2 * Copyright 2014 Facebook, Inc.
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
17 #ifndef FOLLY_BASE_STRING_H_
18 #define FOLLY_BASE_STRING_H_
22 #include <boost/type_traits.hpp>
24 #ifdef _GLIBCXX_SYMVER
25 #include <ext/hash_set>
26 #include <ext/hash_map>
29 #include <unordered_set>
30 #include <unordered_map>
32 #include "folly/Conv.h"
33 #include "folly/Demangle.h"
34 #include "folly/FBString.h"
35 #include "folly/FBVector.h"
36 #include "folly/Portability.h"
37 #include "folly/Range.h"
38 #include "folly/ScopeGuard.h"
40 // Compatibility function, to make sure toStdString(s) can be called
41 // to convert a std::string or fbstring variable s into type std::string
42 // with very little overhead if s was already std::string
46 std::string toStdString(const folly::fbstring& s) {
47 return std::string(s.data(), s.size());
51 const std::string& toStdString(const std::string& s) {
55 // If called with a temporary, the compiler will select this overload instead
56 // of the above, so we don't return a (lvalue) reference to a temporary.
58 std::string&& toStdString(std::string&& s) {
63 * C-Escape a string, making it suitable for representation as a C string
64 * literal. Appends the result to the output string.
66 * Backslashes all occurrences of backslash and double-quote:
70 * Replaces all non-printable ASCII characters with backslash-octal
74 * Note that we use backslash-octal instead of backslash-hex because the octal
75 * representation is guaranteed to consume no more than 3 characters; "\3760"
76 * represents two characters, one with value 254, and one with value 48 ('0'),
77 * whereas "\xfe0" represents only one character (with value 4064, which leads
78 * to implementation-defined behavior).
80 template <class String>
81 void cEscape(StringPiece str, String& out);
84 * Similar to cEscape above, but returns the escaped string.
86 template <class String>
87 String cEscape(StringPiece str) {
94 * C-Unescape a string; the opposite of cEscape above. Appends the result
95 * to the output string.
97 * Recognizes the standard C escape sequences:
99 * \' \" \? \\ \a \b \f \n \r \t \v
103 * In strict mode (default), throws std::invalid_argument if it encounters
104 * an unrecognized escape sequence. In non-strict mode, it leaves
105 * the escape sequence unchanged.
107 template <class String>
108 void cUnescape(StringPiece str, String& out, bool strict = true);
111 * Similar to cUnescape above, but returns the escaped string.
113 template <class String>
114 String cUnescape(StringPiece str, bool strict = true) {
116 cUnescape(str, out, strict);
121 * URI-escape a string. Appends the result to the output string.
123 * Alphanumeric characters and other characters marked as "unreserved" in RFC
124 * 3986 ( -_.~ ) are left unchanged. In PATH mode, the forward slash (/) is
125 * also left unchanged. In QUERY mode, spaces are replaced by '+'. All other
126 * characters are percent-encoded.
128 enum class UriEscapeMode : unsigned char {
129 // The values are meaningful, see generate_escape_tables.py
134 template <class String>
135 void uriEscape(StringPiece str,
137 UriEscapeMode mode = UriEscapeMode::ALL);
140 * Similar to uriEscape above, but returns the escaped string.
142 template <class String>
143 String uriEscape(StringPiece str, UriEscapeMode mode = UriEscapeMode::ALL) {
145 uriEscape(str, out, mode);
150 * URI-unescape a string. Appends the result to the output string.
152 * In QUERY mode, '+' are replaced by space. %XX sequences are decoded if
153 * XX is a valid hex sequence, otherwise we throw invalid_argument.
155 template <class String>
156 void uriUnescape(StringPiece str,
158 UriEscapeMode mode = UriEscapeMode::ALL);
161 * Similar to uriUnescape above, but returns the unescaped string.
163 template <class String>
164 String uriUnescape(StringPiece str, UriEscapeMode mode = UriEscapeMode::ALL) {
166 uriUnescape(str, out, mode);
171 * stringPrintf is much like printf but deposits its result into a
172 * string. Two signatures are supported: the first simply returns the
173 * resulting string, and the second appends the produced characters to
174 * the specified string and returns a reference to it.
176 std::string stringPrintf(const char* format, ...)
177 __attribute__ ((format (printf, 1, 2)));
179 /** Similar to stringPrintf, with different signiture.
181 void stringPrintf(std::string* out, const char* fmt, ...)
182 __attribute__ ((format (printf, 2, 3)));
184 std::string& stringAppendf(std::string* output, const char* format, ...)
