src/strings_internal.h

   1 /*
   2  * This file is part of OpenTTD.
   3  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
   4  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   5  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
   6  */
   7
   8 /** @file strings_interal.h Types and functions related to the internal workings of formatting OpenTTD's strings. */
   9
  10 #ifndef STRINGS_INTERNAL_H
  11 #define STRINGS_INTERNAL_H
  12
  13 #include "strings_func.h"
  14 #include "string_func.h"
  15
  16 /** The data required to format and validate a single parameter of a string. */
  17 struct StringParameter {
  18         StringParameterData data; ///< The data of the parameter.
  19         char32_t type; ///< The #StringControlCode to interpret this data with when it's the first parameter, otherwise '\0'.
  20 };
  21
  22 class StringParameters {
  23 protected:
  24         StringParameters *parent = nullptr; ///< If not nullptr, this instance references data from this parent instance.
  25         std::span<StringParameter> parameters = {}; ///< Array with the actual parameters.
  26
  27         size_t offset = 0; ///< Current offset in the parameters span.
  28         char32_t next_type = 0; ///< The type of the next data that is retrieved.
  29
  30         StringParameters(std::span<StringParameter> parameters = {}) :
  31                 parameters(parameters)
  32         {}
  33
  34         const StringParameter &GetNextParameterReference();
  35
  36 public:
  37         /**
  38          * Create a new StringParameters instance that can reference part of the data of
  39          * the given parent instance.
  40          */
  41         StringParameters(StringParameters &parent, size_t size) :
  42                 parent(&parent),
  43                 parameters(parent.parameters.subspan(parent.offset, size))
  44         {}
  45
  46         void PrepareForNextRun();
  47         void SetTypeOfNextParameter(char32_t type) { this->next_type = type; }
  48
  49         /**
  50          * Get the current offset, so it can be backed up for certain processing
  51          * steps, or be used to offset the argument index within sub strings.
  52          * @return The current offset.
  53          */
  54         size_t GetOffset() { return this->offset; }
  55
  56         /**
  57          * Set the offset within the string from where to return the next result of
  58          * \c GetInt64 or \c GetInt32.
  59          * @param offset The offset.
  60          */
  61         void SetOffset(size_t offset)
  62         {
  63                 /*
  64                  * The offset must be fewer than the number of parameters when it is
  65                  * being set. Unless restoring a backup, then the original value is
  66                  * correct as well as long as the offset was not changed. In other
  67                  * words, when the offset was already at the end of the parameters and
  68                  * the string did not consume any parameters.
  69                  */
  70                 assert(offset < this->parameters.size() || this->offset == offset);
  71                 this->offset = offset;
  72         }
  73
  74         /**
  75          * Advance the offset within the string from where to return the next result of
  76          * \c GetInt64 or \c GetInt32.
  77          * @param advance The amount to advance the offset by.
  78          */
  79         void AdvanceOffset(size_t advance)
  80         {
  81                 this->offset += advance;
  82                 assert(this->offset <= this->parameters.size());
  83         }
  84
  85         /**
  86          * Get the next parameter from our parameters.
  87          * This updates the offset, so the next time this is called the next parameter
  88          * will be read.
  89          * @return The next parameter's value.
  90          */
  91         template <typename T>
  92         T GetNextParameter()
  93         {
  94                 const auto &param = GetNextParameterReference();
  95                 const uint64_t *data = std::get_if<uint64_t>(&param.data);
  96                 if (data != nullptr) return static_cast<T>(*data);
  97                 throw std::out_of_range("Attempt to read string parameter as integer");
  98         }
  99
 100         /**
 101          * Get the next string parameter from our parameters.
 102          * This updates the offset, so the next time this is called the next parameter
 103          * will be read.
 104          * @return The next parameter's value.
 105          */
 106         const char *GetNextParameterString()
 107         {
 108                 const auto &param = GetNextParameterReference();
 109                 const std::string *data = std::get_if<std::string>(&param.data);
 110                 if (data != nullptr) return data->c_str();
 111                 throw std::out_of_range("Attempt to read integer parameter as string");
 112         }
 113
 114         /**
 115          * Get a new instance of StringParameters that is a "range" into the
 116          * remaining existing parameters. Upon destruction the offset in the parent
 117          * is not updated. However, calls to SetDParam do update the parameters.
