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------------------------------------------------------------------------------ -- -- -- GNAT RUN-TIME COMPONENTS -- -- -- -- ADA.STRINGS.UTF_ENCODING.WIDE_WIDE_STRINGS -- -- -- -- B o d y -- -- -- -- Copyright (C) 2010-2011, Free Software Foundation, Inc. -- -- -- -- GNAT is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- -- ware Foundation; either version 3, or (at your option) any later ver- -- -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- -- or FITNESS FOR A PARTICULAR PURPOSE. -- -- -- -- As a special exception under Section 7 of GPL version 3, you are granted -- -- additional permissions described in the GCC Runtime Library Exception, -- -- version 3.1, as published by the Free Software Foundation. -- -- -- -- You should have received a copy of the GNU General Public License and -- -- a copy of the GCC Runtime Library Exception along with this program; -- -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- -- <http://www.gnu.org/licenses/>. -- -- -- -- GNAT was originally developed by the GNAT team at New York University. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ package body Ada.Strings.UTF_Encoding.Wide_Wide_Strings is use Interfaces; ------------ -- Decode -- ------------ -- Decode UTF-8/UTF-16BE/UTF-16LE input to Wide_Wide_String function Decode (Item : UTF_String; Input_Scheme : Encoding_Scheme) return Wide_Wide_String is begin if Input_Scheme = UTF_8 then return Decode (Item); else return Decode (To_UTF_16 (Item, Input_Scheme)); end if; end Decode; -- Decode UTF-8 input to Wide_Wide_String function Decode (Item : UTF_8_String) return Wide_Wide_String is Result : Wide_Wide_String (1 .. Item'Length); -- Result string (worst case is same length as input) Len : Natural := 0; -- Length of result stored so far Iptr : Natural; -- Input string pointer C : Unsigned_8; R : Unsigned_32; procedure Get_Continuation; -- Reads a continuation byte of the form 10xxxxxx, shifts R left by 6 -- bits, and or's in the xxxxxx to the low order 6 bits. On return Ptr -- is incremented. Raises exception if continuation byte does not exist -- or is invalid. ---------------------- -- Get_Continuation -- ---------------------- procedure Get_Continuation is begin if Iptr > Item'Last then Raise_Encoding_Error (Iptr - 1); else C := To_Unsigned_8 (Item (Iptr)); Iptr := Iptr + 1; if C not in 2#10_000000# .. 2#10_111111# then Raise_Encoding_Error (Iptr - 1); else R := Shift_Left (R, 6) or Unsigned_32 (C and 2#00_111111#); end if; end if; end Get_Continuation; -- Start of processing for Decode begin Iptr := Item'First; -- Skip BOM at start if Item'Length >= 3 and then Item (Iptr .. Iptr + 2) = BOM_8 then Iptr := Iptr + 3; -- Error if bad BOM elsif Item'Length >= 2 and then (Item (Iptr .. Iptr + 1) = BOM_16BE or else Item (Iptr .. Iptr + 1) = BOM_16LE) then Raise_Encoding_Error (Iptr); end if; -- Loop through input characters while Iptr <= Item'Last loop C := To_Unsigned_8 (Item (Iptr)); Iptr := Iptr + 1; -- Codes in the range 16#00# - 16#7F# are represented as -- 0xxxxxxx if C <= 16#7F# then R := Unsigned_32 (C); -- No initial code can be of the form 10xxxxxx. Such codes are used -- only for continuations. elsif C <= 2#10_111111# then Raise_Encoding_Error (Iptr - 1); -- Codes in the range 16#80# - 16#7FF# are represented as -- 110yyyxx 10xxxxxx elsif C <= 2#110_11111# then R := Unsigned_32 (C and 2#000_11111#); Get_Continuation; -- Codes in the range 16#800# - 16#FFFF# are represented as -- 1110yyyy 10yyyyxx 10xxxxxx elsif C <= 2#1110_1111# then R := Unsigned_32 (C and 2#0000_1111#); Get_Continuation; Get_Continuation; -- Codes in the range 16#10000# - 16#10FFFF# are represented as -- 11110zzz 10zzyyyy 10yyyyxx 10xxxxxx elsif C <= 2#11110_111# then R := Unsigned_32 (C and 2#00000_111#); Get_Continuation; Get_Continuation; Get_Continuation; -- Any other code is an error else Raise_Encoding_Error (Iptr - 1); end if; Len := Len + 1; Result (Len) := Wide_Wide_Character'Val (R); end loop; return Result (1 .. Len); end Decode; -- Decode UTF-16 input to Wide_Wide_String function Decode (Item : UTF_16_Wide_String) return Wide_Wide_String is Result : Wide_Wide_String (1 .. Item'Length); -- Result cannot be longer than the input string Len : Natural := 0; -- Length of result Iptr : Natural; -- Pointer to next element in Item C : Unsigned_16; R : Unsigned_32; begin -- Skip UTF-16 BOM at start Iptr := Item'First; if Iptr <= Item'Last and then Item (Iptr) = BOM_16 (1) then Iptr := Iptr + 1; end if; -- Loop through input characters while Iptr <= Item'Last loop C := To_Unsigned_16 (Item (Iptr)); Iptr := Iptr + 1; -- Codes in the range 16#0000#..16#D7FF# or 16#E000#..16#FFFD# -- represent their own value. if C <= 16#D7FF# or else C in 16#E000# .. 