1------------------------------------------------------------------------------ 2-- -- 3-- GNAT RUN-TIME COMPONENTS -- 4-- -- 5-- ADA.STRINGS.UTF_ENCODING.WIDE_STRINGS -- 6-- -- 7-- B o d y -- 8-- -- 9-- Copyright (C) 2010-2012, Free Software Foundation, Inc. -- 10-- -- 11-- GNAT is free software; you can redistribute it and/or modify it under -- 12-- terms of the GNU General Public License as published by the Free Soft- -- 13-- ware Foundation; either version 3, or (at your option) any later ver- -- 14-- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- 15-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- 16-- or FITNESS FOR A PARTICULAR PURPOSE. -- 17-- -- 18-- As a special exception under Section 7 of GPL version 3, you are granted -- 19-- additional permissions described in the GCC Runtime Library Exception, -- 20-- version 3.1, as published by the Free Software Foundation. -- 21-- -- 22-- You should have received a copy of the GNU General Public License and -- 23-- a copy of the GCC Runtime Library Exception along with this program; -- 24-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- 25-- <http://www.gnu.org/licenses/>. -- 26-- -- 27-- GNAT was originally developed by the GNAT team at New York University. -- 28-- Extensive contributions were provided by Ada Core Technologies Inc. -- 29-- -- 30------------------------------------------------------------------------------ 31 32package body Ada.Strings.UTF_Encoding.Wide_Strings is 33 use Interfaces; 34 35 ------------ 36 -- Decode -- 37 ------------ 38 39 -- Decode UTF-8/UTF-16BE/UTF-16LE input to Wide_String 40 41 function Decode 42 (Item : UTF_String; 43 Input_Scheme : Encoding_Scheme) return Wide_String 44 is 45 begin 46 if Input_Scheme = UTF_8 then 47 return Decode (Item); 48 else 49 return Decode (To_UTF_16 (Item, Input_Scheme)); 50 end if; 51 end Decode; 52 53 -- Decode UTF-8 input to Wide_String 54 55 function Decode (Item : UTF_8_String) return Wide_String is 56 Result : Wide_String (1 .. Item'Length); 57 -- Result string (worst case is same length as input) 58 59 Len : Natural := 0; 60 -- Length of result stored so far 61 62 Iptr : Natural; 63 -- Input Item pointer 64 65 C : Unsigned_8; 66 R : Unsigned_16; 67 68 procedure Get_Continuation; 69 -- Reads a continuation byte of the form 10xxxxxx, shifts R left by 6 70 -- bits, and or's in the xxxxxx to the low order 6 bits. On return Ptr 71 -- is incremented. Raises exception if continuation byte does not exist 72 -- or is invalid. 73 74 ---------------------- 75 -- Get_Continuation -- 76 ---------------------- 77 78 procedure Get_Continuation is 79 begin 80 if Iptr > Item'Last then 81 Raise_Encoding_Error (Iptr - 1); 82 83 else 84 C := To_Unsigned_8 (Item (Iptr)); 85 Iptr := Iptr + 1; 86 87 if C not in 2#10_000000# .. 2#10_111111# then 88 Raise_Encoding_Error (Iptr - 1); 89 else 90 R := Shift_Left (R, 6) or Unsigned_16 (C and 2#00_111111#); 91 end if; 92 end if; 93 end Get_Continuation; 94 95 -- Start of processing for Decode 96 97 begin 98 Iptr := Item'First; 99 100 -- Skip BOM at start 101 102 if Item'Length >= 3 103 and then Item (Iptr .. Iptr + 2) = BOM_8 104 then 105 Iptr := Iptr + 3; 106 107 -- Error if bad BOM 108 109 elsif Item'Length >= 2 110 and then (Item (Iptr .. Iptr + 1) = BOM_16BE 111 or else 112 Item (Iptr .. Iptr + 1) = BOM_16LE) 113 then 114 Raise_Encoding_Error (Iptr); 115 end if; 116 117 while Iptr <= Item'Last loop 118 C := To_Unsigned_8 (Item (Iptr)); 119 Iptr := Iptr + 1; 120 121 -- Codes in the range 16#00# - 16#7F# are represented as 122 -- 0xxxxxxx 123 124 if C <= 16#7F# then 125 R := Unsigned_16 (C); 126 127 -- No initial code can be of the form 10xxxxxx. Such codes are used 128 -- only for continuations. 