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------------------------------------------------------------------------------
-- --
-- GNAT RUNTIME COMPONENTS --
-- --
-- G N A T . S P E L L I N G _ C H E C K E R --
-- --
-- B o d y --
-- --
-- Copyright (C) 1998-2003 Ada Core Technologies, 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, 59 Temple Place - Suite 330, Boston, --
-- MA 02111-1307, 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. --
-- --
------------------------------------------------------------------------------
package body GNAT.Spelling_Checker is
------------------------
-- Is_Bad_Spelling_Of --
------------------------
function Is_Bad_Spelling_Of
(Found : String;
Expect : String)
return Boolean
is
FN : constant Natural := Found'Length;
FF : constant Natural := Found'First;
FL : constant Natural := Found'Last;
EN : constant Natural := Expect'Length;
EF : constant Natural := Expect'First;
EL : constant Natural := Expect'Last;
begin
-- If both strings null, then we consider this a match, but if one
-- is null and the other is not, then we definitely do not match
if FN = 0 then
return (EN = 0);
elsif EN = 0 then
return False;
-- If first character does not match, then definitely not misspelling
elsif Found (FF) /= Expect (EF) then
return False;
-- Not a bad spelling if both strings are 1-2 characters long
elsif FN < 3 and then EN < 3 then
return False;
-- Lengths match. Execute loop to check for a single error, single
-- transposition or exact match (we only fall through this loop if
-- one of these three conditions is found).
elsif FN = EN then
for J in 1 .. FN - 2 loop
if Expect (EF + J) /= Found (FF + J) then
-- If both mismatched characters are digits, then we do
-- not consider it a misspelling (e.g. B345 is not a
-- misspelling of B346, it is something quite different)
if Expect (EF + J) in '0' .. '9'
and then Found (FF + J) in '0' .. '9'
then
return False;
elsif Expect (EF + J + 1) = Found (FF + J + 1)
and then Expect (EF + J + 2 .. EL) = Found (FF + J + 2 .. FL)
then
return True;
elsif Expect (EF + J) = Found (FF + J + 1)
and then Expect (EF + J + 1) = Found (FF + J)
and then Expect (EF + J + 2 .. EL) = Found (FF + J + 2 .. FL)
then
return True;
else
return False;
end if;
end if;
end loop;
-- At last character. Test digit case as above, otherwise we
-- have a match since at most this last character fails to match.
if Expect (EL) in '0' .. '9'
and then Found (FL) in '0' .. '9'
and then Expect (EL) /= Found (FL)
then
return False;
else
return True;
end if;
-- Length is 1 too short. Execute loop to check for single deletion
elsif FN = EN - 1 then
for J in 1 .. FN - 1 loop
if Found (FF + J) /= Expect (EF + J) then
return Found (FF + J .. FL) = Expect (EF + J + 1 .. EL);
end if;
end loop;
-- If we fall through then the last character was missing, which
-- we consider to be a match (e.g. found xyz, expected xyza).
return True;
-- Length is 1 too long. Execute loop to check for single insertion
elsif FN = EN + 1 then
for J in 1 .. EN - 1 loop
if Found (FF + J) /= Expect (EF + J) then
return Found (FF + J + 1 .. FL) = Expect (EF + J .. EL);
end if;
end loop;
-- If we fall through then the last character was an additional
-- character, which is a match (e.g. found xyza, expected xyz).
return True;
-- Length is completely wrong
else
return False;
end if;
end Is_Bad_Spelling_Of;
end GNAT.Spelling_Checker;
|
