Re: How change grammar to equivalent LL(1) ?

silas poulson <Silas8642@hotmail.co.uk>
Wed, 11 Nov 2020 08:27:35 -0800 (PST)

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Re: How change grammar to equivalent LL(1) ? Silas8642@hotmail.co.uk (silas poulson) (2020-11-11)
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From: silas poulson <Silas8642@hotmail.co.uk>
Newsgroups: comp.compilers
Date: Wed, 11 Nov 2020 08:27:35 -0800 (PST)
Organization: Compilers Central
References: 19-12-023 20-04-009 20-04-010
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Keywords: parse
Posted-Date: 11 Nov 2020 11:51:35 EST

An even later response, but thought quote from course notes (§5.6.5
available here <http://cs.rhul.ac.uk/courses/CS3470/>) I'm currently
pursuing might be useful.


*LL(1) grammars*
Grammars which admit non-back-tracking top down LL(1) parsers are
  precisely the ones which are left factored, follow determined and have
  no left recursion.


Thus we have the following definition: A context-free grammar is LL(1) if
for all non-terminals A and productions A ::= α|β we have
1. first(α) ∩ first(β) = ∅
2. If A ∗⇒ ε then first(A) ∩ follow(A) =∅.


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