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Diffstat (limited to 'gcc-4.3.1/gcc/ada/s-wchcon.ads')
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diff --git a/gcc-4.3.1/gcc/ada/s-wchcon.ads b/gcc-4.3.1/gcc/ada/s-wchcon.ads new file mode 100644 index 000000000..af0eb7006 --- /dev/null +++ b/gcc-4.3.1/gcc/ada/s-wchcon.ads @@ -0,0 +1,224 @@ +------------------------------------------------------------------------------ +-- -- +-- GNAT COMPILER COMPONENTS -- +-- -- +-- S Y S T E M . W C H _ C O N -- +-- -- +-- S p e c -- +-- -- +-- Copyright (C) 1992-2007, 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 2, 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. See the GNU General Public License -- +-- for more details. You should have received a copy of the GNU General -- +-- Public License distributed with GNAT; see file COPYING. If not, write -- +-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, -- +-- Boston, MA 02110-1301, USA. -- +-- -- +-- As a special exception, if other files instantiate generics from this -- +-- unit, or you link this unit with other files to produce an executable, -- +-- this unit does not by itself cause the resulting executable to be -- +-- covered by the GNU General Public License. This exception does not -- +-- however invalidate any other reasons why the executable file might be -- +-- covered by the GNU Public License. -- +-- -- +-- GNAT was originally developed by the GNAT team at New York University. -- +-- Extensive contributions were provided by Ada Core Technologies Inc. -- +-- -- +------------------------------------------------------------------------------ + +-- This package defines the codes used to identify the encoding method for +-- wide characters in string and character constants. This is needed both +-- at compile time and at runtime (for the wide character runtime routines) + +-- 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 Warnings (Off); +pragma Compiler_Unit; +pragma Warnings (On); + +package System.WCh_Con is + pragma Pure; + + ------------------------------------- + -- Wide_Character Encoding Methods -- + ------------------------------------- + + -- A wide character encoding method is a method for uniquely representing + -- a Wide_Character or Wide_Wide_Character value using a one or more + -- Character values. Three types of encoding method are supported by GNAT: + + -- An escape encoding method uses ESC as the first character of the + -- sequence, and subsequent characters determine the wide character + -- value that is represented. Any character other than ESC stands + -- for itself as a single byte (i.e. any character in Latin-1, other + -- than ESC itself, is represented as a single character: itself). + + -- An upper half encoding method uses a character in the upper half + -- range (i.e. in the range 16#80# .. 16#FF#) as the first byte of + -- a wide character encoding sequence. Subsequent characters are + -- used to determine the wide character value that is represented. + -- Any character in the lower half (16#00# .. 16#7F#) represents + -- itself as a single character. + + -- The brackets notation, where a wide character is represented by the + -- sequence ["xx"] or ["xxxx"] or ["xxxxxx"] where xx are hexadecimal + -- characters. Note that currently this is the only encoding that + -- supports the full UTF-32 range. + + -- Note that GNAT does not currently support escape-in, escape-out + -- encoding methods, where an escape sequence is used to set a mode + -- used to recognize subsequent characters. All encoding methods use + -- individual character-by-character encodings, so that a sequence of + -- wide characters is represented by a sequence of encodings. + + -- To add new encoding methods, the following steps are required: + + -- 1. Define a code for a new value of type WC_Encoding_Method + -- 2. Adjust the definition of WC_Encoding_Method accordingly + -- 3. Provide appropriate conversion routines in System.Wch_Cnv + -- 4. Adjust definition of WC_Longest_Sequence if necessary + -- 5. Add an entry in WC_Encoding_Letters for the new method + -- 6. Add proper code to s-wchstw.adb, s-wchwts.adb, s-widwch.adb + -- 7. Update documentation (remember section on form strings) + + -- Note that the WC_Encoding_Method values must be kept ordered so that + -- the definitions of the subtypes WC_Upper_Half_Encoding_Method and + -- WC_ESC_Encoding_Method are still correct. + + --------------------------------- + -- Encoding Method Definitions -- + --------------------------------- + + type WC_Encoding_Method is range 1 .. 