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-- --
-- package Strings_Edit.UTF8 Copyright (c) Dmitry A. Kazakov --
-- Implementation Luebeck --
-- Spring, 2005 --
-- --
-- Last revision : 10:11 25 Jun 2005 --
-- --
-- This library is free software; you can redistribute it and/or --
-- modify it under the terms of the GNU General Public License as --
-- published by the Free Software Foundation; either version 2 of --
-- the License, or (at your option) any later version. This library --
-- is distributed in the hope that it will be useful, but WITHOUT --
-- 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 along with --
-- this library; if not, write to the Free Software Foundation, --
-- Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. --
-- --
-- --
-- --
-- --
-- --
-- --
-- --
--____________________________________________________________________--
with Ada.IO_Exceptions; use Ada.IO_Exceptions;
package body Strings_Edit.UTF8 is
procedure Get
( Source : String;
Pointer : in out Integer;
Value : out UTF8_Code_Point
) is
Accum : UTF8_Code_Point'Base;
Code : UTF8_Code_Point'Base;
Index : Integer := Pointer;
begin
if Index < Source'First then
raise Layout_Error;
end if;
if Index > Source'Last then
if Index = Source'Last + 1 then
raise End_Error;
else
raise Layout_Error;
end if;
end if;
Code := UTF8_Code_Point (Character'Pos (Source (Index)));
case Code is
when 0..16#7F# => -- 1 byte (ASCII)
Value := Code;
Pointer := Index + 1;
return;
when 16#C2#..16#DF# => -- 2 bytes
Accum := (Code and 16#1F#) * 2**6;
goto Last;
when 16#E0# => -- 3 bytes
Index := Index + 1;
if Index >= Source'Last then
raise Data_Error;
end if;
Code := UTF8_Code_Point (Character'Pos (Source (Index)));
if Code not in 16#A0#..16#BF# then
raise Data_Error;
end if;
Accum := (Code and 16#3F#) * 2**6;
goto Last;
when 16#E1#..16#EF# => -- 3 bytes
Accum := (Code and 16#0F#) * 2**12;
when 16#F0# => -- 4 bytes
Index := Index + 1;
if Index >= Source'Last then
raise Data_Error;
end if;
Code := UTF8_Code_Point (Character'Pos (Source (Index)));
if Code not in 16#90#..16#BF# then
raise Data_Error;
end if;
Accum := (Code and 16#3F#) * 2**12;
when 16#F1#..16#F3# => -- 4 bytes
Accum := (Code and 16#07#) * 2**18;
Index := Index + 1;
if Index >= Source'Last then
raise Data_Error;
end if;
Code := UTF8_Code_Point (Character'Pos (Source (Index)));
if Code not in 16#80#..16#BF# then
raise Data_Error;
end if;
Accum := Accum or (Code and 16#3F#) * 2**12;
when 16#F4# => -- 4 bytes
Accum := (Code and 16#07#) * 2**18;
Index := Index + 1;
if Index >= Source'Last then
raise Data_Error;
end if;
Code := UTF8_Code_Point (Character'Pos (Source (Index)));
if Code not in 16#80#..16#8F# then
raise Data_Error;
end if;
Accum := Accum or (Code and 16#3F#) * 2**12;
when others =>
raise Data_Error;
end case;
Index := Index + 1;
if Index >= Source'Last then
raise Data_Error;
end if;
Code := UTF8_Code_Point (Character'Pos (Source (Index)));
if Code not in 16#80#..16#BF# then
raise Data_Error;
end if;
Accum := Accum or (Code and 16#3F#) * 2**6;
<<Last>>
Index := Index + 1;
if Index > Source'Last then
raise Data_Error;
end if;
Code := UTF8_Code_Point (Character'Pos (Source (Index)));
if Code not in 16#80#..16#BF# then
raise Data_Error;
end if;
Value := Accum or (Code and 16#3F#);
Pointer := Index + 1;
end Get;
function Image (Value : UTF8_Code_Point) return String is
Result : String (1..4);
Pointer : Integer := Result'First;
begin
Put (Result, Pointer, Value);
return Result (1..Pointer - 1);
end Image;
function Length (Source : String) return Natural is
Count : Natural := 0;
Accum : UTF8_Code_Point;
Index : Integer := Source'First;
begin
while Index <= Source'Last loop
Get (Source, Index, Accum);
Count := Count + 1;
end loop;
return Count;
end Length;
procedure Put
( Destination : in out String;
Pointer : in out Integer;
Value : UTF8_Code_Point
) is
begin
if Pointer not in Destination'Range then
raise Layout_Error;
end if;
if Value <= 16#7F# then
Destination (Pointer) := Character'Val (Value);
Pointer := Pointer + 1;
elsif Value <= 16#7FF# then
if Pointer >= Destination'Last then
raise Layout_Error;
end if;
Destination (Pointer) :=
Character'Val (16#C0# or Value / 2**6);
Destination (Pointer + 1) :=
Character'Val (16#80# or (Value and 16#3F#));
Pointer := Pointer + 2;
elsif Value <= 16#FFFF# then
if 1 >= Destination'Last - Pointer then
raise Layout_Error;
end if;
Destination (Pointer) :=
Character'Val (16#E0# or Value / 2**12);
Destination (Pointer + 1) :=
Character'Val (16#80# or (Value / 2**6 and 16#3F#));
Destination (Pointer + 2) :=
Character'Val (16#80# or (Value and 16#3F#));
Pointer := Pointer + 3;
else
if 2 >= Destination'Last - Pointer then
raise Layout_Error;
end if;
Destination (Pointer) :=
Character'Val (16#F0# or Value / 2**18);
Destination (Pointer + 1) :=
Character'Val (16#80# or (Value / 2**12 and 16#3F#));
Destination (Pointer + 2) :=
Character'Val (16#80# or (Value / 2**6 and 16#3F#));
Destination (Pointer + 3) :=
Character'Val (16#80# or (Value and 16#3F#));
Pointer := Pointer + 4;
end if;
end Put;
procedure Reverse_Put
( Destination : in out String;
Pointer : in out Integer;
Prefix : String;
Position : Natural
) is
begin
if ( Pointer not in Destination'Range
or else
Pointer - Destination'First < Prefix'Length
)
then
raise Layout_Error;
end if;
Destination (Pointer) := Character'Val (Position);
Pointer := Pointer - 1;
for Index in reverse Prefix'Range loop
Destination (Pointer) := Prefix (Index);
Pointer := Pointer - 1;
end loop;
end Reverse_Put;
procedure Skip
( Source : String;
Pointer : in out Integer;
Count : Natural := 1
) is
begin
if Count > 0 then
declare
Accum : UTF8_Code_Point;
Index : Integer := Source'First;
begin
for Character in 1..Count loop
Get (Source, Index, Accum);
end loop;
Pointer := Index;
end;
elsif ( Pointer < Source'First
or else
( Pointer > Source'Last
and then
Pointer - 1 > Source'Last
) )
then
raise Layout_Error;
end if;
end Skip;
function Value (Source : String) return UTF8_Code_Point is
Pointer : Integer := Source'First;
Result : UTF8_Code_Point;
begin
Get (Source, Pointer, Result);
if Pointer /= Source'Last + 1 then
raise Data_Error;
end if;
return Result;
end Value;
end Strings_Edit.UTF8;
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