 118          *
 119          * The returned StringParameters must not outlive this StringParameters.
 120          * @return A "range" of the string parameters.
 121          */
 122         StringParameters GetRemainingParameters() { return GetRemainingParameters(this->offset); }
 123
 124         /**
 125          * Get a new instance of StringParameters that is a "range" into the
 126          * remaining existing parameters from the given offset. Upon destruction the
 127          * offset in the parent is not updated. However, calls to SetDParam do
 128          * update the parameters.
 129          *
 130          * The returned StringParameters must not outlive this StringParameters.
 131          * @param offset The offset to get the remaining parameters for.
 132          * @return A "range" of the string parameters.
 133          */
 134         StringParameters GetRemainingParameters(size_t offset)
 135         {
 136                 return StringParameters(this->parameters.subspan(offset, this->parameters.size() - offset));
 137         }
 138
 139         /** Return the amount of elements which can still be read. */
 140         size_t GetDataLeft() const
 141         {
 142                 return this->parameters.size() - this->offset;
 143         }
 144
 145         /** Get the type of a specific element. */
 146         char32_t GetTypeAtOffset(size_t offset) const
 147         {
 148                 assert(offset < this->parameters.size());
 149                 return this->parameters[offset].type;
 150         }
 151
 152         void SetParam(size_t n, const StringParameterData &v)
 153         {
 154                 assert(n < this->parameters.size());
 155                 this->parameters[n].data = v;
 156         }
 157
 158         void SetParam(size_t n, uint64_t v)
 159         {
 160                 assert(n < this->parameters.size());
 161                 this->parameters[n].data = v;
 162         }
 163
 164         template <typename T, std::enable_if_t<std::is_base_of<StrongTypedefBase, T>::value, int> = 0>
 165         void SetParam(size_t n, T v)
 166         {
 167                 SetParam(n, v.base());
 168         }
 169
 170         void SetParam(size_t n, const char *str)
 171         {
 172                 assert(n < this->parameters.size());
 173                 this->parameters[n].data = str;
 174         }
 175
 176         void SetParam(size_t n, const std::string &str) { this->SetParam(n, str.c_str()); }
 177
 178         void SetParam(size_t n, std::string &&str)
 179         {
 180                 assert(n < this->parameters.size());
 181                 this->parameters[n].data = std::move(str);
 182         }
 183
 184         const StringParameterData &GetParam(size_t n) const
 185         {
 186                 assert(n < this->parameters.size());
 187                 return this->parameters[n].data;
 188         }
 189 };
 190
 191 /**
 192  * Extension of StringParameters with its own statically sized buffer for
 193  * the parameters.
 194  */
 195 template <size_t N>
 196 class ArrayStringParameters : public StringParameters {
 197         std::array<StringParameter, N> params{}; ///< The actual parameters
 198
 199 public:
 200         ArrayStringParameters()
 201         {
 202                 this->parameters = std::span(params.data(), params.size());
 203         }
 204
 205         ArrayStringParameters(ArrayStringParameters&& other) noexcept
 206         {
 207                 *this = std::move(other);
 208         }
 209
 210         ArrayStringParameters& operator=(ArrayStringParameters &&other) noexcept
 211         {
 212                 this->offset = other.offset;
 213                 this->next_type = other.next_type;
 214                 this->params = std::move(other.params);
 215                 this->parameters = std::span(params.data(), params.size());
 216                 return *this;
 217         }
 218
 219         ArrayStringParameters(const ArrayStringParameters &other) = delete;
 220         ArrayStringParameters& operator=(const ArrayStringParameters &other) = delete;
 221 };
 222
 223 /**
 224  * Helper to create the StringParameters with its own buffer with the given
 225  * parameter values.
 226  * @param args The parameters to set for the to be created StringParameters.
 227  * @return The constructed StringParameters.
