OCI8 Adapter (convertPositionalToNamedPlaceholders) Statemachine doesn't consider comments and strings

<?php
$s = '-- Testkomm?ntar
	select	/* ? *//* ??? */ ?||\'H"al?l"o?\' as "h?""llo" union /* "? Kommentar" \' */
	/* ?" */ select \'/*Hallo\'||to_char( ? ) union select \'--Welt\'
	union--
	select ?';

echo 'In: ' . $s . PHP_EOL;

$bind = 0;
$skip = array( '--' => PHP_EOL, '/*' => '*/', '"' => '"', "'" => "'" );
for( $i = 0; $i < strlen( $s ) /* size of string might change! */; /* yes, no increment here! */ )
{
	// Skipping comments and literals
	foreach( $skip as $begin => $end )
	{
		$matches = substr_compare( $s, $begin, $i, strlen( $begin ) );
		if( $matches !== false && $matches == 0 )
		{
			$pos = strpos( $s, $end, $i+strlen( $begin ) );
			// echo "Found $begin, skipping at $i to $end at $pos" . PHP_EOL;
			if( $pos === false )
			{
				// No more data or illegal statement - anyway: no more replacements!
				// echo "EOD" . PHP_EOL;
				break 2;
			}
			$i = $pos + strlen( $end );
			continue 2; // Ensure we match /*..*//*..*/, '''' or """" - that's why we don't ++$i in the for-loop!
		}
	}
	if( $s[$i] == "?" )
	{
		// Positional to named
		// echo "Replace $bind" . PHP_EOL;
		$r = ':name' . ++$bind;
		$s = substr_replace( $s, $r, $i, 1 );
		$i += strlen( $r );
	}
	++$i;
}

echo 'Out: ' . $s . PHP_EOL;