How to convert string with index number to target slice item

I have this string:

"books[1]"

And I have this slice:

books := []string{"wadidaw", "bededaw", "celepaw"}

How to convert this string: "books[1]" to be able to target books index 1 like the following:

fmt.Println("Book title: ", books[1]) // Book title: bededaw

You'll need to parse string as code.

package main
import (
"fmt"
"strconv"
)
func main() {
books := map[int]string{
0: "wadidaw",
1: "bededaw",
2: "celepaw",
}
target := "books[1]"
value, err := getValueByString(target, books)
if err != nil {
fmt.Println("Error:", err)
} else {
fmt.Println("Book title:", value)
}
}
func getValueByString(target string, data map[int]string) (interface{}, error) {
parts := splitTarget(target)
if len(parts) != 2 {
return nil, fmt.Errorf("invalid target format: %s", target)
}
// Get the variable name and index
varName := parts[0]
index, err := strconv.Atoi(parts[1])
if err != nil {
return nil, fmt.Errorf("invalid index: %s", parts[1])
}
// Check if the variable exists
value, ok := data[index]
if !ok {
return nil, fmt.Errorf("variable not found: %s", varName)
}
return value, nil
}
func splitTarget(target string) []string {
parts := make([]string, 2)
// Find the index of the opening bracket
braceIndex := -1
for i, char := range target {
if char == '[' {
braceIndex = i
break
}
}
// Extract the variable name and index
if braceIndex != -1 {
parts[0] = target[:braceIndex]
parts[1] = target[braceIndex+1 : len(target)-1]
}
return parts
}

Please feel free to use the Go playground

https://go.dev/play/p/-q2JUn-N4Sg

Here is a very simple approach to parse the string and getting the index value.

package main
import (
"fmt"
"strconv"
"strings"
)
func main() {
books := []string{
"wadidaw",
"bededaw",
"celepaw",
}
str := "books[1]"
index, sliceName, err := getIndex(str)
if err != nil {
panic(err)
}
// Check the index is valid as it will be greater than 0 and less than (slice length - 1)
if index < 0 || index > len(books)-1 {
panic("invalid index")
}
fmt.Println("Slice name : ", sliceName)
fmt.Println("Value : ", books[index])
}
func getIndex(str string) (int, string, error) {
// split the string at [
parts := strings.Split(str, "[")
if len(parts) != 2 {
return 0, "", fmt.Errorf("unable to parse %v, invalid syntax", str)
}
name := parts[0]
index := strings.TrimSuffix(parts[1], "]")
// convert the index into int
indexInt, err := strconv.Atoi(index)
if err != nil {
return 0, "", fmt.Errorf("unable to parse '%s' into int", index)
}
return indexInt, name, nil
}