gets the loaded php file within a wordpress theme

get_loaded_theme_file.php

<?php

function get_loaded_theme_files() {
	$sdir = realpath( get_stylesheet_directory() ) . DIRECTORY_SEPARATOR;
	$tdir = realpath( get_template_directory() ) . DIRECTORY_SEPARATOR;

	return array_filter( get_included_files(), function ( $file ) use ( $sdir, $tdir ) {
		$r = realpath( $file );
		$d = dirname( $r ) . DIRECTORY_SEPARATOR;

		if ( $d !== $sdir || $d !== $tdir ) {
			return false;
		}

		$b = basename( $file );
		if ( in_array( $b, [ 'functions.php', 'header.php', 'footer.php' ] ) ) {
			return false;
		}

		return true;
	} );
}

function get_loaded_theme_file() {
	return array_shift( get_loaded_theme_files() );
}