delphi实现的Sunday字符串搜索算法
type
TBMKey=record
Length:Integer;
Offsets:array[0..255] of Integer;
ps:PAnsiChar;
end;
procedure InitKeyDistance(var AKey:TBMKey);
var
I:Integer;
begin
AKey.Length:=StrLen(AKey.ps);
for I := 0 to 255 do
AKey.Offsets[I]:=AKey.Length;
for I := 0 to AKey.Length-1 do
AKey.Offsets[Ord(AKey.ps[I])]:=AKey.Length-I-1;
end;
function SundayStrStrA(s:PAnsiChar;const Key:TBMKey):PAnsiChar;
var
i,pos,ls:Integer;
begin
if s=nil then
Result:=nil
else if Key.ps=nil then
Result:=s
else
begin
ls:=StrLen(s);
Result:=nil;
pos:=1;
while pos<=ls-Key.Length do
begin
I:=pos-1;
while I-pos+1
begin
if s[I]<>Key.ps[I-pos+1] then
Break;
Inc(I);
end;
if i-pos+1=Key.Length then
begin
Result:=s+pos-1;
Break;
end
else
Inc(pos,Key.Offsets[Ord(s[pos+Key.Length-1])]+1);
end;
end;
end;
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