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FileStreamLineEx.pas
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// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
unit
FileStreamLineEx;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
interface
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
uses
Classes;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
type
TFileStreamLineEx = class
private
Stream: TStream;
CurrentLine: String;
public
constructor Create(Stream: TStream);
public
function ReadLine(var OutputLine: String): Boolean;
private
function TryFindLineTerminator(const CurrentLine: String; var Position, Length: Integer): Boolean;
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
implementation
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
const
LINE_READ_CHUNK = 2048;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
constructor TFileStreamLineEx.Create(Stream: TStream);
begin
Self.Stream := Stream; SetLength(Self.CurrentLine, 0);
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
function TFileStreamLineEx.TryFindLineTerminator(const CurrentLine: String; var Position, Length: Integer): Boolean;
var
i: Integer;
begin
i := Pos(#13#10, CurrentLine);
if (i > 0) then begin
Position := i; Length := 2; Result := True; Exit;
end;
i := Pos(#10, CurrentLine);
if (i > 0) then begin
Position := i; Length := 1; Result := True; Exit;
end;
Result := False;
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
function TFileStreamLineEx.ReadLine(var OutputLine: String): Boolean;
var
ChunkData: String; ChunkSize: Integer; LineTerminatorFound: Boolean; LineTerminatorPosition, LineTerminatorLength: Integer;
begin
LineTerminatorFound := Self.TryFindLineTerminator(Self.CurrentLine, LineTerminatorPosition, LineTerminatorLength); while not LineTerminatorFound do begin
SetLength(ChunkData, LINE_READ_CHUNK); ChunkSize := Stream.Read(ChunkData[1], LINE_READ_CHUNK); if (ChunkSize > 0) then begin
Self.CurrentLine := Self.CurrentLine + Copy(ChunkData, 1, ChunkSize);
LineTerminatorFound := Self.TryFindLineTerminator(Self.CurrentLine, LineTerminatorPosition, LineTerminatorLength);
end else begin
Break;
end;
end; if LineTerminatorFound then begin
OutputLine := Copy(Self.CurrentLine, 1, LineTerminatorPosition - 1); Delete(Self.CurrentLine, 1, LineTerminatorPosition + LineTerminatorLength - 1);
Result := True;
end else begin
OutputLine := Self.CurrentLine; SetLength(Self.CurrentLine, 0);
Result := False;
end;
end;
// --------------------------------------------------------------------------
//
// --------------------------------------------------------------------------
end.