Re: Extended CFGs

SM Ryan <wyrmwif@tsoft.org>
3 Feb 2006 18:41:15 -0500

          From comp.compilers
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Extended CFGs rpboland@gmail.com (Ralph Boland) (2006-02-02)
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Re: Extended CFGs wyrmwif@tsoft.org (SM Ryan) (2006-02-03)
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From: SM Ryan <wyrmwif@tsoft.org>
Newsgroups: comp.compilers
Date: 3 Feb 2006 18:41:15 -0500
Organization: Quick STOP Groceries
References: 06-02-013
Keywords: parse
Posted-Date: 03 Feb 2006 18:41:15 EST

# I might want to write productions to capture this idea as follows:
#
# Mult --> MULT ? # ? means optional
# Multiply --> Expression Mult Expression


or
<product> ::= <product> * <factor> | <product><factor>


# Now the Mult production is nullable and thus not allowed in my parser
# generator. I have a workaround for this particular problem but
# perhaps there are other problems.


Get a real parser generator.


# CAN ANYONE POINT OUT FURTHER PROBLEMS RESULTING FROM DISALLOWING
# NULLABLE PRODUCTIONS?


All null productions except a null sentential form can be
mechanically elimenated, though it changes the parse trees.


--
SM Ryan http://www.rawbw.com/~wyrmwif/
A bunch of savages in this town.

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