Utility functions for debugging WordPress websites

wp-debug-util.php

<?php

function wp_debug_util_get_hook_handlers( $hook_name ) {
    global $wp_filter;

    $hook_handlers = array();

    foreach ( $wp_filter[ $hook_name ] as $priority => $handlers ) {
        foreach ( $handlers as $handler ) {
            if ( is_array( $handler['function'] ) && is_callable( $handler['function'] ) && is_object( $handler['function'][0] ) ) {
                $class = new ReflectionClass( get_class( $handler['function'][0] ) );
                $method = new ReflectionMethod( $class->getName(), $handler['function'][1] );

                $hook_handlers[] = array(
                    'priority' => $priority,
                    'handler' => $class->getName() . ( $method->isStatic() ? '::' : '->' ) . $method->getName(),
                    'file' => $class->getFileName(),
                    'line' => $method->getStartLine(),
                );
            } elseif ( is_array( $handler['function'] ) && is_callable( $handler['function'] ) && is_string( $handler['function'][0] ) ) {
                $class = new ReflectionClass( $handler['function'][0] );
                $method = new ReflectionMethod( $class->getName(), $handler['function'][1] );

                $hook_handlers[] = array(
                    'priority' => $priority,
                    'handler' => $class->getName() . ( $method->isStatic() ? '::' : '->' ) . $method->getName(),
                    'file' => $class->getFileName(),
                    'line' => $method->getStartLine(),
                );
            } elseif ( $handler['function'] instanceof Closure ) {
                $function = new ReflectionFunction( $handler['function'] );

                $hook_handlers[] = array(
                    'priority' => $priority,
                    'handler' => 'Closure',
                    'file' => $function->getFileName(),
                    'line' => $function->getStartLine(),
                );
            } elseif ( is_string( $handler['function'] ) && function_exists( $handler['function'] ) ) {
                $function = new ReflectionFunction( $handler['function'] );

                $hook_handlers[] = array(
                    'priority' => $priority,
                    'handler' => $handler['function'],
                    'file' => $function->getFileName(),
                    'line' => $function->getStartLine(),
                );
            } else {
                $hook_handlers[] = array(
                    'handler' => $handler['function'],
                );
            }
        }
    }

    return $hook_handlers;
}