001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.commons.configuration2.convert; 018 019import java.util.ArrayList; 020import java.util.Collection; 021import java.util.List; 022 023/** 024 * <p> 025 * A specialized implementation of the {@code ListDelimiterHandler} interface 026 * which disables list splitting. 027 * </p> 028 * <p> 029 * This class does not recognize any list delimiters; passed in strings are 030 * returned unchanged. Also the {@code escape()} method is a dummy - there is no 031 * need for escaping delimiter characters as none are supported. Note that the 032 * method for escaping a list throws an {@code UnsupportedOperationException}. 033 * If list delimiters are not supported, there is no point in squashing multiple 034 * values into a single one. 035 * </p> 036 * <p> 037 * Implementation note: An instance of this class can be shared between multiple 038 * configuration objects. It is state-less and thread-safe. 039 * </p> 040 * 041 * @since 2.0 042 */ 043public class DisabledListDelimiterHandler extends AbstractListDelimiterHandler 044{ 045 /** 046 * A default instance of this class. Because it is safe to share 047 * {@code DisabledListDelimiterHandler} objects this instance can be used 048 * whenever such an object is needed. 049 */ 050 public static final ListDelimiterHandler INSTANCE = 051 new DisabledListDelimiterHandler(); 052 053 /** 054 * {@inheritDoc} This implementation always throws an 055 * {@code UnsupportedOperationException} exception. 056 */ 057 @Override 058 public Object escapeList(final List<?> values, final ValueTransformer transformer) 059 { 060 throw new UnsupportedOperationException( 061 "Escaping lists is not supported!"); 062 } 063 064 /** 065 * {@inheritDoc} This implementation always returns a collection containing 066 * the passed in string as its single element. The string is not changed, 067 * the {@code trim} flag is ignored. (The {@code trim} flag refers to the 068 * components extracted from the string. Because no components are extracted 069 * nothing is trimmed.) 070 */ 071 @Override 072 protected Collection<String> splitString(final String s, final boolean trim) 073 { 074 final Collection<String> result = new ArrayList<>(1); 075 result.add(s); 076 return result; 077 } 078 079 /** 080 * {@inheritDoc} This implementation returns the passed in string without 081 * any changes. 082 */ 083 @Override 084 protected String escapeString(final String s) 085 { 086 return s; 087 } 088}