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|---|---|---|---|
| 1 | // | ||
| 2 | // Copyright (c) 2021 Vinnie Falco (vinnie dot falco at gmail dot com) | ||
| 3 | // | ||
| 4 | // Distributed under the Boost Software License, Version 1.0. (See accompanying | ||
| 5 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) | ||
| 6 | // | ||
| 7 | // Official repository: https://github.com/boostorg/url | ||
| 8 | // | ||
| 9 | |||
| 10 | #ifndef BOOST_URL_GRAMMAR_STRING_TOKEN_HPP | ||
| 11 | #define BOOST_URL_GRAMMAR_STRING_TOKEN_HPP | ||
| 12 | |||
| 13 | #include <boost/url/detail/config.hpp> | ||
| 14 | #include <boost/core/detail/string_view.hpp> | ||
| 15 | #include <boost/url/detail/except.hpp> | ||
| 16 | #include <memory> | ||
| 17 | #include <string> | ||
| 18 | |||
| 19 | namespace boost { | ||
| 20 | namespace urls { | ||
| 21 | namespace string_token { | ||
| 22 | |||
| 23 | /** Base class for string tokens, and algorithm parameters | ||
| 24 | |||
| 25 | This abstract interface provides a means | ||
| 26 | for an algorithm to generically obtain a | ||
| 27 | modifiable, contiguous character buffer | ||
| 28 | of prescribed size. As the author of an | ||
| 29 | algorithm simply declare an rvalue | ||
| 30 | reference as a parameter type. | ||
| 31 | |||
| 32 | <br> | ||
| 33 | |||
| 34 | Instances of this type are intended only | ||
| 35 | to be used once and then destroyed. | ||
| 36 | |||
| 37 | @par Example | ||
| 38 | The declared function accepts any | ||
| 39 | temporary instance of `arg` to be | ||
| 40 | used for writing: | ||
| 41 | @code | ||
| 42 | void algorithm( string_token::arg&& dest ); | ||
| 43 | @endcode | ||
| 44 | |||
| 45 | To implement the interface for your type | ||
| 46 | or use-case, derive from the class and | ||
| 47 | implement the prepare function. | ||
| 48 | */ | ||
| 49 | struct arg | ||
| 50 | { | ||
| 51 | /** Return a modifiable character buffer | ||
| 52 | |||
| 53 | This function attempts to obtain a | ||
| 54 | character buffer with space for at | ||
| 55 | least `n` characters. Upon success, | ||
| 56 | a pointer to the beginning of the | ||
| 57 | buffer is returned. Ownership is not | ||
| 58 | transferred; the caller should not | ||
| 59 | attempt to free the storage. The | ||
| 60 | buffer shall remain valid until | ||
| 61 | `this` is destroyed. | ||
| 62 | |||
| 63 | @note | ||
| 64 | This function may only be called once. | ||
| 65 | After invoking the function, the only | ||
| 66 | valid operation is destruction. | ||
| 67 | */ | ||
| 68 | virtual char* prepare(std::size_t n) = 0; | ||
| 69 | |||
| 70 | /// Virtual destructor | ||
| 71 | 6744 | virtual ~arg() = default; | |
| 72 | |||
| 73 | /// Default constructor | ||
| 74 | 3372 | arg() = default; | |
| 75 | |||
| 76 | /// Default move constructor | ||
| 77 | arg(arg&&) = default; | ||
| 78 | |||
| 79 | /// Deleted copy constructor | ||
| 80 | arg(arg const&) = delete; | ||
| 81 | |||
| 82 | /// Deleted move assignment | ||
| 83 | arg& operator=(arg&&) = delete; | ||
| 84 | |||
