gcc/ada/g-spchge.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
   4 --                                                                          --
   5 --          G N A T . S P E L L I N G _ C H E C K E R _ G E N E R I C       --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --                     Copyright (C) 1998-2013, AdaCore                     --
  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 pragma Compiler_Unit_Warning;
  33
  34 package body GNAT.Spelling_Checker_Generic is
  35
  36    ------------------------
  37    -- Is_Bad_Spelling_Of --
  38    ------------------------
  39
  40    function Is_Bad_Spelling_Of
  41      (Found  : String_Type;
  42       Expect : String_Type) return Boolean
  43    is
  44       FN : constant Natural := Found'Length;
  45       FF : constant Natural := Found'First;
  46       FL : constant Natural := Found'Last;
  47
  48       EN : constant Natural := Expect'Length;
  49       EF : constant Natural := Expect'First;
  50       EL : constant Natural := Expect'Last;
  51
  52       Letter_o : constant Char_Type := Char_Type'Val (Character'Pos ('o'));
  53       Digit_0  : constant Char_Type := Char_Type'Val (Character'Pos ('0'));
  54       Digit_9  : constant Char_Type := Char_Type'Val (Character'Pos ('9'));
  55
  56    begin
  57       --  If both strings null, then we consider this a match, but if one
  58       --  is null and the other is not, then we definitely do not match
  59
  60       if FN = 0 then
  61          return (EN = 0);
  62
  63       elsif EN = 0 then
  64          return False;
  65
  66          --  If first character does not match, then we consider that this is
  67          --  definitely not a misspelling. An exception is when we expect a
  68          --  letter O and found a zero.
  69
  70       elsif Found (FF) /= Expect (EF)
  71         and then (Found (FF) /= Digit_0 or else Expect (EF) /= Letter_o)
  72       then
  73          return False;
  74
  75       --  Not a bad spelling if both strings are 1-2 characters long
  76
  77       elsif FN < 3 and then EN < 3 then
  78          return False;
  79
  80       --  Lengths match. Execute loop to check for a single error, single
  81       --  transposition or exact match (we only fall through this loop if
  82       --  one of these three conditions is found).
  83
  84       elsif FN = EN then
  85          for J in 1 .. FN - 2 loop
  86             if Expect (EF + J) /= Found (FF + J) then
  87
  88                --  If both mismatched characters are digits, then we do
  89                --  not consider it a misspelling (e.g. B345 is not a
  90                --  misspelling of B346, it is something quite different)
  91
  92                if Expect (EF + J) in Digit_0 .. Digit_9
  93                  and then Found (FF + J) in Digit_0 .. Digit_9
  94                then
  95                   return False;
  96
  97                elsif Expect (EF + J + 1) = Found (FF + J + 1)
  98                  and then Expect (EF + J + 2 .. EL) = Found (FF + J + 2 .. FL)
  99                then
 100                   return True;
 101
 102                elsif Expect (EF + J) = Found (FF + J + 1)
 103                  and then Expect (EF + J + 1) = Found (FF + J)
 104                  and then Expect (EF + J + 2 .. EL) = Found (FF + J + 2 .. FL)
 105                then
 106                   return True;
 107
 108                else
 109                   return False;
 110                end if;
 111             end if;
 112          end loop;
 113
 114          --  At last character. Test digit case as above, otherwise we
 115          --  have a match since at most this last character fails to match.
 116
 117          if Expect (EL) in Digit_0 .. Digit_9
 118            and then Found (FL) in Digit_0 .. Digit_9
 119            and then Expect (EL) /= Found (FL)
 120          then
 121             return False;
 122          else
 123             return True;
 124          end if;
 125
 126       --  Length is 1 too short. Execute loop to check for single deletion
 127
 128       elsif FN = EN - 1 then
 129          for J in 1 .. FN - 1 loop
 130             if Found (FF + J) /= Expect (EF + J) then
 131                return Found (FF + J .. FL) = Expect (EF + J + 1 .. EL);
 132             end if;
 133          end loop;
 134
 135          --  If we fall through then the last character was missing, which
 136          --  we consider to be a match (e.g. found xyz, expected xyza).
 137
 138          return True;
 139
 140       --  Length is 1 too long. Execute loop to check for single insertion
 141
 142       elsif FN = EN + 1 then
 143          for J in 1 .. EN - 1 loop
 144             if Found (FF + J) /= Expect (EF + J) then
 145                return Found (FF + J + 1 .. FL) = Expect (EF + J .. EL);
 146             end if;
 147          end loop;
 148
 149          --  If we fall through then the last character was an additional
 150          --  character, which is a match (e.g. found xyza, expected xyz).
 151
 152          return True;
 153
 154       --  Length is completely wrong
 155
 156       else
 157          return False;
 158       end if;
 159    end Is_Bad_Spelling_Of;
 160
 161 end GNAT.Spelling_Checker_Generic;