TLineStream class implementation
Contributor: MARTIN WALDENBURG
{+--------------------------------------------------------------------------+
| Class: TLineStream
| Created: 8.97
| Author: Martin Waldenburg
| Copyright 1997, all rights reserved.
| Description: TLineStream gives a buffered access to the lines of a
file.
| Every line must end with CRLF. Don't forget to flush the
| Memory after writing.
| Version: 1.2
| State: FreeWare
| Disclaimer:
| This is provided as is, expressly without a warranty of any kind.
| You use it at your own risc.
+--------------------------------------------------------------------------+}
unit mwLineStream;
interface
uses
SysUtils, Classes;
type
TLineStream = class(TFileStream)
private
fLineStart: PChar;
fMaxMemorySize:Longint;
fMaxLineSize:Longint;
fMemorySize: LongInt;
fLineSize:Longint;
fMemory:PChar;
fLine: PChar;
fFileEof:Boolean;
fMemoryPos: LongInt;
fEof:Boolean;
function GetMemoryFull:Boolean;
procedure SetMaxLineSize(NewValue:Longint);
procedure SetMaxMemorySize(NewValue:Longint);
protected
public
constructor create(Const FileName: string; Mode: Word);
destructor destroy;override;
procedure FillMemory;
function ReadLine:PChar;
procedure WriteLine(NewLine: String);
procedure FlushMemory;
procedure Reset;
property MaxMemorySize:Longint read fMaxMemorySize write
SetMaxMemorySize;
property MaxLineSize:Longint read fMaxLineSize write SetMaxLineSize;
property Memory:PChar read fMemory write fMemory;
property MemoryFull:Boolean read GetMemoryFull;
property FileEof:Boolean read fFileEof;
property Eof:Boolean read fEof write fEof;
published
end; { TLineStream }
implementation
constructor TLineStream.create(Const FileName: string; Mode: Word);
var
fHandle: Integer;
begin
if not FileExists(FileName) then
begin
fHandle:= FileCreate(FileName);
FileClose(fHandle);
end;
inherited create(FileName, Mode);
fEof:= False;
fFileEof:= False;
MaxMemorySize:= 65535;
fMemorySize:= 0;
fMemoryPos:= 0;
MaxLineSize:= 4096;
Position:= 0;
end; { create }
destructor TLineStream.destroy;
begin
ReallocMem(fMemory, 0);
ReallocMem(fLine, 0);
inherited destroy;
end; { destroy }
procedure TLineStream.SetMaxMemorySize(NewValue:Longint);
begin
fMaxMemorySize:= NewValue;
ReallocMem(fMemory, fMaxMemorySize +1);
end; { SetMaxMemorySize }
procedure TLineStream.SetMaxLineSize(NewValue:Longint);
begin
fMaxLineSize:= NewValue;
ReallocMem(fLine, fMaxLineSize +1);
end; { SetMaxLineSize }
procedure TLineStream.FillMemory;
var
Readed: LongInt;
begin
Readed:= Read(fMemory^, fMaxMemorySize);
fMemorySize:= Readed;
if Readed = 0 then fFileEof:= True;
if fMemorySize > 0 then
while fMemory[fMemorySize -2] <> #13 do dec(fMemorySize);
fMemory[fMemorySize]:= #0;
Position:= Position -Readed + fMemorySize +1;
fLineStart:= fMemory;
end; { FillMemory }
function TLineStream.GetMemoryFull:Boolean;
begin
if fMemorySize > 0 then Result:= True else Result:= False;
end; { GetMemoryFull }
function TLineStream.ReadLine:PChar;
var
Run: PChar;
begin
if (fMemorySize = 0) and not FileEof then FillMemory;
if fMemorySize > 0 then
begin
Run:= fLineStart;
while Run^ <> #13 do inc(Run);
fLineSize:= Run - fLineStart;
inc(Run, 2);
StrLCopy(fLine, fLineStart, fLineSize);
fLine[fLineSize]:= #0;
Result:= fLine;
fLineStart:= Run;
Case Run^ of #0: FillMemory end;
end;
if fMemorySize = 0 then fEof:= True;
end; { ReadLine }
procedure TLineStream.WriteLine(NewLine: String);
var
Count, Pos: Longint;
begin
NewLine:= NewLine + #13#10;
Count:= Length(NewLine);
if (fMemoryPos >= 0) and (Count >= 0) then
begin
Pos := fMemoryPos + Count;
if Pos > 0 then
begin
if Pos > FMaxMemorySize then
begin
FlushMemory;
end;
StrECopy((fMemory + fMemoryPos), PChar(NewLine));
fMemoryPos:= fMemoryPos + Count;
fMemory[fMemoryPos]:= #0;
end;
end;
end; { WriteLine }
procedure TLineStream.FlushMemory;
begin
Write(fMemory^, fMemoryPos);
fMemoryPos:= 0;
end; { FlushMemory }
procedure TLineStream.Reset;
begin
fEof:= False;
fFileEof:= False;
fMemorySize:= 0;
fMemoryPos:= 0;
Position:= 0;
end; { Reset }
end