php preg_match_all，在可用时返回多个可选值

Question

Example of the haystack:

INTERVENTIONS:
---------------------
Med Given: Versed - 9:50 PM Med Admin Route: Intravenous    Dosage: 20.00 MG
Med Given: Lidocaine - 9:50 PM  Med Admin Route: Intravenous    Dosage: 150.00 MG
Med Given: Succinylcholine - 9:50 PM    Med Admin Route: Intravenous    Dosage: 200.00 MG
Med Given: Oxygen - 7:23 PM Dosage: 2.00 L/MIN
Med Given: Vancomycin
Med Given: Fentanyl
Med Given: Dopamine
Med Given: Dextrose
Med Given: Gentamicin

As you cans see, sometimes there are times ( - H:MM AM/PM), sometimes "Med Admin Route: ..." and "Dosage: ...", I always want the name (Versed, Oxygen, etc) and if available - the time (H:MM AM/PM), route (Intravenous, Oral, etc) and dosage (20.00 MG, 2.00 L/MIN, etc) all stored in an array. I've thought that I've had it in the past but when I throw a different haystack at it it fails... Also note that it appears that sometimes there is a tab instead of a space between the variables like time-Admin or Admin-Dosage...

Answer 1

preg_match_all('~Med Given: ((?:(?!-\s*\d{1,2}:\d{1,2} (?:A|P)M|Med Admin Route:|Dosage:|$).)+)(?:\s*-\s*(.*?(?:A|P)M))?(?:\s*Med Admin Route:((?:(?!Dosage:|$).)+))?(?:\s*Dosage:\s*(.*))?~',$content,$matches);

Got the job done thanks to the guys at phpfreaks.com