I have a piece of HTML markup, for which I need to add a specific CSS rule to it. The HTML is like this:
<tr>
<td style="color:#555555;padding-top: 3px;padding-bottom: 20px;">In order to stop receiving similar emails, simply remove the relevant saved search from your account.</td>
</tr>
As you can see td already contains a style tag, so my idea is to match the last ; of it and replace it with a ; plus the rule I need to add...
The problem is that, although I used the appropriate non-capturing group, I still can't figure out how to do this properly... Take a look at this experiment please: https://regex101.com/r/qlVq6A/1
(<td.*style=".*)(;)(".*>)(?:In order to stop receiving)
On the other hand, when I assign a capturing group to the last part (the text in English that's there just to identify which td I'm interested in) it works OK, but I feel like this is an indirect way to make this work... Take a look at this experiment: https://regex101.com/r/qhVatN/1
(<td.*style=".*)(;)(".*>In order to stop receiving)
Can someone explain to me why the first route doesn't work? Basically, why the non-capturing group still captures the text inside of it...
In your second pattern, you use 3 capture groups and you use the style that you want to add in the replacement and the 3rd group contains In order to stop receiving which will be present after using group 3 in the replacement.
But in your first pattern, you use a non capture group (?: and that will match but is not part of the replacement.
Note that when using a non capture group like that you can just omit it at all because the grouping by itself like that without for example a quantifier or alternation has no additional purpose.
You can use a pattern for the example string, but this can be error prone and using a DOM parser would be a better option.
A way to write the pattern with just 2 capture groups:
(<td[^>]*\bstyle="[^"]*;)([^"]*">In order to stop receiving)
In the replacement use:
$1font-size: 80%;$2
Explanation
( Capture group 1
<td[^>]* Match <td and then optionally repeat any char except >
\bstyle="[^"]*; Match style=" and then optionally repeat matching any char except " and then match the last semicolon (note that it is part of group 1 now)
) Close group 1
( Capture group 2
[^"]*">In order to stop receiving Optionally repeat matching any char except : and then match "> followed by the expected text
) Close group 2
See a regex demo.
Another option to write the pattern without capture groups making use of \K to forget what is matched so far, and a positive lookahead (?= to assert the expected text to the right:
<td[^>]*\bstyle="[^"]*;\K(?=[^"]*">In order to stop receiving)
See another regex demo.
Related
I am trying to extract part of a long text, such as information about caring for a plant. The text contains paragraphs and blank lines. I am not able to capture the specific text I want, the second problem is that the last word isn't showing in the extracted text, and the last problem is when my search starts at the beginning of the line.
I tried searching for the text I want to extract by using a word that isn't at the beginning of the line, it worked except that the end of the desired text is missing a word, and if that word is on new line, it won't show any results at all.
I was using https://scriptun.com/tools/php/preg_match for testing
//The first word to start the search is 'How to'. And I want to capture it as well
// The second word where the text I want ends is '(optional):'
'/(?=How to).*?\s(?=\(optional\):)/'
The sample text I am using to test is:
//Text comes before this..
How to care for Split Leaf Plant
The Split leaf philodendron, also called monstera deliciosa or swiss
cheese plant, is a large, popular, easy- care houseplant that is not
really in the philodendron family. There is a great deal of confusion
about what to call this plant; the various names have become
inter-changeable over the years.
Here is more info (optional):
//And more text goes here
I want to extract all the text from the word 'How to' ending with '(optional):'. Regardless of how many lines or paragraphs are in between
The expected extracted text:
How to care for Split Leaf Plant
The Split leaf philodendron, also called monstera deliciosa or swiss
cheese plant, is a large, popular, easy- care houseplant that is not
really in the philodendron family. There is a great deal of confusion
about what to call this plant; the various names have become
inter-changeable over the years.
Here is more info (optional):
Thank you
That's pretty easy. You can use the following pattern:
https://regex101.com/r/TjE2x8/2
Pattern: ^How to[\w\W]+?\(optional\):$
Pattern: ^How to(?:.|\R)*optional\):$
demo on regex101
Explanation:
^ match the first instance where How to appears at the beginning of the line
(?: ) non capturing group. We need it because of the following OR instruction which is the pipe |. But we don't need to capture the contents. That's why we use ?: after the first parenthesis.
. every character
| or
\R every kind of new line
* make sure to capture zero to every instance of the group
optional\):$ match the word optional with parenthesis (escaped, because it is not an instruction) \) and a colon : at the very end of the text $
Pattern 2: /^How to.*optional\):$/ms
demo on regex101
This pattern is even simpler, but requires the m and s flag to be set in order to match multiline and the . character class to match new lines.
My title probably doesn't explain exactly what I mean. Take the following string:
POWERSTART9^{{2|3}}POWERENDx{{3^EXSTARTxEXEND}}=POWERSTART27^{{1|4}}POWEREND
What I want to do here is isolate the parts that are like this:
{{2|3}} or {{1|4}}
The following expression works to an extent, it selects the first one {{2|3}} with no issue:
\{\{(.*?)\|(.*?)\}\}
The problem is, it's not just selecting the first if {{2|3}} and the second of {{1|4}} because after the first one we have {{3^EXSTARTxEXEND}} so it's taking the starting point from {{3 and going right until the end of the second part I want |4}}
Here it is highlighted on RegExr:
I've never been great with regex and can't work out how to stop it doing that. Any ideas? I basically want it to only match the exact pattern and not something that contains it.
