Author: Attila T.P.

Quick Search string searching

Answer:
1   
2   procedure TForm1.QuickSearch(const AText, APattern: string);
3   var
4     i, k, N, M: integer;
5     v_found: boolean;
6     v_Shift: array[0..255] of byte;
7   
8     procedure InitShift;
9     var
10      x: byte;
11      j, M: integer;
12    begin
13      M := Length(APattern);
14      x := 0;
15      while x <> 255 do
16      begin
17        v_Shift[x] := M + 1;
18        x := Succ(x);
19      end;
20      v_Shift[x] := M + 1;
21      j := 0;
22      while j < M do
23      begin
24        inc(j);
25        v_Shift[Ord(APattern[j])] := M + 1 - j;
26      end;
27    end;
28  begin
29    InitShift;
30    i := 0;
31    k := 0;
32    M := Length(APattern);
33    N := Length(AText);
34    while (i <= N - M + 1) and (k < M) do
35    begin
36      if AText[i + k] = APattern[1 + k] then
37        inc(k)
38      else
39      begin
40        i := i + v_Shift[ord(AText[i + M])];
41        k := 0;
42      end;
43    end;
44    v_found := (k = M);
45    //  if v_found then
46    //  begin
47    //    RichEdit1.SelStart := i - 1;
48    //    RichEdit1.SelLength := M;
49    //  end;
50  end;