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16-Apr 11:16 UTC
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Mailing List Archive: 49091 messages
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Parse rules for Rebol values

 [1/5] from: al:bri:xtra at: 23-Sep-2002 12:34


Rebol has these: time? -- for testing a value to see if it's a time! value. time! -- to indicate a value of time! type. time -- a generic value that contains a time! value. What would be a suitable name for a parse rule that picks out a time value from text? How about: time^ Andrew Martin ICQ: 26227169 http://valley.150m.com/

 [2/5] from: greggirwin:mindspring at: 23-Sep-2002 11:24


Hi Andrew, << Rebol has these: time? -- for testing a value to see if it's a time! value. time! -- to indicate a value of time! type. time -- a generic value that contains a time! value. What would be a suitable name for a parse rule that picks out a time value from text? How about: time^
>>
If you already have other parse rules that map to REBOL datatypes, go for consistency. If not, maybe that's something we should all think about. #"!" is actually a valid character for use in words, correct? Would it be too confusing to use that as a basis (e.g. time!!)? While 'time! would also be valid, that might be *really* confusing. The EBNF standard for a production rule ( ::= ) contains colons so that's out as an option, unless we write parser to translate EBNF grammars for use with REBOL. :) --Gregg

 [3/5] from: jason:cunliffe:verizon at: 23-Sep-2002 21:08


hmm... time time! time? time^ time* I prefer time* for your parse rule suggestion, because it evokes wild cards. While I associate ^ with common control characters strings like print "Content-type: text/html^/^/" ./Jason.0.02

 [4/5] from: brett::codeconscious::com at: 24-Sep-2002 17:21


> The EBNF standard for a production rule ( ::= ) contains colons so that's > out as an option, unless we write parser to translate EBNF grammars for
use
> with REBOL. :)
Tangential to the thread, I fiddled BNF rules a whle ago - brain bending stuff. For interest here is the script - expect bugs and it being incomplete. I did it as an excercise. http://www.codeconscious.com/rebol/scripts/bnf-tools.r Regards, Brett.

 [5/5] from: greggirwin:mindspring at: 24-Sep-2002 9:39


Hi Brett, << Tangential to the thread, I fiddled BNF rules a whle ago - brain bending stuff. >> Wow. No kidding. I'll have to find some time to look at that. I think most of the old BNF stuff I have around was in VisualParse++ which may have used a slightly non-standard syntax. Thanks! --Gregg