faststrings.pas

自己写的一个 RSS 阅读器

unit FastStrings;

interface

uses
   {$IFNDEF LINUX}
     Windows,
   {$ENDIF}
   SysUtils,Classes,ActiveX;

//This TYPE declaration will become apparent later
type
  TBMJumpTable = array[0..255] of Integer;
  TFastPosProc = function (const aSource, aFind: Pointer; const aSourceLen, aFindLen: Integer; var JumpTable: TBMJumpTable): Pointer;
  TFastPosIndexProc = function (const aSourceString, aFindString: string; const aSourceLen, aFindLen, StartPos: Integer; var JumpTable: TBMJumpTable): Integer;
  TFastTagReplaceProc = procedure (var Tag: string; const UserData: Integer);


//Boyer-Moore routines
procedure MakeBMTable(Buffer: PChar; BufferLen: Integer; var JumpTable: TBMJumpTable);
procedure MakeBMTableNoCase(Buffer: PChar; BufferLen: Integer; var JumpTable: TBMJumpTable);
function BMPos(const aSource, aFind: Pointer; const aSourceLen, aFindLen: Integer; var JumpTable: TBMJumpTable): Pointer;
function BMPosNoCase(const aSource, aFind: Pointer; const aSourceLen, aFindLen: Integer; var JumpTable: TBMJumpTable): Pointer;

function FastAnsiReplace(const S, OldPattern, NewPattern: string; Flags: TReplaceFlags): string;
procedure FastCharMove(const Source; var Dest; Count : Integer);
function FastCharPos(const aSource : string; const C: Char; StartPos : Integer): Integer;
function FastCharPosNoCase(const aSource : string; C: Char; StartPos : Integer): Integer;
function FastPos(const aSourceString, aFindString : string; const aSourceLen, aFindLen, StartPos : Integer) : Integer;
function FastPosNoCase(const aSourceString, aFindString : string; const aSourceLen, aFindLen, StartPos : Integer) : Integer;
function FastPosBack(const aSourceString, aFindString : string; const aSourceLen, aFindLen, StartPos : Integer) : Integer;
function FastPosBackNoCase(const aSourceString, aFindString : string; const aSourceLen, aFindLen, StartPos : Integer) : Integer;
function FastReplace(const aSourceString : string; const aFindString, aReplaceString : string;
  CaseSensitive : Boolean = False) : string;
function FastTagReplace(const SourceString, TagStart, TagEnd: string;
  FastTagReplaceProc: TFastTagReplaceProc; const UserData: Integer): string;
function SmartPos(const SearchStr,SourceStr : string;
                  const CaseSensitive : Boolean = TRUE;
                  const StartPos : Integer = 1;
                  const ForwardSearch : Boolean = TRUE) : Integer;

function SplitString(const Source,ch:string):TStringList;
function CreateGuid: string;
function ExtractURLPath(aURL:WideString):WideString;
function CheckSpecialChar(AText:string):Boolean;

implementation

const
  cDeltaSize = 1.5;

var
  GUpcaseTable : array[0..255] of char;
  GUpcaseLUT: Pointer;

//MakeBMJumpTable takes a FindString and makes a JumpTable
procedure MakeBMTable(Buffer: PChar; BufferLen: Integer; var JumpTable: TBMJumpTable);
begin
  if BufferLen = 0 then raise Exception.Create('BufferLen is 0');
  asm
        push    EDI
        push    ESI

        mov     EDI, JumpTable
        mov     EAX, BufferLen
        mov     ECX, $100
        REPNE   STOSD

        mov     ECX, BufferLen
        mov     EDI, JumpTable
        mov     ESI, Buffer
        dec     ECX
        xor     EAX, EAX
@@loop:
        mov     AL, [ESI]
        lea     ESI, ESI + 1
        mov     [EDI + EAX * 4], ECX
        dec     ECX
        jg      @@loop

