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Diffstat (limited to 'vendor/golang.org/x/net/html/escape.go')
-rw-r--r-- | vendor/golang.org/x/net/html/escape.go | 258 |
1 files changed, 258 insertions, 0 deletions
diff --git a/vendor/golang.org/x/net/html/escape.go b/vendor/golang.org/x/net/html/escape.go new file mode 100644 index 0000000..d856139 --- /dev/null +++ b/vendor/golang.org/x/net/html/escape.go | |||
@@ -0,0 +1,258 @@ | |||
1 | // Copyright 2010 The Go Authors. All rights reserved. | ||
2 | // Use of this source code is governed by a BSD-style | ||
3 | // license that can be found in the LICENSE file. | ||
4 | |||
5 | package html | ||
6 | |||
7 | import ( | ||
8 | "bytes" | ||
9 | "strings" | ||
10 | "unicode/utf8" | ||
11 | ) | ||
12 | |||
13 | // These replacements permit compatibility with old numeric entities that | ||
14 | // assumed Windows-1252 encoding. | ||
15 | // https://html.spec.whatwg.org/multipage/syntax.html#consume-a-character-reference | ||
16 | var replacementTable = [...]rune{ | ||
17 | '\u20AC', // First entry is what 0x80 should be replaced with. | ||
18 | '\u0081', | ||
19 | '\u201A', | ||
20 | '\u0192', | ||
21 | '\u201E', | ||
22 | '\u2026', | ||
23 | '\u2020', | ||
24 | '\u2021', | ||
25 | '\u02C6', | ||
26 | '\u2030', | ||
27 | '\u0160', | ||
28 | '\u2039', | ||
29 | '\u0152', | ||
30 | '\u008D', | ||
31 | '\u017D', | ||
32 | '\u008F', | ||
33 | '\u0090', | ||
34 | '\u2018', | ||
35 | '\u2019', | ||
36 | '\u201C', | ||
37 | '\u201D', | ||
38 | '\u2022', | ||
39 | '\u2013', | ||
40 | '\u2014', | ||
41 | '\u02DC', | ||
42 | '\u2122', | ||
43 | '\u0161', | ||
44 | '\u203A', | ||
45 | '\u0153', | ||
46 | '\u009D', | ||
47 | '\u017E', | ||
48 | '\u0178', // Last entry is 0x9F. | ||
49 | // 0x00->'\uFFFD' is handled programmatically. | ||
50 | // 0x0D->'\u000D' is a no-op. | ||
51 | } | ||
52 | |||
53 | // unescapeEntity reads an entity like "<" from b[src:] and writes the | ||
54 | // corresponding "<" to b[dst:], returning the incremented dst and src cursors. | ||
55 | // Precondition: b[src] == '&' && dst <= src. | ||
56 | // attribute should be true if parsing an attribute value. | ||
57 | func unescapeEntity(b []byte, dst, src int, attribute bool) (dst1, src1 int) { | ||
58 | // https://html.spec.whatwg.org/multipage/syntax.html#consume-a-character-reference | ||
59 | |||
60 | // i starts at 1 because we already know that s[0] == '&'. | ||
61 | i, s := 1, b[src:] | ||
62 | |||
63 | if len(s) <= 1 { | ||
64 | b[dst] = b[src] | ||
65 | return dst + 1, src + 1 | ||
66 | } | ||
67 | |||
68 | if s[i] == '#' { | ||
69 | if len(s) <= 3 { // We need to have at least "&#.". | ||
70 | b[dst] = b[src] | ||
71 | return dst + 1, src + 1 | ||
72 | } | ||
73 | i++ | ||
74 | c := s[i] | ||
75 | hex := false | ||
76 | if c == 'x' || c == 'X' { | ||
77 | hex = true | ||
78 | i++ | ||
79 | } | ||
80 | |||
81 | x := '\x00' | ||
82 | for i < len(s) { | ||
83 | c = s[i] | ||
84 | i++ | ||
85 | if hex { | ||
86 | if '0' <= c && c <= '9' { | ||
87 | x = 16*x + rune(c) - '0' | ||
88 | continue | ||
89 | } else if 'a' <= c && c <= 'f' { | ||
90 | x = 16*x + rune(c) - 'a' + 10 | ||
91 | continue | ||
92 | } else if 'A' <= c && c <= 'F' { | ||
93 | x = 16*x + rune(c) - 'A' + 10 | ||
94 | continue | ||
95 | } | ||
96 | } else if '0' <= c && c <= '9' { | ||
97 | x = 10*x + rune(c) - '0' | ||
98 | continue | ||
99 | } | ||
100 | if c != ';' { | ||
101 | i-- | ||
102 | } | ||
103 | break | ||
104 | } | ||
105 | |||
106 | if i <= 3 { // No characters matched. | ||
107 | b[dst] = b[src] | ||
108 | return dst + 1, src + 1 | ||
109 | } | ||
110 | |||
111 | if 0x80 <= x && x <= 0x9F { | ||
112 | // Replace characters from Windows-1252 with UTF-8 equivalents. | ||
113 | x = replacementTable[x-0x80] | ||
114 | } else if x == 0 || (0xD800 <= x && x <= 0xDFFF) || x > 0x10FFFF { | ||
115 | // Replace invalid characters with the replacement character. | ||
116 | x = '\uFFFD' | ||
117 | } | ||
118 | |||
119 | return dst + utf8.EncodeRune(b[dst:], x), src + i | ||
120 | } | ||
121 | |||
122 | // Consume the maximum number of characters possible, with the | ||
123 | // consumed characters matching one of the named references. | ||
124 | |||
125 | for i < len(s) { | ||
126 | c := s[i] | ||
127 | i++ | ||
128 | // Lower-cased characters are more common in entities, so we check for them first. | ||
