Parsing commands CLI program Python

Question

I used to write my (simple) Python programs in Python 2, but it seems that Python 3 is quite mature. I now have a CLI program called ratjuice.py and when I execute it the program asks for a command input (which I have made some tab completion thing for).

So I might have commands like html which could output the subcommands like parse or destroy. I might want to use the command html parse rat.html. So I am looking for a Python module which allows me to parse this input based on a white list. So I would basically tell what is allowed and the rest is ignored or rejected (I might forget some things if I sanitize the input...)

Is there any good way to do this other than mere string manipulation?

Answer 1

Have a look at the cmd module. It does line-editing and remembers history (supposedly).

Answer 2

A string parsing version I just slapped together that requires no additional libraries, that works with your "whitelist" idea:

def foo1(bar):
 print '1. ' + bar
def foo2(bar):
 print '2. ' + bar
def foo3(bar):
 print '3. ' + bar
cmds = {
 'html': {
 'parse': foo1,
 'dump': foo2,
 'read': {
 'file': foo3,
 }
 }
}
def argparse(cmd):
 cmd = cmd.strip()
 cmdsLevel = cmds
 while True:
 candidate = [key for key in cmdsLevel.keys() if cmd.startswith(key)]
 if not candidate:
 print "Failure"
 break
 cmdsLevel = cmdsLevel[candidate[0]]
 cmd = cmd[len(candidate[0]):].strip()
 if not isinstance(cmdsLevel, dict):
 cmdsLevel(cmd)
 break
argparse('html parse rat.html')
argparse('foo')
argparse('html read file rat.html')
argparse('html dump rat.html')