get_post_type_capabilities()

function get_post_type_capabilities( $args ) {
	if ( ! is_array( $args->capability_type ) ) {
		$args->capability_type = array( $args->capability_type, $args->capability_type . 's' );
	}

	// Singular base for meta capabilities, plural base for primitive capabilities.
	list( $singular_base, $plural_base ) = $args->capability_type;

	$default_capabilities = array(
		// Meta capabilities.
		'edit_post'          => 'edit_' . $singular_base,
		'read_post'          => 'read_' . $singular_base,
		'delete_post'        => 'delete_' . $singular_base,
		// Primitive capabilities used outside of map_meta_cap():
		'edit_posts'         => 'edit_' . $plural_base,
		'edit_others_posts'  => 'edit_others_' . $plural_base,
		'delete_posts'       => 'delete_' . $plural_base,
		'publish_posts'      => 'publish_' . $plural_base,
		'read_private_posts' => 'read_private_' . $plural_base,
	);

	// Primitive capabilities used within map_meta_cap():
	if ( $args->map_meta_cap ) {
		$default_capabilities_for_mapping = array(
			'read'                   => 'read',
			'delete_private_posts'   => 'delete_private_' . $plural_base,
			'delete_published_posts' => 'delete_published_' . $plural_base,
			'delete_others_posts'    => 'delete_others_' . $plural_base,
			'edit_private_posts'     => 'edit_private_' . $plural_base,
			'edit_published_posts'   => 'edit_published_' . $plural_base,
		);
		$default_capabilities             = array_merge( $default_capabilities, $default_capabilities_for_mapping );
	}

	$capabilities = array_merge( $default_capabilities, $args->capabilities );

	// Post creation capability simply maps to edit_posts by default:
	if ( ! isset( $capabilities['create_posts'] ) ) {
		$capabilities['create_posts'] = $capabilities['edit_posts'];
	}

	// Remember meta capabilities for future reference.
	if ( $args->map_meta_cap ) {
		_post_type_meta_capabilities( $capabilities );
	}

	return (object) $capabilities;
}