You may use
\{\{((?:(?!{{).)*?)\|(.*?)}}
See the regex demo.
If there can be no { and } inside the {{...}} substrings, you may use a simpler \{\{([^{}|]*)\|([^{}]*)}} expression (see demo).
Details
\{\{ - a {{ substring
((?:(?!{{).)*?) - Capturing group 1: any char (.), as few as possible (*?), that does not start a {{ char sequence (tempered greedy token)
[^{}|]* - any 0 or more chars other than {, } and |
\| - a | char
(.*?) - Capturing group 2: any 0 or more chars, as few as possible
[^{}]* - any 0 or more chars other than { and }
}} - a }} substring.
Try this \{\{([^\^|]*)\|([^\^|]*)\}\}
https://regex101.com/r/bLF8Oq/1
I am trying to retrieve matches from a comma separated list that is located inside parenthesis using regular expression. (I also retrieve the version number in the first capture group, though that's not important to this question)
What's worth noting is that the expression should ideally handle all possible cases, where the list could be empty or could have more than 3 entries = 0 or more matches in the second capture group.
The expression I have right now looks like this:
SomeText\/(.*)\s\(((,\s)?([\w\s\.]+))*\)
The string I am testing this on looks like this:
SomeText/1.0.4 (debug, OS X 10.11.2, Macbook Pro Retina)
Result of this is:
1. [6-11] `1.0.4`
2. [32-52] `, Macbook Pro Retina`
3. [32-34] `, `
4. [34-52] `Macbook Pro Retina`
The desired result would look like this:
1. [6-11] `1.0.4`
2. [32-52] `debug`
3. [32-34] `OS X 10.11.2`
4. [34-52] `Macbook Pro Retina`
According to the image above (as far as I can see), the expression should work on the test string. What is the cause of the weird results and how could I improve the expression?
I know there are other ways of solving this problem, but I would like to use a single regular expression if possible. Please don't suggest other options.
When dealing with a varying number of groups, regex ain't the best. Solve it in two steps.
First, break down the statement using a simple regex:
SomeText\/([\d.]*) \(([^)]*)\)
1. [9-14] `1.0.4`
2. [16-55] `debug, OS X 10.11.2, Macbook Pro Retina`
Then just explode the second result by ',' to get your groups.
Probably the \G anchor works best here for binding the match to an entry point. This regex is designed for input that is always similar to the sample that is provided in your question.
(?<=SomeText\/|\G(?!^))[(,]? *\K[^,)(]+
(?<=SomeText\/|\G) the lookbehind is the part where matches should be glued to
\G matches where the previous match ended (?!^) but don't match start
[(,]? *\ matches optional opening parenthesis or comma followed by any amount of space
\K resets beginning of the reported match
[^,)(]+ matches the wanted characters, that are none of ( ) ,
Demo at regex101 (grab matches of $0)
Another idea with use of capture groups.
SomeText\/([^(]*)\(|\G(?!^),? *([^,)]+)
This one without lookbehind is a bit more accurate (it also requires the opening parenthesis), of better performance (needs fewer steps) and probably easier to understand and maintain.
SomeText\/([^(]*)\( the entry anchor and version is captured here to $1
|\G(?!^),? *([^,)]+) or glued to previous match: capture to $2 one or more characters, that are not , ) preceded by optional space or comma.
Another demo at regex101
Actually, stribizhev was close:
(?:SomeText\/([^() ]*)\s*\(|(?!^)\G),?\s*([^(),]+)(?=[^()]*\))
Just had to make that one class expect at least one match
(?:SomeText\/([0-9.]+)\s*\(|(?!^)\G),?\s*([^(),]+)(?=[^()]*\)) is a little more clear as long as the version number is always numbers and periods.
I wanted to come up with something more elegant than this (though this does actually work):
SomeText\/(.*)\s\(([^\,]+)?\,?\s?([^\,]+)?\,?\s?([^\,]+)?\,?\s?([^\,]+)?\,?\s?([^\,]+)?\,?\s?([^\,]+)?\,?\s?\)
Obviously, the
([^\,]+)?\,?\s?
is repeated 6 times.
(It can be repeated any number of times and it will work for any number of comma-separated items equal to or below that number of times).
I tried to shorten the long, repetitive list of ([^\,]+)?\,?\s? above to
(?:([^\,]+)\,?\s?)*
but it doesn't work and my knowledge of regex is not currently good enough to say why not.
This should solve your problem. Use the code you already have and add something like this. It will determine where commas are in your string and delete them.
Use trim() to delete white spaces at the start or the end.
$a = strpos($line, ",");
$line = trim(substr($line, 55-$a));
I hope, this helps you!
