Martijn van Oosterhout writes:
> On the otherhand, I think requiring an "overall longest match" makes
> your implementation non-polynomial complexity.
Only if you don't know how to implement it -- a DFA-based implementation
doesn't have much trouble with this.
> [ equivalence of knapsack problem
On Mon, Mar 05, 2012 at 11:28:24AM -0500, Tom Lane wrote:
> Robert Haas writes:
> > I think the right way to imagine this is as though the regular
> > expression were being matched to the source text in left-to-right
> > fashion.
>
> No, it isn't. You are headed down the garden path that leads t
On Mon, Mar 5, 2012 at 11:28 AM, Tom Lane wrote:
> Robert Haas writes:
>> I think the right way to imagine this is as though the regular
>> expression were being matched to the source text in left-to-right
>> fashion.
>
> No, it isn't. You are headed down the garden path that leads to a
> Perl-s
Robert Haas writes:
> I think the right way to imagine this is as though the regular
> expression were being matched to the source text in left-to-right
> fashion.
No, it isn't. You are headed down the garden path that leads to a
Perl-style definition-by-implementation, and in particular you are
On 5 March 2012 17:23, Robert Haas wrote:
> This is different from what Perl does, but I think Perl's behavior
> here is batty: given a+|a+b+ and the string aaabbb, it picks the first
> branch and matches only aaa.
Yeah, this is sometimes referred to as "ordered alternation",
basically that the b
On Sun, Mar 4, 2012 at 3:20 PM, Tom Lane wrote:
> hubert depesz lubaczewski writes:
>> I stand on position that mixing greedy and non-greedy operators should
>> be possible, and that it should work according to POLA - i.e. greedines
>> of given atom shouldn't be influenced by other atoms.
>
> [ s
On 5 March 2012 04:34, Tom Lane wrote:
> Brendan Jurd writes:
>> On 4 March 2012 17:53, Tom Lane wrote:
>>> Brendan Jurd writes:
>> While it's true that POSIX doesn't contemplate non-greed, after
>> reading the spec I would have expected an expression *as a whole* to
>> still prefer the longest
hubert depesz lubaczewski writes:
> I stand on position that mixing greedy and non-greedy operators should
> be possible, and that it should work according to POLA - i.e. greedines
> of given atom shouldn't be influenced by other atoms.
[ shrug... ] That sounds good, but it's pretty much vacuous
On Sun, Mar 04, 2012 at 12:34:22PM -0500, Tom Lane wrote:
> Well, that's just an arbitrary example. The cases I remember people
> complaining about in practice were the other way round: greedy
> quantifier followed by non-greedy, and they were unhappy that the
> non-greediness was effectively not
Brendan Jurd writes:
> On 4 March 2012 17:53, Tom Lane wrote:
>> Brendan Jurd writes:
>>> I'll admit that this is a pretty obscure point, but we do appear to be
>>> in direct violation of POSIX here.
>> How so? POSIX doesn't contain any non-greedy constructs. If you use
>> only the POSIX-comp
On 4 March 2012 17:53, Tom Lane wrote:
> Brendan Jurd writes:
>> I'll admit that this is a pretty obscure point, but we do appear to be
>> in direct violation of POSIX here.
>
> How so? POSIX doesn't contain any non-greedy constructs. If you use
> only the POSIX-compatible greedy constructs, th
Brendan Jurd writes:
> I am in the process of accelerating down the rabbit hole of regex
> internals. Something that came up during my reading, is that a POSIX
> compliant regex engine ought to always prefer the longest possible
> match, when multiple matches are possible beginning from the same
Hello folks,
I am in the process of accelerating down the rabbit hole of regex
internals. Something that came up during my reading, is that a POSIX
compliant regex engine ought to always prefer the longest possible
match, when multiple matches are possible beginning from the same
location in the
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