129 | if 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z' || '0' <= c && c <= '9' { | ||
130 | continue | ||
131 | } | ||
132 | if c != ';' { | ||
133 | i-- | ||
134 | } | ||
135 | break | ||
136 | } | ||
137 | |||
138 | entityName := string(s[1:i]) | ||
139 | if entityName == "" { | ||
140 | // No-op. | ||
141 | } else if attribute && entityName[len(entityName)-1] != ';' && len(s) > i && s[i] == '=' { | ||
142 | // No-op. | ||
143 | } else if x := entity[entityName]; x != 0 { | ||
144 | return dst + utf8.EncodeRune(b[dst:], x), src + i | ||
145 | } else if x := entity2[entityName]; x[0] != 0 { | ||
146 | dst1 := dst + utf8.EncodeRune(b[dst:], x[0]) | ||
147 | return dst1 + utf8.EncodeRune(b[dst1:], x[1]), src + i | ||
148 | } else if !attribute { | ||
149 | maxLen := len(entityName) - 1 | ||
150 | if maxLen > longestEntityWithoutSemicolon { | ||
151 | maxLen = longestEntityWithoutSemicolon | ||
152 | } | ||
153 | for j := maxLen; j > 1; j-- { | ||
154 | if x := entity[entityName[:j]]; x != 0 { | ||
155 | return dst + utf8.EncodeRune(b[dst:], x), src + j + 1 | ||
156 | } | ||
157 | } | ||
158 | } | ||
159 | |||
160 | dst1, src1 = dst+i, src+i | ||
161 | copy(b[dst:dst1], b[src:src1]) | ||
162 | return dst1, src1 | ||
163 | } | ||
164 | |||
165 | // unescape unescapes b's entities in-place, so that "a<b" becomes "a<b". | ||
166 | // attribute should be true if parsing an attribute value. | ||
167 | func unescape(b []byte, attribute bool) []byte { | ||
168 | for i, c := range b { | ||
169 | if c == '&' { | ||
170 | dst, src := unescapeEntity(b, i, i, attribute) | ||
171 | for src < len(b) { | ||
172 | c := b[src] | ||
173 | if c == '&' { | ||
174 | dst, src = unescapeEntity(b, dst, src, attribute) | ||
175 | } else { | ||
176 | b[dst] = c | ||
177 | dst, src = dst+1, src+1 | ||
178 | } | ||
179 | } | ||
180 | return b[0:dst] | ||
181 | } | ||
182 | } | ||
183 | return b | ||
184 | } | ||
185 | |||
186 | // lower lower-cases the A-Z bytes in b in-place, so that "aBc" becomes "abc". | ||
187 | func lower(b []byte) []byte { | ||
188 | for i, c := range b { | ||
189 | if 'A' <= c && c <= 'Z' { | ||
190 | b[i] = c + 'a' - 'A' | ||
191 | } | ||
192 | } | ||
193 | return b | ||
194 | } | ||
195 | |||
196 | const escapedChars = "&'<>\"\r" | ||
197 | |||
198 | func escape(w writer, s string) error { | ||
199 | i := strings.IndexAny(s, escapedChars) | ||
200 | for i != -1 { | ||
201 | if _, err := w.WriteString(s[:i]); err != nil { | ||
202 | return err | ||
203 | } | ||
204 | var esc string | ||
205 | switch s[i] { | ||
206 | case '&': | ||
207 | esc = "&" | ||
208 | case '\'': | ||
209 | // "'" is shorter than "'" and apos was not in HTML until HTML5. | ||
210 | esc = "'" | ||
211 | case '<': | ||
212 | esc = "<" | ||
213 | case '>': | ||
214 | esc = ">" | ||
215 | case '"': | ||
216 | // """ is shorter than """. | ||
217 | esc = """ | ||
218 | case '\r': | ||
219 | esc = " " | ||
220 | default: | ||
221 | panic("unrecognized escape character") | ||
222 | } | ||
223 | s = s[i+1:] | ||
224 | if _, err := w.WriteString(esc); err != nil { | ||
225 | return err | ||
226 | } | ||
227 | i = strings.IndexAny(s, escapedChars) | ||
228 | } | ||
229 | _, err := w.WriteString(s) | ||
230 | return err | ||
231 | } | ||
232 | |||
233 | // EscapeString escapes special characters like "<" to become "<". It | ||
234 | // escapes only five such characters: <, >, &, ' and ". | ||
235 | // UnescapeString(EscapeString(s)) == s always holds, but the converse isn't | ||
236 | // always true. | ||
237 | func EscapeString(s string) string { | ||
238 | if strings.IndexAny(s, escapedChars) == -1 { | ||
239 | return s | ||
240 | } | ||
241 | var buf bytes.Buffer | ||
242 | escape(&buf, s) | ||
243 | return buf.String() | ||
244 | } | ||
245 | |||
246 | // UnescapeString unescapes entities like "<" to become "<". It unescapes a | ||
247 | // larger range of entities than EscapeString escapes. For example, "á" | ||
248 | // unescapes to "รก", as does "á" and "&xE1;". | ||
249 | // UnescapeString(EscapeString(s)) == s always holds, but the converse isn't | ||
250 | // always true. | ||
251 | func UnescapeString(s string) string { | ||
252 | for _, c := range s { | ||
253 | if c == '&' { | ||
254 | return string(unescape([]byte(s), false)) | ||
255 | } | ||
256 | } | ||
257 | return s | ||
258 | } | ||