I think this won't count much combinations please, I need to remove from string a paragraph that has specific class (It is consistent)
Example:
<p class="special_class">Some content</p>
I want to remove the content of every paragraph which has special_class only. So I would like to run a regex that returns empty. I do not want to use a parser to do this please, i am using this in very little function inside my script.
Thank you :)
It is generally a bad idea to use regex for the HTML parsing. Take a look at Simple HTML DOM Parser instead to find out the specified and remove it.
If you want to use regex anyway, you could trt this instead:
preg_replace('/<p class="special_class">[\w\s]*<\/p>/', '<p class="special_class"></p>');
$result = preg_replace('%<p\s+class="special_class">.*?</p>%s', '', $subject);
should work. It will remove the entire paragraph from the opening to the closing p tag. It expects that the p tag is properly closed. But you already seem to know about the drawbacks of handling HTML with regexes...
Related
I have this block of html:
<div>
<p>First, nested paragraph</p>
</div>
<p>First, non-nested paragraph.</p>
<p>Second paragraph.</p>
<p>Last paragraph.</p>
I'm trying to select the first, non-nested paragraph in that block. I'm using PHP's (perl style) preg_match to find it, but can't seem to figure out how to ignore the p tag contained within the div.
This is what I have so far, but it selects the contents of the first paragraph contained above.
/<p>(.+?)<\/p>/is
Thanks!
EDIT
Unfortunately, I don't have the luxury of a DOM Parser.
I completely appreciate the suggestions to not use RegEx to parse HTML, but that's not really helping my particular use case. I have a very controlled case where an internal application generated structured text. I'm trying to replace some text if it matches a certain pattern. This is a simplified case where I'm trying to ignore text nested within other text and HTML was the simplest case I could think of to explain. My actual case looks something a little more like this (But a lot more data and minified):
#[BILLINGCODE|12345|11|15|2001|15|26|50]#
[ITEM1|{{Escaped Description}}|1|1|4031|NONE|15]
#[{{Additional Details }}]#
[ITEM2|{{Escaped Description}}|3|1|7331|NONE|15]
[ITEM3|{{Escaped Description}}|1|1|9431|NONE|15]
[ITEM4|{{Escaped Description}}|1|1|5131|NONE|15]
I have to reformat a certain column of certain rows to a ton of rows similar to that. Helping my first question would help actual project.
Your regex won't work. Even if you had only non nested paragraph, your capturing parentheses would match First, non-nested ... Last paragraph..
Try:
<([^>]+)>([^<]*<(?!/?\1)[^<]*)*<\1>
and grab \2 if \1 is p.
But an HTML parser would do a better job of that imho.
How about something like this?
<p>([^<>]+)<\/p>(?=(<[^\/]|$))
Does a look-ahead to make sure it is not inside a closing tag; but can be at the end of a string. There is probably a better way to look for what is in the paragraph tags but you need to avoid being too greedy (a .+? will not suffice).
Use a two three step process. First, pray that everything is well formed. Second, First, remove everything that is nested.
s{<div>.*?</div>}{}g; # HTML example
s/#.*?#//g; # 2nd example
Then get your result. Everything that is left is now not nested.
$result = m{<p>(.*?)</p>}; # HTML example
$result = m{\[(.*?)\]}; # 2nd example
(this is Perl. Don't know how different it would look in PHP).
"You shouldn't use regex to parse HTML."
It is what everybody says but nobody really offers an example of how to actually do it, they just preach it. Well, thanks to some motivation from Levi Morrison I decided to read into DomDocument and figure out how to do it.
To everybody that says "Oh, it is too hard to learn the parser, I'll just use regex." Well, I've never done anything with DomDocument or XPath before and this took me 10 minutes. Go read the docs on DomDocument and parse HTML the way you're supposed to.
