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/*
* Copyright (c) 2010 Google Inc.
*
* Licensed 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 com.google.api.client.escape;
/**
* An object that converts literal text into a format safe for inclusion in a
* particular context (such as an XML document). Typically (but not always), the
* inverse process of "unescaping" the text is performed automatically by the
* relevant parser.
*
*
* For example, an XML escaper would convert the literal string {@code
* "Foo"} into {@code "Foo<Bar>"} to prevent {@code ""} from
* being confused with an XML tag. When the resulting XML document is parsed,
* the parser API will return this text as the original literal string {@code
* "Foo"}.
*
*
* An {@code Escaper} instance is required to be stateless, and safe when used
* concurrently by multiple threads.
*
*
* Several popular escapers are defined as constants in the class
* {@link CharEscapers}.
*
* @since 1.0
*/
public abstract class Escaper {
/**
* Returns the escaped form of a given literal string.
*
*
* Note that this method may treat input characters differently depending on
* the specific escaper implementation.
*
* - {@link UnicodeEscaper} handles UTF-16 correctly, including
* surrogate character pairs. If the input is badly formed the escaper should
* throw {@link IllegalArgumentException}.
*
*
* @param string the literal string to be escaped
* @return the escaped form of {@code string}
* @throws NullPointerException if {@code string} is null
* @throws IllegalArgumentException if {@code string} contains badly formed
* UTF-16 or cannot be escaped for any other reason
*/
public abstract String escape(String string);
}