I got this pattern(I am using php):
'/\[link\=((https?:\/\/)?([\da-z\.-]+)\.([a-z\.]{2,6})([\/\w \.-]*)*\/?)\]/i'
When i search for this string: http://phpquest.zapto.org/users/register.php
The matches are(The order is 0-5):
'[link=http://phpquest.zapto.org/users/register.php]'
'http://phpquest.zapto.org/users/register.php'
'http://'
'phpquest.zapto'
org
''
When i replace the * with + inside the last subpattern like that:
'/\[link\=((https?:\/\/)?([\da-z\.-]+)\.([a-z\.]{2,6})([\/\w \.-]+)*\/?)\]/i'
The matches are(The order is 0-5):
'[link=http://phpquest.zapto.org/users/register.php]'
'http://phpquest.zapto.org/users/register.php'
'http://'
'phpquest.zapto'
org
'/users/register.php'
If anyone can help me understand why is that i will be very thankful, Thank you all and have a nice day.
Maybe a simpler example is when you compare this to this.
The regexes involved are:
(a*)*
and
(a+)*
And the test string is aaaaaa.
What happens is that after capturing the main group (in the example I provided, the series of a's) it attempts to match more, but cannot. But wait! It can also match nothing, because * means 0 or more times!
Therefore, after matching all the a's, it will match and catch a 'nothing' and since only the last captured part is stored, you get '' as result of the capture group.
In (a+)*, after matching and catching aaaaaa, it cannot match or catch anything more (+ prevents it to match nothing, as opposed to *) and hence, aaaaaa is the last match.
This can be simplified with the following pattern.
/\[link=(https?:\/\/)(([a-z0-9]+\.?)+)((\/[^\/]+)+)\/?\]/i
The regex symbol * is not greedy, while + is. Hence, when using the + in the second attempt, all path components are matched and that group is captured; however, in the first attempt with *, since you were only capturing the inner * group with parenthesis, you matched the un-greedy sample of the *, in this case nothing.
I'd like to capture up to four groups of text between <p> and </p>. I can do that using the following regex:
<h5>Trivia<\/h5><p>(.*)<\/p><p>(.*)<\/p><p>(.*)<\/p><p>(.*)<\/p>
The text to match on:
<h5>Trivia</h5><p>Was discovered by a freelance photographer while sunbathing on Bournemouth Beach in August 2003.</p><p>Supports Southampton FC.</p><p>She has 11 GCSEs and 2 'A' Levels.</p><p>Listens to soul, R&B, Stevie Wonder, Aretha Franklin, Usher Raymond, Michael Jackson and George Michael.</p>
It outputs the four lines of text. It also works as intended if there are more trivia items or <p> occurrences.
But if there are less than 4 trivia items or <p> groups, it outputs nothing since it cannot find the fourth group. How do I make that group optional?
I've tried: <h5>Trivia<\/h5><p>(.*?)<\/p>(?:<p>(.*?)<\/p>)?(?:<p>(.*?)<\/p>)?(?:<p>(.*?)<\/p>)?(?:<p>(.*?)<\/p>)? and that works according to http://gskinner.com/RegExr/ but it doesn't work if I put it inside PHP code. It only detects one group and puts everything in it.
The magic word is either 'escaping' or 'delimiters', read on.
The first regex:
<h5>Trivia<\/h5><p>(.*)<\/p><p>(.*)<\/p><p>(.*)<\/p><p>(.*)<\/p>
worked because you escaped the / characters in tags like </h5> to <\/h5>.
But in your second regex (correctly enclosing each paragraph in a optional non-capturing group, fetching 1 to 5 paragraphs):
<h5>Trivia</h5><p>(.*?)</p>(?:<p>(.*?)</p>)?(?:<p>(.*?)</p>)?(?:<p>(.*?)</p>)?(?:<p>(.*?)</p>)?
you forgot to escape those / characters.
It should then have been:
$pattern = '/<h5>Trivia<\/h5><p>(.*?)<\/p>(?:<p>(.*?)<\/p>)?(?:<p>(.*?)<\/p>)?(?:<p>(.*?)<\/p>)?(?:<p>(.*?)<\/p>)?/';
The above is assuming you were putting your regex between two / "delimiters" characters (out of conventional habit).
To dive a little deeper into the rabbit-hole, one should note that in php the first and last character of a regular expression is usually a "delimiter", so one can add modifiers at the end (like case-insensitive etc).
So instead of escaping your regex, you could also use a ~ character (or #, etc) as a delimiter.
Thus you could also use the same identical (second) regex that you posted and enclose for example like this:
$pattern = '~<h5>Trivia</h5><p>(.*?)</p>(?:<p>(.*?)</p>)?(?:<p>(.*?)</p>)?(?:<p>(.*?)</p>)?(?:<p>(.*?)</p>)?~';
Here is a working (web-based) example of that, using # as delimiter (just because we can).
You can use the question mark to make each <p>...</p> optional:
$pattern = '~<h5>Trivia</h5>(?:<p>(.*?)</p>)?(?:<p>(.*?)</p>)?(?:<p>(.*?)</p>)?(?:<p>(.*?)</p>)?~';
Use the Dom is a good option too.