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正在阅读:Delphi学习:2个不错的通配符比较函数Delphi学习:2个不错的通配符比较函数

2004-09-13 14:41 出处:CSDN 作者:Stanley_Xu 责任编辑:linjixiong

  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)



  // ===========================
  // Function 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;



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  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;


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  // ===========================
  // Function 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;

 


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  //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

 


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  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 "]"

 


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  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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