Regex: Select only the first instance of search results / first match

Vasile Caraus

hello. I have a html bug. And I have to change it in more then 2000 files.

I need to replace only the first instance of a search result.

For example, I have this line <div class=“pagination”> . The problem is that this line is repeated 5 times in each html file. So, if I want to search and replace this line, I risk to delete all other same lines.

My search should stop of first match.

I made a little regex, but does’t work for me.

^.*(<div class="pagination">)((?s:)).*/

Can anyone help me, please?

guy038

Hello Vasile,

I’ve got a solution, based on the one I gave in my last post, on the topic : Regex : Double your words, below, where I also matched all the remaining contents of the file, in order to be certain that will be ONE replacement, only, per file !

https://notepad-plus-plus.org/community/topic/12341/regex-double-your-words/9

I, also, supposed, Vasile, that the line, containing your string <div class=“pagination”>, may have some characters before and/or after that specific string.

Well, Let’s go !

To change the contents of the FIRST line, ONLY, of the current file, which contains the string <div class=“pagination”>, use :

SEARCH : (?-s)(?:.*\R)*?\K.*<div class=“pagination”>.*(?s)(\R.*)

REPLACE : New contents of the line\1

To change the contents of the LAST line, ONLY, of the current file, which contains the string <div class=“pagination”>, use :

SEARCH : (?-s)(?:.*\R)*\K.*<div class=“pagination”>.*(?s)(\R.*)

REPLACE : New contents of the line\1

***** With the help of Vasile, see, below, in my next post, a shorter version of these two regexes ! *****

Notes :

I won’t speak about the (?-s) and (?s) in-line modifiers ! You already aware about their use :-)
The first part (?:.*\R)*? catches the minimum number of complete lines, before the line containing the string <div class=“pagination”>
Then, again, the \K syntax forces the regex engine to forget the present match and reset the cursor location just before the first character of the line to be changed
Then the next part .*<div class=“pagination”>.* corresponds to all the standard characters of the line to be changed
And the final part (\R.*) stands for the EOL character(s) of the line to be changed, followed by all the text, till the end of the current file
In the second S/R, the first part (?:.*\R)* catches the maximum number of complete lines, before the line containing the string <div class=“pagination”>
In replacement, we just changed the contents of line, containing the string <div class=“pagination”>, by the string New contents of the line, followed by the contents of group 1 ( = text from the next line to the end of the current file )

IMPORTANT :

As usual, if you perform these S/R, on a few files, using the Replace dialog ( CTRL + H ), just remember these two rules :

Firstly, go to the very beginning of the current file ( CTRL + Origin )
Secondly use, exclusively, the Replace All button ( Due to the \K syntax, the step by step replacement, with the Replace button, does NOT work ! )

Cheers,

guy038

P.S. :

Of course, if the Find/Replace dialog would contain the four, non standard, options :

Skip the first N matches
Find/Replace the next M matches, only
Per Line : [X] or Per File : [X]

Vasile, you just would have to type 0 for number N, 1 for number M and check the Per File option.

Then, this simple following S/R would be enough !

SEARCH : (?-s).*<div class=“pagination”>.*

REPLACE : New contents of the line

Vasile Caraus

hello guy, I must say you have always something great to say about regex. You helped me a lot !

about the first part, the two regex works fine.

But, I don’t really understand the last part (P.S. :) the four, non standard, options

I cannot see the

or Per File : [X]

I guess, something is missing on my part. Can u give me a print screen?

Vasile Caraus

I found on internet a more simple way

Step1. Enable the . matches newline option

Search
<div class=“pagination”>(.*)\z
Replace by:
Anything $1

guy038

Hi, Vasile,

Two points :

Firstly, Vasile, don’t be mistaken about what I wrote, at the end of my previous post ! I was just dreaming about it ! Of course, these options are NOT part of the present “Find/Replace” dialog. And they, probably, will NEVER be :-((

I just wanted to point out that these additional options could help us, in some cases, to build more simple regexes !

Secondly, yes, you’re right : your regex is more elegant ! But it works ONLY IF there is ONE string <div class=“pagination”>, exactly, in your current file. And seemingly, you said :

The problem is that this line is repeated 5 times in each html file

But, indeed, it’s incredible how our brain is disposed to make simple things more complicated:-(( So, from your interesting regex, we can, still, simplify the previous regexes :

To change the contents of the FIRST line, ONLY, of the current file, containing the string <div class=“pagination”>, use :

SEARCH : (?s)<div class=“pagination”>(.*)

REPLACE : Anything else\1

To change the contents of the LAST line, ONLY, of the current file, containing the string <div class=“pagination”>, use :

SEARCH : (?s).*\K<div class=“pagination”>(.*)

REPLACE : Anything else\1

I don’t think we’ll be able to get shorter regexes !!

