {
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return obj;
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}
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}
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public Object orElseGet(Object le) {
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if (obj == null) {
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// EL 3.0 specification says parameter is LambdaExpression but it
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// may already have been evaluated. If that is the case, the
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// original parameter will have been checked to ensure it was a
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// LambdaExpression before it was evaluated.
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if (le instanceof LambdaExpression) {
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return ((LambdaExpression) le).invoke((Object[]) null);
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} else {
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return le;
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}
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} else {
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return obj;
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}
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}
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}
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