430 lines
13 KiB
Ada
430 lines
13 KiB
Ada
------------------------------------------------------------------------------
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-- --
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-- GNAT RUN-TIME COMPONENTS --
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-- --
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-- ADA.STRINGS.UTF_ENCODING.WIDE_WIDE_STRINGS --
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-- --
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-- B o d y --
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-- --
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-- Copyright (C) 2010-2012, Free Software Foundation, Inc. --
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-- --
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-- GNAT is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 3, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. --
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-- --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception, --
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-- version 3.1, as published by the Free Software Foundation. --
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-- --
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-- You should have received a copy of the GNU General Public License and --
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-- a copy of the GCC Runtime Library Exception along with this program; --
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-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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-- <http://www.gnu.org/licenses/>. --
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-- --
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-- GNAT was originally developed by the GNAT team at New York University. --
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-- Extensive contributions were provided by Ada Core Technologies Inc. --
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-- --
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------------------------------------------------------------------------------
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package body Ada.Strings.UTF_Encoding.Wide_Wide_Strings is
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use Interfaces;
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------------
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-- Decode --
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------------
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-- Decode UTF-8/UTF-16BE/UTF-16LE input to Wide_Wide_String
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function Decode
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(Item : UTF_String;
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Input_Scheme : Encoding_Scheme) return Wide_Wide_String
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is
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begin
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if Input_Scheme = UTF_8 then
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return Decode (Item);
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else
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return Decode (To_UTF_16 (Item, Input_Scheme));
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end if;
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end Decode;
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-- Decode UTF-8 input to Wide_Wide_String
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function Decode (Item : UTF_8_String) return Wide_Wide_String is
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Result : Wide_Wide_String (1 .. Item'Length);
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-- Result string (worst case is same length as input)
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Len : Natural := 0;
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-- Length of result stored so far
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Iptr : Natural;
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-- Input string pointer
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C : Unsigned_8;
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R : Unsigned_32;
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procedure Get_Continuation;
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-- Reads a continuation byte of the form 10xxxxxx, shifts R left by 6
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-- bits, and or's in the xxxxxx to the low order 6 bits. On return Ptr
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-- is incremented. Raises exception if continuation byte does not exist
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-- or is invalid.
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----------------------
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-- Get_Continuation --
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----------------------
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procedure Get_Continuation is
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begin
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if Iptr > Item'Last then
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Raise_Encoding_Error (Iptr - 1);
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else
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C := To_Unsigned_8 (Item (Iptr));
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Iptr := Iptr + 1;
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if C not in 2#10_000000# .. 2#10_111111# then
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Raise_Encoding_Error (Iptr - 1);
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else
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R := Shift_Left (R, 6) or Unsigned_32 (C and 2#00_111111#);
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end if;
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end if;
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end Get_Continuation;
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-- Start of processing for Decode
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begin
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Iptr := Item'First;
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-- Skip BOM at start
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if Item'Length >= 3
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and then Item (Iptr .. Iptr + 2) = BOM_8
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then
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Iptr := Iptr + 3;
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-- Error if bad BOM
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elsif Item'Length >= 2
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and then (Item (Iptr .. Iptr + 1) = BOM_16BE
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or else
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Item (Iptr .. Iptr + 1) = BOM_16LE)
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then
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Raise_Encoding_Error (Iptr);
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end if;
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-- Loop through input characters
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while Iptr <= Item'Last loop
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C := To_Unsigned_8 (Item (Iptr));
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Iptr := Iptr + 1;
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-- Codes in the range 16#00# - 16#7F# are represented as
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-- 0xxxxxxx
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if C <= 16#7F# then
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R := Unsigned_32 (C);
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-- No initial code can be of the form 10xxxxxx. Such codes are used
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-- only for continuations.
