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Completed
Push — master ( 6f1bf4...7bdf98 )
by Askupa
02:25
created

DynamicCSSCompiler::get_compiled_style()   A

Complexity

Conditions 4
Paths 5

Size

Total Lines 19
Code Lines 11

Duplication

Lines 0
Ratio 0 %

Importance

Changes 1
Bugs 1 Features 1
Metric Value
cc 4
eloc 11
c 1
b 1
f 1
nc 5
nop 1
dl 0
loc 19
rs 9.2
1
<?php
2
/**
3
 * @package   WordPress Dynamic CSS
4
 * @version   1.0.5
5
 * @author    Askupa Software <[email protected]>
6
 * @link      https://github.com/askupasoftware/wp-dynamic-css
7
 * @copyright 2016 Askupa Software
8
 */
9
10
/**
11
 * Dynamic CSS Compiler Utility Class
12
 * 
13
 * 
14
 * Dynamic CSS Syntax
15
 * ------------------
16
 * <pre>
17
 * body {color: $body_color;} 
18
 * </pre>
19
 * In the above example, the variable $body_color is replaced by a value 
20
 * retrieved by the value callback function. The function is passed the variable 
21
 * name without the dollar sign, which can be used with get_option() or 
22
 * get_theme_mod() etc.
23
 */
24
class DynamicCSSCompiler
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Coding Style Compatibility introduced by
PSR1 recommends that each class must be in a namespace of at least one level to avoid collisions.

You can fix this by adding a namespace to your class:

namespace YourVendor;

class YourClass { }

When choosing a vendor namespace, try to pick something that is not too generic to avoid conflicts with other libraries.

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25
{
26
    /**
27
     * @var Singleton The reference to *Singleton* instance of this class
28
     */
29
    private static $instance;
30
    
31
    /**
32
     * @var array The list of dynamic styles paths to compile
33
     */
34
    private $stylesheets = array();
35
    
36
    /**
37
     * @var array 
38
     */
39
    private $callbacks = array();
40
    
41
    /**
42
     * Returns the *Singleton* instance of this class.
43
     *
44
     * @return Singleton The *Singleton* instance.
45
     */
46
    public static function get_instance()
47
    {
48
        if (null === static::$instance) 
0 ignored issues
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Bug introduced by
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.

Let’s assume you have a class which uses late-static binding:

class YourClass
{
    private static $someVariable;

    public static function getSomeVariable()
    {
        return static::$someVariable;
    }
}

The code above will run fine in your PHP runtime. However, if you now create a sub-class and call the getSomeVariable() on that sub-class, you will receive a runtime error:

class YourSubClass extends YourClass { }

YourSubClass::getSomeVariable(); // Will cause an access error.

In the case above, it makes sense to update SomeClass to use self instead:

class SomeClass
{
    private static $someVariable;

    public static function getSomeVariable()
    {
        return self::$someVariable; // self works fine with private.
    }
}
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49
        {
50
            static::$instance = new static();
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Bug introduced by
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.

Let’s assume you have a class which uses late-static binding:

class YourClass
{
    private static $someVariable;

    public static function getSomeVariable()
    {
        return static::$someVariable;
    }
}

The code above will run fine in your PHP runtime. However, if you now create a sub-class and call the getSomeVariable() on that sub-class, you will receive a runtime error:

class YourSubClass extends YourClass { }

YourSubClass::getSomeVariable(); // Will cause an access error.

In the case above, it makes sense to update SomeClass to use self instead:

class SomeClass
{
    private static $someVariable;

    public static function getSomeVariable()
    {
        return self::$someVariable; // self works fine with private.
    }
}
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Documentation Bug introduced by
It seems like new static() of type this<DynamicCSSCompiler> is incompatible with the declared type object<Singleton> of property $instance.

Our type inference engine has found an assignment to a property that is incompatible with the declared type of that property.

Either this assignment is in error or the assigned type should be added to the documentation/type hint for that property..

Loading history...
51
        }
52
        return static::$instance;
0 ignored issues
show
Bug introduced by
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.

Let’s assume you have a class which uses late-static binding:

class YourClass
{
    private static $someVariable;

    public static function getSomeVariable()
    {
        return static::$someVariable;
    }
}

The code above will run fine in your PHP runtime. However, if you now create a sub-class and call the getSomeVariable() on that sub-class, you will receive a runtime error:

class YourSubClass extends YourClass { }

YourSubClass::getSomeVariable(); // Will cause an access error.

