restemplate/indy/System/IdStreamNET.pas

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{
$Project$
$Workfile$
$Revision$
$DateUTC$
$Id$
This file is part of the Indy (Internet Direct) project, and is offered
under the dual-licensing agreement described on the Indy website.
(http://www.indyproject.org/)
Copyright:
(c) 1993-2005, Chad Z. Hower and the Indy Pit Crew. All rights reserved.
}
{
$Log$
}
unit IdStreamNET;
interface
uses
Classes,
IdGlobal;
type
TIdStreamHelperNET = class
public
class function ReadBytes(
AStream: TStream;
var VBytes: TIdBytes;
ACount: Integer = -1;
AOffset: Integer = 0): Integer; static;
class function Write(
const AStream: TStream;
const ABytes: TIdBytes;
const ACount: Integer = -1;
const AOffset: Integer = 0): Integer; static;
class function Seek(
const AStream: TStream;
const AOffset: TIdStreamSize;
const AOrigin: TSeekOrigin) : TIdStreamSize; static;
end;
implementation
// RLebeau: must use a 'var' and not an 'out' for the VBytes parameter,
// or else any preallocated buffer the caller passes in will get wiped out!
class function TIdStreamHelperNET.ReadBytes(AStream: TStream; var VBytes: TIdBytes;
ACount, AOffset: Integer): Integer;
var
LActual: Integer;
begin
Assert(AStream<>nil);
Result := 0;
if VBytes = nil then begin
SetLength(VBytes, 0);
end;
//check that offset<length(buffer)? offset+count?
//is there a need for this to be called with an offset into a nil buffer?
LActual := ACount;
if LActual < 0 then begin
LActual := AStream.Size - AStream.Position;
end;
//this prevents eg reading 0 bytes at Offset=10 from allocating memory
if LActual = 0 then begin
Exit;
end;
if Length(VBytes) < (AOffset+LActual) then begin
SetLength(VBytes, AOffset+LActual);
end;
Assert(VBytes<>nil);
Result := AStream.Read(VBytes, AOffset, LActual);
end;
class function TIdStreamHelperNET.Write(const AStream: TStream;
const ABytes: TIdBytes; const ACount: Integer; const AOffset: Integer): Integer;
var
LActual: Integer;
begin
Result := 0;
Assert(AStream<>nil);
//should we raise assert instead of this nil check?
if ABytes <> nil then
begin
LActual := IndyLength(ABytes, ACount, AOffset);
if LActual > 0 then
begin
// RLebeau: Write raises an exception if the buffer can't be written in full
AStream.Write(ABytes, AOffset, LActual);
Result := LActual;
end;
end;
end;
class function TIdStreamHelperNET.Seek(const AStream: TStream; const AOffset: TIdStreamSize;
const AOrigin: TSeekOrigin): TIdStreamSize;
begin
Result := AStream.Seek(AOffset, AOrigin);
end;
end.