        pop     ESI
        pop     EDI
  end;
end;

procedure MakeBMTableNoCase(Buffer: PChar; BufferLen: Integer; var JumpTable: TBMJumpTable);
begin
  if BufferLen = 0 then raise Exception.Create('BufferLen is 0');
  asm
        push    EDI
        push    ESI

        mov     EDI, JumpTable
        mov     EAX, BufferLen
        mov     ECX, $100
        REPNE   STOSD

        mov     EDX, GUpcaseLUT
        mov     ECX, BufferLen
        mov     EDI, JumpTable
        mov     ESI, Buffer
        dec     ECX
        xor     EAX, EAX
@@loop:
        mov     AL, [ESI]
        lea     ESI, ESI + 1
        mov     AL, [EDX + EAX]
        mov     [EDI + EAX * 4], ECX
        dec     ECX
        jg      @@loop

        pop     ESI
        pop     EDI
  end;
end;

function BMPos(const aSource, aFind: Pointer; const aSourceLen, aFindLen: Integer; var JumpTable: TBMJumpTable): Pointer;
var
  LastPos: Pointer;
begin
  LastPos := Pointer(Integer(aSource) + aSourceLen - 1);
  asm
        push    ESI
        push    EDI
        push    EBX

        mov     EAX, aFindLen
        mov     ESI, aSource
        lea     ESI, ESI + EAX - 1
        std
        mov     EBX, JumpTable

@@comparetext:
        cmp     ESI, LastPos
        jg      @@NotFound
        mov     EAX, aFindLen
        mov     EDI, aFind
        mov     ECX, EAX
        push    ESI //Remember where we are
        lea     EDI, EDI + EAX - 1
        xor     EAX, EAX
@@CompareNext:
        mov     al, [ESI]
        cmp     al, [EDI]
        jne     @@LookAhead
        lea     ESI, ESI - 1
        lea     EDI, EDI - 1
        dec     ECX
        jz      @@Found
        jmp     @@CompareNext

@@LookAhead:
        //Look up the char in our Jump Table
        pop     ESI
        mov     al, [ESI]
        mov     EAX, [EBX + EAX * 4]
        lea     ESI, ESI + EAX
        jmp     @@CompareText

@@NotFound:
        mov     Result, 0
        jmp     @@TheEnd
@@Found:
        pop     EDI //We are just popping, we don't need the value
        inc     ESI
        mov     Result, ESI
@@TheEnd:
        cld
        pop     EBX
        pop     EDI
        pop     ESI
  end;
end;

function BMPosNoCase(const aSource, aFind: Pointer; const aSourceLen, aFindLen: Integer; var JumpTable: TBMJumpTable): Pointer;
var
  LastPos: Pointer;
begin
  LastPos := Pointer(Integer(aSource) + aSourceLen - 1);
  asm
        push    ESI
        push    EDI
        push    EBX

        mov     EAX, aFindLen
        mov     ESI, aSource
        lea     ESI, ESI + EAX - 1
        std
        mov     EDX, GUpcaseLUT

@@comparetext:
        cmp     ESI, LastPos
        jg      @@NotFound
        mov     EAX, aFindLen
        mov     EDI, aFind
        push    ESI //Remember where we are
        mov     ECX, EAX
        lea     EDI, EDI + EAX - 1
        xor     EAX, EAX
@@CompareNext:
        mov     al, [ESI]
        mov     bl, [EDX + EAX]
        mov     al, [EDI]
        cmp     bl, [EDX + EAX]
        jne     @@LookAhead
        lea     ESI, ESI - 1
        lea     EDI, EDI - 1
        dec     ECX
        jz      @@Found
        jmp     @@CompareNext

@@LookAhead:
        //Look up the char in our Jump Table
        pop     ESI
        mov     EBX, JumpTable
        mov     al, [ESI]
        mov     al, [EDX + EAX]
        mov     EAX, [EBX + EAX * 4]
        lea     ESI, ESI + EAX
        jmp     @@CompareText

