How can I optimize this regular expression? - php

Question

I have a regular expression, and I would like to ask whether it is possible to simplify it?
preg_match_all('/([0-9]{2}\.[0-9]{2}\.[0-9]{4}) (([01]?[0-9]|2[0-3])\:[0-5][0-9]\:[0-5][0-9]?) поступление на сумму (\d+) WM([A-Z]) от корреспондента (\d+)/', $message->getMessageBody(), $info);

Answer 1

I think this is the best you can do:
preg_match_all('/((?:\d\d\.){2}\d{4}) (([01]?\d|2[0-3])(:[0-5]\d){1,2}) поступление на сумму (\d+) WM([A-Z]) от корреспондента (\d+)/', $message, $info);
Unless you don't need those exact words in there. Then you could:
preg_match_all('/((?:\d\d\.){2}\d{4}) (([01]?\d|2[0-3])(:[0-5]\d){1,2})\D+(\d+) WM([A-Z])\D+(\d+)/', $message, $info);

Answer 2

You can start by using free-spacing mode and some comments (which will help your and everyone else's understanding - which makes simplifying easier). Note that you'll have to put literal spaces in parentheses now, though:
/
( # group 1
[0-9]{2}\.[0-9]{2}\.[0-9]{4}
# match a date
)
[ ]
( # group 2
( # group 3
[01]?[0-9]# match an hour from 0 to 19
| # or
2[0-3] # match an hour from 20 to 23
)
\:
[0-5][0-9] # minutes
\:
[0-5][0-9]? # seconds
)
[ ]поступление[ ]на[ ]сумму[ ]
# literal text
(\d+) # a number into group 4
[ ]WM # literal text
([A-Z]) # a letter into group 5
[ ]от[ ]корреспондента[ ]
# literal text
(\d+) # a number into group 6
/x
Now we can't simplify the part at the end - unless you don't want to capture the parenthesised things, in which case you can simply omit most of the parentheses.
You can slightly shorten the expression, by using \d as a substitute for \d, in which case \d\d is even shorter than \d{2}.
Next, there is no need to escape colons.
And finally, there seems to be something odd with your seconds. If you want to allow single-digit seconds, make the 0-5 optional, and not the the \d after it:
/
( # group 1
\d\d\.\d\d\.\d{4}
# match a date
)
[ ]
( # group 2
( # group 3
[01]?\d # match an hour from 0 to 19
| # or
2[0-3] # match an hour from 20 to 23
)
:
[0-5]\d # minutes
:
[0-5]?\d # seconds
)
[ ]поступление[ ]на[ ]сумму[ ]
# literal text
(\d+) # a number into group 4
[ ]WM # literal text
([A-Z]) # a letter into group 5
[ ]от[ ]корреспондента[ ]
# literal text
(\d+) # a number into group 6
/x
I don't think it will get much simpler than that.