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diff --git a/gcc/ada/libgnat/g-decstr.ads b/gcc/ada/libgnat/g-decstr.ads new file mode 100644 index 00000000000..1572939c318 --- /dev/null +++ b/gcc/ada/libgnat/g-decstr.ads @@ -0,0 +1,176 @@ +------------------------------------------------------------------------------ +-- -- +-- GNAT RUN-TIME COMPONENTS -- +-- -- +-- G N A T . D E C O D E _ S T R I N G -- +-- -- +-- S p e c -- +-- -- +-- Copyright (C) 2007-2017, AdaCore -- +-- -- +-- 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 generic package provides utility routines for converting from an +-- encoded string to a corresponding Wide_String or Wide_Wide_String value +-- using a specified encoding convention, which is supplied as the generic +-- parameter. UTF-8 is handled especially efficiently, and if the encoding +-- method is known at compile time to be WCEM_UTF8, then the instantiation +-- is specialized to handle only the UTF-8 case and exclude code for the +-- other encoding methods. The package also provides positioning routines +-- for skipping encoded characters in either direction, and for validating +-- strings for correct encodings. + +-- Note: this package is only about decoding sequences of 8-bit characters +-- into corresponding 16-bit Wide_String or 32-bit Wide_Wide_String values. +-- It knows nothing at all about the character encodings being used for the +-- resulting Wide_Character and Wide_Wide_Character values. Most often this +-- will be Unicode/ISO-10646 as specified by the Ada RM, but this package +-- does not make any assumptions about the character coding. See also the +-- packages Ada.Wide_[Wide_]Characters.Unicode for unicode specific functions. + +-- In particular, in the case of UTF-8, all valid UTF-8 encodings, as listed +-- in table 3.6 of the Unicode Standard, version 6.2.0, are recognized as +-- legitimate. This includes the full range 16#0000_0000# .. 16#03FF_FFFF#. +-- This includes codes in the range 16#D800# - 16#DFFF#. These codes all +-- have UTF-8 encoding sequences that are well-defined (e.g. the encoding for +-- 16#D800# is ED A0 80). But these codes do not correspond to defined Unicode +-- characters and are thus considered to be "not well-formed" (see table 3.7 +-- of the Unicode Standard). If you need to exclude these codes, you must do +-- that manually, e.g. use Decode_Wide_Character/Decode_Wide_String and check +-- that the resulting code(s) are not in this range. + +-- Note on the use of brackets encoding (WCEM_Brackets). The brackets encoding +-- method is ambiguous in the context of this package, 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. +-- In the case of the Prev functions, a sequence ending with "] is assumed to +-- be a valid brackets sequence, and an error is raised if it is not. + +with System.WCh_Con; + +generic + Encoding_Method : System.WCh_Con.WC_Encoding_Method; + +package GNAT.Decode_String is + pragma Pure; + + function Decode_Wide_String (S : String) return Wide_String; + pragma Inline (Decode_Wide_String); + -- Decode the given String, which is encoded using the indicated coding + -- method, returning the corresponding decoded Wide_String value. If S + -- contains a character code that cannot be represented with the given + -- encoding, then Constraint_Error is raised. + + procedure Decode_Wide_String + (S : String; + Result : out Wide_String; + Length : out Natural); + -- Similar to the above function except that the result is stored in the + -- given Wide_String variable Result, starting at Result (Result'First). On + -- return, Length is set to the number of characters stored in Result. The + -- caller must ensure that Result is long enough (an easy choice is to set + -- the length equal to the S'Length, since decoding can never increase the + -- string length). If the length of Result is insufficient Constraint_Error + -- will be raised. + + function Decode_Wide_Wide_String (S : String) return Wide_Wide_String; + -- Same as above function but for Wide_Wide_String output + + procedure Decode_Wide_Wide_String + (S : String; + Result : out Wide_Wide_String; + Length : out Natural); + -- Same as above procedure, but for Wide_Wide_String output + + function Validate_Wide_String (S : String) return Boolean; + -- This function inspects the string S to determine if it contains only + -- valid encodings corresponding to Wide_Character values using the + -- given encoding. If a call to Decode_Wide_String (S) would return + -- without raising Constraint_Error, then Validate_Wide_String will + -- return True. If the call would have raised Constraint_Error, then + -- Validate_Wide_String will return False. + + function Validate_Wide_Wide_String (S : String) return Boolean; + -- Similar to Validate_Wide_String, except that it succeeds if the string + -- contains only encodings corresponding to Wide_Wide_Character values. + + procedure Decode_Wide_Character + (Input : String; + Ptr : in out Natural; + Result : out Wide_Character); + pragma Inline (Decode_Wide_Character); + -- This is a lower level procedure that decodes a single character using + -- the given encoding method. The encoded character is stored in Input, + -- starting at Input (Ptr). The resulting output character is stored in + -- Result, and on return Ptr is updated past the input character or + -- encoding sequence. Constraint_Error will be raised if the input has + -- has a character that cannot be represented using the given encoding, + -- or if Ptr is outside the bounds of the Input string. + + procedure Decode_Wide_Wide_Character + (Input : String; + Ptr : in out Natural; + Result : out Wide_Wide_Character); + pragma Inline (Decode_Wide_Wide_Character); + -- Same as above procedure but with Wide_Wide_Character input + + procedure Next_Wide_Character (Input : String; Ptr : in out Natural); + pragma Inline (Next_Wide_Character); + -- This procedure examines the input string starting at Input (Ptr), and + -- advances Ptr past one character in the encoded string, so that on return + -- Ptr points to the next encoded character. Constraint_Error is raised if + -- an invalid encoding is encountered, or the end of the string is reached + -- or if Ptr is less than String'First on entry, or if the character + -- skipped is not a valid Wide_Character code. + + procedure Prev_Wide_Character (Input : String; Ptr : in out Natural); + -- This procedure is similar to Next_Encoded_Character except that it moves + -- backwards in the string, so that on return, Ptr is set to point to the + -- previous encoded character. Constraint_Error is raised if the start of + -- the string is encountered. It is valid for Ptr to be one past the end + -- of the string for this call (in which case on return it will point to + -- the last encoded character). + -- + -- Note: it is not generally possible to do this function efficiently with + -- all encodings, the current implementation is only efficient for the case + -- of UTF-8 (Encoding_Method = WCEM_UTF8) and Brackets (Encoding_Method = + -- WCEM_Brackets). For all other encodings, we work by starting at the + -- beginning of the string and moving forward till Ptr is reached, which + -- is correct but slow. + -- + -- Note: this routine assumes that the sequence prior to Ptr is correctly + -- encoded, it does not have a defined behavior if this is not the case. + + procedure Next_Wide_Wide_Character (Input : String; Ptr : in out Natural); + pragma Inline (Next_Wide_Wide_Character); + -- Similar to Next_Wide_Character except that codes skipped must be valid + -- Wide_Wide_Character codes. + + procedure Prev_Wide_Wide_Character (Input : String; Ptr : in out Natural); + -- Similar to Prev_Wide_Character except that codes skipped must be valid + -- Wide_Wide_Character codes. + +end GNAT.Decode_String; |