Re: Eliminating Left Recursion in Parse::RecDescent

[Anonymous Monk]

in reply to 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) etc.

[Abigail-II]

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}

Abigail

[demerphq]

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

But omitted the R element in the example.

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

Yves / DeMerphq
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