Go equivalent to PHP preg_match

Question

I have a small PHP script that runs through my apache log - and i'm trying to convert this script to Go. However I'm having some difficulties finding a good equivalent to the PHP function preg_match.

In my PHP script I run a preg_match on each line in the log file like this:

preg_match('/([.0-9]+) .*?\[([0-9a-zA-Z:\/+ ]+)\].*?"[A-Z]+ \/([^\/ ]+)\/([a-zA-Z0-9\-.]+).*" ([0-9]{3}) .*"(.*?)"$/', $line, $matches)

Running this expression on this log:

100.100.100.100 - - [23/Feb/2015:03:03:56 +0100] "GET /folder/file.mp3 HTTP/1.1" 206 5637064 "-" "AppleCoreMedia/1.0.0.12B466 (iPhone; U; CPU OS 8_1_3 like Mac OS X; da_dk)"

Returns the following array(where I am only really interested in [1-6]:

Array
(
    [0] => 100.100.100.100 - - [23/Feb/2015:03:03:56 +0100] "GET /folder/file.mp3 HTTP/1.1" 206 5637064 "-" "AppleCoreMedia/1.0.0.12B466 (iPhone; U; CPU OS 8_1_3 like Mac OS X; da_dk)"
    [1] => 100.100.100.100
    [2] => 23/Feb/2015:03:03:56 +0100
    [3] => folder
    [4] => file.mp3
    [5] => 206
    [6] => AppleCoreMedia/1.0.0.12B466 (iPhone; U; CPU OS 8_1_3 like Mac OS X; da_dk)
)

So my question is - is there a good equivalent to this in Go? I have tried some of the different regexp methods but can't seem to find one thats working for me.

Thanks

Answer 1

First you need to know that you might need to modify the regex pattern itself, since go's regex engine does not behave exactly the same as PHP's regex engine. Both are using PCRE regexes where PHP implements more features than go. However, your pattern from the example should work in go without modifications.

Here comes an example program in go that works like PHP's preg_match():

package main

import "fmt"
import "regexp"

func main() {

    str := `100.100.100.100 - - [23/Feb/2015:03:03:56 +0100] "GET /folder/file.mp3 HTTP/1.1" 206 5637064 "-" "AppleCoreMedia/1.0.0.12B466 (iPhone; U; CPU OS 8_1_3 like Mac OS X; da_dk)"`

    r, _ := regexp.Compile(`([.0-9]+) .*?\[([0-9a-zA-Z:\/+ ]+)\].*?"[A-Z]+ \/([^\/ ]+)\/([a-zA-Z0-9\-.]+).*" ([0-9]{3}) .*"(.*?)"$`)

    // Using FindStringSubmatch you are able to access the 
    // individual capturing groups
    for index, match := range r.FindStringSubmatch(str) {
        fmt.Printf("[%d] %s\n", index, match)
    }   
}

Output:

[0] 100.100.100.100 - - [23/Feb/2015:03:03:56 +0100] "GET /folder/file.mp3 HTTP/1.1" 206 5637064 "-" "AppleCoreMedia/1.0.0.12B466 (iPhone; U; CPU OS 8_1_3 like Mac OS X; da_dk)"
[1] 100.100.100.100
[2] 23/Feb/2015:03:03:56 +0100
[3] folder
[4] file.mp3
[5] 206
[6] AppleCoreMedia/1.0.0.12B466 (iPhone; U; CPU OS 8_1_3 like Mac OS X; da_dk)

Please check the manual about go regexes: http://golang.org/pkg/regexp/