$myHtml = <<<MARKUP
<html>
<head>
<title>something</title></head>
<body>
<div>
<p>not valid</p>
</div>
<p>is valid</p>
<p>is not valid</p>
<p>is not valid either</p>
<div>
<p>definitely not valid</p>
</div>
</body>
</html>
MARKUP;
$DomDocument = new DOMDocument();
$DomDocument->loadHTML($myHtml);
$DomXPath = new DOMXPath($DomDocument);
$nodeList = $DomXPath->query('body/p');
$yourNode = $DomDocument->saveHtml($nodeList->item(0));
var_dump($yourNode)
// output '<p>is valid</p>'
You might want to have a look at this post about parsing HTML with Regex.
Because HTML is not a regular language (and Regular Expressions are), you can't pares out arbitrary chunks of HTML using Regex. Use an HTML parser, it'll get the job done considerably more smoothly than trying to hack together some regex.
I'm looking for a way to count html tags in a chunk of html using php. This may not be a full web page with a doctype body tags etc.
For example:
If I had something like this
$string = "
<div></div>
<div style='blah'></div>
<p>hello</p>
<p>its debbie mcgee
<p class='pants'>missing p above</p>
<div></div>";
I want to pass it to a function with a tag name such as
CheckHtml( $string, 'p' );
and I would like it to tell me the number of open <p> tags and the number of close p tags </p>. I don't want it to do anything fancy beyond that (no sneaky trying to fix it).
I have tried with string counts with start tags such as <p but it can too easily find things like and return wrong results.
I had a look as DOMDocument but it doesn't seem to count close tags and always expects <html> tags (although I could work around this).
Any suggestions on what to use.
To get a accurate count, you can't use string matching or regex because of the well-known problems of parsing HTML with regex
Nor can you use the output of a standard parser, because that's a DOM consisting of elements and all the information about the tags that were in the HTML has been discarded. End tags will be inferred even for valid HTML, and even some start tags (e.g. html, head, body, tbody) can be inferred. Moreover things like the adoption agency algorithm can result in there being more elements than there were tags in the HTML mark-up. For example <b><i></b>x</i> will result in there being two i elements in the DOM. At the same time, end tags that can't be matched with start tags are simply discarded, as indeed can start and end tags that appear in the wrong place. (e.g. <caption> not in <table> or <legend> not in <fieldset>)
The only way I can think you could do this in any way reliably is this:
There's an open source PHP library for parsing HTML called html5lib.
In there, there's a file called Tokenizer.php and at the end of that file there's a function called emitToken. At this point, the parser has done all the work of figuring out all the HTML weirdnesses¹, and the $token parameter contains all the information about what kind of token has been recognised, including start and end tags.
You could take the library and modify it so that it counts up the start and end tag tokens at that point, and then exposes those totals to your application code at the end of the parse process.
¹: That is, it's figured out the weirdnesses related to your counting problem. It hasn't begun to figure out the tree construction weirdnesses.
You can use substr_count() to return the number of times the needle substring occurs in the haystack $string.
$open_tag_count = substring_count( $string, '<p' );
$close_tag_count = substring_count( $string, '</p>' );
Be aware that '<param and <pre, so you may need to modify your search to handle two different specific cases:
$open_tag_count_without_attributes = substring_count( $string, '<p>' );
$open_tag_count_with_attributes = substring_count( $string, '<p ' );
$open_tag_count = $open_tag_count_without_attributes + $open_tag_count_with_attributes;
You may also wish to consider using [preg_match()][1]. Using a regular expression to parse HTML comes with a fairly substantial set of pitfalls, so use with caution.
substr_count seems like a good bet.
EDIT: You'll have to use preg_match then
I haven't tested, this but, for an idea..
function checkHTML($string,$htmlTag){
$openTags = preg_match('/<'.$htmlTag.'\b[^>]*>',$string);
$closeTags = preg_match('/<\/'.$htmlTag.'>/',$string);
return array($openTags, $closeTags);
}
$numberOfParagraphTags = checkHTML($string,'p');
echo('Open Tags:'.$numberOfParagraphTags[0].' Close Tags:'.$numberOfParagraphTags[1]);
For the chunk of HTML, try using the DomDocument PHP class instead of a string. Then you can use methods such as getElementsByTagName(); that will allow you to count the tags easier and more accurately. To load your string into a DomDocument, you could do something like this:
$doc = new DOMDocument();
$doc->loadHTML($string);
Then, to count your tags, do the following:
$tagList = $doc->getElementsByTagName($tag);
return $tagList.length;
I am trying to index some content from a series of .html's that share the same format.
