Hi Mariano,

_,,,^..^,,,_ (phone)

On Jul 24, 2017, at 9:21 AM, Mariano Martinez Peck <marianopeck@gmail.com> wrote:

Hi guys,

Is there a portable (that would work in GemStone too) and safe way to know if a String would be a block? 

I must support this kind of strings:

'singleString'   -> false
'multi string' -> false
'      [:a | 42]' -> true
'   '' ''  [:a | 42]' -> true
'[:a | 42]' -> true
' "a commet" [:a | 42]' -> true
' WhateverClass someVeryBadHackishMethod. [:a | 42]' -> true 

I need to identify whether the string is a closure or not. And ideally, I don't want to do an #evaluate: because I don't want any left hand code to be executed. 
I tried with #parse:  why I am having problems. 

Any ideas?

Not sure if you're still stuck but if you dive into evaluate: you'll be able to find the point at which it parses, and find out how to invoke the parser for an expression (a doit).   evaluate: parses an expression so you want to check that the resulting parse tree is that of a return node whose expression is a literal block.  You can also check the block's argument count.

Once you've extracted the parser invocation you can wrap this in a suitable exception handler.  Then you have your block parser.  You still have to validate the parse tree and/or generated code before evaluating since someone could write malicious code within the block right?


Thanks in advance

--
Mariano
http://marianopeck.wordpress.com