unit StreamFile;

interface

Uses

SysUtils;

Procedure AssignStreamFile (var F : Text ; Filename : String);

implementation

Const

BufferSize = 128;

Type

TStreamBuffer = Array [1..High (Integer)] of Char;
TStreamBufferPointer = ^TStreamBuffer;


TStreamFileRecord = Record
Case Integer Of
1:
(
Filehandle : Integer;
Buffer : TStreamBufferPointer;
BufferOffset : Integer;
ReadCount : Integer;
);
2:
(
Dummy : Array [1 .. 32] Of Char
)
End;


Function StreamFileOpen (var F : TTextRec) : Integer;

Var
Status : Integer;
Begin
With TStreamFileRecord (F.UserData) Do
Begin
GetMem (Buffer, BufferSize);
Case F.Mode Of
fmInput:
FileHandle := FileOpen (StrPas (F.Name), fmShareDenyNone);
fmOutput:
FileHandle := FileCreate (StrPas (F.Name));
fmInOut:
Begin
FileHandle := FileOpen (StrPas (F.Name), fmShareDenyNone Or
fmOpenWrite or fmOpenRead);

If FileHandle <> -1 Then
status := FileSeek (FileHandle, 0, 2); { Перемещаемся в конец файла. }
F.Mode := fmOutput;
End;
End;
BufferOffset := 0;
ReadCount := 0;
F.BufEnd := 0; { В этом месте подразумеваем что мы достигли конца файла (eof). }
If FileHandle = -1 Then
Result := -1
Else
Result := 0;
End;
End;

Function StreamFileInOut (var F : TTextRec) : Integer;

Procedure Read (var Data : TStreamFileRecord);
Procedure CopyData;
Begin
While (F.BufEnd < Sizeof (F.Buffer) - 2)
And (Data.BufferOffset <= Data.ReadCount)
And (Data.Buffer [Data.BufferOffset] <> #10) Do
Begin
F.Buffer [F.BufEnd] := Data.Buffer^ [Data.BufferOffset];
Inc (Data.BufferOffset);
Inc (F.BufEnd);
End;
If Data.Buffer [Data.BufferOffset] = #10 Then
Begin
F.Buffer [F.BufEnd] := #13;
Inc (F.BufEnd);
F.Buffer [F.BufEnd] := #10;
Inc (F.BufEnd);
Inc (Data.BufferOffset);
End;
End;


Begin


F.BufEnd := 0;
F.BufPos := 0;
F.Buffer := '';
Repeat
Begin
If (Data.ReadCount = 0) Or (Data.BufferOffset > Data.ReadCount) Then
Begin
Data.BufferOffset := 1;
Data.ReadCount := FileRead (Data.FileHandle, Data.Buffer^, BufferSize);
End;
CopyData;
End Until (Data.ReadCount = 0)
Or (F.BufEnd >= Sizeof (F.Buffer) - 2);
Result := 0;
End;


Procedure Write (var Data : TStreamFileRecord);
Var
Status : Integer;
Destination : Integer;
II : Integer;
Begin
With TStreamFileRecord (F.UserData) Do
Begin
Destination := 0;
For II := 0 To F.BufPos - 1 Do
Begin
If F.Buffer [II] <> #13 Then
Begin
Inc (Destination);
Buffer^[Destination] := F.Buffer [II];
End;
End;
Status := FileWrite (FileHandle, Buffer^, Destination);
F.BufPos := 0;
Result := 0;
End;
End;
Begin
Case F.Mode Of
fmInput:
Read (TStreamFileRecord (F.UserData));
fmOutput:
Write (TStreamFileRecord (F.UserData));
End;
End;

Function StreamFileFlush (var F : TTextRec) : Integer;

Begin
Result := 0;
End;

Function StreamFileClose (var F : TTextRec) : Integer;

Begin
With TStreamFileRecord (F.UserData) Do
Begin
FreeMem (Buffer);
FileClose (FileHandle);
End;
Result := 0;
End;

Procedure AssignStreamFile (var F : Text ; Filename : String);

Begin
With TTextRec (F) Do
Begin
Mode := fmClosed;
BufPtr := @Buffer;
BufSize := Sizeof (Buffer);
OpenFunc := @StreamFileOpen;
InOutFunc := @StreamFileInOut;
FlushFunc := @StreamFileFlush;
CloseFunc := @StreamFileClose;
StrPLCopy (Name, FileName, Sizeof(Name) - 1);
End;
End;
end.