1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "base/strings/string_split.h"
6
7 #include <stddef.h>
8
9 #include "base/logging.h"
10 #include "base/strings/string_util.h"
11 #include "base/third_party/icu/icu_utf.h"
12
13 namespace base {
14
15 namespace {
16
17 // PieceToOutputType converts a StringPiece as needed to a given output type,
18 // which is either the same type of StringPiece (a NOP) or the corresponding
19 // non-piece string type.
20 //
21 // The default converter is a NOP, it works when the OutputType is the
22 // correct StringPiece.
23 template<typename Str, typename OutputType>
PieceToOutputType(BasicStringPiece<Str> piece)24 OutputType PieceToOutputType(BasicStringPiece<Str> piece) {
25 return piece;
26 }
27 template<> // Convert StringPiece to std::string
PieceToOutputType(StringPiece piece)28 std::string PieceToOutputType<std::string, std::string>(StringPiece piece) {
29 return piece.as_string();
30 }
31 template<> // Convert StringPiece16 to string16.
PieceToOutputType(StringPiece16 piece)32 string16 PieceToOutputType<string16, string16>(StringPiece16 piece) {
33 return piece.as_string();
34 }
35
36 // Returns either the ASCII or UTF-16 whitespace.
37 template<typename Str> BasicStringPiece<Str> WhitespaceForType();
WhitespaceForType()38 template<> StringPiece16 WhitespaceForType<string16>() {
39 return kWhitespaceUTF16;
40 }
WhitespaceForType()41 template<> StringPiece WhitespaceForType<std::string>() {
42 return kWhitespaceASCII;
43 }
44
45 // Optimize the single-character case to call find() on the string instead,
46 // since this is the common case and can be made faster. This could have been
47 // done with template specialization too, but would have been less clear.
48 //
49 // There is no corresponding FindFirstNotOf because StringPiece already
50 // implements these different versions that do the optimized searching.
FindFirstOf(StringPiece piece,char c,size_t pos)51 size_t FindFirstOf(StringPiece piece, char c, size_t pos) {
52 return piece.find(c, pos);
53 }
FindFirstOf(StringPiece16 piece,char16 c,size_t pos)54 size_t FindFirstOf(StringPiece16 piece, char16 c, size_t pos) {
55 return piece.find(c, pos);
56 }
FindFirstOf(StringPiece piece,StringPiece one_of,size_t pos)57 size_t FindFirstOf(StringPiece piece, StringPiece one_of, size_t pos) {
58 return piece.find_first_of(one_of, pos);
59 }
FindFirstOf(StringPiece16 piece,StringPiece16 one_of,size_t pos)60 size_t FindFirstOf(StringPiece16 piece, StringPiece16 one_of, size_t pos) {
61 return piece.find_first_of(one_of, pos);
62 }
63
64 // General string splitter template. Can take 8- or 16-bit input, can produce
65 // the corresponding string or StringPiece output, and can take single- or
66 // multiple-character delimiters.
67 //
68 // DelimiterType is either a character (Str::value_type) or a string piece of
69 // multiple characters (BasicStringPiece<Str>). StringPiece has a version of
70 // find for both of these cases, and the single-character version is the most
71 // common and can be implemented faster, which is why this is a template.
72 template<typename Str, typename OutputStringType, typename DelimiterType>
SplitStringT(BasicStringPiece<Str> str,DelimiterType delimiter,WhitespaceHandling whitespace,SplitResult result_type)73 static std::vector<OutputStringType> SplitStringT(
74 BasicStringPiece<Str> str,
75 DelimiterType delimiter,
76 WhitespaceHandling whitespace,
77 SplitResult result_type) {
78 std::vector<OutputStringType> result;
79 if (str.empty())
80 return result;
81
82 size_t start = 0;
83 while (start != Str::npos) {
84 size_t end = FindFirstOf(str, delimiter, start);
85
86 BasicStringPiece<Str> piece;
87 if (end == Str::npos) {
88 piece = str.substr(start);
89 start = Str::npos;
90 } else {
91 piece = str.substr(start, end - start);
92 start = end + 1;
93 }
94
95 if (whitespace == TRIM_WHITESPACE)
96 piece = TrimString(piece, WhitespaceForType<Str>(), TRIM_ALL);
97
98 if (result_type == SPLIT_WANT_ALL || !piece.empty())
99 result.push_back(PieceToOutputType<Str, OutputStringType>(piece));
100 }
101 return result;
102 }
103
AppendStringKeyValue(StringPiece input,char delimiter,StringPairs * result)104 bool AppendStringKeyValue(StringPiece input,
105 char delimiter,
106 StringPairs* result) {
107 // Always append a new item regardless of success (it might be empty). The
108 // below code will copy the strings directly into the result pair.
