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mapper_struct.go
198 lines (169 loc) · 5.24 KB
/
mapper_struct.go
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package structure
import (
"fmt"
"reflect"
"strings"
)
func init() {
RegisterKindMapper(reflect.Struct, reflect.Map, struct2mapMapper)
RegisterKindMapper(reflect.Struct, reflect.Struct, struct2structMapper)
}
func getKind(val reflect.Value) reflect.Kind {
kind := val.Kind()
switch {
case kind >= reflect.Int && kind <= reflect.Int64:
return reflect.Int
case kind >= reflect.Uint && kind <= reflect.Uint64:
return reflect.Uint
case kind >= reflect.Float32 && kind <= reflect.Float64:
return reflect.Float32
default:
return kind
}
}
func isEmptyValue(v reflect.Value) bool {
switch getKind(v) {
case reflect.Array, reflect.Map, reflect.Slice, reflect.String:
return v.Len() == 0
case reflect.Bool:
return !v.Bool()
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
return v.Int() == 0
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
return v.Uint() == 0
case reflect.Float32, reflect.Float64:
return v.Float() == 0
case reflect.Interface, reflect.Ptr:
return v.IsNil()
}
return false
}
func isStructTypeConvertibleToMap(typ reflect.Type, checkMapstructureTags bool, tagName string) bool {
for i := 0; i < typ.NumField(); i++ {
f := typ.Field(i)
if f.PkgPath == "" && !checkMapstructureTags { // check for unexported fields
return true
}
if checkMapstructureTags && f.Tag.Get(tagName) != "" { // check for mapstructure tags inside
return true
}
}
return false
}
func dereferencePtrToStructIfNeeded(v reflect.Value, tagName string) reflect.Value {
if v.Kind() != reflect.Ptr || v.Elem().Kind() != reflect.Struct {
return v
}
deref := v.Elem()
derefT := deref.Type()
if isStructTypeConvertibleToMap(derefT, true, tagName) {
return deref
}
return v
}
func struct2mapMapper(from reflect.Value, to reflect.Value, option *Option) error {
mapType := to.Type()
mapElemType := mapType.Elem()
if to.IsNil() {
to.Set(reflect.MakeMap(mapType))
}
typ := from.Type()
for i := 0; i < typ.NumField(); i++ {
// Get the StructField first since this is a cheap operation. If the
// field is unexported, then ignore it.
f := typ.Field(i)
if f.PkgPath != "" {
continue
}
// Next get the actual value of this field and verify it is assignable
// to the map value.
v := from.Field(i)
if !v.Type().AssignableTo(mapElemType) {
cv, err := ConvertToTypeWithOption(v.Interface(), mapElemType, option)
if err != nil {
return err
}
v = reflect.ValueOf(cv)
}
tagValue := f.Tag.Get(option.TagName)
keyName := f.Name
if tagValue == "" && option.IgnoreUntaggedFields {
continue
}
// If Squash is set in the config, we squash the field down.
squash := option.Squash && v.Kind() == reflect.Struct && f.Anonymous
v = dereferencePtrToStructIfNeeded(v, option.TagName)
// Determine the name of the key in the map
if index := strings.Index(tagValue, ","); index != -1 {
if tagValue[:index] == "-" {
continue
}
// If "omitempty" is specified in the tag, it ignores empty values.
if strings.Index(tagValue[index+1:], "omitempty") != -1 && isEmptyValue(v) {
continue
}
// If "squash" is specified in the tag, we squash the field down.
squash = squash || strings.Index(tagValue[index+1:], "squash") != -1
if squash {
// When squashing, the embedded type can be a pointer to a struct.
if v.Kind() == reflect.Ptr && v.Elem().Kind() == reflect.Struct {
v = v.Elem()
}
// The final type must be a struct
if v.Kind() != reflect.Struct {
return fmt.Errorf("cannot squash non-struct type '%s'", v.Type())
}
}
if keyNameTagValue := tagValue[:index]; keyNameTagValue != "" {
keyName = keyNameTagValue
}
} else if len(tagValue) > 0 {
if tagValue == "-" {
continue
}
keyName = tagValue
}
switch v.Kind() {
// this is an embedded struct, so handle it differently
case reflect.Struct:
x := reflect.New(v.Type())
x.Elem().Set(v)
vType := to.Type()
vKeyType := vType.Key()
vElemType := vType.Elem()
mType := reflect.MapOf(vKeyType, vElemType)
vMap := reflect.MakeMap(mType)
// Creating a pointer to a map so that other methods can completely
// overwrite the map if need be (looking at you decodeMapFromMap). The
// indirection allows the underlying map to be settable (CanSet() == true)
// where as reflect.MakeMap returns an unsettable map.
addrVal := reflect.New(vMap.Type())
reflect.Indirect(addrVal).Set(vMap)
err := MapToValueWithOption(x.Interface(), reflect.Indirect(addrVal), option)
if err != nil {
return err
}
// the underlying map may have been completely overwritten so pull
// it indirectly out of the enclosing value.
vMap = reflect.Indirect(addrVal)
if squash {
for _, k := range vMap.MapKeys() {
to.SetMapIndex(k, vMap.MapIndex(k))
}
} else {
to.SetMapIndex(reflect.ValueOf(keyName), vMap)
}
default:
to.SetMapIndex(reflect.ValueOf(keyName), v)
}
}
return nil
}
func struct2structMapper(from reflect.Value, to reflect.Value, option *Option) error {
mapType := reflect.TypeOf((map[string]any)(nil))
mapValue := reflect.MakeMap(mapType)
if err := struct2mapMapper(from, mapValue, option); err != nil {
return err
}
return map2structMapper(mapValue, to, option)
}