ascii map text-format generator, asserts a test when invoked from cli

asciimap-gen.php

<?php

function ascii_lexan($s) 
{
	$tokens = array();
	$strlen = strlen($s);
	for ($i = 0;$i < $strlen; $i++) {
		$tokens []= ord($s[$i]);
	}
	return $tokens;
}

function ascii_parse($tokens) 
{
	$count = 1;
	$tokenStr = '';
	$prevToken = '';
	$isFirstToken = true;
	$lastIndex = count($tokens) -1;
	foreach ($tokens as $index => $token) {
		// printf("<%s, %s [%s]>\n", $count, $token, $prevToken);
		if ($isFirstToken) {
			$prevToken = $token;
			$isFirstToken = false;
			continue;
		}
		if ($prevToken != $token) {
			$tokenStr .= $count.':'.$prevToken.'|';
			$prevToken = $token;
			$count = 1;
		} else {
			$count++;
		}
		if ($index == $lastIndex) {
			$tokenStr .= $count.':'.$prevToken;
		}
	}
	return $tokenStr;
}


function asciimap_create($s) 
{
  $tokens = ascii_lexan($s);
  return ascii_parse($tokens);
}


function asciimap_read($s) 
{
	$out = '';
	$instructions = explode('|', $s);
	foreach ($instructions as $index => $instruction) {
		$_ = explode(':', $instruction);
		$count = $_[0];
		$ascii = $_[1];
		for ($i = 0;$i < $count; $i++)
			$out .= chr($ascii);
	}
	return $out;
}

// Test wenn Skript direkt aufgerufen wird:
if (count(debug_backtrace()) == 0) {
	$ascii = <<<EOF
  O---O
 / \ / \
O---O---O
 \ / \ /
  O---O
EOF;
	$s = asciimap_create($ascii);
	assert('asciimap_read($s)==$ascii2');
}