How can we programmatically know the syntax error using msscript.ocx?

Question

I have implemented msscript.ocx using c# and it works for VBScript.

Consider the following VBScript code:

For i = 0 To 5

  'The following line has missing 'Then'. It should show an error.
  If i = 2
    Exit For
  End If

Next

How can we tell if there is an error in line containing If (missing Then) without running the script?

Answer 1

You get the error when loading.

Set Arg = WScript.Arguments
set WshShell = createObject("Wscript.Shell")
Set Inp = WScript.Stdin
Set Outp = Wscript.Stdout

Sub VBSCmd
    RawScript = Arg(1)
    'Remove ^ from quoting command line and replace : with vbcrlf so get line number if error
    Script = Replace(RawScript, "^", "")
    Script = Replace(Script, "'", chr(34))
    Script = Replace(Script, ":", vbcrlf)
    'Building the script with predefined statements and the user's code
    Script = "Dim gU" & vbcrlf & "Dim gdU" & vbcrlf & "Set gdU = CreateObject(" & chr(34) & "Scripting.Dictionary" & chr(34) & ")" & vbcrlf & "Function UF(L, LC)" & vbcrlf & "Set greU = New RegExp" & vbcrlf & "On Error Resume Next" & vbcrlf & Script & vbcrlf & "End Function" & vbcrlf

    'Testing the script for syntax errors
    On Error Resume Next
    set ScriptControl1 = wscript.createObject("MSScriptControl.ScriptControl",SC)
        With ScriptControl1
            .Language = "VBScript"
            .UseSafeSubset = False
            .AllowUI = True
        .AddCode Script
    End With
    With ScriptControl1.Error
        If .number <> 0 then
            Outp.WriteBlankLines(1)
            Outp.WriteLine "User function syntax error"
            Outp.WriteLine "=========================="
            Outp.WriteBlankLines(1)
            Outp.Write NumberScript(Script)
            Outp.WriteBlankLines(2)
            Outp.WriteLine "Error " & .number & " " & .description
            Outp.WriteLine "Line " & .line & " " & "Col " & .column
            Exit Sub
        End If
    End With

    ExecuteGlobal(Script)

    'Remove the first line as the parameters are the first line
    'Line=Inp.readline  
    Do Until Inp.AtEndOfStream
        Line=Inp.readline
        LineCount = Inp.Line 

        temp = UF(Line, LineCount)
        If err.number <> 0 then 
            outp.writeline ""
            outp.writeline ""
            outp.writeline "User function runtime error"
            outp.writeline "==========================="
            Outp.WriteBlankLines(1)
            Outp.Write NumberScript(Script)
            Outp.WriteBlankLines(2)
            Outp.WriteLine "Error " & err.number & " " & err.description
            Outp.WriteLine "Source " & err.source

            Outp.WriteLine "Line number and column not available for runtime errors"
            wscript.quit
        End If
        outp.writeline temp
    Loop
End Sub

Vbs

filter vbs "text of a vbs script"

Use colons to seperate statements and lines. Use single quotes in place of double quotes, if you need a single quote use chr(39). Escape brackets and ampersand with the ^ character. If you need a caret use chr(136).

The function is called UF (for UserFunction). It has two parameters, L which contains the current line and LC which contains the linecount. Set the results of the script to UF. See example.

There are three global objects available. An undeclared global variable gU to maintain state. Use it as an array if you need more than one variable. A Dictionary object gdU for saving and accessing previous lines. And a RegExp object greU ready for use.

Example This vbs script inserts the line number and sets the line to the function UF which Filter prints.

filter vbs "uf=LC ^& ' ' ^& L"<"%systemroot%\win.ini"

This is how it looks in memory

Dim gU
Set gdU = CreateObject("Scripting.Dictionary")
Set greU = New RegExp

Function UF(L, LC)

---from command line---
uf=LC & " " & L
---end from command line---

End Function

If there is a syntax error Filter will display debugging details.