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elsif C <= 2#10_111111# then
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Raise_Encoding_Error (Iptr - 1);
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-- Codes in the range 16#80# - 16#7FF# are represented as
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-- 110yyyxx 10xxxxxx
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elsif C <= 2#110_11111# then
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R := Unsigned_32 (C and 2#000_11111#);
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Get_Continuation;
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-- Codes in the range 16#800# - 16#FFFF# are represented as
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-- 1110yyyy 10yyyyxx 10xxxxxx
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elsif C <= 2#1110_1111# then
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R := Unsigned_32 (C and 2#0000_1111#);
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Get_Continuation;
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Get_Continuation;
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-- Codes in the range 16#10000# - 16#10FFFF# are represented as
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-- 11110zzz 10zzyyyy 10yyyyxx 10xxxxxx
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elsif C <= 2#11110_111# then
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R := Unsigned_32 (C and 2#00000_111#);
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Get_Continuation;
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Get_Continuation;
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Get_Continuation;
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-- Any other code is an error
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else
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Raise_Encoding_Error (Iptr - 1);
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end if;
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Len := Len + 1;
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Result (Len) := Wide_Wide_Character'Val (R);
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end loop;
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return Result (1 .. Len);
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end Decode;
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-- Decode UTF-16 input to Wide_Wide_String
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function Decode (Item : UTF_16_Wide_String) return Wide_Wide_String is
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Result : Wide_Wide_String (1 .. Item'Length);
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-- Result cannot be longer than the input string
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Len : Natural := 0;
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-- Length of result
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Iptr : Natural;
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-- Pointer to next element in Item
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C : Unsigned_16;
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R : Unsigned_32;
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begin
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-- Skip UTF-16 BOM at start
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Iptr := Item'First;
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if Iptr <= Item'Last and then Item (Iptr) = BOM_16 (1) then
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Iptr := Iptr + 1;
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end if;
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-- Loop through input characters
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while Iptr <= Item'Last loop
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C := To_Unsigned_16 (Item (Iptr));
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Iptr := Iptr + 1;
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-- Codes in the range 16#0000#..16#D7FF# or 16#E000#..16#FFFD#
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-- represent their own value.
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if C <= 16#D7FF# or else C in 16#E000# .. 16#FFFD# then
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Len := Len + 1;
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Result (Len) := Wide_Wide_Character'Val (C);
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-- Codes in the range 16#D800#..16#DBFF# represent the first of the
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-- two surrogates used to encode the range 16#01_000#..16#10_FFFF".
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-- The first surrogate provides 10 high order bits of the result.
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elsif C <= 16#DBFF# then
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R := Shift_Left ((Unsigned_32 (C) - 16#D800#), 10);
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-- Error if at end of string
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if Iptr > Item'Last then
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Raise_Encoding_Error (Iptr - 1);
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-- Otherwise next character must be valid low order surrogate
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-- which provides the low 10 order bits of the result.
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else
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C := To_Unsigned_16 (Item (Iptr));
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Iptr := Iptr + 1;
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if C not in 16#DC00# .. 16#DFFF# then
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Raise_Encoding_Error (Iptr - 1);
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else
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R := R or (Unsigned_32 (C) mod 2 ** 10);
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-- The final adjustment is to add 16#01_0000 to get the
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-- result back in the required 21 bit range.
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R := R + 16#01_0000#;
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Len := Len + 1;
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Result (Len) := Wide_Wide_Character'Val (R);
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end if;
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end if;
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-- Remaining codes are invalid
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else
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Raise_Encoding_Error (Iptr - 1);
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end if;
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end loop;
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return Result (1 .. Len);
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end Decode;
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------------
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-- Encode --
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------------
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-- Encode Wide_Wide_String in UTF-8, UTF-16BE or UTF-16LE
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function Encode
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(Item : Wide_Wide_String;
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Output_Scheme : Encoding_Scheme;
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Output_BOM : Boolean := False) return UTF_String
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is
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begin
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if Output_Scheme = UTF_8 then
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return Encode (Item, Output_BOM);
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else
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return From_UTF_16 (Encode (Item), Output_Scheme, Output_BOM);
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end if;
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end Encode;
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-- Encode Wide_Wide_String in UTF-8
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function Encode
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(Item : Wide_Wide_String;
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Output_BOM : Boolean := False) return UTF_8_String
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is
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Result : String (1 .. 4 * Item'Length + 3);
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-- Worst case is four bytes per input byte + space for BOM
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Len : Natural;
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-- Number of output codes stored in Result
