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List:       busybox
Subject:    Re: math support in busybox shells
From:       Denys Vlasenko <vda.linux () googlemail ! com>
Date:       2009-03-31 22:19:22
Message-ID: 200904010019.22060.vda.linux () googlemail ! com
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On Monday 30 March 2009 06:11, Mike Frysinger wrote:
> ash is the only shell that has math support.  rather than rewrite a new one 
> from scratch for hush, i'm wondering if we can split it out of ash so that it 
> is shared among any/all shells.  more of a parsing library.  i thought about 
> simply wiring up builtin_expr() to do the parsing, but the syntax and 
> operators that it supports is more limited than what is required in the shell.
> 
> looking at ash shows that the math code apparently used to be a sep yacc file, 
> but then the C output of it was merged and cut down.  hopefully this means 
> that it isnt too hard to split back out.
> 
> thinking about it at a higher level, the only thing the engine needs to do is 
> to get and set variables ... all other shell related parsing should already be 
> done at that point.  and the return value should always be a signed long int.  
> thoughts ?

Yes, this is a good plan.
--
vda
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