Cleaning HTML by removing extra/redundant formatting tags

php html dom html-parsing bbcode
Aziz picture Aziz · Apr 20, 2012 · Viewed 19.4k times · Source

I have been using CKEditor wysiwyg editor for a website where users are allowed to use the HTML editor to add some comments. I ended up having some extremely redundant nested HTML code in my database that is slowing down the viewing/editing of these comments.

I have comments that look like this (this is a very small example. I have comments with over 100 nested tags):

<p>
 <strong>
  <span style="font-size: 14px">
   <span style="color: #006400">
     <span style="font-size: 14px">
      <span style="font-size: 16px">
       <span style="color: #006400">
        <span style="font-size: 14px">
         <span style="font-size: 16px">
          <span style="color: #006400">This is a </span>
         </span>
        </span>
       </span>
      </span>
     </span>
    </span>
    <span style="color: #006400">
     <span style="font-size: 16px">
      <span style="color: #b22222">Test</span>
     </span>
    </span>
   </span>
  </span>
 </strong>
</p>

My questions are:

  • Is there any library/code/software that can do a smart (i.e. format-aware) clean-up of the HTML code, removing all redundant tags that have no effect on the formatting (because they're overridden by inner tags) ? I've tried many existing online solutions (such as HTML Tidy). None of them do what I want.

  • If not, I'll need to write some code for HTML parsing and cleaning. I am planning to use PHP Simple HTML DOM to traverse the HTML tree and find all tags that have no effect. Do you suggest any other HTML parser that is more suitable for my purpose?

Thanks

.

Update:

I have written some code to analyze the HTML code that I have. All the HTML tags that I have are:

  • <span> with styles for font-size and/or color
  • <font> with attributes color and/or size
  • <a> for links (with href)
  • <strong>
  • <p> (single tag to wrap the whole comment)
  • <u>

I can easily write some code to convert the HTML code into bbcode (e.g. [b], [color=blue], [size=3], etc). So I above HTML will become something like:

[b][size=14][color=#006400][size=14][size=16][color=#006400]
[size=14][size=16][color=#006400]This is a [/color][/size]
[/size][/color][/size][/size][color=#006400][size=16]
[color=#b22222]Test[/color][/size][/color][/color][/size][/b]

The question now is: Is there an easy way (algorithm/library/etc) to clean-up the messy (as messy as that original HTML) bbcode that will be generated?

thanks again

Answer

Baba picture Baba · Apr 25, 2012

Introduction

The best solution have seen so far is using HTML Tidy http://tidy.sourceforge.net/

Beyond converting the format of a document, Tidy is also able to convert deprecated HTML tags into their cascading style sheet (CSS) counterparts automatically through the use of the clean option. The generated output contains an inline style declaration.

It also ensures that the HTML document is xhtml compatible

Example

$code ='<p>
 <strong>
  <span style="font-size: 14px">
   <span style="color: #006400">
     <span style="font-size: 14px">
      <span style="font-size: 16px">
       <span style="color: #006400">
        <span style="font-size: 14px">
         <span style="font-size: 16px">
          <span style="color: #006400">This is a </span>
         </span>
        </span>
       </span>
      </span>
     </span>
    </span>
    <span style="color: #006400">
     <span style="font-size: 16px">
      <span style="color: #b22222">Test</span>
     </span>
    </span>
   </span>
  </span>
 </strong>
</p>';

If you RUN 

$clean = cleaning($code);
print($clean['body']);

Output

<p>
    <strong>
        <span class="c3">
            <span class="c1">This is a</span> 
                <span class="c2">Test</span>
            </span>
        </strong>
</p>

You can get the CSS 

$clean = cleaning($code);
print($clean['style']);

Output

<style type="text/css">
    span.c3 {
        font-size: 14px
    }

    span.c2 {
        color: #006400;
        font-size: 16px
    }

    span.c1 {
        color: #006400;
        font-size: 14px
    }
</style>

Our the FULL HTML 

$clean = cleaning($code);
print($clean['full']);