 228  */
 229 template <typename... Args>
 230 static auto MakeParameters(const Args&... args)
 231 {
 232         ArrayStringParameters<sizeof...(args)> parameters;
 233         size_t index = 0;
 234         (parameters.SetParam(index++, std::forward<const Args&>(args)), ...);
 235         return parameters;
 236 }
 237
 238 /**
 239  * Equivalent to the std::back_insert_iterator in function, with some
 240  * convenience helpers for string concatenation.
 241  */
 242 class StringBuilder {
 243         std::string *string;
 244
 245 public:
 246         /* Required type for this to be an output_iterator; mimics std::back_insert_iterator. */
 247         using value_type = void;
 248         using difference_type = void;
 249         using iterator_category = std::output_iterator_tag;
 250         using pointer = void;
 251         using reference = void;
 252
 253         /**
 254          * Create the builder of an external buffer.
 255          * @param string The string to write to.
 256          */
 257         StringBuilder(std::string &string) : string(&string) {}
 258
 259         /* Required operators for this to be an output_iterator; mimics std::back_insert_iterator, which has no-ops. */
 260         StringBuilder &operator++() { return *this; }
 261         StringBuilder operator++(int) { return *this; }
 262         StringBuilder &operator*() { return *this; }
 263
 264         /**
 265          * Operator to add a character to the end of the buffer. Like the back
 266          * insert iterators this also increases the position of the end of the
 267          * buffer.
 268          * @param value The character to add.
 269          * @return Reference to this inserter.
 270          */
 271         StringBuilder &operator=(const char value)
 272         {
 273                 return this->operator+=(value);
 274         }
 275
 276         /**
 277          * Operator to add a character to the end of the buffer.
 278          * @param value The character to add.
 279          * @return Reference to this inserter.
 280          */
 281         StringBuilder &operator+=(const char value)
 282         {
 283                 this->string->push_back(value);
 284                 return *this;
 285         }
 286
 287         /**
 288          * Operator to append the given string to the output buffer.
 289          * @param str The string to add.
 290          * @return Reference to this inserter.
 291          */
 292         StringBuilder &operator+=(std::string_view str)
 293         {
 294                 *this->string += str;
 295                 return *this;
 296         }
 297
 298         /**
 299          * Encode the given Utf8 character into the output buffer.
 300          * @param c The character to encode.
 301          */
 302         void Utf8Encode(char32_t c)
 303         {
 304                 auto iterator = std::back_inserter(*this->string);
 305                 ::Utf8Encode(iterator, c);
 306         }
 307
 308         /**
 309          * Remove the given amount of characters from the back of the string.
 310          * @param amount The amount of characters to remove.
 311          */
 312         void RemoveElementsFromBack(size_t amount)
 313         {
 314                 this->string->erase(this->string->size() - std::min(amount, this->string->size()));
 315         }
 316
 317         /**
 318          * Get the current index in the string.
 319          * @return The index.
 320          */
 321         size_t CurrentIndex()
 322         {
 323                 return this->string->size();
 324         }
 325
 326         /**
 327          * Get the reference to the character at the given index.
 328          * @return The reference to the character.
 329          */
 330         char &operator[](size_t index)
 331         {
 332                 return (*this->string)[index];
 333         }
 334 };
 335
 336 void GetStringWithArgs(StringBuilder &builder, StringID string, StringParameters &args, uint case_index = 0, bool game_script = false);
 337 std::string GetStringWithArgs(StringID string, StringParameters &args);
 338
 339 /* Do not leak the StringBuilder to everywhere. */
 340 void GenerateTownNameString(StringBuilder &builder, size_t lang, uint32_t seed);
 341 void GetTownName(StringBuilder &builder, const struct Town *t);
 342 void GRFTownNameGenerate(StringBuilder &builder, uint32_t grfid, uint16_t gen, uint32_t seed);
 343
 344 uint RemapNewGRFStringControlCode(uint scc, const char **str, StringParameters &parameters, bool modify_parameters);
 345
 346 #endif /* STRINGS_INTERNAL_H */