Re: Reduce/Reduce conflict in Algol60 grammar

# primary ::=
# variable |


# boolean_primary ::=
# variable |


# Note the common part between primary and boolean_primary, which leads to
# the conflict. The only way that I could resolve this was to merge arithmetic_expression and


The problem is this is a ambiguous context free grammar, therefore
not LR(k). To reduce the variable you need to match it to the
declaration elsewhere to decide if it is a Boolean or arithmetic
variable.


So, yes, you instead use a larger grammar that includes erroneous
programs, and then use some post parsing work to enforce context
sensitive rules.


# [You could try building types into the grammar like boolean_variable
# and boolean_function_designator, but it's not going to be pretty. -John]


Unless you use a two-level grammar, you cannot write enough productions.


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

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