[VBScript] CliVE - Command Language Interpreter VBScript Environment

A few years back ZATZ Publishing, in their DominoPower Magazine, published an article entitled Using Python to create a command line interpreter for Notes. Not being that au fait with Python I decided to have a go at doing the same thing in VBScript. CliVE is the result.

CliVE takes the basic CLI mechanism of my previous posting ([VBScript] CLI Framework) and adds a couple of extra bits: Loading, Saving, and a shorthand for 'WScript.Echo'

First the code supporting the standard header.

option explicit Function GetEnv( strEnvVar ) Dim oProcessEnvironment Dim sResult With CreateObject( "WScript.Shell" ) GetEnv = .Environment( "PROCESS" )( UCase( strEnvVar ) ) End With End Function Sub Include( scriptName ) Dim sScript Dim oStream 'on error resume next err.clear With CreateObject( "Scripting.FileSystemobject" ) Set oStream = .OpenTextFile( scriptName ) End With If Err.Number > 0 Then MsgBox "Could not open " & scriptName WScript.Quit End If Err.Clear sScript = oStream.ReadAll() oStream.Close ExecuteGlobal sScript If Err.Number <> 0 Then Die "Error in loaded script" End If On Error Goto 0 End Sub Include "C:\Script\StandardLibrary.vbs"

Then support for putting script files on the commandline. Files specified on the command line are loaded and interpreted, one after the other.

Dim oArgs Set oArgs = WScript.Arguments.Unnamed Dim i If oArgs.Count > 0 Then For i = 0 to oArgs.Count - 1 LoadRun oArgs( i ) Next End If

This is the main interpreter loop.

The aSession array stores each line passed to Evaluate so that a given session's script can be stored.

In the main loop, a prompt is output and input received. The sLine is split into a two element list: the first element being the keyword; the second being all subsequent text.

There are a few keywords starting with a dot. These are peculiar to CliVE:

.quit

.exit

Synonyms for WScript.Quit

.echo

?

Synonyms for WScript.Echo. Unlike other dot commands, the line starting with this command is passed to the Evaluate function.

.save

Saves the contents of the aSession array to SaveClive.clive unless a filename is given as an argument.

.run

.load

Reads the filename given in the argument and executes the code therein by passing it to ExecuteGlobal.

.debug

An empty procedure. A place to put test code.

All other commands are treated as VBScript commands and are passed to the Evaluate subroutine.

Dim aSession Dim sLine Dim aLine Dim sKeyword Dim sArguments Dim sClip ReDim aSession( -1 ) Do While True WScript.StdOut.Write "cliVE> " sLine = WScript.StdIn.ReadLine aLine = Split( sLine, " ", 2 ) If UBound( aLine ) > -1 Then sKeyword = aLine( 0 ) If UBound( aLine ) > 0 Then sArguments = LTrim( RTrim( aLine( 1 ) ) ) Else sArguments = vbNullString End If Select Case LCase( sKeyword ) Case ".quit", ".exit" Exit Do Case ".echo", "?" Evaluate "WScript.Echo " & sArguments Case ".save" Save sArguments Case ".run", ".load" LoadRun sArguments Case ".debug" DoDebug Case Else Evaluate sLine End Select End If Loop

Evaluate, Save, LoadRun and Debug.

Note that the code for Evaluate traps errors, and displays an error message. Note also that LoadRun has no such protection. It's something one might want to add ASAP!

Note also the call to AAdd, which adds the evaluated command to the aSession array if the command works without error.

Sub Evaluate( sArg ) On Error Resume Next ExecuteGlobal sArg If Err.Number <> 0 Then WScript.Echo "Error:",Err.Number WScript.Echo vbTab, Err.Source WScript.Echo vbTab, Err.Description Err.Clear Else AAdd aSession, sArg End If On Error GoTo 0 End Sub Sub Save( sFilename ) Dim nMode If sFilename = vbNullString Then sFileName = "SaveClive.clive" nMode = WF_APPEND Else nMode = WF_CREATE End If WriteFile sFilename, Join( aSession, vbNewLine ), nMode End Sub Sub LoadRun( sFileName ) If sFileName <> vbNullString Then If Exists( sFileName ) Then ExecuteGlobal ReadFile( sFileName ) WScript.Echo sFilename & " evaluated without error" Else WScript.Echo sFileName & " not found" End If Else WScript.Echo "Please specify filename" End If End Sub Sub DoDebug End SUb

Rather than reproduce the entire StandardLibrary (1500+ lines), here are the referenced routines (AAdd, Exists, ReadFile, WriteFile), plus supporting symbols.

Function AAdd( ByRef aToThis, ByVal xAddThis ) Dim nPos nPos = UBound( aToThis ) + 1 ReDim Preserve aToThis( nPos ) aToThis( nPos ) = xAddThis AAdd = nPos End Function Dim oFSO Set oFSO = CreateObject( "Scripting.FileSystemobject" ) Function Exists( sFile ) Exists = oFSO.FileExists( sFile ) End Function Function ReadFile( FileName) Dim oStream Dim sData sData = VBNullString Set oStream = oFSO.OpenTextFile(FileName) sData = oStream.ReadAll oStream.Close ReadFile = sData End Function Const WF_APPEND = 1 Const WF_CREATE = 2 Const WF_FOR_APPENDING = 8 Const WF_FOR_WRITING = 2 Const WF_CREATE_NONEXISTING = True Sub WriteFile( sFilename, sContents, nMode ) Dim oStream If nMode = WF_APPEND Then Set oStream = oFSO.OpenTextFile( sFilename, WF_FOR_APPENDING, WF_CREATE_NONEXISTING ) ElseIf nMode = WF_CREATE Then Set oStream = oFSO.OpenTextFile( sFilename, WF_FOR_WRITING, WF_CREATE_NONEXISTING ) Else Die "Mode incorrectly set for WriteFile2" End If oStream.Write sContents oStream.Close End Sub