package main
import (
"regexp"
"fmt"
)
func main() {
var re = regexp.MustCompile(`(?m)(?<=http://example\.com/)(fr/|de/|eng/)?.*(?=document_title\d\.php)`)
var str = `http://example.com/a/v/c/document_title1.php
http://example.com/fr/x/1/o/document_title2.php
http://example.com/de/a/a/2/document_title3.php
http://example.com/eng/6/z/z/document_title4.php`
var substitution = "$1"
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/