So I get a lot of lines like this: <a href="meh">[18] blah blah blah < a...
And the idea is to extract the number (18) and the text next to it (blah...). Furthermore, I know that every qualifying line will start with "> and end with either <a or </p. The issue stems from the need to keep all other htmHTML tags as part of the text (<i>, <u>, etc.).
So then I have something like this:
$docString = file_get_contents("http://whatever.com/some.htm");
$regex="/\">\ [(.*?)\ ] (<\/a>)(.) *?(<)/";
preg_match_all($regex,$docString,$match);
Let's look at $regex for a sec. Ignore it's spaces, I just put them here because else some characters disappear. I specify that it will start with ">. Then I do the numbers inside the [] thing. Then I single out the </a>. So far so good.
At the end, I do a (.)*?(<). This is the turning point. By leaving the last bit, (<) like that, The text will be interrupted when an underline or italics tag is found. However, if I put (<a|</p) the resulting array ends up empty. I've tried changing that to only (<a), but it seems that 2 characters mess up the whole ting.
What can I do? I've been struggling with this all day.
PHP Tidy is your friend. Don't use regexes.
Something like /">\[(.*)\](.*)(?:<(?:a|\/p))/ seems to work fine for given your example and description. Perhaps adding non-capturing subpatterns does it? Please provide a counterexample wherein this doesn't work for you.
Though I agree that RegEx isn't a parser, it sounds like what you're looking for is part of a regularly behaved string - which is exactly what RegEx is strong at.
As you've found, using a regex to parse HTML is not very easy. This is because HTML is not particularly regular.
I suggest using an XML parser such as PHP's DomDocument.
Create an object, then use the loadHTMLFile method to open the file. Extract your a tags with getElementsByTagName, and then extract the content as the NodeValue property.
It might look like
// Create a DomDocument object
$html = new DOMDocument();
// Load the url's contents into the DOM
$html->loadHTMLFile("http://whatever.com/some.htm");
// make an array to hold the text
$anchors = array();
//Loop through the a tags and store them in an array
foreach($html->getElementsByTagName('a') as $link) {
$anchors[] = $link->nodeValue;
}
One alternative to this style of XML/HTML parser is phpquery. The documentation on their page should do a good job of explaining how to extract the tags. If you know jQuery, the interface may seem more natural.
I googled a lot, for those kind of problems have been asked a lot in the past. But I didn't find anything to match my needs.
I have a html formatted text from a form. Just like this:
Hey, I am just some kind of <strong>formatted</strong> text!
Now, I want to strip all html tags, that I don't allow. PHP's built-in strip_tags() Method does that very well.
But I want to go a step further: I want to allow some Tags only inside or not inside of other tags. I also want to define my own XML Tags.
Another example:
I am a custom xml tag: <book><strong>Hello!</strong></book>. Ok... <strong>Hi!</strong>
Now, I want the <strong/> inside of <book/> to be stripped, but the <strong>Hi!</strong> can stay the way it is.
So, I want to define some rules of what I allow or don't allow, and want to have any filter do the rest.
Is there any easy way to do that? Regexp aren't what I'm looking for, for they can't parse html properly.
Regards, Jan Oliver
Don't think there is such a thing, I think not even HTML Purifier does that.
I suggest you parse the XHTML by hand using something like Simple HTML Dom.
Use a second argument to strip_tags, which is allowable tags.
$text = strip_tags($text, '<book><myxml:tag>');
I don't think there's a way to only strip certain tags if they're not inside other tags, without using regex.