Output

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
    <title></title>
    <style type="text/css">
/*<![CDATA[*/
    span.c3 {font-size: 14px}
    span.c2 {color: #006400; font-size: 16px}
    span.c1 {color: #006400; font-size: 14px}
    /*]]>*/
    </style>
  </head>
  <body>
    <p>
      <strong><span class="c3"><span class="c1">This is a</span>
      <span class="c2">Test</span></span></strong>
    </p>
  </body>
</html>

Function Used

function cleaning($string, $tidyConfig = null) {
    $out = array ();
    $config = array (
            'indent' => true,
            'show-body-only' => false,
            'clean' => true,
            'output-xhtml' => true,
            'preserve-entities' => true 
    );
    if ($tidyConfig == null) {
        $tidyConfig = &$config;
    }
    $tidy = new tidy ();
    $out ['full'] = $tidy->repairString ( $string, $tidyConfig, 'UTF8' );
    unset ( $tidy );
    unset ( $tidyConfig );
    $out ['body'] = preg_replace ( "/.*<body[^>]*>|<\/body>.*/si", "", $out ['full'] );
    $out ['style'] = '<style type="text/css">' . preg_replace ( "/.*<style[^>]*>|<\/style>.*/si", "", $out ['full'] ) . '</style>';
    return ($out);
}

================================================

Edit 1 : Dirty Hack (Not Recommended)

================================================

Based on your last comment its like you want to retain the depreciate style .. HTML Tidy might not allow you to do that since its depreciated but you can do this 

$out = cleaning ( $code );
$getStyle = new css2string ();
$getStyle->parseStr ( $out ['style'] );
$body = $out ['body'];
$search = array ();
$replace = array ();

foreach ( $getStyle->css as $key => $value ) {
    list ( $selector, $name ) = explode ( ".", $key );
    $search [] = "<$selector class=\"$name\">";
    $style = array ();
    foreach ( $value as $type => $att ) {
        $style [] = "$type:$att";
    }
    $replace [] = "<$selector style=\"" . implode ( ";", $style ) . ";\">";
}

Output

<p>
  <strong>
      <span style="font-size:14px;">
        <span style="color:#006400;font-size:14px;">This is a</span>
        <span style="color:#006400;font-size:16px;">Test</span>
        </span>
  </strong>
</p>

Class Used 

//Credit : http://stackoverflow.com/a/8511837/1226894
class css2string {
var $css;

function parseStr($string) {
    preg_match_all ( '/(?ims)([a-z0-9, \s\.\:#_\-@]+)\{([^\}]*)\}/', $string, $arr );
    $this->css = array ();
    foreach ( $arr [0] as $i => $x ) {
        $selector = trim ( $arr [1] [$i] );
        $rules = explode ( ';', trim ( $arr [2] [$i] ) );
        $this->css [$selector] = array ();
        foreach ( $rules as $strRule ) {
            if (! empty ( $strRule )) {
                $rule = explode ( ":", $strRule );
                $this->css [$selector] [trim ( $rule [0] )] = trim ( $rule [1] );
            }
        }
    }
}

function arrayImplode($glue, $separator, $array) {
    if (! is_array ( $array ))
        return $array;
    $styleString = array ();
    foreach ( $array as $key => $val ) {
        if (is_array ( $val ))
            $val = implode ( ',', $val );
        $styleString [] = "{$key}{$glue}{$val}";

    }
    return implode ( $separator, $styleString );
}

function getSelector($selectorName) {
    return $this->arrayImplode ( ":", ";", $this->css [$selectorName] );
}

}

Related questions

Grabbing the href attribute of an A element

Trying to find the links on a page. my regex is: /<a\s[^>]*href=(\"\'??)([^\"\' >]*?)[^>]*>(.*)<\/a>/ but seems to fail at <a title="this" href="that">what?</a> …

Read More
PHP code inside a Javascript's "document.write()"

I need to write some PHP code inside a Javascript's "document.write()". This is a dummy example, but in the future Javascript will generate automatically that PHP code. This is the Hello World I have coded: MyFile.php <html&…

Read More
How to insert HTML to PHP DOMNode?

Is there any way I can insert an HTML template to existing DOMNode without content being encoded? I have tried to do that with: $dom->createElement('div', '<h1>Hello world</h1>'); $dom->…

Read More