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Re: Using bison without Flex
From: |
Hans Åberg |
Subject: |
Re: Using bison without Flex |
Date: |
Thu, 23 Apr 2015 23:15:36 +0200 |
> On 23 Apr 2015, at 16:34, brahim sahbi <address@hidden> wrote:
> can we use bison without flex by describing grammatical
> rules for tokens(like number <- list_of_digits).
A lexer like generated by Flex scans forward to find the longest match which
may require significant lookahead. A Bison generated parser just looks ahead at
most one token.
So in theory yes, but in practise not really.
> Can it recognize a language's keywords and prohibit an identifier to be a
> keyword?
You can hardcode keywords. Otherwise, one typically has an identifier lookup
table, for environments a stacked table, which the lexer checks and returns the
correct token value. This way, one can have keywords depending on context as
well.
Re: Using bison without Flex,
Hans Åberg <=