Re: any better explanation of look ahead assertions

2018-05-10 Thread ToddAndMargo 

On 05/10/2018 07:12 PM, Brad Gilbert wrote:

On Thu, May 10, 2018 at 9:09 PM, ToddAndMargo  wrote:

On 05/10/2018 07:06 PM, Brad Gilbert wrote:


You could read how they work in PCRE



What is PCRE?


Perl Compatible Regular Expressions,

Basically someone reimplemented the regular expression engine found in Perl,
and that is the basis of what every other language uses.



$ rpm -qa pcre
pcre-8.42-1.fc28.i686
pcre-8.42-1.fc28.x86_64

Well now!


--
~~
Computers are like air conditioners.
They malfunction when you open windows
~~

Re: any better explanation of look ahead assertions

2018-05-10 Thread Brad Gilbert 
On Thu, May 10, 2018 at 9:09 PM, ToddAndMargo  wrote:
> On 05/10/2018 07:06 PM, Brad Gilbert wrote:
>>
>> You could read how they work in PCRE
>
>
> What is PCRE?

Perl Compatible Regular Expressions,

Basically someone reimplemented the regular expression engine found in Perl,
and that is the basis of what every other language uses.

Re: any better explanation of look ahead assertions

2018-05-10 Thread ToddAndMargo 

On 05/10/2018 07:06 PM, Brad Gilbert wrote:

You could read how they work in PCRE


What is PCRE?

Re: any better explanation of look ahead assertions

2018-05-10 Thread Brad Gilbert 
On Thu, May 10, 2018 at 8:13 PM, ToddAndMargo  wrote:
> Hi All,
>
> Looking at:
> https://docs.perl6.org/language/regexes#Lookahead_Assertions
> https://docs.perl6.org/language/regexes#Lookbehind_assertions
>
> I can't tell heads from tails.  Does anyone know of a better
> reference/explanation for beginners?
>

You could read how they work in PCRE, as there are a lot more sources for it.

It is difficult to wrap your head around, as it matches some text without moving
the current position.

Also I find that I don't use it that often, so you might just want to
put off learning it
until you are more experienced using regexes. Who knows, maybe by then it will
be easier to understand.

I might look into making it easier to understand.
(I'm all talk though, so I wouldn't hold your breath)

any better explanation of look ahead assertions

2018-05-10 Thread ToddAndMargo 

Hi All,

Looking at:
https://docs.perl6.org/language/regexes#Lookahead_Assertions
https://docs.perl6.org/language/regexes#Lookbehind_assertions

I can't tell heads from tails.  Does anyone know of a better
reference/explanation for beginners?


Many thanks,
-T