@@NotFound:
        mov     Result, 0
        jmp     @@TheEnd
@@Found:
        pop     EDI //We are just popping, we don't need the value
        inc     ESI
        mov     Result, ESI
@@TheEnd:
        cld
        pop     EBX
        pop     EDI
        pop     ESI
  end;
end;


//NOTE : FastCharPos and FastCharPosNoCase do not require you to pass the length
//       of the string, this was only done in FastPos and FastPosNoCase because
//       they are used by FastReplace many times over, thus saving a LENGTH()
//       operation each time.  I can't see you using these two routines for the
//       same purposes so I didn't do that this time !
function FastCharPos(const aSource : string; const C: Char; StartPos : Integer) : Integer;
var
  L                           : Integer;
begin
  //If this assert failed, it is because you passed 0 for StartPos, lowest value is 1 !!
  Assert(StartPos > 0);

  Result := 0;
  L := Length(aSource);
  if L = 0 then exit;
  if StartPos > L then exit;
  Dec(StartPos);
  asm
      PUSH EDI                 //Preserve this register

      mov  EDI, aSource        //Point EDI at aSource
      add  EDI, StartPos
      mov  ECX, L              //Make a note of how many chars to search through
      sub  ECX, StartPos
      mov  AL,  C              //and which char we want
    @Loop:
      cmp  Al, [EDI]           //compare it against the SourceString
      jz   @Found
      inc  EDI
      dec  ECX
      jnz  @Loop
      jmp  @NotFound
    @Found:
      sub  EDI, aSource        //EDI has been incremented, so EDI-OrigAdress = Char pos !
      inc  EDI
      mov  Result,   EDI
    @NotFound:

      POP  EDI
  end;
end;

function FastCharPosNoCase(const aSource : string; C: Char; StartPos : Integer) : Integer;
var
  L                           : Integer;
begin
  Result := 0;
  L := Length(aSource);
  if L = 0 then exit;
  if StartPos > L then exit;
  Dec(StartPos);
  if StartPos < 0 then StartPos := 0;

  asm
      PUSH EDI                 //Preserve this register
      PUSH EBX
      mov  EDX, GUpcaseLUT

      mov  EDI, aSource        //Point EDI at aSource
      add  EDI, StartPos
      mov  ECX, L              //Make a note of how many chars to search through
      sub  ECX, StartPos

      xor  EBX, EBX
      mov  BL,  C
      mov  AL, [EDX+EBX]
    @Loop:
      mov  BL, [EDI]
      inc  EDI
      cmp  Al, [EDX+EBX]
      jz   @Found
      dec  ECX
      jnz  @Loop
      jmp  @NotFound
    @Found:
      sub  EDI, aSource        //EDI has been incremented, so EDI-OrigAdress = Char pos !
      mov  Result,   EDI
    @NotFound:

      POP  EBX
      POP  EDI
  end;
end;

//The first thing to note here is that I am passing the SourceLength and FindLength
//As neither Source or Find will alter at any point during FastReplace there is
//no need to call the LENGTH subroutine each time !
function FastPos(const aSourceString, aFindString : string; const aSourceLen, aFindLen, StartPos : Integer) : Integer;
var
  JumpTable: TBMJumpTable;
begin
  //If this assert failed, it is because you passed 0 for StartPos, lowest value is 1 !!
  Assert(StartPos > 0);
  if aFindLen < 1 then begin
    Result := 0;
    exit;
  end;
  if aFindLen > aSourceLen then begin
    Result := 0;
    exit;
  end;