Notes :

As usual, the in-line modifier (?s) prevent us to mind about checking/unchecking the .matches newline option
In the second regex, we need to add, at the beginning, the form .*\K, in order to get the maximum range of characters till the last string <div class=“pagination”>, of the current file
The last part of the regex (.*) represents the remaining text, after the matched string <div class=“pagination”>, till the very end of file

Cheers,

guy038

Vasile Caraus

hello guy, works wonderful. Thank you.

But one more thing, I cannot get the solution. At the regex below, as you can see, first part I select all before a word. And part two select all after a word. Practicaly, I select a middle text from a file. Works beautiful. I use Replace All for more then 2000 files.

(?s)((^.*)(DELETE_UNTIL_THIS_TEXT)|(DELETE_AFTER_THIS_TEXT)(.*$))

Sometimes, the problem is when I have more instances at the last part. For exemple:

text_1
DELETE_UNTIL_THIS_TEXT (text_1)
–my text–
–my text–
DELETE_AFTER_THIS_TEXT (text_2)
text_2
text_2
text_2

So as you can see at the last part, I have three (or much more) instances (occurences) of the same “text_2.”
When I run regex, will delete all the instances text_2.

So, I want to delete just the last instance of text_2 in the regex. I will right again, but it should be modify a little bit for the second part.

(?s)((^.*)(text_1)|(text_2)(.*$))

guy038

Hello Vasile,

As you know, regexes force and help us to keep a rigorous attitude, as well as programming do ! So I, slightly, change your example text, in order to exactly see what you need !

So, let’s suppose the example text, of 20 lines, below :

Line 01
Line 02
Line 03 Text_1
Line 04
Line_05
Text_1
Line 07
Line 08
Line 09 Text_1
Line_10
Line_11
Text_2 Line 12
Line_13
Line_14
Text_2
Line_16
Line_17
Text_2 Line_18
Line_19
Line_20

Do you like to delete, in one go, :

All lines till the first occurrence of Text_1 ( so, lines 01,02 and 03 ) AND all lines from the first occurrence of Text_2 ( so, from lines 12 to 20 ) = case A
All lines till the first occurrence of Text_1 ( so, lines 01,02 and 03 ) AND all lines from the last occurrence of Text_2 ( so, lines 18, 19 and 20 ) = case B
All lines till the last occurrence of Text_1 ( so, from lines 01 to 09 ) AND all lines from the first occurrence of Text_2 ( so, from lines 12 to 20 ) = case C
All lines till the last occurrence of Text_1 ( so, from lines 01 to 09 ) AND all lines from the last occurrence of Text_2 ( so, lines 18, 19 and 20 ) = case D

Just, tell me which case ( A, B, C or D ), we’ll have to find out the regex for ?

Keep in mind, that I, implicitly, suppose that :

No string Text_1 may occur, after the first occurrence of string Text_2 !!
The strings Text_1 and/or Text_2 may appeared alone, in a line

See you later,

Best regards

guy038

P.S. :

Anyway, Vasile, I updated my reply, one hour, later !

Here are, below, the solution to the FOUR cases, given the exact previous example text, above.

We just have to make, successively, each quantifier Star, lazy or greedy ! So :

Case A : SEARCH = (?s).*?Text_1\R(.*?)Text_2.* , which keeps the lines 04 to 11, only
Case B : SEARCH = (?s).*?Text_1\R(.*)Text_2.* , which keeps the lines 04 to 17, only
Case C : SEARCH = (?s).*Text_1\R(.*?)Text_2.* , which keeps the lines 10 to 11, only
Case D : SEARCH = (?s).*Text_1\R(.*)Text_2.* , which keeps the lines 10 to 17, only

NOTE :

For these four cases, the replacement regex is, simply, \1 OR $1

Vasile Caraus

guy, works great. But if I want to replace the entire line from fisrt part (?s).*?Text_1\R(.*?), so not only from a word, but the entire line that contains that word

Scott Sumner

guy038 should get paid a consulting rate for his excellent quality and quantity of answers! His perseverance is remarkable!

Vasile Caraus

Guy, is a very talented and smart. He is the one that helps notepad users to grow and develop, step by step.

Maybe someday, somebody will need the answers of my questions, and Guy is the one that make possible !

Evolution starts with questions…and answers !

by the way, I am not a programmer, in fact, I don’t have almost any connection with this domain. But, I learn basic, which helps me a lot in other way ! Thank you Guy038 !

guy038

Hello Vasile and Scott,

Yeah, Scott, you’re right about it ! So, I could drink some more beers, as the weather is quite hot, presently, in Grenoble !!

