I want to get the indexes of the following pattern (\.\.#\.\.) in the following string :
...#...#....#.....#..#..#..#.......
But Golang does not manage overlapping matching.
Thus I got : [[1 6 1 6] [10 15 10 15] [16 21 16 21] [22 27 22 27]]
As one can see, two points . do precede and suffix the second # but it's not return by the method FindAllStringSubmatchIndex.
I tried to use different methods from regexp without success. Searching the documentation, I found nothing useful on https://golang.org/pkg/regexp and https://golang.org/src/regexp/regexp.go
On the contrary, it seems regexp does not natively support this functionality :
// If 'All' is present, the routine matches successive non-overlapping matches of the entire expression.
I can solve the issue but since I am doing this exercise to learn Golang, I want to know. thanks :)
Here is my code for reference :
matches := r.pattern.FindAllStringSubmatchIndex(startingState)
fmt.Println(r.pattern)
fmt.Println(matches)
for _, m := range matches {
tempState = tempState[:m[0]+2] + "#" + tempState[m[0]+3:]
fmt.Println(tempState)
}
There's no reason to use a regex for this. Regex is overkill for such a simple task--it's over complex, and less efficient. Instead you should just use strings.Index, and a for loop:
input := "...#...#....#.....#..#..#..#......."
idx := []int{}
j := 0
for {
i := strings.Index(input[j:], "..#..")
if i == -1 {
break
}
fmt.Println(j)
idx = append(idx, j+i)
j += i+1
}
fmt.Println("Indexes:", idx)
Go is for programmers. For example,
package main
import (
"fmt"
"strings"
)
func findIndices(haystack, needle string) []int {
var x []int
for i := 0; i < len(haystack)-len(needle); i++ {
j := strings.Index(haystack[i:], needle)
if j < 0 {
break
}
i += j
x = append(x, i)
}
return x
}
func main() {
haystack := `...#...#....#.....#..#..#..#.......`
needle := `..#..`
fmt.Println(findIndices(haystack, needle))
}
Playground: https://play.golang.org/p/nNE5IB1feQT
Output:
[1 5 10 16 19 22 25]
Regular Expression References:
Regular Expression Matching Can Be Simple And Fast