Ticket #41422: 41422.diff

src/wp-includes/plugin.php

@@ -908 +908 @@
                 return $function[0] . '::' . $function[1];
         }
 }
+
+/**
+ * Returns the first parameter unchanged
+ * 
+ * Implements dummy filter used for disabled filters.
+ *
+ * Instead of unsetting the function for a disabled filter we replace it with a simple function that returns the value first thought of.
+ * 
+ * @param mixed $arg
+ * @return mixed whatever we got passed in the first arg 
+ */
+function disabled_filter( $arg ) {
+        return $arg;
+} 
+
+/**
+ * Disables a filter but leaves it in place
+ * 
+ * @param string $tag the filter name e.g. 'the_content'
+ * @param string $function_to_replace the name of the filter function to remove (well, replace)
+ * @param integer $priority the priority of the function. This has to match
+ * 
+ * @uses replace_filter()
+ *
+ */
+function disable_filter( $tag, $function_to_replace, $priority=10 ) {
+        replace_filter( $tag, $function_to_replace, $priority );
+}
+
+/**
+ * Replaces a filter function with one of our own
+ *
+ * @param string $tag - the filter name e.g. 'the_content'
+ * @param callable $function_to_replace - the name of the filter function to remove (well, replace)
+ * @param integer $priority - the priority of the function. This has to match
+ * @param string $new_function - the replacement function
+ *
+ * @notes This code, based on remove_filter() from wp-includes/plugin.php, does not deal with $merged_filters since it's not adding or deleting
+ * 
+ * It now works for filters implemented as object's methods.
+ */
+function replace_filter( $tag, $function_to_replace, $priority=10, $new_function="disabled_filter" ) {
+        global $wp_filter;
+        $function_key = _wp_filter_build_unique_id( $tag, $function_to_replace, false );
+        $r = isset( $wp_filter[$tag][$priority][$function_key] );
+        if ( $r ) { 
+                $wp_hook_object = $wp_filter[$tag];
+                $wp_hook_object->callbacks[$priority][$function_key]['replaced'] = $function_to_replace;
+                $wp_hook_object->callbacks[$priority][$function_key]['function'] = $new_function;
+        }
+}
+
+/**
+ * Restores a filter
+ *
+ * @param string $tag - the filter name e.g. 'the_content'
+ * @param string $function_to_restore - the name of the filter function to be restored
+ * @param integer $priority - the priority of the function. This has to match
+ */
+function restore_filter( $tag, $function_to_restore, $priority= 10 ) {
+        global $wp_filter;
+        $function_key = _wp_filter_build_unique_id( $tag, $function_to_restore, false );
+        $r = isset( $wp_filter[$tag][$priority][$function_key]['replaced'] );
+        if ( $r ) { 
+                $wp_hook_object = $wp_filter[$tag];
+                $wp_hook_object->callbacks[$priority][$function_key]['function'] = 
+                $wp_hook_object->callbacks[$priority][$function_key]['replaced']; 
+        }
+}
+
+

tests/phpunit/tests/filters.php

@@ -380 +380 @@
                 global $wp_filter;
                 $this->current_priority = $wp_filter[ 'the_content' ]->current_priority();
         }
+        
+        /**
+         * @ticket 41422
+         */
+        public function replace_a_with_b( $string, $arg2 ) {
+                $string = str_replace( "a", "b", $string );
+                return $string;
+        }
+
+        public function replace_b_with_c( $string, $arg2 ) {
+                $string = str_replace( "b", "c", $string );
+                return $string;
+        }
+
+        /**
+         * replace_filter enables us to respect the order in which filters have been attached.
+         */
+        public function test_replace_filter() {
+                add_filter( "41422", array( $this, "replace_a_with_b" ), 10, 2 );
+                add_filter( "41422", array( $this, "replace_b_with_c" ), 10, 2 );
+                $output = apply_filters( "41422", "abc", "dummy" );
+                $this->assertEquals( "ccc", $output );
+
+                disable_filter( "41422", array( $this, "replace_a_with_b" ), 10 );
+                $output = apply_filters( "41422", "abc", "dummy" );
+                $this->assertEquals( "acc", $output );
+
+                restore_filter( "41422", array( $this, "replace_a_with_b" ), 10 );
+                $output = apply_filters( "41422", "abc", "dummy" );
+                $this->assertEquals( "ccc", $output );
+        }
+
+        /**
+         * We can disable and restore them in any order without affecting the results when both restored
+         */ 
+        function test_replace_both_filters() {
+        
+                add_filter( "41422", array( $this, "replace_a_with_b" ), 10, 2 );
+                add_filter( "41422", array( $this, "replace_b_with_c" ), 10, 2 );
+                $output = apply_filters( "41422", "abc", "dummy" );
+                $this->assertEquals( "ccc", $output );
+
+                disable_filter( "41422", array( $this, "replace_a_with_b" ), 10 );
+                disable_filter( "41422", array( $this, "replace_b_with_c" ), 10 );
+                $output = apply_filters( "41422", "abc", "dummy" );
+                $this->assertEquals( "abc", $output );
+
+                restore_filter( "41422", array( $this, "replace_b_with_c" ), 10 );
+                restore_filter( "41422", array( $this, "replace_a_with_b" ), 10 );
+                $output = apply_filters( "41422", "abc", "dummy" );
+                $this->assertEquals( "ccc", $output );
+        }
+
+        /**
+         * Removing then adding a filter doesn't respect the order in which filters were originally attached.
+         * The result of applying the filters, which are now in a different order, is different from before.
+         */
+        public function test_remove_add_filter() {
+                add_filter( "41422", array( $this, "replace_a_with_b" ), 10, 2 );
+                add_filter( "41422", array( $this, "replace_b_with_c" ), 10, 2 );
+                $output = apply_filters( "41422", "abc", "dummy" );
+                $this->assertEquals( "ccc", $output );
+
+                remove_filter( "41422", array( $this, "replace_a_with_b" ), 10, 2 );
+                $output = apply_filters( "41422", "abc", "dummy" );
+                $this->assertEquals( "acc", $output );
+
+                add_filter( "41422", array( $this, "replace_a_with_b" ), 10, 2 );
+                $output = apply_filters( "41422", "abc", "dummy" );
+                $this->assertEquals( "bcc", $output );
+        }
 }