eaglercraft-1.8/sources/main/java/com/google/common/escape/Escaper.java

123 lines
4.7 KiB
Java
Raw Normal View History

2022-12-25 01:12:28 -08:00
/*
* Copyright (C) 2008 The Guava Authors
*
* 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.common.escape;
import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtCompatible;
import com.google.common.base.Function;
/**
* 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.
*
* <p>
* For example, an XML escaper would convert the literal string
* {@code "Foo<Bar>"} into {@code
* "Foo&lt;Bar&gt;"} to prevent {@code "<Bar>"} 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<Bar>"}.
*
* <p>
* An {@code Escaper} instance is required to be stateless, and safe when used
* concurrently by multiple threads.
*
* <p>
* Because, in general, escaping operates on the code points of a string and not
* on its individual {@code char} values, it is not safe to assume that
* {@code escape(s)} is equivalent to
* {@code escape(s.substring(0, n)) + escape(s.substing(n))} for arbitrary
* {@code n}. This is because of the possibility of splitting a surrogate pair.
* The only case in which it is safe to escape strings and concatenate the
* results is if you can rule out this possibility, either by splitting an
* existing long string into short strings adaptively around
* {@linkplain Character#isHighSurrogate surrogate}
* {@linkplain Character#isLowSurrogate pairs}, or by starting with short
* strings already known to be free of unpaired surrogates.
*
* <p>
* The two primary implementations of this interface are {@link CharEscaper} and
* {@link UnicodeEscaper}. They are heavily optimized for performance and
* greatly simplify the task of implementing new escapers. It is strongly
* recommended that when implementing a new escaper you extend one of these
* classes. If you find that you are unable to achieve the desired behavior
* using either of these classes, please contact the Java libraries team for
* advice.
*
* <p>
* Several popular escapers are defined as constants in classes like
* {@link com.google.common.html.HtmlEscapers},
* {@link com.google.common.xml.XmlEscapers}, and {@link SourceCodeEscapers}. To
* create your own escapers, use {@link CharEscaperBuilder}, or extend
* {@code CharEscaper} or {@code UnicodeEscaper}.
*
* @author David Beaumont
* @since 15.0
*/
@Beta
@GwtCompatible
public abstract class Escaper {
// TODO(user): evaluate custom implementations, considering package private
// constructor.
/** Constructor for use by subclasses. */
protected Escaper() {
}
/**
* Returns the escaped form of a given literal string.
*
* <p>
* Note that this method may treat input characters differently depending on the
* specific escaper implementation.
*
* <ul>
* <li>{@link UnicodeEscaper} handles
* <a href="http://en.wikipedia.org/wiki/UTF-16">UTF-16</a> correctly, including
* surrogate character pairs. If the input is badly formed the escaper should
* throw {@link IllegalArgumentException}.
* <li>{@link CharEscaper} handles Java characters independently and does not
* verify the input for well formed characters. A {@code CharEscaper} should not
* be used in situations where input is not guaranteed to be restricted to the
* Basic Multilingual Plane (BMP).
* </ul>
*
* @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);
private final Function<String, String> asFunction = new Function<String, String>() {
@Override
public String apply(String from) {
return escape(from);
}
};
/**
* Returns a {@link Function} that invokes {@link #escape(String)} on this
* escaper.
*/
public final Function<String, String> asFunction() {
return asFunction;
}
}