No problem, Vasile. So, I’m starting with the original text below :

Line 01
Line 02
Line 03 Text_1 Line 03
Line 04
Line_05
Line 06 Text_1 Line 06
Line 07
Line 08
Line 09 Text_1 Line 09
Line 10
Line 11
Line 12 Text_2 Line 12
Line 13
Line 14
Line 15 Text_2 Line 15
Line 16
Line 17
Line 18 Text_2 Line 18
Line 19
Line 20

As you can see, this time, the strings Text_1 and Text_2, in lines 03, 06, 09, 12, 15 and 18 are, all, embedded in the template Line ##......Line ##

I keep the same principle, using lazy and greedy quantifiers star *. That leads to the four regexes, below :

Case A : SEARCH = (?s).*?Text_1(?-s).*\R((?:.*\R)*?).*Text_2(?s).* , which keeps the lines 04 to 11
Case B : SEARCH = (?s).*?Text_1(?-s).*\R((?:.*\R)*).*Text_2(?s).* , which keeps the lines 04 to 17
Case C : SEARCH = (?s).*Text_1(?-s).*\R((?:.*\R)*?).*Text_2(?s).* , which keeps the lines 10 to 11
Case D : SEARCH = (?s).*Text_1(?-s).*\R((?:.*\R)*).*Text_2(?s).* , which keeps the lines 10 to 17

Remark :

Remember that an in-line modifier keeps set, till an opposite modifier is met in the regex or till the end of the regex is reached !
The replacement regex has not changed : \1 or $1

Cheers

guy038

P.S… :

If some parts of the regexes seems too difficult, just ask me for further information ! It’s, simply, a question of mind’s gymnastics, that anyone can learn about !

Also, try, to visualize the position of the regex engine, while executing the regex, especially when Look-Around ( Look-Behind or Look-Ahead ) are used. Indeed, in that case, the location of the regex engine does NOT change while evaluating the look-around !

For instance, with the subject text This is a simple text to visualize the cursor location of the regex engine

Then, the regex (?-s)(?=.*regex).{4} matches the four letters of this sentence ( the word this ). Let’s us split the process :

Cursor location is just before the first letter T of the text
The regex engine tries to verify if, from the present cursor location, the look-ahead. In other words, if there is, further on, on the same line, the string regex ?
As this condition is true, the regex engine goes on, executing the following regex code .{4}
But the working position of the regex engine, is, STILL, before the first letter T of the text !
Therefore, the regex engine matches the first four characters of the subject string, that is to say, the word this

Note that IF the word regex would NOT have been found, in the text, the regex engine would have delivered the message :
Can't find the text "(?-s)(?=.*regex).{4}" !

Vasile Caraus

thanks a lot Guy !

Vasile Caraus

hello Guy. And If I want to matc (in the last formulas) the first instance of Text_1 and the last instance of Text_2?

guy038

Hi Vasile,

I, first, thought that the regex (?s).*?\KText_1|.*\KText_2 would give you the exact matches that you said :

And If I want to match (in the last formulas) the first instance of Text_1 and the last instance of Text_2?

Unfortunately, when using the search functionality, only, this regex matches any string Text_1, then the last string text_2 ! And, I was not able to get the right regex, which could find, in the current file, the first instance of Text_1, then the last instance of Text_2 :-((

However, the regex (?s).*?\KText_1.*Text_2 allows us to select, in one go, all the gap, between these two specific boundaries, included !

Best Regards,

guy038

Vasile Caraus

hello again. I have many of <tr></tr> tags on a html page. I want to select with regex only this first instance of <tr> tags. I made a regex, but this formula selects both <tr>. tags. I want only the first one, not the second one with Other Code

FIND: \b<tr>[\s\S]+</tr>\b

<tr>
<td class="right">On December 15, 2012, in <a href="https://mywebsite.com/index.html" title="See all articles here" class="external" rel="category tag">Expert-Expert</a>, by Michael Ende</td>
`</tr>

and more

<tr>
Other Code
</tr>

Terry R

@Vasile-Caraus said in Regex: Select only the first instance of search results / first match:

FIND: \b<tr>[\s\S]+</tr>\b

The simplest change I can see is to put a ? behind the + character as your regex is greedy. I presume it is currently going to the last </tr> in the file.

Also as far as I can see the \s\S combination means every character including CR and LF one’s. The whole thing could be rewritten as (?s)\b<tr>.+?</tf>\b.

I’m not on a PC to currently check my answer so apologies if I have it slightly wrong.

Terry

Vasile Caraus

@Terry-R said in Regex: Select only the first instance of search results / first match:

(?s)\b<tr>.+?</tf>\b

your (?s)\b<tr>.+?</tr>\b is not working :(

I also try something different, also not working :( (?:^(?ms)(<tr>).*?(</tr>))

Vasile Caraus

I also try another combination, not working (?-s)(\b(?!^<tr>(.+)</tr>)

:((

<tr>
<td class="right">On December 15, 2012, in <a href="https://mywebsite.com/index.html" title="See all articles here" class="external" rel="category tag">Expert-Expert</a>, by Michael Ende</td>
</tr>

code

<tr>
Other Code
</tr>

Terry R

@Vasile-Caraus said in Regex: Select only the first instance of search results / first match:

your (?s)\b<tr>.+?</tr>\b is not working :(

What does it do? Does it select anything. And sorry for the typo with the tf which I see you caught.
The (?s) is necessary to cross lines. As you had \b I also included them although they could both be removed as a test.

Terry

Vasile Caraus

I believe only @guy038 can find a good answer :)