$re = '/(?xXmi)
(?:
(?# use non-capture for details in debugging)
(?:
(?<match>
(?# If quoted value)
(?<quot_char>(?<!\\\\)["\'])
(?# Quoted content)
(?:
(?:
(?# Match as many characters that aren\'t quotation char)
(?# or escape char as possible. )
(?:(?:(?!\k<quot_char>|\\\\)).+)
(?:
(?# Match any/all escape chars that do not have the)
(?# quotation char following it. )
(?:(?:\\\\)*(?!\k<quot_char>))?
(?# If there is an escape char followed by the quotation)
(?# quotation char match them. )
(?:[\\\\]\k<quot_char>)?
)*?
)
)
(?<close_quot>\k<quot_char>)
|
(?# if simple token)
(?<basic>[^ \n]+)+
)
)
(?<trail_ws>[ ]+)?
)/m';
$str = '-t1a1
-t2a1 -t2a2
-t3a1 -t3a2
-t4a1 Test1value -t4a2 test4a2value -t4a3 t4a3value
-t5a1EscQuot \\\'t5a1valueESQ\\\' -t5a2EscQuot \\"t5a2valueEDQ\\"
-t6a1 "t6a1value1DQWord1 t6a1value1DQWord1" -t6a2SQuot \'t6a2value1SQWord1 t6a2value1SQWord2 t6a2value1SQWord3 \'
-t7a1SQuotEmpty \'\' -t7a2DQuotEmpty ""
';
$subst = "\n${match}";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php