117 lines
6.3 KiB
Ada
117 lines
6.3 KiB
Ada
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------------------------------------------------------------------------------
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-- --
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-- GNAT RUN-TIME COMPONENTS --
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-- --
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-- S Y S T E M . W C H _ C N V --
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-- --
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-- S p e c --
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-- --
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-- Copyright (C) 1992-2013, 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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-- This package contains generic subprograms used for converting between
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-- sequences of Character and Wide_Character. Wide_Wide_Character values
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-- are also handled, but represented using integer range types defined in
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-- this package, so that this package can be used from applications that
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-- are restricted to Ada 95 compatibility (such as the compiler itself).
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-- All the algorithms for encoding and decoding are isolated in this package
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-- and in System.WCh_JIS and should not be duplicated elsewhere. The only
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-- exception to this is that GNAT.Decode_String and GNAT.Encode_String have
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-- their own circuits for UTF-8 conversions, for improved efficiency.
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-- This unit may be used directly from an application program by providing
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-- an appropriate WITH, and the interface can be expected to remain stable.
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pragma Compiler_Unit_Warning;
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with System.WCh_Con;
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package System.WCh_Cnv is
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pragma Pure;
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type UTF_32_Code is range 0 .. 16#7FFF_FFFF#;
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for UTF_32_Code'Size use 32;
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-- Range of allowed UTF-32 encoding values
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type UTF_32_String is array (Positive range <>) of UTF_32_Code;
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generic
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with function In_Char return Character;
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function Char_Sequence_To_Wide_Char
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(C : Character;
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EM : System.WCh_Con.WC_Encoding_Method) return Wide_Character;
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-- C is the first character of a sequence of one or more characters which
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-- represent a wide character sequence. Calling the function In_Char for
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-- additional characters as required, Char_To_Wide_Char returns the
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-- corresponding wide character value. Constraint_Error is raised if the
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-- sequence of characters encountered is not a valid wide character
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-- sequence for the given encoding method.
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--
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-- Note on the use of brackets encoding (WCEM_Brackets). The brackets
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-- encoding method is ambiguous in the context of this function, since
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-- there is no way to tell if ["1234"] is eight unencoded characters or
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-- one encoded character. In the context of Ada sources, any sequence
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-- starting [" must be the start of an encoding (since that sequence is
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-- not valid in Ada source otherwise). The routines in this package use
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-- the same approach. If the input string contains the sequence [" then
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-- this is assumed to be the start of a brackets encoding sequence, and
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-- if it does not match the syntax, an error is raised.
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generic
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with function In_Char return Character;
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function Char_Sequence_To_UTF_32
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(C : Character;
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EM : System.WCh_Con.WC_Encoding_Method) return UTF_32_Code;
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-- This is similar to the above, but the function returns a code from
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-- the full UTF_32 code set, which covers the full range of possible
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-- values in Wide_Wide_Character. The result can be converted to
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-- Wide_Wide_Character form using Wide_Wide_Character'Val.
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generic
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with procedure Out_Char (C : Character);
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procedure Wide_Char_To_Char_Sequence
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(WC : Wide_Character;
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EM : System.WCh_Con.WC_Encoding_Method);
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-- Given a wide character, converts it into a sequence of one or
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-- more characters, calling the given Out_Char procedure for each.
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-- Constraint_Error is raised if the given wide character value is
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-- not a valid value for the given encoding method.
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--
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-- Note on brackets encoding (WCEM_Brackets). For the input routines above,
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-- upper half characters can be represented as ["hh"] but this procedure
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-- will only use brackets encodings for codes higher than 16#FF#, so upper
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-- half characters will be output as single Character values.
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generic
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with procedure Out_Char (C : Character);
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procedure UTF_32_To_Char_Sequence
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(Val : UTF_32_Code;
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EM : System.WCh_Con.WC_Encoding_Method);
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-- This is similar to the above, but the input value is a code from the
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-- full UTF_32 code set, which covers the full range of possible values
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-- in Wide_Wide_Character. To convert a Wide_Wide_Character value, the
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-- caller can use Wide_Wide_Character'Pos in the call.
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end System.WCh_Cnv;
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