gcc/ada/widechar.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                             W I D E C H A R                              --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2018, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNAT was originally developed  by the GNAT team at  New York University. --
  28 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 --  Subprograms for manipulation of wide character sequences. Note that in
  33 --  this package, wide character and wide wide character are not distinguished
  34 --  since this package is basically concerned with syntactic notions, and it
  35 --  deals with Char_Code values, rather than values of actual Ada types.
  36
  37 with Types; use Types;
  38
  39 package Widechar is
  40
  41    Wide_Char_Byte_Count : Nat := 0;
  42    --  This value is incremented whenever Scan_Wide or Skip_Wide is called.
  43    --  The amount added is the length of the wide character sequence minus
  44    --  one. This means that the count that accumulates here represents the
  45    --  difference between the length in characters and the length in bytes.
  46    --  This is used for checking the line length in characters.
  47
  48    function Length_Wide return Nat;
  49    --  Returns the maximum length in characters for the escape sequence that
  50    --  is used to encode wide character literals outside the ASCII range. Used
  51    --  only in the implementation of the attribute Width for Wide_Character
  52    --  and Wide_Wide_Character.
  53
  54    procedure Scan_Wide
  55      (S   : Source_Buffer_Ptr;
  56       P   : in out Source_Ptr;
  57       C   : out Char_Code;
  58       Err : out Boolean);
  59    --  On entry S (P) points to the first character in the source text for
  60    --  a wide character (i.e. to an ESC character, a left bracket, or an
  61    --  upper half character, depending on the representation method). A
  62    --  single wide character is scanned. If no error is found, the value
  63    --  stored in C is the code for this wide character, P is updated past
  64    --  the sequence and Err is set to False. If an error is found, then
  65    --  P points to the improper character, C is undefined, and Err is
  66    --  set to True.
  67
  68    procedure Set_Wide
  69      (C : Char_Code;
  70       S : in out String;
  71       P : in out Natural);
  72    --  The escape sequence (including any leading ESC character) for the
  73    --  given character code is stored starting at S (P + 1), and on return
  74    --  P points to the last stored character (i.e. P is the count of stored
  75    --  characters on entry and exit, and the escape sequence is appended to
  76    --  the end of the stored string). The character code C represents a code
  77    --  originally constructed by Scan_Wide, so it is known to be in a range
  78    --  that is appropriate for the encoding method in use.
  79
  80    procedure Skip_Wide (S : String; P : in out Natural);
  81    --  On entry, S (P) points to an ESC character for a wide character escape
  82    --  sequence or to an upper half character if the encoding method uses the
  83    --  upper bit, or to a left bracket if the brackets encoding method is in
  84    --  use. On exit, P is bumped past the wide character sequence. No error
  85    --  checking is done, since this is only used on escape sequences generated
  86    --  by Set_Wide, which are known to be correct.
  87
  88    procedure Skip_Wide (S : Source_Buffer_Ptr; P : in out Source_Ptr);
  89    --  Similar to the above procedure, but operates on a source buffer
  90    --  instead of a string, with P being a Source_Ptr referencing the
  91    --  contents of the source buffer.
  92
  93    function Is_Start_Of_Wide_Char
  94      (S : Source_Buffer_Ptr;
  95       P : Source_Ptr) return Boolean;
  96    --  Determines if S (P) is the start of a wide character sequence
  97
  98 private
  99    pragma Inline (Is_Start_Of_Wide_Char);
 100
 101 end Widechar;