1 // Copyright 2017 The Abseil Authors.
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 // https://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 #include "absl/strings/str_split.h"
16
17 #include <algorithm>
18 #include <cstddef>
19 #include <cstdlib>
20 #include <cstring>
21
22 #include "absl/base/config.h"
23 #include "absl/base/internal/raw_logging.h"
24 #include "absl/strings/string_view.h"
25
26 namespace absl {
27 ABSL_NAMESPACE_BEGIN
28
29 namespace {
30
31 // This GenericFind() template function encapsulates the finding algorithm
32 // shared between the ByString and ByAnyChar delimiters. The FindPolicy
33 // template parameter allows each delimiter to customize the actual find
34 // function to use and the length of the found delimiter. For example, the
35 // Literal delimiter will ultimately use absl::string_view::find(), and the
36 // AnyOf delimiter will use absl::string_view::find_first_of().
37 template <typename FindPolicy>
GenericFind(absl::string_view text,absl::string_view delimiter,size_t pos,FindPolicy find_policy)38 absl::string_view GenericFind(absl::string_view text,
39 absl::string_view delimiter, size_t pos,
40 FindPolicy find_policy) {
41 if (delimiter.empty() && text.length() > 0) {
42 // Special case for empty string delimiters: always return a zero-length
43 // absl::string_view referring to the item at position 1 past pos.
44 return absl::string_view(text.data() + pos + 1, 0);
45 }
46 size_t found_pos = absl::string_view::npos;
47 absl::string_view found(text.data() + text.size(),
48 0); // By default, not found
49 found_pos = find_policy.Find(text, delimiter, pos);
50 if (found_pos != absl::string_view::npos) {
51 found = absl::string_view(text.data() + found_pos,
52 find_policy.Length(delimiter));
53 }
54 return found;
55 }
56
57 // Finds using absl::string_view::find(), therefore the length of the found
58 // delimiter is delimiter.length().
59 struct LiteralPolicy {
Findabsl::__anone98186780111::LiteralPolicy60 static size_t Find(absl::string_view text, absl::string_view delimiter,
61 size_t pos) {
62 return text.find(delimiter, pos);
63 }
Lengthabsl::__anone98186780111::LiteralPolicy64 static size_t Length(absl::string_view delimiter) {
65 return delimiter.length();
66 }
67 };
68
69 // Finds using absl::string_view::find_first_of(), therefore the length of the
70 // found delimiter is 1.
71 struct AnyOfPolicy {
Findabsl::__anone98186780111::AnyOfPolicy72 static size_t Find(absl::string_view text, absl::string_view delimiter,
73 size_t pos) {
74 return text.find_first_of(delimiter, pos);
75 }
Lengthabsl::__anone98186780111::AnyOfPolicy76 static size_t Length(absl::string_view /* delimiter */) { return 1; }
77 };
78
79 } // namespace
80
81 //
82 // ByString
83 //
84
ByString(absl::string_view sp)85 ByString::ByString(absl::string_view sp) : delimiter_(sp) {}
86
Find(absl::string_view text,size_t pos) const87 absl::string_view ByString::Find(absl::string_view text, size_t pos) const {
88 if (delimiter_.length() == 1) {
89 // Much faster to call find on a single character than on an
90 // absl::string_view.
91 size_t found_pos = text.find(delimiter_[0], pos);
92 if (found_pos == absl::string_view::npos)
93 return absl::string_view(text.data() + text.size(), 0);
94 return text.substr(found_pos, 1);
95 }
96 return GenericFind(text, delimiter_, pos, LiteralPolicy());
97 }
98
Find(absl::string_view text,size_t pos) const99 absl::string_view ByAsciiWhitespace::Find(absl::string_view text,
100 size_t pos) const {
101 return GenericFind(text, " \t\v\f\r\n", pos, AnyOfPolicy());
102 }
103
104 //
105 // ByChar
106 //
107
Find(absl::string_view text,size_t pos) const108 absl::string_view ByChar::Find(absl::string_view text, size_t pos) const {
109 size_t found_pos = text.find(c_, pos);
110 if (found_pos == absl::string_view::npos)
111 return absl::string_view(text.data() + text.size(), 0);
112 return text.substr(found_pos, 1);
113 }
114
115 //
116 // ByAnyChar
117 //
118
ByAnyChar(absl::string_view sp)119 ByAnyChar::ByAnyChar(absl::string_view sp) : delimiters_(sp) {}
120
Find(absl::string_view text,size_t pos) const121 absl::string_view ByAnyChar::Find(absl::string_view text, size_t pos) const {
122 return GenericFind(text, delimiters_, pos, AnyOfPolicy());
123 }
124
125 //
126 // ByLength
127 //
ByLength(ptrdiff_t length)128 ByLength::ByLength(ptrdiff_t length) : length_(length) {
129 ABSL_RAW_CHECK(length > 0, "");
130 }
131
Find(absl::string_view text,size_t pos) const132 absl::string_view ByLength::Find(absl::string_view text, size_t pos) const {
133 pos = std::min(pos, text.size()); // truncate `pos`
134 absl::string_view substr = text.substr(pos);
135 // If the string is shorter than the chunk size we say we
136 // "can't find the delimiter" so this will be the last chunk.
137 if (substr.length() <= static_cast<size_t>(length_))
138 return absl::string_view(text.data() + text.size(), 0);
139
140 return absl::string_view(substr.data() + length_, 0);
141 }
142
143 ABSL_NAMESPACE_END
144 } // namespace absl
145