Python regex matching in conditionals

Question

I am parsing file and I want to check each line against a few complicated regexs. Something like this

if re.match(regex1, line): do stuff elif re.match(regex2, line): do other stuff elif re.match(regex3, line): do still more stuff ... 

Of course, to do the stuff, I need the match objects. I can only think of three possibilities, each of which leaves something to be desired.

if re.match(regex1, line):      m = re.match(regex1, line)     do stuff elif re.match(regex2, line):     m = re.match(regex2, line)     do other stuff ... 

which requires doing the complicated matching twice (these are long files and long regex :/)

m = re.match(regex1, line) if m: do stuff else:     m = re.match(regex2, line)     if m: do other stuff     else:        ... 

which gets terrible as I indent further and further.

while True:     m = re.match(regex1, line)     if m:         do stuff         break     m = re.match(regex2, line)     if m:         do other stuff         break     ... 

which just looks weird.

What's the right way to do this?

Answer 1

You could define a function for the action required by each regex and do something like

def dostuff():     stuff  def dootherstuff():     otherstuff  def doevenmorestuff():     evenmorestuff  actions = ((regex1, dostuff), (regex2, dootherstuff), (regex3, doevenmorestuff))  for regex, action in actions:     m = re.match(regex, line)     if m:          action()         break