| 85 | /// Deleted copy assignment | ||
| 86 | arg& operator=(arg const&) = delete; | ||
| 87 | }; | ||
| 88 | |||
| 89 | //------------------------------------------------ | ||
| 90 | |||
| 91 | /** Metafunction returning true if T is a StringToken | ||
| 92 | */ | ||
| 93 | #ifdef BOOST_URL_DOCS | ||
| 94 | template<class T> | ||
| 95 | using is_token = __see_below__; | ||
| 96 | #else | ||
| 97 | namespace see_below { | ||
| 98 | /** Metafunction returning true if T is a StringToken | ||
| 99 | */ | ||
| 100 | template<class T, class = void> | ||
| 101 | struct is_token : std::false_type {}; | ||
| 102 | |||
| 103 | /** Metafunction returning true if T is a StringToken | ||
| 104 | */ | ||
| 105 | template<class T> | ||
| 106 | struct is_token<T, void_t< | ||
| 107 | decltype(std::declval<T&>().prepare( | ||
| 108 | std::declval<std::size_t>())), | ||
| 109 | decltype(std::declval<T&>().result()) | ||
| 110 | > > : std::integral_constant<bool, | ||
| 111 | std::is_convertible<decltype( | ||
| 112 | std::declval<T&>().result()), | ||
| 113 | typename T::result_type>::value && | ||
| 114 | std::is_same<decltype( | ||
| 115 | std::declval<T&>().prepare(0)), | ||
| 116 | char*>::value && | ||
| 117 | std::is_base_of<arg, T>::value && | ||
| 118 | std::is_convertible<T const volatile*, | ||
| 119 | arg const volatile*>::value | ||
| 120 | > | ||
| 121 | { | ||
| 122 | }; | ||
| 123 | } // see_below | ||
| 124 | |||
| 125 | /** Metafunction returning true if T is a StringToken | ||
| 126 | */ | ||
| 127 | template<class T> | ||
| 128 | using is_token = see_below::is_token<T>; | ||
| 129 | #endif | ||
| 130 | |||
| 131 | //------------------------------------------------ | ||
| 132 | |||
| 133 | /** A token for returning a plain string | ||
| 134 | */ | ||
| 135 | #ifdef BOOST_URL_DOCS | ||
| 136 | using return_string = __implementation_defined__; | ||
| 137 | #else | ||
| 138 | namespace implementation_defined { | ||
| 139 | struct return_string | ||
| 140 | : arg | ||
| 141 | { | ||
| 142 | using result_type = std::string; | ||
| 143 | |||
| 144 | char* | ||
| 145 | 3028 | prepare(std::size_t n) override | |
| 146 | { | ||
| 147 | 3028 | s_.resize(n); | |
| 148 | 3028 | return &s_[0]; | |
| 149 | } | ||
| 150 | |||
| 151 | result_type | ||
| 152 | 3028 | result() noexcept | |
| 153 | { | ||
| 154 | 3028 | return std::move(s_); | |
| 155 | } | ||
| 156 | |||
| 157 | private: | ||
| 158 | result_type s_; | ||
| 159 | }; | ||
| 160 | } // implementation_defined | ||
| 161 | |||
| 162 | /** A token for returning a plain string | ||
| 163 | */ | ||
| 164 | using return_string = implementation_defined::return_string; | ||
| 165 | #endif | ||
| 166 | |||
| 167 | //------------------------------------------------ | ||
| 168 | |||
| 169 | /** A token for appending to a plain string | ||
| 170 | */ | ||
| 171 | #ifdef BOOST_URL_DOCS | ||
| 172 | template< | ||
| 173 | class Allocator = | ||
| 174 | std::allocator<char>> | ||
| 175 | __implementation_defined__ | ||
| 176 | append_to( | ||
| 177 | std::basic_string< | ||
