'Classes/System/IO/StreamReader.ab

Namespace System
Namespace IO

/*
@brief ストリームから読み取りを行うTextReaderの実装。
@date 2008/02/25
@auther Egtra
*/
Class StreamReader
	Inherits TextReader
Public
	/*
	@date 2008/02/25
	@auther Egtra
	*/
	Sub StreamReader(path As String)
		init(New FileStream(path, FileMode.Open, FileAccess.Read, FileShare.Read))
	End Sub

	/*
	@date 2008/02/25
	@auther Egtra
	*/
	Sub StreamReader(stream As Stream)
		init(stream)
	End Sub

Public
	/*
	@brief 基になるストリームを取得する
	@date 2008/09/02
	@auther NoWest
	*/
	Function BaseStream () As Stream
		Return s
	End Function


Protected
	/*
	@date 2008/02/25
	@auther Egtra
	*/
	Override Sub Dispose(disposing As Boolean)
		If disposing Then
			If Not ActiveBasic.IsNothing(s) Then
				s.Dispose(True)
			End If
		End If
		s = Nothing
	End Sub

	/*
	@date 2008/12/27
	@auther Egtra
	*/
	Override Function Underflow() As Boolean
		Dim nextRead As *Byte
		Dim readSize = s.Read(mbBuf + bufSize, 0, bufCapacity - bufSize)
		If readSize = 0 Then
			If bufSize <> 0 Then
#ifdef UNCODE
				Buffer.Append(&hfffd As WCHAR)
#else
				Buffer.Append("?")
#endif
			End If
			Underflow = False
			Exit Function
		End If
		Dim mbLen = bufSize + readSize
		'文字全体が揃っている部分を抽出する。
		Dim pNext = mbBuf
		Do
			Dim q = e.NextChar(pNext, ((mbBuf + mbLen) - pNext) As Long)
			If q = pNext Then
				Exit Do
			End If
			pNext = q
		Loop
		'文字全体が揃っている部分を変換しTextReaderのバッファに送る。
		Dim wcBufCapacity = e.GetMaxCharCount(mbLen)
		Dim wcBuf = GC_malloc_atomic(wcBufCapacity * SizeOf (WCHAR)) As *WCHAR
		Dim wcLen = e.GetChars(mbBuf, (pNext - mbBuf) As Long, wcBuf, wcBufCapacity)
		Dim appendStr As PCTSTR
		Dim appendLen = GetStr(wcBuf, wcLen As SIZE_T, appendStr)
		Dim readerBuffer = Buffer
		readerBuffer.Append(appendStr, 0, appendLen)
		'マルチバイトの揃っていない部分を手前に連れてくる。
		bufSize = ((mbBuf + mbLen) - pNext) As Long
		If bufSize <> 0 Then
			memmove(mbBuf, mbBuf + mbLen, bufSize)
		End If
		Underflow = True
	End Function
Private

	/*
	@date 2008/02/25
	@auther Egtra
	*/
	Sub init(str As Stream)
		s = str
		e = New Text.Detail.WindowsCodePageEncoding(CP_ACP) '暫定。
		bufCapacity = 8192
		mbBuf = GC_malloc_atomic(bufCapacity) As *Byte
		bufSize = 0
	End Sub

	s As Stream
	e As Text.Encoding
	mbBuf As *Byte
	bufSize As Long
	bufCapacity As Long
End Class

End Namespace
End Namespace