Search++ (\W)'(\w) regex replace failure

[M Andre Z Eckenrode]

M-Andre-Z-Eckenrode said:

Note that only one CRLF became just LF (line 8)

Correction: Only one CRLF became just CR.

[guy038]

Hello, @m-andre-z-eckenrode, @alan-kilborn, @coises, @mpheath, @thomas-knoefel and All,

Just an observation : if you modify the proposed replacement :

FIND (\W)'(\w)

REPLACE \1’\2

by this one :

FIND (?<=\W)'(?=\w)

REPLACE ’

No problem occurs for a step by step replacement sequence or a Replace All operation for, either, an ANSI or UTF-8 encoded file. I verified this assumption with four regex engines :

• The native Search > Replace dialog of N++

• The Plugins > Column++ > Search... dialog

• The Plugins > Search++ > Search... dialog

• The Plugins > MultiReplace > MultiReplace... dialog

---

May be, this result will help to resolve possible bugs, with the other regex syntaxes

Best Regards,

guy038

[Coises]

@m-andre-z-eckenrode:

I’ve been looking, but so far I have not found a potential cause for the results you obtained.

@guy038’s post just led me to think of something.

The debug information in the post where you asked about the failure to replace in Notepad++ showed that you have Columns++ installed.

The search and replace code Search++ uses is derived from what I used in Columns++, but I have made some changes. Would you try and see if you can get the search in Columns++ to misbehave under the same circumstances as the one in Search++? (It’s fine to use the installed version of Notepad++ for this test.)

Knowing whether or not the fault also appears in Columns++ could help me narrow the scope of what I could be missing.

As always, I understand if you don’t have the time for this sort of thing. Thank you for your observations so far, and many thanks in advance if you are willing to do this additional test.

[guy038]

Hi, @m-andre-z-eckenrode, @alan-kilborn, @coises, @mpheath, @thomas-knoefel and All,

@coises, personally, I confirm that the step by step replacement with the regex pattern :

• FIND (\W)'(\w)

• REPLACE \1’\2

Works correctly with both your two plugins Columns++ and Search++ and with the MultiReplace plugin as well, when using the N++ v8.9 release !

The bug seems to occur only with native N++ regex engine !

BR

guy038

[M Andre Z Eckenrode]

@Coises said:

Would you try and see if you can get the search in Columns++ to misbehave under the same circumstances as the one in Search++?

In installed NPP, using Columns++ search in regex mode with a rectangular selection of multiple copies of my previously shown example text, I find that only the instances of “ 'r” (preceded by a regular space, NOT by any EOL) are matched, and are all replaced correctly with no anomalous characters. To be clear, this, again, is the starting text:

this
'Cos I am
that

this
'Round and 'round
that

this
'Cos I am
that

this
'Round and 'round
that

And resulting text:

this
'Cos I am
that

this
'Round and ’round
that

this
'Cos I am
that

this
'Round and ’round
that

[M Andre Z Eckenrode]

@guy038 said:

The bug seems to occur only with native N++ regex engine !

I’m confused. You’re saying that a native N++ regex replacement, using my example text and regex strings, results in anomalous characters for you? I haven’t seen that at all.

[guy038]

Hello, @m-andre-z-eckenrode, @coises and All,

@m-andre-z-eckenrode, you said :

I’m confused. You’re saying that a native N++ regex replacement, using my example text and regex strings, results in anomalous characters for you? I haven’t seen that at all.

I didn’t say that anormalous characters appear. I just said that no replacement occurs at all !

Indeed, with the native regex N++ replacement, and the text below :

this
'Cos I am
that

this
'Round and 'round
that

and with the following REPLACEMENT :

• FIND (\W)'(\w)

• REPLACE \1’\2

The first two replacements do not occur ! Only the last one will change the normal quote ' into the ’ character ( \x{2019} RIGHT SINGLE QUOTATION MARK )

IMPORTANT : This test was done with N++ v8.9. May be, the last v8.9.7 release would produce a different result !

Best Regards,

guy038

[Coises]

@M-Andre-Z-Eckenrode said:

using Columns++ search in regex mode with a rectangular selection of multiple copies of my previously shown example text, I find that only the instances of “ 'r” (preceded by a regular space, NOT by any EOL) are matched

I’m sorry… I didn’t think to mention that quirk. If you start with a rectangular selection, Columns++ searches each row independently, so the ones with ' at the beginning of a line would fail to match.