6; + -- Type covering the range of values used to represent wide character + -- encoding methods. An enumeration type might be a little neater, but + -- more trouble than it's worth, given the need to pass these values + -- from the compiler to the backend, and to record them in the ALI file. + + WCEM_Hex : constant WC_Encoding_Method := 1; + -- The wide character with code 16#abcd# is represented by the escape + -- sequence ESC a b c d (five characters, where abcd are ASCII hex + -- characters, using upper case for letters). This method is easy + -- to deal with in external environments that do not support wide + -- characters, and covers the whole 16-bit BMP. Codes larger than + -- 16#FFFF# are not representable using this encoding method. + + WCEM_Upper : constant WC_Encoding_Method := 2; + -- The wide character with encoding 16#abcd#, where the upper bit is on + -- (i.e. a is in the range 8-F) is represented as two bytes 16#ab# and + -- 16#cd#. The second byte may never be a format control character, but + -- is not required to be in the upper half. This method can be also used + -- for shift-JIS or EUC where the internal coding matches the external + -- coding. Codes larger than 16#FFFF# are not representable using this + -- encoding method. + + WCEM_Shift_JIS : constant WC_Encoding_Method := 3; + -- A wide character is represented by a two character sequence 16#ab# + -- and 16#cd#, with the restrictions described for upper half encoding + -- as described above. The internal character code is the corresponding + -- JIS character according to the standard algorithm for Shift-JIS + -- conversion. See the body of package System.JIS_Conversions for + -- further details. Codes larger than 16#FFFF are not representable + -- using this encoding method. + + WCEM_EUC : constant WC_Encoding_Method := 4; + -- A wide character is represented by a two character sequence 16#ab# and + -- 16#cd#, with both characters being in the upper half set. The internal + -- character code is the corresponding JIS character according to the EUC + -- encoding algorithm. See the body of package System.JIS_Conversions for + -- further details. Codes larger than 16#FFFF# are not representable using + -- this encoding method. + + WCEM_UTF8 : constant WC_Encoding_Method := 5; + -- An ISO 10646-1 BMP/Unicode wide character is represented in UCS + -- Transformation Format 8 (UTF-8), as defined in Annex R of ISO + -- 10646-1/Am.2. Depending on the character value, a Unicode character + -- is represented as the one to six byte sequence. + -- + -- 16#0000_0000#-16#0000_007f#: 2#0xxxxxxx# + -- 16#0000_0080#-16#0000_07ff#: 2#110xxxxx# 2#10xxxxxx# + -- 16#0000_0800#-16#0000_ffff#: 2#1110xxxx# 2#10xxxxxx# 2#10xxxxxx# + -- 16#0001_0000#-16#001F_FFFF#: 2#11110xxx# 2#10xxxxxx# 2#10xxxxxx# + -- 2#10xxxxxx# + -- 16#0020_0000#-16#03FF_FFFF#: 2#111110xx# 2#10xxxxxx# 2#10xxxxxx# + -- 2#10xxxxxx# 2#10xxxxxx# + -- 16#0400_0000#-16#7FFF_FFFF#: 2#1111110x# 2#10xxxxxx# 2#10xxxxxx# + -- 2#10xxxxxx# 2#10xxxxxx# 2#10xxxxxx# + -- + -- where the xxx bits correspond to the left-padded bits of the + -- 16-bit character value. Note that all lower half ASCII characters + -- are represented as ASCII bytes and all upper half characters and + -- other wide characters are represented as sequences of upper-half. This + -- encoding method can represent the entire range of Wide_Wide_Character. + + WCEM_Brackets : constant WC_Encoding_Method := 6; + -- A wide character is represented using one of the following sequences: + -- + -- ["xx"] + -- ["xxxx"] + -- ["xxxxxx"] + -- ["xxxxxxxx"] + -- + -- where xx are hexadecimal digits representing the character code. This + -- encoding method can represent the entire range of Wide_Wide_Character + -- but in the general case results in ambiguous representations (there is + -- no ambiguity in Ada sources, since the above sequences are illegal Ada). + + WC_Encoding_Letters : constant array (WC_Encoding_Method) of Character := + (WCEM_Hex => 'h', + WCEM_Upper => 'u', + WCEM_Shift_JIS => 's', + WCEM_EUC => 'e', + WCEM_UTF8 => '8', + WCEM_Brackets => 'b'); + -- Letters used for selection of wide character encoding method in the + -- compiler options (-gnatW? switch) and for Wide_Text_IO (WCEM parameter + -- in the form string). + + subtype WC_ESC_Encoding_Method is + WC_Encoding_Method range WCEM_Hex .. WCEM_Hex; + -- Encoding methods using an ESC character at the start of the sequence + + subtype WC_Upper_Half_Encoding_Method is + WC_Encoding_Method range WCEM_Upper .. WCEM_UTF8; + -- Encoding methods using an upper half character (16#80#..16#FF) at + -- the start of the sequence. + + WC_Longest_Sequence : constant := 12; + -- The longest number of characters that can be used for a wide character + -- or wide wide character sequence for any of the active encoding methods. + + WC_Longest_Sequences : constant array (WC_Encoding_Method) of Natural := + (WCEM_Hex => 5, + WCEM_Upper => 2, + WCEM_Shift_JIS => 2, + WCEM_EUC => 2, + WCEM_UTF8 => 6, + WCEM_Brackets => 12); + -- The longest number of characters that can be used for a wide character + -- or wide wide character sequence using the given encoding method. + + function Get_WC_Encoding_Method (C : Character) return WC_Encoding_Method; + -- Given a character C, returns corresponding encoding method (see array + -- WC_Encoding_Letters above). Raises Constraint_Error if not in list. + + function Get_WC_Encoding_Method (S : String) return WC_Encoding_Method; + -- Given a lower case string that is one of hex, upper, shift_jis, euc, + -- utf8, brackets, return the corresponding encoding method. Raises + -- Constraint_Error if not in list. + + function Is_Start_Of_Encoding + (C : Character; + EM : WC_Encoding_Method) return Boolean; + pragma Inline (Is_Start_Of_Encoding); + -- Returns True if the Character C is the start of a multi-character + -- encoding sequence for the given encoding method EM. If EM is set to + -- WCEM_Brackets, this function always returns False. + +end System.WCh_Con; |