[Caml-list] Str broken

[Caml-list] Str broken

[skaller]

The Str module seems not to work:

open Str;;
let re = "(a\\|b)*abb"
let cre = regexp re
let s = "ababababb"
;;
string_match cre s 0
;;

returns false. This is the classic test from the Dragon book.
Before I post a bug report can someone confirm this result please?
I'm using: Objective Caml version 3.09+dev0 (2004-07-13)

-- 
John Skaller, mailto:skaller@users.sf.net
voice: 061-2-9660-0850, 
snail: PO BOX 401 Glebe NSW 2037 Australia
Checkout the Felix programming language http://felix.sf.net



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Re: [Caml-list] Str broken

[micha-1]

On Tuesday 14 September 2004 11:26, skaller wrote:
> The Str module seems not to work:
>
> open Str;;
> let re = "(a\\|b)*abb"

it works with:

 let re = "\\(a\\|b\\)*abb"


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Re: [Caml-list] Str broken

[skaller]

On Tue, 2004-09-14 at 19:35, micha-1@fantasymail.de wrote:
> On Tuesday 14 September 2004 11:26, skaller wrote:
> > The Str module seems not to work:
> >
> > open Str;;
> > let re = "(a\\|b)*abb"
> 
> it works with:
> 
>  let re = "\\(a\\|b\\)*abb"

Ah, you are right that I messed the notation (despite
actually checking the manual). Thx!


-- 
John Skaller, mailto:skaller@users.sf.net
voice: 061-2-9660-0850, 
snail: PO BOX 401 Glebe NSW 2037 Australia
Checkout the Felix programming language http://felix.sf.net



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Re: [Caml-list] Str broken

[Erik de Castro Lopo]

On 14 Sep 2004 19:26:59 +1000
skaller <skaller@users.sourceforge.net> wrote:

> The Str module seems not to work:
> 
> open Str;;
> let re = "(a\\|b)*abb"
> let cre = regexp re
> let s = "ababababb"
> ;;
> string_match cre s 0
> ;;
> 
> returns false. This is the classic test from the Dragon book.
> Before I post a bug report can someone confirm this result please?
> I'm using: Objective Caml version 3.09+dev0 (2004-07-13)

I'm using 3.07+2 here. The code you posted produced a warning for
me. It seems that for ocaml some extra escaping is required in
comparison with other languages.

Fixing this code:

    open Str ;;

    let re = "\\(a\\|b\\)*abb" ;;
    let cre = regexp re ;;
    let s = "ababababb" ;;

    if string_match cre s 0 then print_endline "true"
    else print_endline "false" ;;

prints "true" for me.

Cheers,
Erik
-- 
+-----------------------------------------------------------+
  Erik de Castro Lopo  nospam@mega-nerd.com (Yes it's valid)
+-----------------------------------------------------------+
"Debugging is twice as hard as writing the code in the first place.
 Therefore, if you write the code as cleverly as possible, you are,
 by definition, not smart enough to debug it."
--Brian Kernighan

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Re: [Caml-list] Str broken

[Keith Wansbrough]

Erik wrote:
> On 14 Sep 2004 19:26:59 +1000
> skaller <skaller@users.sourceforge.net> wrote:
> 
> > The Str module seems not to work:
[..]
> > let re = "(a\\|b)*abb"
[..]
> I'm using 3.07+2 here. The code you posted produced a warning for
> me. It seems that for ocaml some extra escaping is required in
> comparison with other languages.

The documentation says "The syntax for regular expressions is the same
as in Gnu Emacs." (sec 22.1).

My emacs documentation (v21.2.1) says about regexps:

> The special characters are `$', `^', `.', `*', `+', `?',
> `[', `]' and `\'.  Any other character appearing in a regular
> expression is ordinary, unless a `\' precedes it.

This is similar to GNU grep (basic) regular expressions, except for
the inclusion of '?', and the exclusion of character classes.

It's not clear from the documentation whether the other Emacs
constructs not listed in the OCaml manual entry are supported,
e.g. \(?: ... \), \`, \B, \<, etc.

--KW 8-)

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