VBA解析复合文档07——Parse参数IReadWrite

Function Read(b() As Byte) As Long

End Function
Function ReadByte() As Byte

End Function
Function ReadInteger() As Integer

End Function
Function ReadLong() As Long

End Function
Function ReadDate() As Date

End Function
'在offset处开始读取
Function ReadAt(b() As Byte, offset As Long) As Long

End Function

'设置读取的位置
Function SeekFile(offsetZeroBase As Long, whence As SeekPos) As Long

End Function

'写入文件
Function WriteFile(b() As Byte) As Long
    
End Function
Function WriteLong(l As Long) As Long
    
End Function

Option Explicit

Implements IReadWrite

'下标为0的Byte数组
Private bSrc() As Byte
'当前读取的下标
Private pos As Long
'数组的长度
Private lLen As Long

'设置数据源
Property Let SetData(v() As Byte)
    bSrc = v
    lLen = UBound(bSrc) + 1
End Property
'获取数据源
Property Get GetData() As Byte()
    GetData = bSrc
End Property

Function Read(b() As Byte) As Long
    Dim i As Long
    Dim ilen As Long
    
    ilen = UBound(b) + 1
    If ilen + pos > lLen Then ilen = lLen + (lLen - pos)
    
    For i = 0 To ilen - 1
        b(i) = ReadByte()
    Next
    
    Read = ilen
End Function
Function ReadAt(b() As Byte, offset As Long) As Long
    pos = offset
    ReadAt = Read(b)
End Function
Function ReadByte() As Byte
    If pos >= lLen Then
        Exit Function
    End If
    
    ReadByte = bSrc(pos)
    pos = pos + 1
End Function
Function ReadInteger() As Integer
    Dim b1 As Byte, b2 As Byte
    
    b1 = ReadByte()
    b2 = ReadByte()
    
    ReadInteger = BitMoveLeftInt(VBA.CInt(b2), 8) Or VBA.CInt(b1)
End Function
Function ReadLong() As Long
    Dim l(4 - 1) As Long
    Dim i As Long
    
    For i = 0 To 4 - 1
        l(i) = VBA.CLng(ReadByte())
    Next
    
    ReadLong = BitMoveLeft(l(3), 3 * 8) Or BitMoveLeft(l(2), 2 * 8) Or BitMoveLeft(l(1), 1 * 8) Or l(0)
End Function

Function ReadDate() As Date
    Dim l(8 - 1) As Long
    Dim i As Long
    
    For i = 0 To 8 - 1
        l(i) = VBA.CLng(ReadByte())
    Next
    
    'TODO 待完成
    ReadDate = 0
End Function

Function SeekFile(offsetZeroBase As Long, whence As vbapIO.SeekPos) As Long
    If whence = SeekPos.OriginF Then
        pos = offsetZeroBase
    ElseIf whence = SeekPos.CurrentF Then
        pos = pos + offsetZeroBase
    Else
        pos = lLen - offsetZeroBase - 1
    End If
    
    SeekFile = pos
End Function
Function WriteFile(b() As Byte) As Long
    'TODO 待完成
End Function
Function WriteLong(l As Long) As Long
    'TODO 待完成
End Function

'实现接口
Private Function IReadWrite_Read(b() As Byte) As Long
    IReadWrite_Read = Read(b)
End Function
Private Function IReadWrite_ReadAt(b() As Byte, offset As Long) As Long
    IReadWrite_ReadAt = ReadAt(b, offset)
End Function
Private Function IReadWrite_ReadByte() As Byte
    IReadWrite_ReadByte = ReadByte()
End Function
Private Function IReadWrite_ReadDate() As Date
    IReadWrite_ReadDate = ReadDate()
End Function
Private Function IReadWrite_ReadInteger() As Integer
    IReadWrite_ReadInteger = ReadInteger()
End Function
Private Function IReadWrite_ReadLong() As Long
    IReadWrite_ReadLong = ReadLong()
End Function
Private Function IReadWrite_SeekFile(offsetZeroBase As Long, whence As vbapIO.SeekPos) As Long
    IReadWrite_SeekFile = SeekFile(offsetZeroBase, whence)
End Function
Private Function IReadWrite_WriteFile(b() As Byte) As Long
    IReadWrite_WriteFile = WriteFile(b)
End Function
Private Function IReadWrite_WriteLong(l As Long) As Long
    IReadWrite_WriteLong = WriteLong(l)
End Function