$re = '/(\bSTDMETHOD_?\b([\s\S]*?)\bPURE\b)/';
$str = 'STDMETHOD_(MyFunc)(
D2D1_SIZE_U size,
_In_opt_ CONST void *srcData,
) PURE;
STDMETHOD(MyFunc2)(
_In_opt_ CONST void *srcData2,
UINT32 pitch2,
) PURE;\\
STDMETHOD_(void, GetFactory)(
_Outptr_ ID2D1Factory **factory
) CONST PURE;';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
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