golang list: general helper functions

main.go

/* 
 * 
 * Demo: https://repl.it/@wangpin34/array-utils
 */

/*
 * Filter elements which pass the test function
 */
func filter(in interface{}, testFunc func(interface{}) bool) *[]interface{} {
  b, _ := json.Marshal(in)
  array := make([]interface{}, 0, 10)
  err := json.Unmarshal(b, &array)
  if err == nil {
    s := make([]interface{}, 0, len(array))
    for _, value := range array {
      if testFunc(value) == true {
        s = append(s, value)
      }
    }
    return &s
  } 
  fmt.Printf("Error while filter elements: %s \n", err.Error())
  return nil
}

/*
 * Find the first element which pass the test function, if no element pass, return nil
 */
func find(in interface{}, testFunc func(interface{}) bool) *interface{} {
  b, _ := json.Marshal(in)
  array := make([]interface{}, 0, 10)
  err := json.Unmarshal(b, &array)
  if err == nil {
    for _, value := range array {
      if testFunc(value) == true {
        return &value
      }
	  }
  }
	return nil
}

/*
 * Find the index of first element which pass the test function, if no element pass, return -1
 */
func findIndex(in interface{}, testFunc func(interface{}) bool) int {
  b, _ := json.Marshal(in)
  array := make([]interface{}, 0, 10)
  err := json.Unmarshal(b, &array)
  if err == nil {
    for index, value := range array {
      if testFunc(value) == true {
        return index
      }
    }
  }
	return -1
}