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Re: Eliminating Left Recursion in Parse::RecDescent

by Abigail-II (Bishop)
on May 29, 2002 at 10:42 UTC ( [id://170029]=note: print w/replies, xml ) Need Help??


in reply to Re: Eliminating Left Recursion in Parse::RecDescent
in thread Eliminating Left Recursion in Parse::RecDescent

all this does is change the expression to
expr : term '+' term | term
which works fine but does not solve the problem. (a+b) + (c+d)

That is because demerphq applied the rule wrongly. After applying the rule, we should get: 

    expr      :     term expr_tail
    expr_tail : '+' term expr_tail | {1}

[download]

Abigail

Replies are listed 'Best First'.
Re: Re: Eliminating Left Recursion in Parse::RecDescent
by demerphq (Chancellor) on May 29, 2002 at 14:55 UTC
    Doh. Yes. I did too. And you guys are the first to spot the error as well.

    In my defence, I got it right in one part, here 

    A : y R
R : x R | e

    [download]
    But omitted the R element in the example.

    I have updated the node. Thanks for your hawklike eyes.

    Yves / DeMerphq
    ---
    Writing a good benchmark isnt as easy as it might look.

[reply]
[d/l]

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