[Pharo-dev] Is there a portable way to check if a string is a block?
eliot.miranda at gmail.com
Sat Aug 12 22:32:51 EDT 2017
> On Jul 24, 2017, at 9:21 AM, Mariano Martinez Peck <marianopeck at 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
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