VBScript code minifier written in VBScript

USAGE

Dim text
text = "x = 1" & vbCrLF & "y = 2"
text = New VBSMin.minify(text)
' Results to: "x=1:y=2"

DESCRIPTION

This class implements the minification feature of VBScript codes written in VBScript.

I found the only two implementations: one is written on Python [1] and has partial support of minification, second is Ruby-based library [2] having wide support.

I thought, it's good idea to implement this feature on VBScript itself. This class does all the best to minify the code. Initially it was translated from Ruby and implemented in a procedural style [3]. Now it is OOP-styled and uses RegExp actively and produces a bit shorter output than the Ruby library.

LIMITATIONS

In most cases minification works and a minified code is executed fine. However two cases exist when a minified code fails completely.

Both are having to do with the If ... Then .. Else ... statement [4].

No more investigations were done.

Execution failure with the single-line If ... Then ... Else ...

VBScript supports a single-line syntax for If ... Then ... Else .... A minified code having a single-line construction doesn't start at all and fails with the compilation error Expected 'If'.

There is short example demonstrating a failure:

Function max(a, b)
	If a > b Then max = a Else max = b
End Function

The minified version of the code above doesn't work. To make it working, it was minified, further the minified version was modified manually until it stopped throwing compilation errors.

Function max(a,b):If a>b Then max=a Else max=b:
End Function

Execution failure with the ElseIf and Else keywords

Also the minified code doesn't work, if it contains ElseIf and Else keywords within a line among other commands. The VBScript engine requires them to be placed in the beginning of lines (to be the first keyword in the line). The minified code stops execution with the compilation errors Must be first statement on the line and Expected 'End'.

There is another example:

Function sgn(a)
	If a > 0 Then
		sgn = +1
	ElseIf a<0 Then
		sgn = -1
	Else
		sgn = 0
	End If
End Function

The minified version of the code above doesn't work. To make it working, it was minified, further the minified version was modified manually until it stopped throwing compilation errors.

Function sign(a):If a>0 Then
sign=+1:
ElseIf a<0 Then:sign=-1:
Else:sign=0:End If:End Function

To resolve these issues a deeper analysis is needed to distinguish these specialties and put the line breaks immediately before ElseIf and Else and after the single-line construction. But I am not sure if it's really possible with regexps only.

None of existsing minifiers resolve these issues.

SEE ALSO

• [1] Python implementation: https://github.com/freginold/thinIt
• [2] Ruby implementation: https://github.com/noraj/vbsmin
• [3] VBScript implementation (my first public version): https://forum.script-coding.com/viewtopic.php?pid=143579#p143579
• [4] If .. Then ... Else ... statement: https://docs.microsoft.com/en-us/dotnet/visual-basic/language-reference/statements/if-then-else-statement

AUTHORS

Copyright 2021, Ildar Shaimordanov

MIT