Celestin Apprentice 7/Apprentice-Release7.iso/Environments/Small Eiffel 0.4.8/lib_show/gcd/integer.e

Text File | 1997-04-13 | 5KB | 223 lines

-- Part of SmallEiffel -- Read DISCLAIMER file -- Copyright (C)
-- Dominique COLNET and Suzanne COLLIN -- [e-mail]
--
expanded class  INTEGER

inherit
   INTEGER_REF
      redefine
     infix "+", infix "-", infix "*", infix "/",
     infix "\\", infix "//", infix "<",
     compare, prefix "-", prefix "+"
      end;

feature {ANY}

   infix "+"(other: INTEGER): INTEGER is
     -- Add `other' to Current.
      external "CSE"
      end;

   infix "-" (other : INTEGER): INTEGER is
     -- Subtract `other' from Current.
      external "CSE"
      end;

   infix "*" (other : INTEGER) : INTEGER is
     -- Multiply `other' by Current.
      external "CSE"
      end;

   infix "/" (other : INTEGER): INTEGER is
     -- Divide Current by `other'.
     -- Note : Integer division
      external "CSE"
      end;

   infix "//" (other : INTEGER) : INTEGER is
     -- Divide Current by `other'.
     -- Note : Integer division
      external "CSE"
      end;

   infix "\\" (other : INTEGER) : INTEGER is
     -- Remainder of division of Current by `other'.
      external "CSE"
      end;

   infix "<" (other: INTEGER): BOOLEAN is
     -- Is Current less than `other'?
      external "CSE"
      end;

   prefix "+": INTEGER is
      do
     Result := Current
      end;

   prefix "-" : INTEGER is
     -- Unary minus of Current
      external "CSE"
      end;

   compare(other: INTEGER): INTEGER is
     -- Compare Current with `other'.
     -- '<' <==> Result < 0
     -- '>' <==> Result > 0
     -- Otherwise Result = 0
      do
     Result := Current - other
      end;

   to_string: STRING is
     -- Convert the INTEGER into a new allocated STRING.
     -- Note: see `append_in' to save memory.
      do
     !!Result.make(0);
     append_in(Result);
      end;

   append_in(str: STRING) is
     -- Append the equivalent of `to_string' at the end of
     -- `str'. Thus you can save memory because no other
     -- STRING is allocate for the job.
      require
     str /= Void;
      local
     val, i: INTEGER;
      do
     if Current = 0 then
        str.extend('0');
     else
        if Current < 0 then
           str.extend('-');
           (- Current).append_in(str);
        else
           from
          i := str.count + 1;
          val := Current;
           until
          val = 0
           loop
          str.extend((val \\ 10).digit);
          val := val // 10;
           end;
           from
          val := str.count;
           until
          i >= val
           loop
          str.swap(i,val);
          val := val - 1;
          i := i + 1;
           end;
        end;
     end;
      end;

   to_string_format(s: INTEGER): STRING is
     -- Same as `to_string' but the result is on `s' character and the
     -- number is right aligned.
     -- Note: see `append_in_format' to save memory.
      require
     to_string.count <= s;
      do
     from
        tmp_string.clear;
        append_in(tmp_string);
     until
        tmp_string.count >= s
     loop
        tmp_string.add_first(' ');
     end;
     Result := clone(tmp_string);
      ensure
     Result.count = s;
      end;

   append_in_format(str: STRING; s: INTEGER) is
     -- Append the equivalent of `to_string_format' at the end of
     -- `str'. Thus you can save memory because no other
     -- STRING is allocate for the job.
      do
     from
        tmp_string.clear;
        append_in(tmp_string);
     until
        tmp_string.count >= s
     loop
        tmp_string.add_first(' ');
     end;
     str.append(tmp_string);
      ensure
     str.count >= (old str.count) + s;
      end;

   digit: CHARACTER is
     -- Gives the corresponding CHARACTER for range 0..9.
      require
     0 <= Current;
     Current <= 9;
      do
     Result := ("0123456789").item(Current + 1);
      ensure
     ("0123456789").has(Result);
     Result.value = Current;
      end;

   gcd(other: INTEGER): INTEGER is
     -- Great Common Divisor of `Current' and `other'.
      require
     Current > 0;
     other > 0;
      local
     the_other: INTEGER;
      do
     from
        Result := Current;
        the_other := other;
     invariant
        Result > 0;
        the_other > 0;
        Result.gcd(the_other) = Current.gcd(other);
     variant
        Result.max(the_other)
     until
        Result = the_other
     loop
        if Result > the_other then
           Result := Result - the_other;
        else
           the_other := the_other - Result;
        end;
     end;
      ensure
     Result = other.gcd(Current);
      end;

feature {NONE}

   tmp_string: STRING is "0123456789";

   to_character_table : STRING is "%
     %%/000/%/001/%/002/%/003/%/004/%/005/%/006/%/007/%
     %%/008/%/009/%/010/%/011/%/012/%/013/%/014/%/015/%
     %%/016/%/017/%/018/%/019/%/020/%/021/%/022/%/023/%
     %%/024/%/025/%/026/%/027/%/028/%/029/%/030/%/031/%
     %%/032/%/033/%/034/%/035/%/036/%/037/%/038/%/039/%
     %%/040/%/041/%/042/%/043/%/044/%/045/%/046/%/047/%
     %%/048/%/049/%/050/%/051/%/052/%/053/%/054/%/055/%
     %%/056/%/057/%/058/%/059/%/060/%/061/%/062/%/063/%
     %%/064/%/065/%/066/%/067/%/068/%/069/%/070/%/071/%
     %%/072/%/073/%/074/%/075/%/076/%/077/%/078/%/079/%
     %%/080/%/081/%/082/%/083/%/084/%/085/%/086/%/087/%
     %%/088/%/089/%/090/%/091/%/092/%/093/%/094/%/095/%
     %%/096/%/097/%/098/%/099/%/100/%/101/%/102/%/103/%
     %%/104/%/105/%/106/%/107/%/108/%/109/%/110/%/111/%
     %%/112/%/113/%/114/%/115/%/116/%/117/%/118/%/119/%
     %%/120/%/121/%/122/%/123/%/124/%/125/%/126/%/127/%
     %";

end -- class INTEGER