how do I match a any repeating character using regexp?

Question

I need to match any character that's repeated twice, for example:

"abccdeff"

Should match "cc" and "ff". In any other regex syntax, let's use Javascript as a quick example, I could do:

var str = "abccdeff";
var r = /([a-z]{1})\1/g
console.log(str.match(r))

Which returns

[ 'cc', 'ff' ]

But Go's regexp doesn't seem to allow that. Is it possible to do this in Go?

Answer 1

Since backreference is not supported by re2, you would need:

• either to use another regex library (like glenn-brown/golang-pkg-pcre)
• or code a loop which does the analysis without regexp