Regexp matching equal number of the same character on each side of a string

How do you match only equal numbers of the same character (up to 3) on each side of a string in python?

For example, let's say I am trying to match equal signs

=abc= or ==abc== or ===abc===

but not

=abc== 开发者_运维问答or ==abc=

etc.

I figured out how to do each individual case, but can't seem to get all of them.

(={1}(?=abc={1}))abc(={1})

as | of the same character

((={1}(?=abc={1}))|(={2}(?=abc={2})))abc(={1}|={2})

doesn't seem to work.

Use the following regex:

^(=+)abc\1$

Edit:

If you are talking about only max three =

^(={1,3})abc\1$

This is not a regular language. However, you can do it with backreferences:

(=+)[^=]+\1

consider that sample is a single string, here's a non-regex approach (out of many others)

>>> string="===abc==="
>>> string.replace("abc"," ").split(" ")
['===', '===']
>>> a,b = string.replace("abc"," ").split(" ")
>>> if a == b:
...   print "ok"
...
ok

You said you want to match equal characters on each side, so regardless of what characters, you just need to check a and b are equal.

You are going to want to use a back reference. Check this post for an example:

Regex, single quote or double quote