Also, regex aren't not good at parsing HTML, but it's slow compared to the options. But that's not what you're doing here, anyways. You're going through the string and removing things you don't want. And for your complex requirement I think your only option is to use regex.
To be completely honest I think you should decide which tags are allowable and which aren't. Whether or not they are inside of other tags shouldn't matter at all. It's markup, not a script.
The second argument shows that you cal allow some tags:
string strip_tags ( string $str [, string $allowable_tags ] )
From php.net
I wrote my own Filter class based on the DOM classes of PHP. Look here: XHTMLFilter class
WordPress spits posts in this format:
<h2>Some header</h>
<p>First paragraph of the post</p>
<p>Second paragraph of the post</p>
etc.
To get my cool styling on the first paragraph (it's one of those things that looks good only sparingly) I need to hook into the get_posts function to filter its output with a preg_replace.
The goal is to get the above code to look like:
<h2>Some header</h>
<p class="first">First paragraph of the post</p>
<p>Second paragraph of the post</p>
I have this so far but it's not even working (the error is: "preg_replace() [function.preg-replace]: Unknown modifier ']'")
$output=preg_replace('<p[^>]*>', '<p class="first">', $content);
I can't use CSS3 meta-selectors because I need to support IE6, and I can't apply the :first-line meta-selector (this is one that IE6 supports) on the parent container because it would hit the H2 instead of the first P.
You may find it easier and more reliable to use an HTML parser such as this one. HTML is notoriously difficult to parse reliably (technically, impossible) with regular expressions, and the parser will give you a very simple means to find the nodes you're interested in. The first page of the doc has a tab labelled "How to modify HTML elements".
Two right possibilities :
Do that in Javascript. Using jQuery, for example, it's a matter of one line : $("h2").next().addClass("first")
Use an HTML parser. Indeed, regexp are not a good tool to do what you want to do. Since loading a whole HTML parser for just this purpose is overkill, you'd really better be using Javascript.
The wrong way
Of course, in order to anwser the question, here is the best way I can't think of to make it happends with regexp. Though, I don't recommend it.
preg_replace('#(</h2>\s*<p[^>]*)>#im', '$1 class="first">', '<h2>Some header</h> <p>First paragraph of the post</p> <p>Second paragraph of the post</p> ');
What we do is:
using preg_replace so we can use advanced regexp to replace the code;
using "m" and "i" flag so the regexp does not bother about line break or case;
using </h2>\s* to match the closing "h2" tags and all the spaces/line breaks after;
using *<p[^>]* to match the "p" tag and its current attributs;
using parenthesis to save that;
using "$1" to replace to replace the matched string we the part we save;
adding the class and closing the ">".
The first draw back I can think of is that it doesn't handle the case where a class already exists.
Of, and by the way, you have <h2>...</h> instead of <h2>...</h2>. I don't know if it's a typo but I assumed it was. Replace in the regexp accordingly if it's not.
The problem is that the first character of the regex in a preg_* function is taken as a modifier delimiter. What you'd need is something like:
$output = preg_replace('~<p\b([^>]*)>~', '<p class="first" \1>', $content, 1);
This also puts back any extra attributes the <p> may have.
Overall, though, it's cleaner to do with CSS selectors and a JS fallback for IE.
EDIT: Added replacement limit and word break.
in this particular case regexp solution would be fairly easy
echo preg_replace('~</h2>\s*<p~', "$0 class='first'", $html);
Reading through the answers there are some that will work but all have drawbacks of either using an external parsing library or possibly matching tags other than the P tag or also matching its attributes.
I ended up using this solution with the str_replace_once function from here:
str_replace_once('<p>', '<p class="first">', $content);
Simple enough and it works just as intended. Here's full WordPress code snippet to filter the first paragraph any time the_content() is called:
add_filter('the_content', 'first_p_style');
function first_p_style($content) {
$output=str_replace_once('<p>', '<p class="first">', $content);
return ($output);
}
Thanks for all the answers!