  MakeBMTable(PChar(aFindString), aFindLen, JumpTable);
  Result := Integer(BMPos(PChar(aSourceString) + (StartPos - 1), PChar(aFindString),aSourceLen - (StartPos-1), aFindLen, JumpTable));
  if Result > 0 then
    Result := Result - Integer(@aSourceString[1]) +1;
end;

function FastPosNoCase(const aSourceString, aFindString : string; const aSourceLen, aFindLen, StartPos : Integer) : Integer;
var
  JumpTable: TBMJumpTable;
begin
  //If this assert failed, it is because you passed 0 for StartPos, lowest value is 1 !!
  Assert(StartPos > 0);
  if aFindLen < 1 then begin
    Result := 0;
    exit;
  end;
  if aFindLen > aSourceLen then begin
    Result := 0;
    exit;
  end;

  MakeBMTableNoCase(PChar(AFindString), aFindLen, JumpTable);
  Result := Integer(BMPosNoCase(PChar(aSourceString) + (StartPos - 1), PChar(aFindString),aSourceLen - (StartPos-1), aFindLen, JumpTable));
  if Result > 0 then
    Result := Result - Integer(@aSourceString[1]) +1;
end;

function FastPosBack(const aSourceString, aFindString : string; const aSourceLen, aFindLen, StartPos : Integer) : Integer;
var
  SourceLen : Integer;
begin
  if aFindLen < 1 then begin
    Result := 0;
    exit;
  end;
  if aFindLen > aSourceLen then begin
    Result := 0;
    exit;
  end;

  if (StartPos = 0) or  (StartPos + aFindLen > aSourceLen) then
    SourceLen := aSourceLen - (aFindLen-1)
  else
    SourceLen := StartPos;

  asm
          push ESI
          push EDI
          push EBX

          mov EDI, aSourceString
          add EDI, SourceLen
          Dec EDI

          mov ESI, aFindString
          mov ECX, SourceLen
          Mov  Al, [ESI]

    @ScaSB:
          cmp  Al, [EDI]
          jne  @NextChar

    @CompareStrings:
          mov  EBX, aFindLen
          dec  EBX
          jz   @FullMatch

    @CompareNext:
          mov  Ah, [ESI+EBX]
          cmp  Ah, [EDI+EBX]
          Jnz  @NextChar

    @Matches:
          Dec  EBX
          Jnz  @CompareNext

    @FullMatch:
          mov  EAX, EDI
          sub  EAX, aSourceString
          inc  EAX
          mov  Result, EAX
          jmp  @TheEnd
    @NextChar:
          dec  EDI
          dec  ECX
          jnz  @ScaSB

          mov  Result,0

    @TheEnd:
          pop  EBX
          pop  EDI
          pop  ESI
  end;
end;


function FastPosBackNoCase(const aSourceString, aFindString : string; const aSourceLen, aFindLen, StartPos : Integer) : Integer;
var
  SourceLen : Integer;
begin
  if aFindLen < 1 then begin
    Result := 0;
    exit;
  end;
  if aFindLen > aSourceLen then begin
    Result := 0;
    exit;
  end;

  if (StartPos = 0) or  (StartPos + aFindLen > aSourceLen) then
    SourceLen := aSourceLen - (aFindLen-1)
  else
    SourceLen := StartPos;

  asm
          push ESI
          push EDI
          push EBX

          mov  EDI, aSourceString
          add  EDI, SourceLen
          Dec  EDI

          mov  ESI, aFindString
          mov  ECX, SourceLen

          mov  EDX, GUpcaseLUT
          xor  EBX, EBX

          mov  Bl, [ESI]
          mov  Al, [EDX+EBX]

    @ScaSB:
          mov  Bl, [EDI]
          cmp  Al, [EDX+EBX]
          jne  @NextChar

    @CompareStrings:
          PUSH ECX
          mov  ECX, aFindLen
          dec  ECX
          jz   @FullMatch

    @CompareNext:
          mov  Bl, [ESI+ECX]
          mov  Ah, [EDX+EBX]
          mov  Bl, [EDI+ECX]
          cmp  Ah, [EDX+EBX]
          Jz   @Matches