<?php

if (preg_match('~^[^\s#+&\'"\\\\]+(?:\s[^\s#+&\'"\\\\]+)*$~', "")) {
	echo "Matched ''\n";
}
if (preg_match('~^[^\s#+&\'"\\\\]+(?:\s[^\s#+&\'"\\\\]+)*$~', " ")) {
	echo "Matched ' '\n";
}
if (preg_match('~^[^\s#+&\'"\\\\]+(?:\s[^\s#+&\'"\\\\]+)*$~', " a")) {
	echo "Matched ' a'\n";
}
if (preg_match('~^[^\s#+&\'"\\\\]+(?:\s[^\s#+&\'"\\\\]+)*$~', "a b")) {
	echo "Matched 'a b'\n";
}
if (preg_match('~^[^\s#+&\'"\\\\]+(?:\s[^\s#+&\'"\\\\]+)*$~', "a  b")) {
	echo "Matched 'a  b'\n";
}