196 lines
7.3 KiB
Ada
196 lines
7.3 KiB
Ada
------------------------------------------------------------------------------
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-- --
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-- GNAT COMPILER COMPONENTS --
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-- --
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-- G N A T . B Y T E _ O R D E R _ M A R K --
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-- --
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-- B o d y --
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-- --
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-- Copyright (C) 2006-2013, AdaCore --
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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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pragma Compiler_Unit_Warning;
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package body GNAT.Byte_Order_Mark is
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--------------
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-- Read_BOM --
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--------------
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procedure Read_BOM
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(Str : String;
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Len : out Natural;
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BOM : out BOM_Kind;
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XML_Support : Boolean := False)
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is
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begin
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-- Note: the order of these tests is important, because in some cases
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-- one sequence is a prefix of a longer sequence, and we must test for
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-- the longer sequence first
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-- UTF-32 (big-endian)
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if Str'Length >= 4
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and then Str (Str'First) = Character'Val (16#00#)
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and then Str (Str'First + 1) = Character'Val (16#00#)
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and then Str (Str'First + 2) = Character'Val (16#FE#)
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and then Str (Str'First + 3) = Character'Val (16#FF#)
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then
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Len := 4;
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BOM := UTF32_BE;
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-- UTF-32 (little-endian)
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elsif Str'Length >= 4
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and then Str (Str'First) = Character'Val (16#FF#)
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and then Str (Str'First + 1) = Character'Val (16#FE#)
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and then Str (Str'First + 2) = Character'Val (16#00#)
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and then Str (Str'First + 3) = Character'Val (16#00#)
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then
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Len := 4;
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BOM := UTF32_LE;
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-- UTF-16 (big-endian)
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elsif Str'Length >= 2
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and then Str (Str'First) = Character'Val (16#FE#)
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and then Str (Str'First + 1) = Character'Val (16#FF#)
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then
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Len := 2;
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BOM := UTF16_BE;
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-- UTF-16 (little-endian)
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elsif Str'Length >= 2
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and then Str (Str'First) = Character'Val (16#FF#)
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and then Str (Str'First + 1) = Character'Val (16#FE#)
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then
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Len := 2;
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BOM := UTF16_LE;
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-- UTF-8 (endian-independent)
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elsif Str'Length >= 3
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and then Str (Str'First) = Character'Val (16#EF#)
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and then Str (Str'First + 1) = Character'Val (16#BB#)
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and then Str (Str'First + 2) = Character'Val (16#BF#)
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then
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Len := 3;
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BOM := UTF8_All;
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-- UCS-4 (big-endian) XML only
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elsif XML_Support
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and then Str'Length >= 4
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and then Str (Str'First) = Character'Val (16#00#)
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and then Str (Str'First + 1) = Character'Val (16#00#)
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and then Str (Str'First + 2) = Character'Val (16#00#)
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and then Str (Str'First + 3) = Character'Val (16#3C#)
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then
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Len := 0;
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BOM := UCS4_BE;
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-- UCS-4 (little-endian) XML case
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elsif XML_Support
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and then Str'Length >= 4
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and then Str (Str'First) = Character'Val (16#3C#)
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and then Str (Str'First + 1) = Character'Val (16#00#)
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and then Str (Str'First + 2) = Character'Val (16#00#)
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and then Str (Str'First + 3) = Character'Val (16#00#)
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then
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Len := 0;
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BOM := UCS4_LE;
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-- UCS-4 (unusual byte order 2143) XML case
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elsif XML_Support
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and then Str'Length >= 4
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and then Str (Str'First) = Character'Val (16#00#)
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and then Str (Str'First + 1) = Character'Val (16#00#)
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and then Str (Str'First + 2) = Character'Val (16#3C#)
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and then Str (Str'First + 3) = Character'Val (16#00#)
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then
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Len := 0;
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BOM := UCS4_2143;
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-- UCS-4 (unusual byte order 3412) XML case
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elsif XML_Support
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and then Str'Length >= 4
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and then Str (Str'First) = Character'Val (16#00#)
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and then Str (Str'First + 1) = Character'Val (16#3C#)
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and then Str (Str'First + 2) = Character'Val (16#00#)
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and then Str (Str'First + 3) = Character'Val (16#00#)
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then
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Len := 0;
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BOM := UCS4_3412;
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-- UTF-16 (big-endian) XML case
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elsif XML_Support
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and then Str'Length >= 4
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and then Str (Str'First) = Character'Val (16#00#)
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and then Str (Str'First + 1) = Character'Val (16#3C#)
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and then Str (Str'First + 2) = Character'Val (16#00#)
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and then Str (Str'First + 3) = Character'Val (16#3F#)
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then
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Len := 0;
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BOM := UTF16_BE;
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-- UTF-32 (little-endian) XML case
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elsif XML_Support
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and then Str'Length >= 4
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and then Str (Str'First) = Character'Val (16#3C#)
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and then Str (Str'First + 1) = Character'Val (16#00#)
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and then Str (Str'First + 2) = Character'Val (16#3F#)
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and then Str (Str'First + 3) = Character'Val (16#00#)
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then
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Len := 0;
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BOM := UTF16_LE;
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-- Unrecognized special encodings XML only
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elsif XML_Support
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and then Str'Length >= 4
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and then Str (Str'First) = Character'Val (16#3C#)
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and then Str (Str'First + 1) = Character'Val (16#3F#)
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and then Str (Str'First + 2) = Character'Val (16#78#)
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and then Str (Str'First + 3) = Character'Val (16#6D#)
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then
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-- UTF-8, ASCII, some part of ISO8859, Shift-JIS, EUC,...
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Len := 0;
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BOM := Unknown;
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-- No BOM recognized
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else
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Len := 0;
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BOM := Unknown;
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end if;
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end Read_BOM;
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end GNAT.Byte_Order_Mark;
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