98 lines
3.6 KiB
Java
98 lines
3.6 KiB
Java
/* Copyright 2010 Abhinav Sarkar <abhinav@abhinavsarkar.net>
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*
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* This file is a part of SpelHelper library.
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*
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* SpelHelper library is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License (GNU LGPL) as
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* published by the Free Software Foundation, either version 3 of the License,
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* or (at your option) any later version.
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*
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* SpelHelper library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with SpelHelper library. If not, see <http://www.gnu.org/licenses/>.
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*/
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package net.abhinavsarkar.spelhelper;
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import static java.util.Collections.unmodifiableList;
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import static java.util.Collections.unmodifiableMap;
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import static java.util.Collections.unmodifiableSet;
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import java.util.Arrays;
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import java.util.HashMap;
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import java.util.HashSet;
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import java.util.List;
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import java.util.Map;
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import java.util.Set;
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import org.springframework.util.Assert;
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/**
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* Provides some extension functions to create some basic collection types
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* inline in SpEL expressions.
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* These functions are automatically registered with {@link SpelHelper}.
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*
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* **See Also:**
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* [Spring Docs on extension functions](http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/expressions.html#expressions-ref-functions)
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* @author Abhinav Sarkar _abhinav@abhinavsarkar.net_
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*/
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public final class ExtensionFunctions {
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private ExtensionFunctions() {
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}
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/**
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* Creates an unmodifiable {@link List} of the arguments provided.
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*
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* Example use: `"#list('one', 'two', 'three')"`
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* @param <T> Type of the arguments provided.
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* @param args Arguments to create list of.
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* @return An unmodifiable list of the arguments provided.
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*/
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public static <T> List<T> list(final T... args) {
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return unmodifiableList(Arrays.asList(args));
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}
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/**
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* Creates an unmodifiable {@link Set} of the arguments provided.
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*
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* Example use: `"#set('one', 'two', 'three')"`
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* @param <T> Type of the arguments provided.
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* @param args Arguments to create set of.
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* @return An unmodifiable set of the arguments provided.
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*/
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public static <T> Set<T> set(final T... args) {
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return unmodifiableSet(new HashSet<T>(list(args)));
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}
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/**
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* Creates an unmodifiable {@link Map} using the {@link List} of keys
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* provided as the first argument and the {@link List} of values provided
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* as the second argument.
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*
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* Example use: `"#map(#list('one', 'two', 'three'), #list(1, 2, 3))"`
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* @param <K> Type of the keys of the map.
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* @param <V> Type of the values of map.
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* @param keys List of the keys.
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* @param values List of the values.
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* @return A unmodifiable map created from the key and value lists.
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* @throws IllegalArgumentException if the number of keys and the number of
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* values is not equal.
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*/
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public static <K,V> Map<K,V> map(final List<? extends K> keys,
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final List<? extends V> values) {
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Assert.isTrue(keys.size() == values.size(),
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"There should be equal number of keys and values");
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Map<K,V> map = new HashMap<K,V>();
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int length = keys.size();
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for (int i = 0; i < length; i++) {
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map.put(keys.get(i), values.get(i));
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}
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return unmodifiableMap(map);
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}
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}
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