I'm trying to parse the following string:
constructor: function(some, parameters, here) {
With the following regex:
re.search("(\w*):\s*function\((?:(\w*)(?:,\s)*)*\)", line).groups()
And I'm getting:
('constructor', '')
But I was expecting something more like:
('constructor', 'some', 'parameters', 'here')
What am I missing?
If you change your pattern to:
print re.search(r"(\w*):\s*function\((?:(\w+)(?:,\s)?)*\)", line).groups()
You'll get:
('constructor', 'here')
This is because (from docs):
If a group is contained in a part of the pattern that matched multiple times, the last match is returned.
If you can do this in one step, I don't know how. Your alternative, of course is to do something like:
def parse_line(line):
cons, args = re.search(r'(\w*):\s*function\((.*)\)', line).groups()
mats = re.findall(r'(\w+)(?:,\s*)?', args)
return [cons] + mats
print parse_line(line) # ['constructor', 'some', 'parameters', 'here']
re.search(...).groups() do the same thing?One option is to use more advanced regex instead of the stock re. Among other nice things, it supports captures, which, unlike groups, save every matching substring:
>>> line = "constructor: function(some, parameters, here) {"
>>> import regex
>>> regex.search("(\w*):\s*function\((?:(\w+)(?:,\s)*)*\)", line).captures(2)
['some', 'parameters', 'here']
The re module doesn't support repeated captures: the group count is fixed. Possible workarounds include:
1) Capture the parameters as a string and then split it:
match = re.search("(\w*):\s*function\(([\w\s,]*)\)", line).groups()
args = [arg.strip() for arg in math[1].split(",")]
2) Capture the parameters as a string and then findall it:
match = re.search("(\w*):\s*function\(([\w\s,]*)\)", line).groups()
args = re.findall("(\w+)(?:,\s)*", match[1])
3) If your input string has already been verified, you can just findall the whole thing:
re.findall("(\w+)[:,)]", string)
Alternatively, you can use the regex module and captures(), as suggested by @georg.
You might need two operations here (search and findall):
[re.search(r'[^:]+', given_string).group()] + re.findall(r'(?<=[ (])\w+?(?=[,)])', given_string)
Output: ['constructor', 'some', 'parameters', 'here']
