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------------------------------------------------------------------------------
-- --
-- GNAT RUN-TIME COMPONENTS --
-- --
-- S Y S T E M . W C H _ C N V --
-- --
-- S p e c --
-- --
-- Copyright (C) 1992-2009, 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. --
-- --
------------------------------------------------------------------------------
-- This package contains generic subprograms used for converting between
-- sequences of Character and Wide_Character. Wide_Wide_Character values
-- are also handled, but represented using integer range types defined in
-- this package, so that this package can be used from applications that
-- are restricted to Ada 95 compatibility (such as the compiler itself).
-- All the algorithms for encoding and decoding are isolated in this package
-- and in System.WCh_JIS and should not be duplicated elsewhere. The only
-- exception to this is that GNAT.Decode_String and GNAT.Encode_String have
-- their own circuits for UTF-8 conversions, for improved efficiency.
-- This unit may be used directly from an application program by providing
-- an appropriate WITH, and the interface can be expected to remain stable.
pragma Compiler_Unit;
with System.WCh_Con;
package System.WCh_Cnv is
pragma Pure;
type UTF_32_Code is range 0 .. 16#7FFF_FFFF#;
for UTF_32_Code'Size use 32;
-- Range of allowed UTF-32 encoding values
type UTF_32_String is array (Positive range <>) of UTF_32_Code;
generic
with function In_Char return Character;
function Char_Sequence_To_Wide_Char
(C : Character;
EM : System.WCh_Con.WC_Encoding_Method) return Wide_Character;
-- C is the first character of a sequence of one or more characters which
-- represent a wide character sequence. Calling the function In_Char for
-- additional characters as required, Char_To_Wide_Char returns the
-- corresponding wide character value. Constraint_Error is raised if the
-- sequence of characters encountered is not a valid wide character
-- sequence for the given encoding method.
--
-- Note on the use of brackets encoding (WCEM_Brackets). The brackets
-- encoding method is ambiguous in the context of this function, since
-- there is no way to tell if ["1234"] is eight unencoded characters or
-- one encoded character. In the context of Ada sources, any sequence
-- starting [" must be the start of an encoding (since that sequence is
-- not valid in Ada source otherwise). The routines in this package use
-- the same approach. If the input string contains the sequence [" then
-- this is assumed to be the start of a brackets encoding sequence, and
-- if it does not match the syntax, an error is raised.
generic
with function In_Char return Character;
function Char_Sequence_To_UTF_32
(C : Character;
EM : System.WCh_Con.WC_Encoding_Method) return UTF_32_Code;
-- This is similar to the above, but the function returns a code from
-- the full UTF_32 code set, which covers the full range of possible
-- values in Wide_Wide_Character. The result can be converted to
-- Wide_Wide_Character form using Wide_Wide_Character'Val.
generic
with procedure Out_Char (C : Character);
procedure Wide_Char_To_Char_Sequence
(WC : Wide_Character;
EM : System.WCh_Con.WC_Encoding_Method);
-- Given a wide character, converts it into a sequence of one or
-- more characters, calling the given Out_Char procedure for each.
-- Constraint_Error is raised if the given wide character value is
-- not a valid value for the given encoding method.
--
-- Note on brackets encoding (WCEM_Brackets). For the input routines above,
-- upper half characters can be represented as ["hh"] but this procedure
-- will only use brackets encodings for codes higher than 16#FF#, so upper
-- half characters will be output as single Character values.
generic
with procedure Out_Char (C : Character);
procedure UTF_32_To_Char_Sequence
(Val : UTF_32_Code;
EM : System.WCh_Con.WC_Encoding_Method);
-- This is similar to the above, but the input value is a code from the
-- full UTF_32 code set, which covers the full range of possible values
-- in Wide_Wide_Character. To convert a Wide_Wide_Character value, the
-- caller can use Wide_Wide_Character'Pos in the call.
end System.WCh_Cnv;
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