16#FFFD# then Len := Len + 1; Result (Len) := Wide_Wide_Character'Val (C); -- Codes in the range 16#D800#..16#DBFF# represent the first of the -- two surrogates used to encode the range 16#01_000#..16#10_FFFF". -- The first surrogate provides 10 high order bits of the result. elsif C <= 16#DBFF# then R := Shift_Left ((Unsigned_32 (C) - 16#D800#), 10); -- Error if at end of string if Iptr > Item'Last then Raise_Encoding_Error (Iptr - 1); -- Otherwise next character must be valid low order surrogate -- which provides the low 10 order bits of the result. else C := To_Unsigned_16 (Item (Iptr)); Iptr := Iptr + 1; if C not in 16#DC00# .. 16#DFFF# then Raise_Encoding_Error (Iptr - 1); else R := R or (Unsigned_32 (C) mod 2 ** 10); -- The final adjustment is to add 16#01_0000 to get the -- result back in the required 21 bit range. R := R + 16#01_0000#; Len := Len + 1; Result (Len) := Wide_Wide_Character'Val (R); end if; end if; -- Remaining codes are invalid else Raise_Encoding_Error (Iptr - 1); end if; end loop; return Result (1 .. Len); end Decode; ------------ -- Encode -- ------------ -- Encode Wide_Wide_String in UTF-8, UTF-16BE or UTF-16LE function Encode (Item : Wide_Wide_String; Output_Scheme : Encoding_Scheme; Output_BOM : Boolean := False) return UTF_String is begin if Output_Scheme = UTF_8 then return Encode (Item, Output_BOM); else return From_UTF_16 (Encode (Item), Output_Scheme, Output_BOM); end if; end Encode; -- Encode Wide_Wide_String in UTF-8 function Encode (Item : Wide_Wide_String; Output_BOM : Boolean := False) return UTF_8_String is Result : String (1 .. 4 * Item'Length + 3); -- Worst case is four bytes per input byte + space for BOM Len : Natural; -- Number of output codes stored in Result C : Unsigned_32; -- Single input character procedure Store (C : Unsigned_32); pragma Inline (Store); -- Store one output code (input is in range 0 .. 255) ----------- -- Store -- ----------- procedure Store (C : Unsigned_32) is begin Len := Len + 1; Result (Len) := Character'Val (C); end Store; -- Start of processing for Encode begin -- Output BOM if required if Output_BOM then Result (1 .. 3) := BOM_8; Len := 3; else Len := 0; end if; -- Loop through characters of input for Iptr in Item'Range loop C := To_Unsigned_32 (Item (Iptr)); -- Codes in the range 16#00#..16#7F# are represented as -- 0xxxxxxx if C <= 16#7F# then Store (C); -- Codes in the range 16#80#..16#7FF# are represented as -- 110yyyxx 10xxxxxx elsif C <= 16#7FF# then Store (2#110_00000# or Shift_Right (C, 6)); Store (2#10_000000# or (C and 2#00_111111#)); -- Codes in the range 16#800#..16#D7FF# or 16#E000#..16#FFFD# are -- represented as -- 1110yyyy 10yyyyxx 10xxxxxx elsif C <= 16#D7FF# or else C in 16#E000# .. 16#FFFD# then Store (2#1110_0000# or Shift_Right (C, 12)); Store (2#10_000000# or Shift_Right (C and 2#111111_000000#, 6)); Store (2#10_000000# or (C and 2#00_111111#)); -- Codes in the range 16#10000# - 16#10FFFF# are represented as -- 11110zzz 10zzyyyy 10yyyyxx 10xxxxxx elsif C in 16#1_0000# .. 16#10_FFFF# then Store (2#11110_000# or Shift_Right (C, 18)); Store (2#10_000000# or Shift_Right (C and 2#111111_000000_000000#, 12)); Store (2#10_000000# or Shift_Right (C and 2#111111_000000#, 6)); Store (2#10_000000# or (C and 2#00_111111#)); -- All other codes are invalid else Raise_Encoding_Error (Iptr); end if; end loop; return Result (1 .. Len); end Encode; -- Encode Wide_Wide_String in UTF-16 function Encode (Item : Wide_Wide_String; Output_BOM : Boolean := False) return UTF_16_Wide_String is Result : UTF_16_Wide_String (1 .. 2 * Item'Length + 1); -- Worst case is each input character generates two output characters -- plus one for possible BOM. Len : Integer; -- Length of output string C : Unsigned_32; begin -- Output BOM if needed if Output_BOM then Result (1) := BOM_16 (1); Len := 1; else Len := 0; end if; -- Loop through input characters encoding them for Iptr in Item'Range loop C := To_Unsigned_32 (Item (Iptr)); -- Codes in the range 16#00_0000#..16#00_D7FF# or 16#E000#..16#FFFD# -- are output unchanged if C <= 16#00_D7FF# or else C in 16#E000# .. 16#FFFD# then Len := Len + 1; Result (Len) := Wide_Character'Val (C); -- Codes in the range 16#01_0000#..16#10_FFFF# are output using two -- surrogate characters. First 16#1_0000# is subtracted from the code -- point to give a 20-bit value. This is then split into two separate -- 10-bit values each of which is represented as a surrogate with the -- most significant half placed in the first surrogate. The ranges of -- values used for the two surrogates are 16#D800#-16#DBFF# for the -- first, most significant surrogate and 16#DC00#-16#DFFF# for the -- second, least significant surrogate. elsif C in 16#1_0000# .. 16#10_FFFF# then C := C - 16#1_0000#; Len := Len + 1; Result (Len) := Wide_Character'Val (16#D800# + C / 2 ** 10); Len := Len + 1; Result (Len) := Wide_Character'Val (16#DC00# + C mod 2 ** 10); -- All other codes are invalid else Raise_Encoding_Error (Iptr); end if; end loop; return Result (1 .. Len); end Encode; end Ada.Strings.UTF_Encoding.Wide_Wide_Strings;
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