package flatmap
import (
"fmt"
"reflect"
)
// Flatten takes a structure and turns into a flat map[string]string.
//
// Within the "thing" parameter, only primitive values are allowed. Structs are
// not supported. Therefore, it can only be slices, maps, primitives, and
// any combination of those together.
//
// See the tests for examples of what inputs are turned into.
func Flatten(thing map[string]interface{}) Map {
result := make(map[string]string)
for k, raw := range thing {
flatten(result, k, reflect.ValueOf(raw))
}
return Map(result)
}
func flatten(result map[string]string, prefix string, v reflect.Value) {
if v.Kind() == reflect.Interface {
v = v.Elem()
}
switch v.Kind() {
case reflect.Bool:
if v.Bool() {
result[prefix] = "true"
} else {
result[prefix] = "false"
}
case reflect.Int:
result[prefix] = fmt.Sprintf("%d", v.Int())
case reflect.Map:
flattenMap(result, prefix, v)
case reflect.Slice:
flattenSlice(result, prefix, v)
case reflect.String:
result[prefix] = v.String()
default:
panic(fmt.Sprintf("Unknown: %s", v))
}
}
func flattenMap(result map[string]string, prefix string, v reflect.Value) {
for _, k := range v.MapKeys() {
if k.Kind() == reflect.Interface {
k = k.Elem()
}
if k.Kind() != reflect.String {
panic(fmt.Sprintf("%s: map key is not string: %s", prefix, k))
}
flatten(result, fmt.Sprintf("%s.%s", prefix, k.String()), v.MapIndex(k))
}
}
func flattenSlice(result map[string]string, prefix string, v reflect.Value) {
prefix = prefix + "."
result[prefix+"#"] = fmt.Sprintf("%d", v.Len())
for i := 0; i < v.Len(); i++ {
flatten(result, fmt.Sprintf("%s%d", prefix, i), v.Index(i))
}
}