| 178 | char, | ||
| 179 | std::char_traits<char>, | ||
| 180 | Allocator>& s); | ||
| 181 | #else | ||
| 182 | namespace implementation_defined { | ||
| 183 | template<class Alloc> | ||
| 184 | struct append_to_t | ||
| 185 | : arg | ||
| 186 | { | ||
| 187 | using string_type = std::basic_string< | ||
| 188 | char, std::char_traits<char>, | ||
| 189 | Alloc>; | ||
| 190 | |||
| 191 | using result_type = string_type&; | ||
| 192 | |||
| 193 | explicit | ||
| 194 | 3 | append_to_t( | |
| 195 | string_type& s) noexcept | ||
| 196 | 3 | : s_(s) | |
| 197 | { | ||
| 198 | 3 | } | |
| 199 | |||
| 200 | char* | ||
| 201 | 3 | prepare(std::size_t n) override | |
| 202 | { | ||
| 203 | 3 | std::size_t n0 = s_.size(); | |
| 204 |
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3 | if(n > s_.max_size() - n0) |
| 205 | ✗ | urls::detail::throw_length_error(); | |
| 206 | 3 | s_.resize(n0 + n); | |
| 207 | 3 | return &s_[n0]; | |
| 208 | } | ||
| 209 | |||
| 210 | result_type | ||
| 211 | 3 | result() noexcept | |
| 212 | { | ||
| 213 | 3 | return s_; | |
| 214 | } | ||
| 215 | |||
| 216 | private: | ||
| 217 | string_type& s_; | ||
| 218 | }; | ||
| 219 | } // implementation_defined | ||
| 220 | |||
| 221 | /** Create a token for appending to a plain string | ||
| 222 | */ | ||
| 223 | template< | ||
| 224 | class Alloc = | ||
| 225 | std::allocator<char>> | ||
| 226 | implementation_defined::append_to_t<Alloc> | ||
| 227 | 3 | append_to( | |
| 228 | std::basic_string< | ||
| 229 | char, | ||
| 230 | std::char_traits<char>, | ||
| 231 | Alloc>& s) | ||
| 232 | { | ||
| 233 | 3 | return implementation_defined::append_to_t<Alloc>(s); | |
| 234 | } | ||
| 235 | #endif | ||
| 236 | |||
| 237 | //------------------------------------------------ | ||
| 238 | |||
| 239 | /** A token for assigning to a plain string | ||
| 240 | */ | ||
| 241 | #ifdef BOOST_URL_DOCS | ||
| 242 | template< | ||
| 243 | class Allocator = | ||
| 244 | std::allocator<char>> | ||
| 245 | __implementation_defined__ | ||
| 246 | assign_to( | ||
| 247 | std::basic_string< | ||
| 248 | char, | ||
| 249 | std::char_traits<char>, | ||
| 250 | Allocator>& s); | ||
| 251 | #else | ||
| 252 | namespace implementation_defined { | ||
| 253 | template<class Alloc> | ||
| 254 | struct assign_to_t | ||
| 255 | : arg | ||
| 256 | { | ||
| 257 | using string_type = std::basic_string< | ||
| 258 | char, std::char_traits<char>, | ||
| 259 | Alloc>; | ||
| 260 | |||
| 261 | using result_type = string_type&; | ||
| 262 | |||
| 263 | explicit | ||
| 264 | 337 | assign_to_t( | |
| 265 | string_type& s) noexcept | ||
| 266 | 337 | : s_(s) | |
| 267 | { | ||
| 268 | 337 | } | |
| 269 | |||
| 270 | char* | ||
| 271 | 337 | prepare(std::size_t n) override | |
| 272 | { | ||
| 273 | 337 | s_.resize(n); | |
| 274 | 337 | return &s_[0]; | |
| 275 | } | ||
| 276 | |||
| 277 | result_type | ||
| 278 | 337 | result() noexcept | |
| 279 | { | ||
| 280 | 337 | return s_; | |
| 281 | } | ||
| 282 | |||
| 283 | private: | ||
| 284 | string_type& s_; | ||
