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From: "Janne Hellsten" <jjhellst@gmail.com>
To: caml-list@inria.fr
Subject: Re: [Caml-list] Matching start of input in lexer created with ocamllex
Date: Thu, 5 Apr 2007 23:58:00 +0300	[thread overview]
Message-ID: <700d600f0704051358g294d540ey96a546f7f57a08e7@mail.gmail.com> (raw)
In-Reply-To: <1175802901.5274.14.camel@rosella.wigram>

> let table = ["for", FOR; "while", WHILE]
> ..
> | space-not-newline + { WHITE }
> | newline { NEWLINE }
> | ident as id { try assoc id table with Not_found -> IDENT id }
>
> An alternative to the WHITE and NEWLINE tokens is a tail
> recursive call to the lexer:
>
> | space + { initial lexbuf }
>
> which just skips over the spaces.

I do have the latter construct in my lexer.  How does the above help
me match the beginning of line in the rule

  | '!' [' ' '\t']* "for" { FOR (current_loc ()) }

I'd like it to look like this:

  | "^!for" { FOR }

where ^ would denote the start of input.  To simplify my question, we
can assume there are no new line chars in my input.  This regexp:

'!' [' ' '\t']* "for"

could actually be simplified to

| "!for"

and I would still need to match the "beginning of input" somehow.

I must've missed your point.

Janne


  reply	other threads:[~2007-04-05 20:58 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-04-05 14:37 Janne Hellsten
2007-04-05 19:55 ` [Caml-list] " skaller
2007-04-05 20:58   ` Janne Hellsten [this message]
2007-04-06  5:52     ` skaller
     [not found] <20070405205804.90509BC76@yquem.inria.fr>
2007-04-06  7:40 ` David Allsopp
2007-04-06 20:14   ` Janne Hellsten

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