1 /* Copyright (c) 2008 Google Inc.
2 *
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at
6 *
7 * http://www.apache.org/licenses/LICENSE-2.0
8 *
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
14 */
15
16 package org.yaml.snakeyaml.external.com.google.gdata.util.common.base;
17
18 /**
19 * An object that converts literal text into a format safe for inclusion in a
20 * particular context (such as an XML document). Typically (but not always), the
21 * inverse process of "unescaping" the text is performed automatically by the
22 * relevant parser.
23 *
24 * <p>
25 * For example, an XML escaper would convert the literal string
26 * {@code "Foo<Bar>"} into {@code "Foo<Bar>"} to prevent {@code "<Bar>"}
27 * from being confused with an XML tag. When the resulting XML document is
28 * parsed, the parser API will return this text as the original literal string
29 * {@code "Foo<Bar>"}.
30 *
31 * <p>
32 * An {@code Escaper} instance is required to be stateless, and safe when used
33 * concurrently by multiple threads.
34 *
35 * <p>
36 * Several popular escapers are defined as constants in the class
37 * {@link CharEscapers}. To create your own escapers, use
38 * {@link CharEscaperBuilder}, or extend {@link CharEscaper} or
39 * {@code UnicodeEscaper}.
40 *
41 *
42 */
43 public interface Escaper {
44 /**
45 * Returns the escaped form of a given literal string.
46 *
47 * <p>
48 * Note that this method may treat input characters differently depending on
49 * the specific escaper implementation.
50 * <ul>
51 * <li>{@link UnicodeEscaper} handles <a
52 * href="http://en.wikipedia.org/wiki/UTF-16">UTF-16</a> correctly,
53 * including surrogate character pairs. If the input is badly formed the
54 * escaper should throw {@link IllegalArgumentException}.
55 * <li>{@link CharEscaper} handles Java characters independently and does
56 * not verify the input for well formed characters. A CharEscaper should not
57 * be used in situations where input is not guaranteed to be restricted to
58 * the Basic Multilingual Plane (BMP).
59 * </ul>
60 *
61 * @param string
62 * the literal string to be escaped
63 * @return the escaped form of {@code string}
64 * @throws NullPointerException
65 * if {@code string} is null
66 * @throws IllegalArgumentException
67 * if {@code string} contains badly formed UTF-16 or cannot be
68 * escaped for any other reason
69 */
70 public String escape(String string);
71
72 /**
73 * Returns an {@code Appendable} instance which automatically escapes all
74 * text appended to it before passing the resulting text to an underlying
75 * {@code Appendable}.
76 *
77 * <p>
78 * Note that this method may treat input characters differently depending on
79 * the specific escaper implementation.
80 * <ul>
81 * <li>{@link UnicodeEscaper} handles <a
82 * href="http://en.wikipedia.org/wiki/UTF-16">UTF-16</a> correctly,
83 * including surrogate character pairs. If the input is badly formed the
84 * escaper should throw {@link IllegalArgumentException}.
85 * <li>{@link CharEscaper} handles Java characters independently and does
86 * not verify the input for well formed characters. A CharEscaper should not
87 * be used in situations where input is not guaranteed to be restricted to
88 * the Basic Multilingual Plane (BMP).
89 * </ul>
90 *
91 * @param out
92 * the underlying {@code Appendable} to append escaped output to
93 * @return an {@code Appendable} which passes text to {@code out} after
94 * escaping it.
95 */
96 public Appendable escape(Appendable out);
97 }