Write a regular expression which matches a given string consisting of three non-negative, space-separated integers if and only if the last integer is the sum of the previous two. Answers may be for integers of any numeral system with radix between 2 and 10.
These should fail:
0 1 2 10 20 1000
These should match:
10 20 30 28657 46368 75025 0 0 0
Your answer should consist of a single regex, without any additional code (except, optionally, a list of regex modifiers required to make your solution work). You must not use features of your language's regex flavour that allow you to invoke code in the hosting language (e.g. Perl's e modifier).
Please specify your regex flavour in your answer.
This is regex golf, so the shortest regex in bytes wins. If your language requires delimiters (usually /.../) to denote regular expressions, don't count the delimiters themselves. If your solution requires modifiers, add one byte per modifier.
I have reason to believe it's possible based on the solution of Martin Ender for finding and incrementing integers with regex.