99 lines
2.4 KiB
Go
99 lines
2.4 KiB
Go
package reflectext
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import (
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"reflect"
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"strings"
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)
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// GetMapPath returns the value deep inside a hierahically nested map structure
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// eg:
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// x := langext.H{"K1": langext.H{"K2": 665}}
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// GetMapPath[int](x, "K1.K2") == 665
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func GetMapPath[TData any](mapval any, path string) (TData, bool) {
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var ok bool
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split := strings.Split(path, ".")
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for i, key := range split {
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if i < len(split)-1 {
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mapval, ok = GetMapField[any](mapval, key)
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if !ok {
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return *new(TData), false
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}
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} else {
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return GetMapField[TData](mapval, key)
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}
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}
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return *new(TData), false
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}
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// GetMapField gets the value of a map, without knowing the actual types (mapval is any)
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// eg:
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// x := langext.H{"K1": 665}
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// GetMapPath[int](x, "K1") == 665
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//
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// works with aliased types and autom. dereferences pointes
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func GetMapField[TData any, TKey comparable](mapval any, key TKey) (TData, bool) {
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rval := reflect.ValueOf(mapval)
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for rval.Kind() == reflect.Ptr && !rval.IsNil() {
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rval = rval.Elem()
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}
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if rval.Kind() != reflect.Map {
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return *new(TData), false // mapval is not a map
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}
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kval := reflect.ValueOf(key)
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if !kval.Type().AssignableTo(rval.Type().Key()) {
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return *new(TData), false // key cannot index mapval
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}
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eval := rval.MapIndex(kval)
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if !eval.IsValid() {
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return *new(TData), false // key does not exist in mapval
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}
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destType := reflect.TypeOf(new(TData)).Elem()
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if eval.Type() == destType {
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return eval.Interface().(TData), true
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}
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if eval.CanConvert(destType) && !preventConvert(eval.Type(), destType) {
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return eval.Convert(destType).Interface().(TData), true
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}
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if (eval.Kind() == reflect.Ptr || eval.Kind() == reflect.Interface) && eval.IsNil() && destType.Kind() == reflect.Ptr {
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return *new(TData), false // special case: mapval[key] is nil
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}
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for (eval.Kind() == reflect.Ptr || eval.Kind() == reflect.Interface) && !eval.IsNil() {
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eval = eval.Elem()
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if eval.Type() == destType {
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return eval.Interface().(TData), true
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}
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if eval.CanConvert(destType) && !preventConvert(eval.Type(), destType) {
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return eval.Convert(destType).Interface().(TData), true
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}
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}
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return *new(TData), false // mapval[key] is not of type TData
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}
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func preventConvert(t1 reflect.Type, t2 reflect.Type) bool {
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if t1.Kind() == reflect.String && t1.Kind() != reflect.String {
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return true
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}
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if t2.Kind() == reflect.String && t1.Kind() != reflect.String {
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return true
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}
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return false
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}
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