| 285 | }; | ||
| 286 | } // implementation_defined | ||
| 287 | |||
| 288 | /** A token for assigning to a plain string | ||
| 289 | */ | ||
| 290 | template< | ||
| 291 | class Alloc = | ||
| 292 | std::allocator<char>> | ||
| 293 | implementation_defined::assign_to_t<Alloc> | ||
| 294 | 337 | assign_to( | |
| 295 | std::basic_string< | ||
| 296 | char, | ||
| 297 | std::char_traits<char>, | ||
| 298 | Alloc>& s) | ||
| 299 | { | ||
| 300 | 337 | return implementation_defined::assign_to_t<Alloc>(s); | |
| 301 | } | ||
| 302 | #endif | ||
| 303 | |||
| 304 | //------------------------------------------------ | ||
| 305 | |||
| 306 | /** A token for producing a durable core::string_view from a temporary string | ||
| 307 | */ | ||
| 308 | #ifdef BOOST_URL_DOCS | ||
| 309 | template< | ||
| 310 | class Allocator = | ||
| 311 | std::allocator<char>> | ||
| 312 | __implementation_defined__ | ||
| 313 | preserve_size( | ||
| 314 | std::basic_string< | ||
| 315 | char, | ||
| 316 | std::char_traits<char>, | ||
| 317 | Allocator>& s); | ||
| 318 | #else | ||
| 319 | namespace implementation_defined { | ||
| 320 | template<class Alloc> | ||
| 321 | struct preserve_size_t | ||
| 322 | : arg | ||
| 323 | { | ||
| 324 | using result_type = core::string_view; | ||
| 325 | |||
| 326 | using string_type = std::basic_string< | ||
| 327 | char, std::char_traits<char>, | ||
| 328 | Alloc>; | ||
| 329 | |||
| 330 | explicit | ||
| 331 | 4 | preserve_size_t( | |
| 332 | string_type& s) noexcept | ||
| 333 | 4 | : s_(s) | |
| 334 | { | ||
| 335 | 4 | } | |
| 336 | |||
| 337 | char* | ||
| 338 | 4 | prepare(std::size_t n) override | |
| 339 | { | ||
| 340 | 4 | n_ = n; | |
| 341 | // preserve size() to | ||
| 342 | // avoid value-init | ||
| 343 |
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4 | if(s_.size() < n) |
| 344 | 2 | s_.resize(n); | |
| 345 | 4 | return &s_[0]; | |
| 346 | } | ||
| 347 | |||
| 348 | result_type | ||
| 349 | 4 | result() noexcept | |
| 350 | { | ||
| 351 | 4 | return core::string_view( | |
| 352 | 8 | s_.data(), n_); | |
| 353 | } | ||
| 354 | |||
| 355 | private: | ||
| 356 | string_type& s_; | ||
| 357 | std::size_t n_ = 0; | ||
| 358 | }; | ||
| 359 | } // implementation_defined | ||
| 360 | |||
| 361 | /** A token for producing a durable core::string_view from a temporary string | ||
| 362 | */ | ||
| 363 | template< | ||
| 364 | class Alloc = | ||
| 365 | std::allocator<char>> | ||
| 366 | implementation_defined::preserve_size_t<Alloc> | ||
| 367 | 4 | preserve_size( | |
| 368 | std::basic_string< | ||
| 369 | char, | ||
| 370 | std::char_traits<char>, | ||
| 371 | Alloc>& s) | ||
| 372 | { | ||
| 373 | 4 | return implementation_defined::preserve_size_t<Alloc>(s); | |
| 374 | } | ||
| 375 | #endif | ||
| 376 | |||
| 377 | } // string_token | ||
| 378 | |||
| 379 | namespace grammar { | ||
| 380 | namespace string_token = ::boost::urls::string_token; | ||
| 381 | } // grammar | ||
| 382 | |||
| 383 | } // urls | ||
| 384 | } // boost | ||
| 385 | |||
| 386 | #endif | ||
| 387 |