129 130 elsif C <= 2#10_111111# then 131 Raise_Encoding_Error (Iptr - 1); 132 133 -- Codes in the range 16#80# - 16#7FF# are represented as 134 -- 110yyyxx 10xxxxxx 135 136 elsif C <= 2#110_11111# then 137 R := Unsigned_16 (C and 2#000_11111#); 138 Get_Continuation; 139 140 -- Codes in the range 16#800# - 16#FFFF# are represented as 141 -- 1110yyyy 10yyyyxx 10xxxxxx 142 143 elsif C <= 2#1110_1111# then 144 R := Unsigned_16 (C and 2#0000_1111#); 145 Get_Continuation; 146 Get_Continuation; 147 148 -- Codes in the range 16#10000# - 16#10FFFF# are represented as 149 -- 11110zzz 10zzyyyy 10yyyyxx 10xxxxxx 150 151 -- Such codes are out of range for Wide_String output 152 153 else 154 Raise_Encoding_Error (Iptr - 1); 155 end if; 156 157 Len := Len + 1; 158 Result (Len) := Wide_Character'Val (R); 159 end loop; 160 161 return Result (1 .. Len); 162 end Decode; 163 164 -- Decode UTF-16 input to Wide_String 165 166 function Decode (Item : UTF_16_Wide_String) return Wide_String is 167 Result : Wide_String (1 .. Item'Length); 168 -- Result is same length as input (possibly minus 1 if BOM present) 169 170 Len : Natural := 0; 171 -- Length of result 172 173 Iptr : Natural; 174 -- Index of next Item element 175 176 C : Unsigned_16; 177 178 begin 179 -- Skip UTF-16 BOM at start 180 181 Iptr := Item'First; 182 183 if Item'Length > 0 and then Item (Iptr) = BOM_16 (1) then 184 Iptr := Iptr + 1; 185 end if; 186 187 -- Loop through input characters 188 189 while Iptr <= Item'Last loop 190 C := To_Unsigned_16 (Item (Iptr)); 191 Iptr := Iptr + 1; 192 193 -- Codes in the range 16#0000#..16#D7FF# or 16#E000#..16#FFFD# 194 -- represent their own value. 195 196 if C <= 16#D7FF# or else C in 16#E000# .. 16#FFFD# then 197 Len := Len + 1; 198 Result (Len) := Wide_Character'Val (C); 199 200 -- Codes in the range 16#D800#..16#DBFF# represent the first of the 201 -- two surrogates used to encode the range 16#01_000#..16#10_FFFF". 202 -- Such codes are out of range for 16-bit output. 203 204 -- The case of input in the range 16#DC00#..16#DFFF# must never 205 -- occur, since it means we have a second surrogate character with 206 -- no corresponding first surrogate. 207 208 -- Codes in the range 16#FFFE# .. 16#FFFF# are also invalid since 209 -- they conflict with codes used for BOM values. 210 211 -- Thus all remaining codes are invalid 212 213 else 214 Raise_Encoding_Error (Iptr - 1); 215 end if; 216 end loop; 217 218 return Result (1 .. Len); 219 end Decode; 220 221 ------------ 222 -- Encode -- 223 ------------ 224 225 -- Encode Wide_String in UTF-8, UTF-16BE or UTF-16LE 226 227 function Encode 228 (Item : Wide_String; 229 Output_Scheme : Encoding_Scheme; 230 Output_BOM : Boolean := False) return UTF_String 231 is 232 begin 233 -- Case of UTF_8 234 235 if Output_Scheme = UTF_8 then 236 return Encode (Item, Output_BOM); 237 238 -- Case of UTF_16LE or UTF_16BE, use UTF-16 intermediary 239 240 else 241 return From_UTF_16 (UTF_16_Wide_String'(Encode (Item)), 242 Output_Scheme, Output_BOM); 243 end if; 244 end Encode; 245 246 -- Encode Wide_String in UTF-8 247 248 function Encode 249 (Item : Wide_String; 250 Output_BOM : Boolean := False) return UTF_8_String 251 is 252 Result : UTF_8_String (1 .. 