109 result->resize(result->size() + 1);
110 auto& result_pair = result->back();
111
112 // Find the delimiter.
113 size_t end_key_pos = input.find_first_of(delimiter);
114 if (end_key_pos == std::string::npos) {
115 DVLOG(1) << "cannot find delimiter in: " << input;
116 return false; // No delimiter.
117 }
118 input.substr(0, end_key_pos).CopyToString(&result_pair.first);
119
120 // Find the value string.
121 StringPiece remains = input.substr(end_key_pos, input.size() - end_key_pos);
122 size_t begin_value_pos = remains.find_first_not_of(delimiter);
123 if (begin_value_pos == StringPiece::npos) {
124 DVLOG(1) << "cannot parse value from input: " << input;
125 return false; // No value.
126 }
127 remains.substr(begin_value_pos, remains.size() - begin_value_pos)
128 .CopyToString(&result_pair.second);
129
130 return true;
131 }
132
133 template <typename Str, typename OutputStringType>
SplitStringUsingSubstrT(BasicStringPiece<Str> input,BasicStringPiece<Str> delimiter,WhitespaceHandling whitespace,SplitResult result_type,std::vector<OutputStringType> * result)134 void SplitStringUsingSubstrT(BasicStringPiece<Str> input,
135 BasicStringPiece<Str> delimiter,
136 WhitespaceHandling whitespace,
137 SplitResult result_type,
138 std::vector<OutputStringType>* result) {
139 using Piece = BasicStringPiece<Str>;
140 using size_type = typename Piece::size_type;
141
142 result->clear();
143 for (size_type begin_index = 0, end_index = 0; end_index != Piece::npos;
144 begin_index = end_index + delimiter.size()) {
145 end_index = input.find(delimiter, begin_index);
146 Piece term = end_index == Piece::npos
147 ? input.substr(begin_index)
148 : input.substr(begin_index, end_index - begin_index);
149
150 if (whitespace == TRIM_WHITESPACE)
151 term = TrimString(term, WhitespaceForType<Str>(), TRIM_ALL);
152
153 if (result_type == SPLIT_WANT_ALL || !term.empty())
154 result->push_back(PieceToOutputType<Str, OutputStringType>(term));
155 }
156 }
157
158 } // namespace
159
SplitString(StringPiece input,StringPiece separators,WhitespaceHandling whitespace,SplitResult result_type)160 std::vector<std::string> SplitString(StringPiece input,
161 StringPiece separators,
162 WhitespaceHandling whitespace,
163 SplitResult result_type) {
164 if (separators.size() == 1) {
165 return SplitStringT<std::string, std::string, char>(
166 input, separators[0], whitespace, result_type);
167 }
168 return SplitStringT<std::string, std::string, StringPiece>(
169 input, separators, whitespace, result_type);
170 }
171
SplitString(StringPiece16 input,StringPiece16 separators,WhitespaceHandling whitespace,SplitResult result_type)172 std::vector<string16> SplitString(StringPiece16 input,
173 StringPiece16 separators,
174 WhitespaceHandling whitespace,
175 SplitResult result_type) {
176 if (separators.size() == 1) {
177 return SplitStringT<string16, string16, char16>(
178 input, separators[0], whitespace, result_type);
179 }
180 return SplitStringT<string16, string16, StringPiece16>(
181 input, separators, whitespace, result_type);
182 }
183
SplitStringPiece(StringPiece input,StringPiece separators,WhitespaceHandling whitespace,SplitResult result_type)184 std::vector<StringPiece> SplitStringPiece(StringPiece input,
185 StringPiece separators,
186 WhitespaceHandling whitespace,