185 __attribute__ ((format (printf, 2, 3)));
188 * Backslashify a string, that is, replace non-printable characters
189 * with C-style (but NOT C compliant) "\xHH" encoding. If hex_style
190 * is false, then shorthand notations like "\0" will be used instead
191 * of "\x00" for the most common backslash cases.
193 * There are two forms, one returning the input string, and one
194 * creating output in the specified output string.
196 * This is mainly intended for printing to a terminal, so it is not
197 * particularly optimized.
199 * Do *not* use this in situations where you expect to be able to feed
200 * the string to a C or C++ compiler, as there are nuances with how C
201 * parses such strings that lead to failures. This is for display
202 * purposed only. If you want a string you can embed for use in C or
203 * C++, use cEscape instead. This function is for display purposes
206 template <class String1, class String2>
207 void backslashify(const String1& input, String2& output, bool hex_style=false);
209 template <class String>
210 String backslashify(const String& input, bool hex_style=false) {
212 backslashify(input, output, hex_style);
217 * Take a string and "humanify" it -- that is, make it look better.
218 * Since "better" is subjective, caveat emptor. The basic approach is
219 * to count the number of unprintable characters. If there are none,
220 * then the output is the input. If there are relatively few, or if
221 * there is a long "enough" prefix of printable characters, use
222 * backslashify. If it is mostly binary, then simply hex encode.
224 * This is an attempt to make a computer smart, and so likely is wrong
227 template <class String1, class String2>
228 void humanify(const String1& input, String2& output);
230 template <class String>
231 String humanify(const String& input) {
233 humanify(input, output);
238 * Same functionality as Python's binascii.hexlify. Returns true
239 * on successful conversion.
241 * If append_output is true, append data to the output rather than
244 template<class InputString, class OutputString>
245 bool hexlify(const InputString& input, OutputString& output,
249 * Same functionality as Python's binascii.unhexlify. Returns true
250 * on successful conversion.
252 template<class InputString, class OutputString>
253 bool unhexlify(const InputString& input, OutputString& output);
256 * A pretty-printer for numbers that appends suffixes of units of the
257 * given type. It prints 4 sig-figs of value with the most
260 * If `addSpace' is true, we put a space between the units suffix and
264 * PRETTY_TIME - s, ms, us, ns, etc.
265 * PRETTY_BYTES_METRIC - kB, MB, GB, etc (goes up by 10^3 = 1000 each time)
266 * PRETTY_BYTES - kB, MB, GB, etc (goes up by 2^10 = 1024 each time)
267 * PRETTY_BYTES_IEC - KiB, MiB, GiB, etc
268 * PRETTY_UNITS_METRIC - k, M, G, etc (goes up by 10^3 = 1000 each time)
269 * PRETTY_UNITS_BINARY - k, M, G, etc (goes up by 2^10 = 1024 each time)
270 * PRETTY_UNITS_BINARY_IEC - Ki, Mi, Gi, etc
272 * @author Mark Rabkin <mrabkin@fb.com>
279 PRETTY_BYTES = PRETTY_BYTES_BINARY,
280 PRETTY_BYTES_BINARY_IEC,
281 PRETTY_BYTES_IEC = PRETTY_BYTES_BINARY_IEC,
285 PRETTY_UNITS_BINARY_IEC,
290 std::string prettyPrint(double val, PrettyType, bool addSpace = true);
293 * Write a hex dump of size bytes starting at ptr to out.
295 * The hex dump is formatted as follows:
297 * for the string "abcdefghijklmnopqrstuvwxyz\x02"
298 00000000 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f 70 |abcdefghijklmnop|
299 00000010 71 72 73 74 75 76 77 78 79 7a 02 |qrstuvwxyz. |
301 * that is, we write 16 bytes per line, both as hex bytes and as printable
302 * characters. Non-printable characters are replaced with '.'
303 * Lines are written to out one by one (one StringPiece at a time) without
306 template <class OutIt>
307 void hexDump(const void* ptr, size_t size, OutIt out);
310 * Return the hex dump of size bytes starting at ptr as a string.
312 std::string hexDump(const void* ptr, size_t size);
315 * Return a fbstring containing the description of the given errno value.
316 * Takes care not to overwrite the actual system errno, so calling
317 * errnoStr(errno) is valid.
319 fbstring errnoStr(int err);
322 * Debug string for an exception: include type and what().
324 inline fbstring exceptionStr(const std::exception& e) {
325 return folly::to<fbstring>(demangle(typeid(e)), ": ", e.what());
328 inline fbstring exceptionStr(std::exception_ptr ep) {
330 std::rethrow_exception(ep);
331 } catch (const std::exception& e) {
332 return exceptionStr(e);
334 return "<unknown exception>";
339 * Split a string into a list of tokens by delimiter.
