1 /*
2 * Copyright (C) 2006 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package com.google.common.escape;
18
19 import static com.google.common.base.Preconditions.checkNotNull;
20
21 import com.google.common.annotations.Beta;
22 import com.google.common.annotations.GwtCompatible;
23
24 import java.util.HashMap;
25 import java.util.Map;
26
27 /**
28 * Simple helper class to build a "sparse" array of objects based on the indexes that were added to
29 * it. The array will be from 0 to the maximum index given. All non-set indexes will contain null
30 * (so it's not really a sparse array, just a pseudo sparse array). The builder can also return a
31 * CharEscaper based on the generated array.
32 *
33 * @author Sven Mawson
34 * @since 15.0
35 */
36 @Beta
37 @GwtCompatible
38 public final class CharEscaperBuilder {
39 /**
40 * Simple decorator that turns an array of replacement char[]s into a CharEscaper, this results in
41 * a very fast escape method.
42 */
43 private static class CharArrayDecorator extends CharEscaper {
44 private final char[][] replacements;
45 private final int replaceLength;
46
47 CharArrayDecorator(char[][] replacements) {
48 this.replacements = replacements;
49 this.replaceLength = replacements.length;
50 }
51
52 /*
53 * Overriding escape method to be slightly faster for this decorator. We test the replacements
54 * array directly, saving a method call.
55 */
56 @Override public String escape(String s) {
57 int slen = s.length();
58 for (int index = 0; index < slen; index++) {
59 char c = s.charAt(index);
60 if (c < replacements.length && replacements[c] != null) {
61 return escapeSlow(s, index);
62 }
63 }
64 return s;
65 }
66
67 @Override protected char[] escape(char c) {
68 return c < replaceLength ? replacements[c] : null;
69 }
70 }
71
72 // Replacement mappings.
73 private final Map<Character, String> map;
74
75 // The highest index we've seen so far.
76 private int max = -1;
77
78 /**
79 * Construct a new sparse array builder.
80 */
81 public CharEscaperBuilder() {
82 this.map = new HashMap<Character, String>();
83 }
84
85 /**
86 * Add a new mapping from an index to an object to the escaping.
87 */
88 public CharEscaperBuilder addEscape(char c, String r) {
89 map.put(c, checkNotNull(r));
90 if (c > max) {
91 max = c;
92 }
93 return this;
94 }
95
96 /**
97 * Add multiple mappings at once for a particular index.
98 */
99 public CharEscaperBuilder addEscapes(char[] cs, String r) {
100 checkNotNull(r);
101 for (char c : cs) {
102 addEscape(c, r);
103 }
104 return this;
105 }
106
107 /**
108 * Convert this builder into an array of char[]s where the maximum index is the value of the
109 * highest character that has been seen. The array will be sparse in the sense that any unseen
110 * index will default to null.
111 *
112 * @return a "sparse" array that holds the replacement mappings.
113 */
114 public char[][] toArray() {
115 char[][] result = new char[max + 1][];
116 for (Map.Entry<Character, String> entry : map.entrySet()) {
117 result[entry.getKey()] = entry.getValue().toCharArray();
118 }
119 return result;
120 }
121
122 /**
123 * Convert this builder into a char escaper which is just a decorator around the underlying array
124 * of replacement char[]s.
125 *
126 * @return an escaper that escapes based on the underlying array.
127 */
128 public Escaper toEscaper() {
129 return new CharArrayDecorator(toArray());
130 }
131 }