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C : Unsigned_32;
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-- Single input character
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procedure Store (C : Unsigned_32);
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pragma Inline (Store);
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-- Store one output code (input is in range 0 .. 255)
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-----------
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-- Store --
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-----------
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procedure Store (C : Unsigned_32) is
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begin
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Len := Len + 1;
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Result (Len) := Character'Val (C);
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end Store;
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-- Start of processing for Encode
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begin
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-- Output BOM if required
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if Output_BOM then
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Result (1 .. 3) := BOM_8;
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Len := 3;
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else
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Len := 0;
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end if;
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-- Loop through characters of input
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for Iptr in Item'Range loop
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C := To_Unsigned_32 (Item (Iptr));
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-- Codes in the range 16#00#..16#7F# are represented as
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-- 0xxxxxxx
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if C <= 16#7F# then
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Store (C);
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-- Codes in the range 16#80#..16#7FF# are represented as
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-- 110yyyxx 10xxxxxx
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elsif C <= 16#7FF# then
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Store (2#110_00000# or Shift_Right (C, 6));
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Store (2#10_000000# or (C and 2#00_111111#));
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-- Codes in the range 16#800#..16#D7FF# or 16#E000#..16#FFFD# are
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-- represented as
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-- 1110yyyy 10yyyyxx 10xxxxxx
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elsif C <= 16#D7FF# or else C in 16#E000# .. 16#FFFD# then
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Store (2#1110_0000# or Shift_Right (C, 12));
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Store (2#10_000000# or
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Shift_Right (C and 2#111111_000000#, 6));
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Store (2#10_000000# or (C and 2#00_111111#));
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-- Codes in the range 16#10000# - 16#10FFFF# are represented as
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-- 11110zzz 10zzyyyy 10yyyyxx 10xxxxxx
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elsif C in 16#1_0000# .. 16#10_FFFF# then
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Store (2#11110_000# or
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Shift_Right (C, 18));
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Store (2#10_000000# or
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Shift_Right (C and 2#111111_000000_000000#, 12));
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Store (2#10_000000# or
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Shift_Right (C and 2#111111_000000#, 6));
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Store (2#10_000000# or
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(C and 2#00_111111#));
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-- All other codes are invalid
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else
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Raise_Encoding_Error (Iptr);
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end if;
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end loop;
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return Result (1 .. Len);
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end Encode;
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-- Encode Wide_Wide_String in UTF-16
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function Encode
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(Item : Wide_Wide_String;
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Output_BOM : Boolean := False) return UTF_16_Wide_String
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is
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Result : UTF_16_Wide_String (1 .. 2 * Item'Length + 1);
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-- Worst case is each input character generates two output characters
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-- plus one for possible BOM.
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Len : Integer;
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-- Length of output string
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C : Unsigned_32;
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begin
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-- Output BOM if needed
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if Output_BOM then
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Result (1) := BOM_16 (1);
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Len := 1;
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else
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Len := 0;
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end if;
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-- Loop through input characters encoding them
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for Iptr in Item'Range loop
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C := To_Unsigned_32 (Item (Iptr));
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-- Codes in the range 16#00_0000#..16#00_D7FF# or 16#E000#..16#FFFD#
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-- are output unchanged
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if C <= 16#00_D7FF# or else C in 16#E000# .. 16#FFFD# then
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Len := Len + 1;
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Result (Len) := Wide_Character'Val (C);
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-- Codes in the range 16#01_0000#..16#10_FFFF# are output using two
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-- surrogate characters. First 16#1_0000# is subtracted from the code
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-- point to give a 20-bit value. This is then split into two separate
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-- 10-bit values each of which is represented as a surrogate with the
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-- most significant half placed in the first surrogate. The ranges of
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-- values used for the two surrogates are 16#D800#-16#DBFF# for the
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-- first, most significant surrogate and 16#DC00#-16#DFFF# for the
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-- second, least significant surrogate.
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elsif C in 16#1_0000# .. 16#10_FFFF# then
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C := C - 16#1_0000#;
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Len := Len + 1;
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Result (Len) := Wide_Character'Val (16#D800# + C / 2 ** 10);
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Len := Len + 1;
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Result (Len) := Wide_Character'Val (16#DC00# + C mod 2 ** 10);
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-- All other codes are invalid
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else
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Raise_Encoding_Error (Iptr);
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end if;
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end loop;
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return Result (1 .. Len);
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end Encode;
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end Ada.Strings.UTF_Encoding.Wide_Wide_Strings;
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