Go, trying to loop date Regex results - regex

Question

Doing a FindAllStringSubmatch regex match including named groups for different date formats. I am having trouble looping results. The commented out conditional makes it work, but not cleanly and it breaks as I add additional matches. I feel like I am approaching it wrong and would like some redirection. thx/
package main
import (
"fmt"
"regexp"
"strings"
)
func main() {
text := "12/31/1956 31/11/1960"
reg := []string{`(?P<month>1[12])/(?P<day>\d\d)/(?P<year>19\d\d)`, `(?P<day>\d\d)/(?P<month>1[12])/(?P<year>19\d\d)`}
// Combine them, case ignored
regall := "(?i)" + strings.Join(reg, "|")
myExp := regexp.MustCompile(regall)
match := myExp.FindAllStringSubmatch(text, -1)
fmt.Println("Match", match, len(match))
fmt.Println("Names", myExp.SubexpNames(), len(myExp.SubexpNames()))
for i := 0; i < len(match); i++ {
result := make(map[string]string)
for j, name := range myExp.SubexpNames() {
result[name] = match[i][j]
//if (result["month"] != "" && result["day"] != "" && result["year"] != "") {
fmt.Println(match[i][0],i,j,result["month"] + "/" + result["day"] + "/" + result["year"])
//}
}
}
}
Results in:
Match [[12/31/1956 12 31 1956 ] [31/11/1960 31 11 1960]] 2
Names [ month day year day month year] 7
12/31/1956 0 0 //
12/31/1956 0 1 12//
12/31/1956 0 2 12/31/
12/31/1956 0 3 12/31/1956
12/31/1956 0 4 12//1956
12/31/1956 0 5 //1956
12/31/1956 0 6 //
31/11/1960 1 0 //
31/11/1960 1 1 //
31/11/1960 1 2 //
31/11/1960 1 3 //
31/11/1960 1 4 /31/
31/11/1960 1 5 11/31/
31/11/1960 1 6 11/31/1960

Answer 1

After some rethinking and help from above, with aid of the above answer I came up looping the regex's separately to better handle overlapping named capture groups I came up with this: (posted for benefit of others and any critique is welcome)
package main
import (
"fmt"
"os"
"regexp"
"strconv"
"strings"
)
func main() {
month_d := `(?P<month>1[012]|0?[1-9])`
month_t := `(?P<month>jan(?:uary|.)?|feb(?:ruary|.)?|mar(?:ch|.)?|apr(?:il|.)?|may(.)|jun(?:e|.)?|jul(?:y|.)?|aug(?:ust|.)?|sep(?:tember|t|t.|.)?|oct(?:ober|.)?|nov(?:ember|.)?|dec(?:ember|.)?)`
day := `(?P<day>3[01]|[12][0-9]|[0]?[1-9])(?:\s)?(?:th|rd|nd|st)?`
year := `(?P<year>(?:19|20)?\d\d)`
sep_d := `[?:/.-]`
sep_t := `[?:,\s]`
text := "fedskjnkvdsj February 6 2004 sdffd Jan 12th 56 1/12/2000 2013/12/1 2099/12/5 1/12/1999 dsfjhfdhj"
regs := []string{
"(" + month_d + sep_d + day + sep_d + year + ")",
"(" + year + sep_d + month_d + sep_d + day + ")",
"(" + day + sep_d + month_d + sep_d + year + ")",
"(" + month_t + sep_t + day + sep_t + year + ")",
"(" + day + sep_t + month_t + sep_t + year + ")",
}
for i := 0; i < len(regs); i++ {
myExp, err := regexp.Compile("(?i)" + regs[i])
if err != nil {
fmt.Printf("There is a problem with your regexp.\n")
return
}
match := myExp.FindAllStringSubmatch(text, -1)
//fmt.Println("Match", match, len(match))
//fmt.Println("Names", myExp.SubexpNames(), len(myExp.SubexpNames()))
for j := 0; j < len(match); j++ {
result := make(map[string]string)
for k, name := range myExp.SubexpNames() {
result[name] = match[j][k]
}
// Fix Month
themonth := strings.ToLower(result["month"])
if len(themonth) == 1 {
themonth = "0" + themonth
}
if len(themonth) >= 3 {
themonth = themonth[0:3]
switch themonth {
case "jan":
themonth = "01"
case "feb":
themonth = "02"
case "mar":
themonth = "03"
case "apr":
themonth = "04"
case "may":
themonth = "05"
case "jun":
themonth = "06"
case "jul":
themonth = "07"
case "aug":
themonth = "08"
case "sep":
themonth = "09"
case "oct":
themonth = "10"
case "nov":
themonth = "11"
case "dec":
themonth = "12"
default:
fmt.Println("Month Error: " + themonth)
os.Exit(2)
}
}
// Day
theday := result["day"]
if len(theday) == 1 {
theday = "0" + theday
}
// Fix Year
theyear := result["year"]
if len(theyear) == 2 {
val_year, err := strconv.ParseInt(theyear,10,0)
if err != nil {
// handle error
fmt.Println(err)
os.Exit(2)
}
if val_year > 50 {
theyear = "19" + theyear
} else {
theyear = "20" + theyear
}
}
date := themonth + "/" + theday + "/" + theyear
fmt.Println(date)
}
}
}