187 SplitResult result_type) {
188 if (separators.size() == 1) {
189 return SplitStringT<std::string, StringPiece, char>(
190 input, separators[0], whitespace, result_type);
191 }
192 return SplitStringT<std::string, StringPiece, StringPiece>(
193 input, separators, whitespace, result_type);
194 }
195
SplitStringPiece(StringPiece16 input,StringPiece16 separators,WhitespaceHandling whitespace,SplitResult result_type)196 std::vector<StringPiece16> SplitStringPiece(StringPiece16 input,
197 StringPiece16 separators,
198 WhitespaceHandling whitespace,
199 SplitResult result_type) {
200 if (separators.size() == 1) {
201 return SplitStringT<string16, StringPiece16, char16>(
202 input, separators[0], whitespace, result_type);
203 }
204 return SplitStringT<string16, StringPiece16, StringPiece16>(
205 input, separators, whitespace, result_type);
206 }
207
SplitStringIntoKeyValuePairs(StringPiece input,char key_value_delimiter,char key_value_pair_delimiter,StringPairs * key_value_pairs)208 bool SplitStringIntoKeyValuePairs(StringPiece input,
209 char key_value_delimiter,
210 char key_value_pair_delimiter,
211 StringPairs* key_value_pairs) {
212 key_value_pairs->clear();
213
214 std::vector<StringPiece> pairs = SplitStringPiece(
215 input, std::string(1, key_value_pair_delimiter),
216 TRIM_WHITESPACE, SPLIT_WANT_NONEMPTY);
217 key_value_pairs->reserve(pairs.size());
218
219 bool success = true;
220 for (const StringPiece& pair : pairs) {
221 if (!AppendStringKeyValue(pair, key_value_delimiter, key_value_pairs)) {
222 // Don't return here, to allow for pairs without associated
223 // value or key; just record that the split failed.
224 success = false;
225 }
226 }
227 return success;
228 }
229
SplitStringUsingSubstr(StringPiece16 input,StringPiece16 delimiter,std::vector<string16> * result)230 void SplitStringUsingSubstr(StringPiece16 input,
231 StringPiece16 delimiter,
232 std::vector<string16>* result) {
233 SplitStringUsingSubstrT(input, delimiter, TRIM_WHITESPACE, SPLIT_WANT_ALL,
234 result);
235 }
236
SplitStringUsingSubstr(StringPiece input,StringPiece delimiter,std::vector<std::string> * result)237 void SplitStringUsingSubstr(StringPiece input,
238 StringPiece delimiter,
239 std::vector<std::string>* result) {
240 SplitStringUsingSubstrT(input, delimiter, TRIM_WHITESPACE, SPLIT_WANT_ALL,
241 result);
242 }
243
SplitStringPieceUsingSubstr(StringPiece16 input,StringPiece16 delimiter,WhitespaceHandling whitespace,SplitResult result_type)244 std::vector<StringPiece16> SplitStringPieceUsingSubstr(
245 StringPiece16 input,
246 StringPiece16 delimiter,
247 WhitespaceHandling whitespace,
248 SplitResult result_type) {
249 std::vector<StringPiece16> result;
250 SplitStringUsingSubstrT(input, delimiter, whitespace, result_type, &result);
251 return result;
252 }
253
SplitStringPieceUsingSubstr(StringPiece input,StringPiece delimiter,WhitespaceHandling whitespace,SplitResult result_type)254 std::vector<StringPiece> SplitStringPieceUsingSubstr(
255 StringPiece input,
256 StringPiece delimiter,
257 WhitespaceHandling whitespace,
258 SplitResult result_type) {
259 std::vector<StringPiece> result;
260 SplitStringUsingSubstrT(input, delimiter, whitespace, result_type, &result);
261 return result;
262 }
263
264 } // namespace base
265