3 * Item'Length + 3); 253 -- Worst case is three bytes per input byte + space for BOM 254 255 Len : Natural; 256 -- Number of output codes stored in Result 257 258 C : Unsigned_16; 259 -- Single input character 260 261 procedure Store (C : Unsigned_16); 262 pragma Inline (Store); 263 -- Store one output code, C is in the range 0 .. 255 264 265 ----------- 266 -- Store -- 267 ----------- 268 269 procedure Store (C : Unsigned_16) is 270 begin 271 Len := Len + 1; 272 Result (Len) := Character'Val (C); 273 end Store; 274 275 -- Start of processing for UTF8_Encode 276 277 begin 278 -- Output BOM if required 279 280 if Output_BOM then 281 Result (1 .. 3) := BOM_8; 282 Len := 3; 283 else 284 Len := 0; 285 end if; 286 287 -- Loop through characters of input 288 289 for J in Item'Range loop 290 C := To_Unsigned_16 (Item (J)); 291 292 -- Codes in the range 16#00# - 16#7F# are represented as 293 -- 0xxxxxxx 294 295 if C <= 16#7F# then 296 Store (C); 297 298 -- Codes in the range 16#80# - 16#7FF# are represented as 299 -- 110yyyxx 10xxxxxx 300 301 elsif C <= 16#7FF# then 302 Store (2#110_00000# or Shift_Right (C, 6)); 303 Store (2#10_000000# or (C and 2#00_111111#)); 304 305 -- Codes in the range 16#800# - 16#FFFF# are represented as 306 -- 1110yyyy 10yyyyxx 10xxxxxx 307 308 else 309 Store (2#1110_0000# or Shift_Right (C, 12)); 310 Store (2#10_000000# or 311 Shift_Right (C and 2#111111_000000#, 6)); 312 Store (2#10_000000# or (C and 2#00_111111#)); 313 end if; 314 end loop; 315 316 return Result (1 .. Len); 317 end Encode; 318 319 -- Encode Wide_String in UTF-16 320 321 function Encode 322 (Item : Wide_String; 323 Output_BOM : Boolean := False) return UTF_16_Wide_String 324 is 325 Result : UTF_16_Wide_String 326 (1 .. Item'Length + Boolean'Pos (Output_BOM)); 327 -- Output is same length as input + possible BOM 328 329 Len : Integer; 330 -- Length of output string 331 332 C : Unsigned_16; 333 334 begin 335 -- Output BOM if required 336 337 if Output_BOM then 338 Result (1) := BOM_16 (1); 339 Len := 1; 340 else 341 Len := 0; 342 end if; 343 344 -- Loop through input characters encoding them 345 346 for Iptr in Item'Range loop 347 C := To_Unsigned_16 (Item (Iptr)); 348 349 -- Codes in the range 16#0000#..16#D7FF# or 16#E000#..16#FFFD# are 350 -- output unchanged. 351 352 if C <= 16#D7FF# or else C in 16#E000# .. 16#FFFD# then 353 Len := Len + 1; 354 Result (Len) := Wide_Character'Val (C); 355 356 -- Codes in the range 16#D800#..16#DFFF# should never appear in the 357 -- input, since no valid Unicode characters are in this range (which 358 -- would conflict with the UTF-16 surrogate encodings). Similarly 359 -- codes in the range 16#FFFE#..16#FFFF conflict with BOM codes. 360 -- Thus all remaining codes are illegal. 361 362 else 363 Raise_Encoding_Error (Iptr); 364 end if; 365 end loop; 366 367 return Result; 368 end Encode; 369 370end Ada.Strings.UTF_Encoding.Wide_Strings; 371