RegExp problem with * quantifier

[mLipok]

When I try to use this RegExp pattern

Quote

(?is)(?<=<h3 class="clBlue marginTop">Poprzednie numery.*</h3>)(.{5})

Then I get:

Quote

 

Failed

Bad pattern, error position: 63

(?is)(?<=<h3 class="clBlue marginTop">Poprzednie numery.*</h3>)^ERROR

 

My quick research find out that the problem is with * quantifier (if I remove this single char RegExp is not firing any error)
But I do not know why.

Question:
Why I can not use * quantifier in this RegExpPattern ?

 

Edited December 4, 2018 by mLipok

[FrancescoDiMuro]

@mLipok
Could you please post your test string?

[mLipok]

The problem is not related to any source string.
You can even test it on empty string.
The problem is releated to PCRE behavior and I think some restrictions in PCRE usage.

This question is for Advanced PCRE users .... even for experts ... or just other folks for example which are native english speaker who have some spare time to read PCRE documentation

 

 

Edited December 4, 2018 by mLipok

[FrancescoDiMuro]

@mLipok
Pasting your pattern in regex101, you'll see this:

Quote

/

(?is)(?<=<h3 class="clBlue marginTop">Poprzednie numery.*</h3>)(.{5})

/

gm

All the errors detected are listed below, from left to right, as they appear in the pattern.

* A quantifier inside a lookbehind makes it non-fixed width

/ An unescaped delimiter must be escaped with a backslash (\)

So, I don't think that's some PCRE "bug"

[mLipok]

Did I said "bug" ?

I said :

3 hours ago, mLipok said:

I think some restrictions in PCRE usage.

But thanks for your answer:

Quote

A quantifier inside a lookbehind makes it non-fixed width

/ An unescaped delimiter must be escaped with a backslash (\)

This answer and I should review my statement:

3 hours ago, mLipok said:

This question is for Advanced PCRE users .... even for experts ... or just other folks for example which are native english speaker who have some spare time to read PCRE documentation

or some nice forum member who use a tool which have better error reporting

Thanks @FrancescoDiMuro your answer cleary answer to my question, and I have right that this is PCRE restriction:
 

Quote

* A quantifier inside a lookbehind makes it non-fixed width

but I still do not understand why what this following mean in my case

Quote

// An unescaped delimiter must be escaped with a backslash (\)

 

Edited December 4, 2018 by mLipok
wording: why/what

[mikell]

1 hour ago, mLipok said:

* A quantifier inside a lookbehind makes it non-fixed width

FrancescoDiMuro is right. These are incompatible :

(?<=<h3 class="clBlue marginTop">Poprzednie numery.*</h3>)

You might try something like this instead

(?:<h3 class="clBlue marginTop">Poprzednie numery.*</h3>)

[mLipok]

I need to use lookbehind  feature, so I change this to:

Quote

(?<=<h3 class="clBlue marginTop">)(?:Poprzednie numery.*</h3>)

... and ...

2 hours ago, mLipok said:

but I still do not understand why what this following mean in my case

Quote

// An unescaped delimiter must be escaped with a backslash (\)

 

 

[FrancescoDiMuro]

@mLipok
According to this post, seems that the character / is used as "pattern delimiter" by SRE(R), so, if you want to use it as literal character, you have to escape it.
In fact, if you escape it, you won't have that message anymore

[TheXman]

<Redacted>

Edited December 4, 2018 by TheXman
I didn't fully understand the question so repsonse was not relevant.

[TheXman]

1 hour ago, mLipok said:

but I still do not understand why what this following mean in my case

Quote

// An unescaped delimiter must be escaped with a backslash (\)

 

I understand your question now.  In your case, if using PCRE in AutoIt, that error is not relevant.  That error must have been kicked out by some tool that doesn't take into account how PCRE expressions are implemented in AutoIt.  If it was Regex101.com, then it only takes into account PCRE expressions as they would be implemented in PHP.  IIRC, PCRE in PHP surrounds their expressions with "/".  For instance "/(?i)abc/".  That is why the it said the "/" was unescaped.  In AutoIt, slashes are not used as regular expression delimiters.  So that error, at least in this case, was a red herring.

Edited December 4, 2018 by TheXman
Tidy up my response

[mLipok]

my final solution is:

Quote

(?<=<h3 class="clBlue marginTop">)(?:Poprzednie numery.*<\/h3>)