Re: LL Parser problem

SM Ryan <wyrmwif@tsoft.org>
11 Aug 2004 12:53:27 -0400

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| List of all articles for this month |

From: SM Ryan <wyrmwif@tsoft.org>
Newsgroups: comp.compilers
Date: 11 Aug 2004 12:53:27 -0400
Organization: Quick STOP Groceries
References: 04-08-060
Keywords: lex
Posted-Date: 11 Aug 2004 12:53:27 EDT

jdlessl@yahoo.com (Jared Lessl) wrote:
# > [Special case the lexer to return a mutant < token after an array
# > name. -John]
#
# Except that in AREV, any variable or function return value can be an
# array of this type. The only assurance I can have that a '<' is not
# an array index is if it immediately follows a literal or numerical
# value.


If you have two different derivations


Z -> X -> A<B>
and Z -> Y -> A<B


where B has an unbounded expansion, then it isn't LL(k). To be LL(k) you
have to be able choose X or Y by left context + at most k symbols. In this
case you have traverse the entire expansion of B which can be more than
k symbols.


--
SM Ryan http://www.rawbw.com/~wyrmwif/


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