package main
import (
    "regexp"
    "fmt"
)
func main() {
    var re = regexp.MustCompile(`(?m)(<(\w+)(?:\/|.*?)>)((\w+\s?)+)(<(?:\/|)\2+>)`)
    var str = `'<a class="class">' . $variable . '</a>'
"<a class="class">" . $variable . "</a>"
<a class="class">{{ $variable }}</a>
<a class="class">{{ __("words") }}</a>
<a class="class">some words</a>
<a/>some words<a>
<a/>some words</a>
<a/></a>
<a>Some words</a>
<a><a>Some words</a></a>`
    var substitution = "$1{{ __("$3") }}$5"
    
    fmt.Println(re.ReplaceAllString(str, substitution))
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Golang, please visit: https://golang.org/pkg/regexp/