askupasoftware / wp-dynamic-css

compiler.php

<?php
/**
 * @package   WordPress Dynamic CSS
 * @version   1.0.0
 * @author    Askupa Software <contact@askupasoftware.com>
 * @link      https://github.com/askupasoftware/wp-dynamic-css
 * @copyright 2016 Askupa Software
 */

/**
 * Dynamic CSS Compiler Utility Class
 * 
 * 
 * Dynamic CSS Syntax
 * ------------------
 * <pre>
 * body {color: $body_color;} 
 * </pre>
 * In the above example, the variable $body_color is replaced by a value 
 * that is retrieved by the filter wp_dynamic_css_get_variable_value. The filter 
 * is passed the variable name without the dollar sign, which can be used with
 * get_option() or get_theme_mod() etc.
 */
class DynamicCSSCompiler
{
    /**
     * @var Singleton The reference to *Singleton* instance of this class
     */
    private static $instance;
    
    /**
     * @var array The list of dynamic styles paths to compile
     */
    private $styles = array();
    
    /**
     * Returns the *Singleton* instance of this class.
     *
     * @return Singleton The *Singleton* instance.
     */
    public static function get_instance()
    {
        if (null === static::$instance) 
        {
            static::$instance = new static();
            static::$instance->init();

Since $instance is declared private, accessing it with static will lead to errors in possible sub-classes; consider using self, or increasing the visibility of $instance to at least protected.

        }
        
        return static::$instance;
    }
    
    /**
     * Initiate the compiler by hooking to wp_print_styles
     */
    public function init()
    {
        add_action('wp_print_styles', array($this, 'print_compiled_style'));
    }
    
    /**
     * Add a style path to the pool of styles to be compiled
     * 
     * @param type $path The absolute path to the dynamic style
     */
    public function enqueue_style($path)
    {
        $this->styles[] = $path;
    }
    
    /**
     * Parse all styles in $this->styles and print them
     */
    public function print_compiled_style()
    {
        ob_start();
        foreach ($this->styles as $style) 
        {
            include $style;
            echo "\n";
        }
        $css = $this->parse_css(ob_get_clean());
        include 'style.phtml';
    }
    
    /**
     * Parse the given CSS string by converting the variables to their 
     * corresponding values retrieved by applying the filter 
     * wp_dynamic_css_get_variable_value.
     * 
     * @param string $css A string containing dynamic CSS (pre-compiled CSS with 
     * variables)
     * @uses wp_dynamic_css_get_variable_value filter
     * @return string The compiled CSS after converting the variables to their 
     * corresponding values
     */
    public function parse_css($css)
    {   
        return preg_replace_callback('#\$([\w]+)#', function($matches) {
            return apply_filters('wp_dynamic_css_get_variable_value', $matches[1]);
        }, $css);
    }
}