Re: [Caml-list] unread_char function

[Miles Egan <miles@caddr.com>]

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On Mon, 2003-09-29 at 14:10, Pierre Weis wrote:
> You may also consider scanf and the format %0c that gives you access
> to the current character without incorporating it to the current token
> (as Basile said, this is some form of lookahead, limited to 1
> character as is normally the case for streams).
> 
> To give a more concrete example, here is an elementary scanner for
> strings, numbers, chars, idents and single character symbols: the
> scanneer just decides on the first character (after proper skipping of
> spaces) what is the kind of token to read.
> 
> let scan_tok sb =
>   Scanf.bscanf sb " %0c" (function
>   | '"' ->
>      Scanf.bscanf sb "%S"
>        (fun v -> String v)
>   | '0' .. '9' | '-' | '+' ->
>      Scanf.bscanf sb "%f"
>        (fun v -> Float v)
>   | '\'' ->
>      Scanf.bscanf sb "%C"
>        (fun v -> Char v)
>   | 'a' .. 'z' | 'A' .. 'Z' ->
>      Scanf.bscanf sb "%[a..zA..Z0..9]"
>        (fun v -> Ident v)
>   | c ->
>      Scanf.bscanf sb "%1c"
>        (fun v -> Symbol v));;
> val scan_tok : Scanf.Scanning.scanbuf -> tok = <fun>

I'm trying to write a function that seeks to an arbitrary string
delimiter in an input stream.  It's not immediately obvious to me how
I'd do this with a parser but I'll poke around with it.

-- 
Miles Egan <miles@caddr.com>

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