CentrED/UBufferedStreams.pas

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(*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at
* http://www.opensource.org/licenses/cddl1.php.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at
* http://www.opensource.org/licenses/cddl1.php. If applicable,
* add the following below this CDDL HEADER, with the fields enclosed
* by brackets "[]" replaced with your own identifying * information:
* Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*
*
* Portions Copyright 2007 Andreas Schneider
*)
unit UBufferedStreams;
{$mode objfpc}{$H+}
interface
uses
SysUtils, Classes, UEnhancedMemoryStream;
type
TBufferedStream = class(TEnhancedMemoryStream)
constructor Create(ABaseStream: TStream; AOwnsBaseStream: Boolean = false); virtual;
destructor Destroy; override;
protected
FBaseStream: TStream;
FOwnsBaseStream: Boolean;
public
procedure Refresh; virtual;
procedure Flush; virtual;
end;
TBufferedReader = class(TBufferedStream)
constructor Create(ABaseStream: TStream; AOwnsBaseStream: Boolean = false); override;
destructor Destroy; override;
protected
FReadBuffer: TEnhancedMemoryStream;
public
function Write(const Buffer; Count: Longint): Longint; override;
function Read(var Buffer; Count: Longint): Longint; override;
function Seek(Offset: Longint; Origin: Word): Longint; override;
procedure Refresh; override;
end;
implementation
{ TBufferedStream }
constructor TBufferedStream.Create(ABaseStream: TStream;
AOwnsBaseStream: Boolean);
begin
inherited Create;
FBaseStream := ABaseStream;
FOwnsBaseStream := AOwnsBaseStream;
Refresh;
end;
destructor TBufferedStream.Destroy;
begin
if FOwnsBaseStream and Assigned(FBaseStream) then
FreeAndNil(FBaseStream);
inherited;
end;
procedure TBufferedStream.Flush;
begin
FBaseStream.Size := Size;
FBaseStream.Position := 0;
FBaseStream.CopyFrom(Self, 0);
end;
procedure TBufferedStream.Refresh;
begin
Size := FBaseStream.Size;
Position := 0;
CopyFrom(FBaseStream, 0);
end;
{ TBufferedReader }
constructor TBufferedReader.Create(ABaseStream: TStream;
AOwnsBaseStream: Boolean);
begin
FReadBuffer := TEnhancedMemoryStream.Create;
inherited;
end;
destructor TBufferedReader.Destroy;
begin
if Assigned(FReadBuffer) then FreeAndNil(FReadBuffer);
inherited;
end;
function TBufferedReader.Read(var Buffer; Count: Integer): Longint;
begin
Result := FReadBuffer.Read(Buffer, Count);
end;
procedure TBufferedReader.Refresh;
begin
FReadBuffer.Size := FBaseStream.Size;
FReadBuffer.Position := 0;
FReadBuffer.CopyFrom(FBaseStream, 0);
FReadBuffer.Position := 0;
FBaseStream.Position := 0;
end;
function TBufferedReader.Seek(Offset: Integer; Origin: Word): Longint;
begin
FBaseStream.Seek(Offset, Origin);
Result := FReadBuffer.Seek(Offset, Origin);
end;
function TBufferedReader.Write(const Buffer; Count: Integer): Longint;
begin
FBaseStream.Position := FReadBuffer.Position;
FBaseStream.Write(Buffer, Count);
Result := FReadBuffer.Write(Buffer, Count);
end;
end.