Find full class path by class name using composer class map

findClass.php

#!/usr/bin/env php
<?php

$name = $argv[1];
$pfix = "\\$name";
$len = strlen($pfix);

require "vendor/composer/autoload_static.php";

$tmp = get_declared_classes();
$loaderClass = end($tmp);
$map = $loaderClass::$classMap;

foreach ($map as $class => $path) {
    if (substr_compare($class, $pfix, -$len, $len) === 0) {
        echo "$class\n";
    }
}

Generate class map with composer du -o.

Run script php findClass.php ClassName