How Can I Extract Class Names Containing \'postclass\' from a CSS File Using PHP?

Parse a CSS File with PHP: A Programmatic Approach

For advanced CSS manipulation, parsing it with programming is essential. PHP offers a robust toolset for CSS parsing, and this article delves into a specific technique to extract class names containing a particular substring.

The Problem:

Given a CSS file with multiple class declarations, the goal is to retrieve an array of class names that include "postclass" in their name.

The Solution:

PHP's preg_match_all() function can parse regular expressions in a string. Here's a customized regular expression that accomplishes this task:

<code class="php">/(#[a-z0-9]*?\ .?postclass.*?)\s?\{/g</code>

This regex captures any CSS declaration starting with a hash (#), followed by any combination of alphanumeric characters, a dot (.), and the substring "postclass." The whitespace and curly brace signify the start of a rule set.

The Code:

<code class="php">function parse($file) {
    $css = file_get_contents($file);
    preg_match_all( '/(?ims)([a-z0-9\s\.\:#_\-@,]+)\{([^\}]*)\}/', $css, $arr);
    $result = array();
    foreach ($arr[0] as $i => $x){
        $selector = trim($arr[1][$i]);
        $selectors = explode(',', trim($selector));
        foreach ($selectors as $strSel) {
            if (strpos($strSel, 'postclass') !== false) {
                $result[] = $strSel;
            }
        }
    }
    return $result;
}</code>

Usage:

<code class="php">$arrayClasses = parse('cssfile.css');
print_r($arrayClasses); // Outputs: ['#content.postclass-subcontent', '#content2.postclass-subcontent2']</code>

By utilizing this approach, developers can extract specific class names from a CSS file based on a pattern, enabling customizable CSS manipulation within PHP scripts.

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