341 * The split interface here supports different output types, selected
342 * at compile time: StringPiece, fbstring, or std::string. If you are
343 * using a vector to hold the output, it detects the type based on
344 * what your vector contains. If the output vector is not empty, split
345 * will append to the end of the vector.
347 * You can also use splitTo() to write the output to an arbitrary
348 * OutputIterator (e.g. std::inserter() on a std::set<>), in which
349 * case you have to tell the function the type. (Rationale:
350 * OutputIterators don't have a value_type, so we can't detect the
351 * type in splitTo without being told.)
355 * std::vector<folly::StringPiece> v;
356 * folly::split(":", "asd:bsd", v);
358 * std::set<StringPiece> s;
359 * folly::splitTo<StringPiece>(":", "asd:bsd:asd:csd",
360 * std::inserter(s, s.begin()));
362 * Split also takes a flag (ignoreEmpty) that indicates whether adjacent
363 * delimiters should be treated as one single separator (ignoring empty tokens)
364 * or not (generating empty tokens).
367 template<class Delim, class String, class OutputType>
368 void split(const Delim& delimiter,
370 std::vector<OutputType>& out,
371 bool ignoreEmpty = false);
373 template<class Delim, class String, class OutputType>
374 void split(const Delim& delimiter,
376 folly::fbvector<OutputType>& out,
377 bool ignoreEmpty = false);
379 template<class OutputValueType, class Delim, class String,
380 class OutputIterator>
381 void splitTo(const Delim& delimiter,
384 bool ignoreEmpty = false);
387 * Split a string into a fixed number of string pieces and/or numeric types
388 * by delimiter. Any numeric type that folly::to<> can convert to from a
389 * string piece is supported as a target. Returns 'true' if the fields were
390 * all successfully populated.
394 * folly::StringPiece name, key, value;
395 * if (folly::split('\t', line, name, key, value))
398 * folly::StringPiece name;
401 * if (folly::split('\t', line, name, value, id))
404 * The 'exact' template parameter specifies how the function behaves when too
405 * many fields are present in the input string. When 'exact' is set to its
406 * default value of 'true', a call to split will fail if the number of fields in
407 * the input string does not exactly match the number of output parameters
408 * passed. If 'exact' is overridden to 'false', all remaining fields will be
409 * stored, unsplit, in the last field, as shown below:
411 * folly::StringPiece x, y.
412 * if (folly::split<false>(':', "a:b:c", x, y))
413 * assert(x == "a" && y == "b:c");
415 * Note that this will likely not work if the last field's target is of numeric
416 * type, in which case folly::to<> will throw an exception.
419 using IsSplitTargetType = std::integral_constant<bool,
420 std::is_arithmetic<T>::value ||
421 std::is_same<T, StringPiece>::value>;
423 template<bool exact = true,
426 class... OutputTypes>
427 typename std::enable_if<IsSplitTargetType<OutputType>::value, bool>::type
428 split(const Delim& delimiter,
431 OutputTypes&... outTail);
434 * Join list of tokens.
436 * Stores a string representation of tokens in the same order with
437 * deliminer between each element.
440 template <class Delim, class Iterator, class String>
441 void join(const Delim& delimiter,
446 template <class Delim, class Container, class String>
447 void join(const Delim& delimiter,
448 const Container& container,
450 join(delimiter, container.begin(), container.end(), output);
453 template <class Delim, class Value, class String>
454 void join(const Delim& delimiter,
455 const std::initializer_list<Value>& values,
457 join(delimiter, values.begin(), values.end(), output);
460 template <class Delim, class Container>
461 std::string join(const Delim& delimiter,
462 const Container& container) {
464 join(delimiter, container.begin(), container.end(), output);
468 template <class Delim, class Value>
469 std::string join(const Delim& delimiter,
470 const std::initializer_list<Value>& values) {
472 join(delimiter, values.begin(), values.end(), output);
478 // Hash functions to make std::string usable with e.g. hash_map
480 // Handle interaction with different C++ standard libraries, which
481 // expect these types to be in different namespaces.
485 struct hash<std::basic_string<C> > : private hash<const C*> {
486 size_t operator()(const std::basic_string<C> & s) const {
487 return hash<const C*>::operator()(s.c_str());
493 #if defined(_GLIBCXX_SYMVER) && !defined(__BIONIC__)
494 namespace __gnu_cxx {
497 struct hash<std::basic_string<C> > : private hash<const C*> {
498 size_t operator()(const std::basic_string<C> & s) const {
499 return hash<const C*>::operator()(s.c_str());
506 // Hook into boost's type traits
509 struct has_nothrow_constructor<folly::basic_fbstring<T> > : true_type {
510 enum { value = true };
514 #include "folly/String-inl.h"