3 Feb
2011
3 Feb
'11
1:01 p.m.
Hi all,
Is there an easy way to define the equivalent of
the following regular expression in PetitParser?
a{n,}
which that the character 'a' must appear at least n times.
Thank you!
Cheers,
Alberto
3 Feb
3 Feb
1:09 p.m.
To be more precise,
I cannot use
#letter plus
because this would imply that I can both parse:
'aa', which is correct; but also:
'ab', which is not correct.
I need a way to specify that I want the same letter, or character, to be
repeated.
Thank you,
Alberto
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1:38 p.m.
Hi,
I did never use it but i found in PetitParser-Parsers this parser PPRepeatingParser that
maybe can solve your problem.
Cheers,
Fabrizio
On 3 Feb 2011, at 13:09, sback wrote:
To be more precise,
I cannot use
#letter plus
because this would imply that I can both parse:
'aa', which is correct; but also:
'ab', which is not correct.
I need a way to specify that I want the same letter, or character, to be
repeated.
Thank you,
Alberto
--
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1:55 p.m.
$a min: n
On 3 February 2011 13:01, Alberto Bacchelli <alberto.bacchelli(a)usi.ch> wrote:
Hi all,
Is there an easy way to define the equivalent of
the following regular expression in PetitParser?
a{n,}
which that the character 'a' must appear at least n times.
Thank you!
Cheers,
Alberto
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Lukas Renggli
www.lukas-renggli.ch
2:12 p.m.
On 3 Feb 2011, at 13:55, Lukas Renggli wrote:
$a min: n
Cool, yes my idea was something like:
PPRepeatingParser on: $a asParser min: anInteger.
But i see that you already putted some sugar.
Cheers,
Fabrizio
On 3 February 2011 13:01, Alberto Bacchelli <alberto.bacchelli(a)usi.ch> wrote:
Hi all,
Is there an easy way to define the equivalent of
the following regular expression in PetitParser?
a{n,}
which that the character 'a' must appear at least n times.
Thank you!
Cheers,
Alberto
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Lukas Renggli
www.lukas-renggli.ch
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2:23 p.m.
$a asParser min: n
is fine for one character, but what if I want to specify that I want
any character, or digit, repeated at least n times?
I could do:
($a asParser min: n) / ($b asParser min: n) / ...
but that would be a bit ugly :)
Thanks
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3:14 p.m.
As far as I understand, you would want something that parses any of the following:
"aa"
"bb"
"cc"
"dd"
The simplest way would be something like:
($a asParser , $a asParser) / ($b asParser , $b asParser) ...
The problem is that this will result in many objects and redundant checks.
I think I would implement it as a specialization of PPPredicateSequenceParser in which you
store the first element, and add the extra condition that any of the following elements
must be the same.
Cheers,
Doru
On 3 Feb 2011, at 14:23, sback wrote:
$a asParser min: n
is fine for one character, but what if I want to specify that I want
any character, or digit, repeated at least n times?
I could do:
($a asParser min: n) / ($b asParser min: n) / ...
but that would be a bit ugly :)
Thanks
--
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"Presenting is storytelling."
6 p.m.
If you know what you do then parsers can have side-effects:
| head tail char |
head := #any asParser ==> [ :c | char := c ].
tail := PPPredicateObjectParser
on: [ :c | char = c ]
message: 'same expected'.
parser := head , (tail min: n - 1).
Alternative you can modify the grammar itself on the fly:
| head tail |
head := #any asParser ==> [ :c | tail setParser: c asParser. c ].
tail := PPDelegateParser new.
parser := head , (tail min: n - 1).
Cheers,
Lukas
On Thursday, 3 February 2011, Tudor Girba <tudor.girba(a)gmail.com> wrote:
As far as I understand, you would want something that
parses any of the following:
"aa"
"bb"
"cc"
"dd"
The simplest way would be something like:
($a asParser , $a asParser) / ($b asParser , $b asParser) ...
The problem is that this will result in many objects and redundant checks.
I think I would implement it as a specialization of PPPredicateSequenceParser in which
you store the first element, and add the extra condition that any of the following
elements must be the same.
Cheers,
Doru
On 3 Feb 2011, at 14:23, sback wrote:
$a asParser min: n
is fine for one character, but what if I want to specify that I want
any character, or digit, repeated at least n times?
I could do:
($a asParser min: n) / ($b asParser min: n) / ...
but that would be a bit ugly :)
Thanks
--
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6:30 p.m.
not much to do with the real topic, but just wanted to nastily point out that this is not
a regular expression. :-)
You can specify that you want a particular character repeated (a+), or that you want
anycharacter several repeated (.+)
But I believe regular expression don't allow you to say whatever character comes may
be repeated and only this one ...
nic nitpicking
----- Mail original -----
De: "Lukas Renggli"
<renggli(a)gmail.com>
À: "Moose-related development" <moose-dev(a)iam.unibe.ch>
Envoyé: Jeudi 3 Février 2011 18:00:18
Objet: [Moose-dev] Re: PetitParser, same character multiple times
If you know what you do then parsers can have side-effects:
| head tail char |
head := #any asParser ==> [ :c | char := c ].
tail := PPPredicateObjectParser
on: [ :c | char = c ]
message: 'same expected'.
parser := head , (tail min: n - 1).
Alternative you can modify the grammar itself on the fly:
| head tail |
head := #any asParser ==> [ :c | tail setParser: c asParser. c ].
tail := PPDelegateParser new.
parser := head , (tail min: n - 1).
Cheers,
Lukas
On Thursday, 3 February 2011, Tudor Girba <tudor.girba(a)gmail.com>
wrote:
As far as I understand, you would want something
that parses any of
the following:
"aa"
"bb"
"cc"
"dd"
The simplest way would be something like:
($a asParser , $a asParser) / ($b asParser , $b asParser) ...
The problem is that this will result in many objects and redundant
checks.
I think I would implement it as a specialization of
PPPredicateSequenceParser in which you store the first element, and
add the extra condition that any of the following elements must be
the same.
Cheers,
Doru
On 3 Feb 2011, at 14:23, sback wrote:
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$a asParser min: n
is fine for one character, but what if I want to specify that I
want
any character, or digit, repeated at least n times?
I could do:
($a asParser min: n) / ($b asParser min: n) / ...
but that would be a bit ugly :)
Thanks
--
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6:49 p.m.
On 3 February 2011 18:30, Nicolas Anquetil <nicolas.anquetil(a)inria.fr> wrote:
not much to do with the real topic, but just wanted to
nastily point out that this is not a regular expression. :-)
PetitParser is not about regular expressions, it parses a much larger
set of languages. For example, languages like a^n b^n or a^b b^n c^n
cannot be detected by regular expressions.
You can specify that you want a particular character
repeated (a+), or that you want anycharacter several repeated (.+)
But I believe regular expression don't allow you to say whatever character comes may
be repeated and only this one ...
No, this is not true. Most today's regular expression engines support
back-references and can easily implement the discussed language:
(.)\1{n}
Lukas
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Lukas Renggli
www.lukas-renggli.ch
4834
days inactive
4834
days old
9 comments
6 participants
participants (6)
-
Alberto Bacchelli -
Fabrizio Perin -
Lukas Renggli -
Nicolas Anquetil -
sback
-
Tudor Girba