In the case above, it makes sense to update SomeClass to use self instead:

class SomeClass
{
    private static $someVariable;

    public static function getSomeVariable()
    {
        return self::$someVariable; // self works fine with private.
    }
}
Loading history...
Bug Compatibility introduced by
The expression static::$instance; of type DynamicCSSCompiler|Singleton adds the type DynamicCSSCompiler to the return on line 52 which is incompatible with the return type documented by DynamicCSSCompiler::get_instance of type Singleton.
Loading history...
53
    }
54
    
55
    /**
56
     * Enqueue the PHP script used for compiling dynamic stylesheets that are 
57
     * loaded externally
58
     */
59
    public function wp_enqueue_style()
60
    {
61
        // Only enqueue if there is at least one dynamic stylesheet that is
62
        // set to be loaded externally
63
        if( 0 < count( array_filter($this->stylesheets, array( $this, 'filter_external' ) ) ) )
64
        {
65
            wp_enqueue_style( 'wp-dynamic-css', admin_url( 'admin-ajax.php?action=wp_dynamic_css' ) );
66
        }
67
    }
68
    
69
    /**
70
     * Parse all styles in $this->stylesheets and print them if the flag 'print'
71
     * is set to true. Used for printing styles to the document head.
72
     */
73
    public function compile_printed_styles()
74
    {        
75
        // Compile only if there are styles to be printed
76
        if( 0 < count( array_filter($this->stylesheets, array( $this, 'filter_print' ) ) ) )
77
        {
78
            $compiled_css = $this->get_compiled_styles( true );
79
        
80
            echo "<style id=\"wp-dynamic-css\">\n";
81
            include 'style.phtml';
82
            echo "</style>";
83
        }
84
    }
85
    
86
    /**
87
     * Parse all styles in $this->stylesheets and print them if the flag 'print'
88
     * is not set to true. Used for loading styles externally via an http request.
89
     */
90
    public function compile_external_styles()
91
    {
92
        header( "Content-type: text/css; charset: UTF-8" );
93
        
94
        $compiled_css = $this->get_compiled_styles( false );
95
        
96
        include 'style.phtml';
97
        wp_die();
98
    }
99
    
100
    /**
101
     * Add a style path to the pool of styles to be compiled
102
     * 
103
     * @param string $handle The stylesheet's name/id
104
     * @param string $path The absolute path to the dynamic style
105
     * @param boolean $print Whether to print the compiled CSS to the document
106
     * head, or include it as an external CSS file
107
     * @param boolean $minify Whether to minify the CSS output
108
     * @param boolean $cache Whether to store the compiled version of this 
109
     * stylesheet in cache to avoid compilation on every page load.
110
     */
111
    public function enqueue_style( $handle, $path, $print, $minify, $cache )
112
    {
113
        $this->stylesheets[] = array(
114
            'handle'=> $handle,
115
            'path'  => $path,
116
            'print' => $print,
117
            'minify'=> $minify,
118
            'cache' => $cache
119
        );
120
    }
121
    
122
    /**
123
     * Register a value retrieval function and associate it with the given handle
124
     * 
125
     * @param type $handle The stylesheet's name/id
126
     * @param type $callback
127
     */
128
    public function register_callback( $handle, $callback )
129
    {
130
        $this->callbacks[$handle] = $callback;
131
    }
132
133
    /**
134
     * Compile multiple dynamic stylesheets
135
     * 
136
     * @param boolean $printed
137
     * @return string Compiled CSS
138
     */
139
    protected function get_compiled_styles( $printed )
140
    {
141
        $compiled_css = '';
142
        foreach( $this->stylesheets as $style ) 
143
        {
144
            if( $style['print'] === $printed )
145
            {
146
                $compiled_css .= $this->get_compiled_style( $style )."\n";
147
            }
148
        }
149
        return $compiled_css;
150
    }
151
    
152
    /**
153
     * Get the compiled CSS for the given style. Skips compilation if the compiled
154
     * version can be found in cache.
155
     * 
156
     * @param array $style List of styles with the same structure as they are 
157
     * stored in $this->stylesheets
158
     * @return type
159
     */
160
    protected function get_compiled_style( $style )
161
    {
162
        $cache = DynamicCSSCache::get_instance();
163
        
164
        if( $style['cache'] )
165
        {
166
            $cached_css = $cache->get( $style['handle'] );
167
            if( false !== $cached_css )
168
            {
169
                return $cached_css;
170
            }
171
        }
172
173
        $css = file_get_contents( $style['path'] );
174
        if( $style['minify'] ) $css = $this->minify_css( $css );
175
        $compiled_css = $this->compile_css( $css, $this->callbacks[$style['handle']] );
176
        $cache->update( $style['handle'], $compiled_css );
177
        return $compiled_css;
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Bug Best Practice introduced by
The return type of return $compiled_css; (string) is incompatible with the return type documented by DynamicCSSCompiler::get_compiled_style of type type.

