escaping.h
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1 //
2 // Copyright 2017 The Abseil 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 // https://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 // File: escaping.h
18 // -----------------------------------------------------------------------------
19 //
20 // This header file contains string utilities involved in escaping and
21 // unescaping strings in various ways.
22 
23 #ifndef ABSL_STRINGS_ESCAPING_H_
24 #define ABSL_STRINGS_ESCAPING_H_
25 
26 #include <cstddef>
27 #include <string>
28 #include <vector>
29 
30 #include "absl/base/macros.h"
31 #include "absl/strings/ascii.h"
32 #include "absl/strings/str_join.h"
34 
35 namespace absl {
36 
37 // CUnescape()
38 //
39 // Unescapes a `source` string and copies it into `dest`, rewriting C-style
40 // escape sequences (https://en.cppreference.com/w/cpp/language/escape) into
41 // their proper code point equivalents, returning `true` if successful.
42 //
43 // The following unescape sequences can be handled:
44 //
45 // * ASCII escape sequences ('\n','\r','\\', etc.) to their ASCII equivalents
46 // * Octal escape sequences ('\nnn') to byte nnn. The unescaped value must
47 // resolve to a single byte or an error will occur. E.g. values greater than
48 // 0xff will produce an error.
49 // * Hexadecimal escape sequences ('\xnn') to byte nn. While an arbitrary
50 // number of following digits are allowed, the unescaped value must resolve
51 // to a single byte or an error will occur. E.g. '\x0045' is equivalent to
52 // '\x45', but '\x1234' will produce an error.
53 // * Unicode escape sequences ('\unnnn' for exactly four hex digits or
54 // '\Unnnnnnnn' for exactly eight hex digits, which will be encoded in
55 // UTF-8. (E.g., `\u2019` unescapes to the three bytes 0xE2, 0x80, and
56 // 0x99).
57 //
58 // If any errors are encountered, this function returns `false`, leaving the
59 // `dest` output parameter in an unspecified state, and stores the first
60 // encountered error in `error`. To disable error reporting, set `error` to
61 // `nullptr` or use the overload with no error reporting below.
62 //
63 // Example:
64 //
65 // std::string s = "foo\\rbar\\nbaz\\t";
66 // std::string unescaped_s;
67 // if (!absl::CUnescape(s, &unescaped_s) {
68 // ...
69 // }
70 // EXPECT_EQ(unescaped_s, "foo\rbar\nbaz\t");
71 bool CUnescape(absl::string_view source, std::string* dest, std::string* error);
72 
73 // Overload of `CUnescape()` with no error reporting.
74 inline bool CUnescape(absl::string_view source, std::string* dest) {
75  return CUnescape(source, dest, nullptr);
76 }
77 
78 // CEscape()
79 //
80 // Escapes a 'src' string using C-style escapes sequences
81 // (https://en.cppreference.com/w/cpp/language/escape), escaping other
82 // non-printable/non-whitespace bytes as octal sequences (e.g. "\377").
83 //
84 // Example:
85 //
86 // std::string s = "foo\rbar\tbaz\010\011\012\013\014\x0d\n";
87 // std::string escaped_s = absl::CEscape(s);
88 // EXPECT_EQ(escaped_s, "foo\\rbar\\tbaz\\010\\t\\n\\013\\014\\r\\n");
89 std::string CEscape(absl::string_view src);
90 
91 // CHexEscape()
92 //
93 // Escapes a 'src' string using C-style escape sequences, escaping
94 // other non-printable/non-whitespace bytes as hexadecimal sequences (e.g.
95 // "\xFF").
96 //
97 // Example:
98 //
99 // std::string s = "foo\rbar\tbaz\010\011\012\013\014\x0d\n";
100 // std::string escaped_s = absl::CHexEscape(s);
101 // EXPECT_EQ(escaped_s, "foo\\rbar\\tbaz\\x08\\t\\n\\x0b\\x0c\\r\\n");
102 std::string CHexEscape(absl::string_view src);
103 
104 // Utf8SafeCEscape()
105 //
106 // Escapes a 'src' string using C-style escape sequences, escaping bytes as
107 // octal sequences, and passing through UTF-8 characters without conversion.
108 // I.e., when encountering any bytes with their high bit set, this function
109 // will not escape those values, whether or not they are valid UTF-8.
110 std::string Utf8SafeCEscape(absl::string_view src);
111 
112 // Utf8SafeCHexEscape()
113 //
114 // Escapes a 'src' string using C-style escape sequences, escaping bytes as
115 // hexadecimal sequences, and passing through UTF-8 characters without
116 // conversion.
117 std::string Utf8SafeCHexEscape(absl::string_view src);
118 
119 // Base64Unescape()
120 //
121 // Converts a `src` string encoded in Base64 to its binary equivalent, writing
122 // it to a `dest` buffer, returning `true` on success. If `src` contains invalid
123 // characters, `dest` is cleared and returns `false`.
124 bool Base64Unescape(absl::string_view src, std::string* dest);
125 
126 // WebSafeBase64Unescape()
127 //
128 // Converts a `src` string encoded in Base64 to its binary equivalent, writing
129 // it to a `dest` buffer, but using '-' instead of '+', and '_' instead of '/'.
130 // If `src` contains invalid characters, `dest` is cleared and returns `false`.
131 bool WebSafeBase64Unescape(absl::string_view src, std::string* dest);
132 
133 // Base64Escape()
134 //
135 // Encodes a `src` string into a base64-encoded string, with padding characters.
136 // This function conforms with RFC 4648 section 4 (base64).
137 void Base64Escape(absl::string_view src, std::string* dest);
138 std::string Base64Escape(absl::string_view src);
139 
140 // WebSafeBase64Escape()
141 //
142 // Encodes a `src` string into a base64-like string, using '-' instead of '+'
143 // and '_' instead of '/', and without padding. This function conforms with RFC
144 // 4648 section 5 (base64url).
145 void WebSafeBase64Escape(absl::string_view src, std::string* dest);
146 std::string WebSafeBase64Escape(absl::string_view src);
147 
148 // HexStringToBytes()
149 //
150 // Converts an ASCII hex string into bytes, returning binary data of length
151 // `from.size()/2`.
153 
154 // BytesToHexString()
155 //
156 // Converts binary data into an ASCII text string, returning a string of size
157 // `2*from.size()`.
158 std::string BytesToHexString(absl::string_view from);
159 
160 } // namespace absl
161 
162 #endif // ABSL_STRINGS_ESCAPING_H_
std::string Utf8SafeCEscape(absl::string_view src)
Definition: escaping.cc:1049
std::string CEscape(absl::string_view src)
Definition: escaping.cc:1039
std::string Utf8SafeCHexEscape(absl::string_view src)
Definition: escaping.cc:1053
std::string BytesToHexString(absl::string_view from)
Definition: escaping.cc:1121
bool WebSafeBase64Unescape(absl::string_view src, std::string *dest)
Definition: escaping.cc:1085
Definition: algorithm.h:29
std::string CHexEscape(absl::string_view src)
Definition: escaping.cc:1045
void WebSafeBase64Escape(absl::string_view src, std::string *dest)
Definition: escaping.cc:1094
void Base64Escape(absl::string_view src, std::string *dest)
Definition: escaping.cc:1089
std::string HexStringToBytes(absl::string_view from)
Definition: escaping.cc:1113
bool Base64Unescape(absl::string_view src, std::string *dest)
Definition: escaping.cc:1081
bool CUnescape(absl::string_view source, std::string *dest, std::string *error)
Definition: escaping.cc:1034
size_t from


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autogenerated on Tue Jun 18 2019 19:44:35