Regex timing out - regex

Question

I'm trying to match something like
foo: anything after the colon can be matched with (.*)+
foo.bar1.BAZ: balh5317{}({}(
This is the regex I'm using:
/^((?:(?:(?:[A-Za-z_]+)(?:[0-9]+)?)+[\.]?)+)(?:\s)?(?:\:)(?:\s)?((?:.*)+)$/
Excuse the non-matching groups and extra parens, this is being compiled from a builder class
This works on the examples. The problem arises when I try to put in a string like this:
foo.bar.baz.beef.stew.ect.and.forward
I need to be able to check strings like this, but the regex engine times out or runs infinity (as far as I can tell) after a certain amount of foo.s every time.
I'm sure this is a logical problem I could figure out, but unfortunately I've far from mastered regex and I hoped a more experienced user could shed some light on how I can make this more efficient.
Also, here is a more detailed description of what I need to match:
Property Name: can contain A-z, numbers, and underscores but can't start with a number
<Property Name>.<Property Name>.<Prop...:<Anything after the colon>
Thanks for your time!

Answer 1

Starting with your regex:
^((?:(?:(?:[A-Za-z_]+)(?:[0-9]+)?)+[\.]?)+)(?:\s)?(?:\:)(?:\s)?((?:.*)+)$
^ # Anchors to the beginning to the string.
( # Opens CG1
(?: # Opens NCG
(?: # Opens NCG
(?: # Opens NCG
[A-Za-z_]+ # Character class (any of the characters within)
) # Closes NCG
(?: # Opens NCG
[0-9]+ # Character class (any of the characters within)
)? # Closes NCG
)+ # Closes NCG
[\.]? # Character class (any of the characters within)
)+ # Closes NCG
) # Closes CG1
(?: # Opens NCG
\s # Token: \s (white space)
)? # Closes NCG
(?: # Opens NCG
\: # Literal :
) # Closes NCG
(?: # Opens NCG
\s # Token: \s (white space)
)? # Closes NCG
( # Opens CG2
(?: # Opens NCG
.* # . denotes any single character, except for newline
)+ # Closes NCG
) # Closes CG2
$ # Anchors to the end to the string.
I converted [0-9] to \d, simply for easier readability (both match the same thing). I also removed a lot of non-capturing groups because they weren't really being used.
^((?:(?:[A-Za-z_]+\d*)+\.?)+)\s?\:\s?((?:.*)+)$
I also merged the \s and .* into [\s\S]*, but seeing that it was followed by a + sign, i removed the group and just made [\s\S].
^((?:(?:[A-Za-z_]+\d*)+\.?)+)\s?\:([\s\S]+)$
^
Now I'm not sure what the + above the carat is supposed to do. We can remove it, and thusly the non-capturing group surrounding it.
^((?:[A-Za-z_]+\d*\.?)+)\s?\:([\s\S]+)$
Explanation:
^ # Anchors to the beginning to the string.
( # Opens CG1
(?: # Opens NCG
[A-Za-z_]+ # Character class (any of the characters within)
\d* # Token: \d (digit)
\.? # Literal .
)+ # Closes NCG
) # Closes CG1
\s? # Token: \s (white space)
\: # Literal :
( # Opens CG2
[\s\S]+ # Character class (any of the characters within)
) # Closes CG2
$ # Anchors to the end to the string.
Now, you might want to change the [\s\S]+ back to .* if you're dealing with multiple lines. There are a few different options regarding that but it kind of matters what language you're using.
Honestly, I did this in steps but the largest problem was (?:.*)+ This is telling the engine to match 0 or more characters 1 or more times catastrophic backtracking (as xufox linked to in comments).
The resulting regex, and your original too, permits variables that end in . I'd use something more like this, which your regex really wasn't that far from.
This will match names like foo.ba5r, if that's acceptable, your prior regex wouldn't.
^([A-Za-z_]\w*(?:\.[A-Za-z_]+\w*)*)\s?\:([\s\S]+)$
Explanation:
^ # Anchors to the beginning to the string.
( # Opens CG1
[A-Za-z_] # Character class (any of the characters within)
\w* # Token: \w (a-z, A-Z, 0-9, _)
(?: # Opens NCG
\. # Literal .
[A-Za-z_] # Character class (any of the characters within)
\w* # Token: \w (a-z, A-Z, 0-9, _)
)* # Closes NCG
) # Closes CG1
\s? # Token: \s (white space)
\: # Literal :
( # Opens CG2
[\s\S]+ # Character class (any of the characters within)
) # Closes CG2
$ # Anchors to the end to the string.