2个不错的通配符比较函数

王朝delphi·作者佚名  2006-01-09
窄屏简体版  字體: |||超大  

近日在和朋友讨论 MaskMatch 时偶得2个不错的算法。

函数1 只支持'*','?'模糊匹配。速度比采用递归算法的快近2倍,比TMask方法快很多。

函数2 完全支持正规表达式。速度于之前的相同。(不会正规表达式的朋友慎用)

// ===========================

// Funtion 1

// ===========================

// Check if the string can match the wildcard. It can be used for unicode strings as well!

// C: 2004-07-24 | M: 2004-07-24

function MaskMatch(const aPattern, aSource: string): Boolean;

var

StringPtr, PatternPtr: PChar;

StringRes, PatternRes: PChar;

begin

Result := False;

StringPtr := PChar(UpperCase(aSource));

PatternPtr := PChar(UpperCase(aPattern));

StringRes := nil;

PatternRes := nil;

repeat

repeat // ohne vorangegangenes "*"

case PatternPtr^ of

#0 : begin

Result := StringPtr^ = #0;

if Result or (StringRes = nil) or (PatternRes = nil) then Exit;

StringPtr := StringRes;

PatternPtr := PatternRes;

Break;

end;

'*': begin

Inc(PatternPtr);

PatternRes := PatternPtr;

Break;

end;

'?': begin

if StringPtr^ = #0 then Exit;

Inc(StringPtr);

Inc(PatternPtr);

end;

else begin

if StringPtr^ = #0 then Exit;

if StringPtr^ <> PatternPtr^ then

begin

if (StringRes = nil) or (PatternRes = nil) then Exit;

StringPtr := StringRes;

PatternPtr := PatternRes;

Break;

end else

begin

Inc(StringPtr);

Inc(PatternPtr);

end;

end;

end;

until False;

repeat // mit vorangegangenem "*"

case PatternPtr^ of

#0 : begin

Result := True;

Exit;

end;

'*': begin

Inc(PatternPtr);

PatternRes := PatternPtr;

end;

'?': begin

if StringPtr^ = #0 then Exit;

Inc(StringPtr);

Inc(PatternPtr);

end;

else begin

repeat

if StringPtr^ = #0 then Exit;

if StringPtr^ = PatternPtr^ then Break;

Inc(StringPtr);

until False;

Inc(StringPtr);

StringRes := StringPtr;

Inc(PatternPtr);

Break;

end;

end;

until False;

until False;

end;

// ===========================

// Funtion 2

// ===========================

function _MatchPattern(aPattern, aSource: PChar): Boolean;

begin

Result := True;

while (True) do

begin

case aPattern[0] of

#0 : begin

//End of pattern reached.

Result := (aSource[0] = #0); //TRUE if end of aSource.

Exit;

end;

'*': begin //Match zero or more occurances of any char.

if (aPattern[1] = #0) then

begin

//Match any number of trailing chars.

Result := True;

Exit;

end else

Inc(aPattern);

while (aSource[0] <> #0) do

begin

//Try to match any substring of aSource.

if (_MatchPattern(aSource, aPattern)) then

begin

Result := True;

Exit;

end;

//Continue testing next char...

Inc(aSource);

end;

end;

'?': begin //Match any one char.

if (aSource[0] = #0) then

begin

Result := False;

Exit;

end;

//Continue testing next char...

Inc(aSource);

Inc(aPattern);

end;

'[': begin //Match given set of chars.

if (aPattern[1] in [#0,'[',']']) then

begin

//Invalid Set - So no match.

Result := False;

Exit;

end;

if (aPattern[1] = '^') then

begin

//Match for exclusion of given set...

Inc(aPattern, 2);

Result := True;

while (aPattern[0] <> ']') do

begin

if (aPattern[1] = '-') then

begin

//Match char exclusion range.

if (aSource[0] >= aPattern[0]) and (aSource[0] <= aPattern[2]) then

begin

//Given char failed set exclusion range.

Result := False;

Break;

end else

Inc(aPattern, 3);

end else

begin

//Match individual char exclusion.

if (aSource[0] = aPattern[0]) then

begin

//Given char failed set element exclusion.

Result := False;

Break;

end else

Inc(aPattern);

end;

end;

end else

begin

//Match for inclusion of given set...

Inc(aPattern);

Result := False;

while (aPattern[0] <> ']') do

begin

if (aPattern[1] = '-') then

begin

//Match char inclusion range.

if (aSource[0] >= aPattern[0]) and (aSource[0] <= aPattern[2]) then

begin

//Given char matched set range inclusion.

// Continue testing...

Result := True;

Break;

end else

Inc(aPattern, 3);

end else

begin

//Match individual char inclusion.

if (aSource[0] = aPattern[0]) then

begin

//Given char matched set element inclusion.

// Continue testing...

Result := True;

Break;

end else

Inc(aPattern);

end;

end;

end;

if (Result) then

begin

//Match was found. Continue further.

Inc(aSource);

//Position Pattern to char after "]"

while (aPattern[0] <> ']') and (aPattern[0] <> #0) do Inc(aPattern);

if (aPattern[0] = #0) then

begin

//Invalid Pattern - missing "]"

Result := False;

Exit;

end else

Inc(aPattern);

end else

Exit;

end;

else begin //Match given single char.

if (aSource[0] <> aPattern[0]) then

begin

Result := False;

Break;

end;

//Continue testing next char...

Inc(aSource);

Inc(aPattern);

end;

end;

end;

end;

function MatchPattern(const aPattern, aSource: string): Boolean;

begin

Result := _MatchPattern(PChar(aPattern), PChar(aSource));

end;

 
 
 
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