[Delphinic]

Расскажите плиз как этим чудом пользоваться???


unit BMUni;

(* -------------------------------------------------------------------

Ïîèñê ñòðîêè ìåòîäîì Boyer-Moore.

Ýòî - îäèí èç ñàìûõ áûñòðûõ àëãîðèòìîâ ïîèñêà ñòðîêè.
See a description in:

R. Boyer è S. Moore.
Áûñòðûé àëãîðèòì ïîèñêà ñòðîêè.
Communications of the ACM 20, 1977, ñòðàíèöû 762-772
------------------------------------------------------------------- *)

interface

type
{$IFDEF WINDOWS}

size_t = Word;
{$ELSE}

size_t = LongInt;
{$ENDIF}

type

TTranslationTable = array[char] of char; { òàáëèöà ïåðåâîäà }

TSearchBM = class(TObject)
private
FTranslate: TTranslationTable; { òàáëèöà ïåðåâîäà }
FJumpTable: array[char] of Byte; { òàáëèöà ïåðåõîäîâ }
FShift_1: integer;
FPattern: pchar;
FPatternLen: size_t;

public
procedure Prepare(Pattern: pchar; PatternLen: size_t; IgnoreCase: Boolean);
procedure PrepareStr(const Pattern: string; IgnoreCase: Boolean);

function Search(Text: pchar; TextLen: size_t): pchar;
function Pos(const S: string): integer;
end;

implementation

uses SysUtils;

(* -------------------------------------------------------------------

Èãíîðèðóåì ðåãèñòð òàáëèöû ïåðåâîäà
------------------------------------------------------------------- *)

procedure CreateTranslationTable(var T: TTranslationTable; IgnoreCase: Boolean);
var

c: char;
begin

for c := #0 to #255 do
T[c] := c;

if not IgnoreCase then
exit;

for c := 'a' to 'z' do
T[c] := UpCase(c);

{ Ñâÿçûâàåì âñå íèæíèå ñèìâîëû ñ èõ ýêâèâàëåíòîì âåðõíåãî ðåãèñòðà }

T['Á'] := 'A';
T['À'] := 'A';
T['Ä'] := 'A';
T['Â'] := 'A';

T['á'] := 'A';
T['à'] := 'A';
T['ä'] := 'A';
T['â'] := 'A';

T['É'] := 'E';
T['È'] := 'E';
T['Ë'] := 'E';
T['Ê'] := 'E';

T['é'] := 'E';
T['è'] := 'E';
T['ë'] := 'E';
T['ê'] := 'E';

T['Í'] := 'I';
T['Ì'] := 'I';
T['Ï'] := 'I';
T['Î'] := 'I';

T['í'] := 'I';
T['ì'] := 'I';
T['ï'] := 'I';
T['î'] := 'I';

T['Ó'] := 'O';
T['Ò'] := 'O';
T['Ö'] := 'O';
T['Ô'] := 'O';

T['ó'] := 'O';
T['ò'] := 'O';
T['ö'] := 'O';
T['ô'] := 'O';

T['Ú'] := 'U';
T['Ù'] := 'U';
T['Ü'] := 'U';
T['Û'] := 'U';

T['ú'] := 'U';
T['ù'] := 'U';
T['ü'] := 'U';
T['û'] := 'U';

T['ñ'] := 'Ñ';
end;

(* -------------------------------------------------------------------

Ïîäãîòîâêà òàáëèöû ïåðåõîäîâ
------------------------------------------------------------------- *)

procedure TSearchBM.Prepare(Pattern: pchar; PatternLen: size_t;

IgnoreCase: Boolean);
var

i: integer;
c, lastc: char;
begin

FPattern := Pattern;
FPatternLen := PatternLen;

if FPatternLen < 1 then
FPatternLen := strlen(FPattern);

{ Äàííûé àëãîðèòì áàçèðóåòñÿ íà íàáîðå èç 256 ñèìâîëîâ }

if FPatternLen > 256 then
exit;

{ 1. Ïîäãîòîâêà òàáëèöû ïåðåâîäà }

CreateTranslationTable(FTranslate, IgnoreCase);

{ 2. Ïîäãîòîâêà òàáëèöû ïåðåõîäîâ }

for c := #0 to #255 do
FJumpTable[c] := FPatternLen;

for i := FPatternLen - 1 downto 0 do
begin
c := FTranslate[FPattern[i]];
if FJumpTable[c] >= FPatternLen - 1 then
FJumpTable[c] := FPatternLen - 1 - i;
end;

FShift_1 := FPatternLen - 1;
lastc := FTranslate[Pattern[FPatternLen - 1]];

for i := FPatternLen - 2 downto 0 do
if FTranslate[FPattern[i]] = lastc then
begin
FShift_1 := FPatternLen - 1 - i;
break;
end;

if FShift_1 = 0 then
FShift_1 := 1;
end;

procedure TSearchBM.PrepareStr(const Pattern: string; IgnoreCase: Boolean);
var

str: pchar;
begin

if Pattern <> '' then
begin
{$IFDEF Windows}

str := @Pattern[1];
{$ELSE}

str := pchar(Pattern);
{$ENDIF}

Prepare(str, Length(Pattern), IgnoreCase);
end;
end;

{ Ïîèñê ïîñëåäíåãî ñèìâîëà & ïðîñìîòð ñïðàâà íàëåâî }

function TSearchBM.Search(Text: pchar; TextLen: size_t): pchar;

var
shift, m1, j: integer;
jumps: size_t;


begin
result := nil;
if FPatternLen > 256 then
exit;

if TextLen < 1 then
TextLen := strlen(Text);

m1 := FPatternLen - 1;
shift := 0;
jumps := 0;

{ Ïîèñê ïîñëåäíåãî ñèìâîëà }

while jumps <= TextLen do
begin
Inc(Text, shift);
shift := FJumpTable[FTranslate[Text^]];
while shift <> 0 do
begin
Inc(jumps, shift);
if jumps > TextLen then
exit;

Inc(Text, shift);
shift := FJumpTable[FTranslate[Text^]];
end;

{ Ñðàâíèâàåì ñïðàâà íàëåâî FPatternLen - 1 ñèìâîëîâ }

if jumps >= m1 then
begin
j := 0;
while FTranslate[FPattern[m1 - j]] = FTranslate[(Text - j)^] do
begin
Inc(j);
if j = FPatternLen then
begin
result := Text - m1;
exit;
end;
end;
end;

shift := FShift_1;
Inc(jumps, shift);
end;
end;

function TSearchBM.Pos(const S: string): integer;
var

str, p: pchar;
begin

result := 0;
if S <> '' then
begin
{$IFDEF Windows}

str := @S[1];
{$ELSE}

str := pchar(S);
{$ENDIF}

p := Search(str, Length(S));
if p <> nil then
result := 1 + p - str;
end;
end;

end.