FileLog.vbs

Option Explicit

'--------------------------------------------------------------------------------
' ScriptName    : FileLog.vbs   (was the extensionless note file "log write")
' Creator       : Sungman Han
' Creation Date : 2019-09-16
' Description   : Text file read / write helpers for the logging these SAP scripts
'                 do while running unattended.
'
' Usage         : AppendLine "C:\log\aae.log", "started"
'                 vText  = ReadAllText("C:\log\aae.log")
'                 vLines = ReadLines("C:\log\aae.log")   ' array, empty file -> Array()
'
' Note          : the original file was a pasted note whose quotes were smart quotes
'                 (U+201C / U+201D), so it could not run at all. It is real code now.
'
' OpenTextFile(path, iomode, create, format)
'   iomode  1 = read, 2 = write (truncate), 8 = append
'   create  True = create when missing
'   format -2 = system default, -1 = Unicode (UTF-16LE), 0 = ASCII
'--------------------------------------------------------------------------------

Const FOR_READING   = 1
Const FOR_WRITING   = 2
Const FOR_APPENDING = 8

Const FMT_SYSTEM_DEFAULT = -2
Const FMT_UNICODE        = -1
Const FMT_ASCII          = 0

Sub AppendLine(vPath, vText)
  Dim vStream

  Set vStream = CreateObject("Scripting.FileSystemObject") _
                  .OpenTextFile(vPath, FOR_APPENDING, True, FMT_SYSTEM_DEFAULT)
  vStream.WriteLine vText
  vStream.Close
  Set vStream = Nothing
End Sub

Sub WriteAllText(vPath, vText)
  Dim vStream

  Set vStream = CreateObject("Scripting.FileSystemObject") _
                  .OpenTextFile(vPath, FOR_WRITING, True, FMT_SYSTEM_DEFAULT)
  vStream.Write vText
  vStream.Close
  Set vStream = Nothing
End Sub

Function ReadAllText(vPath)
  Dim vStream

  ReadAllText = ""
  Set vStream = CreateObject("Scripting.FileSystemObject") _
                  .OpenTextFile(vPath, FOR_READING, False, FMT_SYSTEM_DEFAULT)

  ' ReadAll raises on an empty file, so the guard is required
  If Not vStream.AtEndOfStream Then ReadAllText = vStream.ReadAll()

  vStream.Close
  Set vStream = Nothing
End Function

' Returns an array of lines. Splitting the whole text is both shorter and safer
' than ReDim Preserve in a ReadLine loop, which VBScript rejects on the array
' returned by Array().
Function ReadLines(vPath)
  Dim vText

  vText = ReadAllText(vPath)
  If vText = "" Then
    ReadLines = Array()
    Exit Function
  End If

  vText = Replace(Replace(vText, vbCrLf, vbLf), vbCr, vbLf)
  If Right(vText, 1) = vbLf Then vText = Left(vText, Len(vText) - 1)

  ReadLines = Split(vText, vbLf)
End Function