If you return a value from a function or method, it should be a sub-type of the type that is given by the parent type f.e. an interface, or abstract method. This is more formally defined by the Lizkov substitution principle, and guarantees that classes that depend on the parent type can use any instance of a child type interchangably. This principle also belongs to the SOLID principles for object oriented design.

Let’s take a look at an example:

class Author {
    private $name;

    public function __construct($name) {
        $this->name = $name;
    }

    public function getName() {
        return $this->name;
    }
}

abstract class Post {
    public function getAuthor() {
        return 'Johannes';
    }
}

class BlogPost extends Post {
    public function getAuthor() {
        return new Author('Johannes');
    }
}

class ForumPost extends Post { /* ... */ }

function my_function(Post $post) {
    echo strtoupper($post->getAuthor());
}

Our function my_function expects a Post object, and outputs the author of the post. The base class Post returns a simple string and outputting a simple string will work just fine. However, the child class BlogPost which is a sub-type of Post instead decided to return an object, and is therefore violating the SOLID principles. If a BlogPost were passed to my_function, PHP would not complain, but ultimately fail when executing the strtoupper call in its body.

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178
    }
179
    
180
    /**
181
     * Minify a given CSS string by removing comments, whitespaces and newlines
182
     * 
183
     * @see http://stackoverflow.com/a/6630103/1096470
184
     * @param string $css CSS style to minify
185
     * @return string Minified CSS
186
     */
187
    protected function minify_css( $css )
188
    {
189
        return preg_replace( '@({)\s+|(\;)\s+|/\*.+?\*\/|\R@is', '$1$2 ', $css );
190
    }
191
192
    /**
193
     * This filter is used to return only the styles that are set to be printed
194
     * in the document head
195
     * 
196
     * @param array $style
197
     * @return boolean
198
     */
199
    protected function filter_print( $style )
200
    {
201
        return true === $style['print'];
202
    }
203
    
204
    /**
205
     * This filter is used to return only the styles that are set to be loaded
206
     * externally
207
     * 
208
     * @param array $style
209
     * @return boolean
210
     */
211
    protected function filter_external( $style )
212
    {
213
        return true !== $style['print'];
214
    }
215
    
216
    /**
217
     * Parse the given CSS string by converting the variables to their 
218
     * corresponding values retrieved by applying the callback function
219
     * 
220
     * @param callable $callback A function that replaces the variables with 
221
     * their values. The function accepts the variable's name as a parameter
222
     * @param string $css A string containing dynamic CSS (pre-compiled CSS with 
223
     * variables)
224
     * @return string The compiled CSS after converting the variables to their 
225
     * corresponding values
226
     */
227
    protected function compile_css( $css, $callback )
228
    {
229
        return preg_replace_callback( "#\\$([\\w-]+)((?:\\['?[\\w-]+'?\\])*)#", function( $matches ) use ( $callback ) {
230
            // If this variable is an array, get the subscripts
231
            if( '' !== $matches[2] )
232
            {
233
                preg_match_all('/[\w-]+/i', $matches[2], $subscripts);
234
            }
235
            return call_user_func_array( $callback, array($matches[1],@$subscripts[0]) );
0 ignored issues
show
Bug introduced by
The variable $subscripts does not seem to be defined for all execution paths leading up to this point.

If you define a variable conditionally, it can happen that it is not defined for all execution paths.

Let’s take a look at an example:

function myFunction($a) {
    switch ($a) {
        case 'foo':
            $x = 1;
            break;

        case 'bar':
            $x = 2;
            break;
    }

    // $x is potentially undefined here.
    echo $x;
}

In the above example, the variable $x is defined if you pass “foo” or “bar” as argument for $a. However, since the switch statement has no default case statement, if you pass any other value, the variable $x would be undefined.

Available Fixes

  1. Check for existence of the variable explicitly:

    function myFunction($a) {
        switch ($a) {
            case 'foo':
                $x = 1;
                break;
    
            case 'bar':
                $x = 2;
                break;
        }
    
        if (isset($x)) { // Make sure it's always set.
            echo $x;
        }
    }
    
  2. Define a default value for the variable:

    function myFunction($a) {
        $x = ''; // Set a default which gets overridden for certain paths.
        switch ($a) {
            case 'foo':
                $x = 1;
                break;
    
            case 'bar':
                $x = 2;
                break;
        }
    
        echo $x;
    }
    
  3. Add a value for the missing path:

    function myFunction($a) {
        switch ($a) {
            case 'foo':
                $x = 1;
                break;
    
            case 'bar':
                $x = 2;
                break;
    
            // We add support for the missing case.
            default:
                $x = '';
                break;
        }
    
        echo $x;
    }
    
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236
        }, $css);
237
    }
238
}
239