If Auto set is checked (the default) in the Search in indicated region dialog and no region is already indicated, when you start a search with nothing selected the indicated region is set to include the whole document. (You can also select the entire document, or make any multiple line selection or multiple selection, before you search.¹) This is different from a rectangular selection converted to an indicated region: rectangular selections are multiple selections which never include line endings.

(Yet another complication is that Scintilla does not reliably restore indicators (marked text) on undo. I think this only affects cases where a replacement begins at the first character of a contiguous span of marked text — Scintilla restores the text, but not the marker, on undo.)

So it is expected that only occurrences within a single line would match if you start with a rectangular selection. If you start with the entire document selected, or with no selection at all, it should match all the same occurrences as Search++ (with no selection or marked region).

---

¹ The rules are complicated. The confusing nature of the “indicated region” was one of the reasons I wanted to split Search++ entirely instead of doing more work on the search in Columns++. I didn’t want to change the concept for people who are already used to Columns++ search, but outside of the specific case of searching in column selections, I think it is more confusing than it needs to be.

[Coises]

@guy038 said:

I didn’t say that anormalous characters appear. I just said that no replacement occurs at all !

You might be confusing @m-andre-z-eckenrode’s topic (\W)'(\w) Regex replace failure, about Notepad++, and this topic, about Search++, with the same search.

---

He was surprised that Notepad++ found the text but would not replace it. The cause is how Notepad++ treats CRLF pairs combined with how it decides whether Replace should replace or find next — as I wrote there, whether it is a bug is, I suppose, a matter of opinion.

Search++ has a different potentially user-unfriendly behavior: with different find or replace expressions (any regular expression that can match starting with an LF, combined with a replacement string that doesn’t copy the first matched character as the first character of the replacement) a user could invisibly change line endings from CRLF to just CR (though if the user understands the regular expression and replacement entered, it would be expected).

Notepad++ has the same behavior as Search++ when using Replace All (including that it can replace the LF in a CRLF pair with something else); it’s just step-by-step replace that can find but fail to replace (for the same reason that \K doesn’t work in step-by-step native searches).

---

In this topic, the problem is that Search++ is, apparently randomly, replacing with garbage instead of the correct replacement string.

I have not yet found a possible cause. It does not happen on my machine.

[M Andre Z Eckenrode]

@Coises said:

I didn’t think to mention that quirk. If you start with a rectangular selection, Columns++ searches each row independently

Aha. That explains my own confusion. That was actually the first time I’d used the Search feature of Columns++. For the record, any time I’m doing regex search & replace in NPP that either turns out to be more complicated than I expected, or involves some trial and error, or which I’m going to want to utilize again elsewhere (such as this topic), I’m in the habit of typing it out right in the text document I’m working on, and then I select/copy the replacement regex, then select the find regex and open the necessary dialog, expecting the Find what to have been automatically populated from my most recent selection (which, of course, didn’t happen in that case). It didn’t occur to me that that wouldn’t work in Columns++. So, when I opened Columns++’s Search dialog with only the content of one line selected and tried to perform my regex search, it threw this at me:

This command requires a rectangular selection. Extend selection to the last line of the document?

And, Columns++ Search neophyte that I am, I didn’t heed the suggestion. I closed the dialog and created a rectangular selection.

Now that I’ve been made aware of the error of my ways, I’ve redone the experiment with all the my example text selected, and all instances of ' were successfully replaced with ’, without any anomalies.

[Coises]

@M-Andre-Z-Eckenrode said:

This command requires a rectangular selection. Extend selection to the last line of the document?

And, Columns++ Search neophyte that I am, I didn’t heed the suggestion.

Had you heeded it, you would still have gotten a rectangular selection, as it says, extending downward from your selection — not necessarily enclosing the whole document, and in any case not the same as selecting the whole document (or selecting nothing at all) first.

I should re-word that message, I’m just not sure what to say instead. It’s not actually true (since version 0.8) that a rectangular selection is required; as I mentioned before, the rules are complicated. They won’t easily fit into a message box. It makes sense when you’re using Columns++ for working with columns, but the search kind of took on a life of its own, apart from column work… hence, among other reasons, Search++.

I’ve redone the experiment with all the my example text selected, and all instances of ' were successfully replaced with ’, without any anomalies.

Thank you for that information. I do appreciate the help you’ve given me with this. While it doesn’t prove anything (almost nothing is ever proven when dealing with an intermittent bug), it suggests pretty strongly that something I changed in moving the Columns++ search process to Search++ has introduced a hidden instability. I’m still looking for it.