109 lines
2.2 KiB
Go
109 lines
2.2 KiB
Go
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package dynamic
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import (
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"errors"
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"fmt"
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"reflect"
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)
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type StructFieldIterator func(tag string, ft reflect.StructField, fv reflect.Value) error
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var ErrCanNotIterateNilPointer = errors.New("can not iterate struct on a nil pointer")
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func IterateFields(obj interface{}, cb func(ft reflect.StructField, fv reflect.Value) error) error {
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if obj == nil {
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return errors.New("can not iterate field, given object is nil")
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}
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sv := reflect.ValueOf(obj)
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st := reflect.TypeOf(obj)
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if st.Kind() != reflect.Ptr {
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return fmt.Errorf("f should be a pointer of a struct, %s given", st)
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}
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// for pointer, check if it's nil
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if sv.IsNil() {
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return ErrCanNotIterateNilPointer
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}
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// solve the reference
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st = st.Elem()
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sv = sv.Elem()
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if st.Kind() != reflect.Struct {
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return fmt.Errorf("f should be a struct, %s given", st)
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}
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for i := 0; i < sv.NumField(); i++ {
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fv := sv.Field(i)
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ft := st.Field(i)
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// skip unexported fields
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if !st.Field(i).IsExported() {
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continue
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}
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if err := cb(ft, fv); err != nil {
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return err
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}
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}
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return nil
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}
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func isStructPtr(tpe reflect.Type) bool {
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return tpe.Kind() == reflect.Ptr && tpe.Elem().Kind() == reflect.Struct
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}
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func IterateFieldsByTag(obj interface{}, tagName string, children bool, cb StructFieldIterator) error {
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sv := reflect.ValueOf(obj)
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st := reflect.TypeOf(obj)
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if st.Kind() != reflect.Ptr {
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return fmt.Errorf("obj should be a pointer of a struct, %s given", st)
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}
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// for pointer, check if it's nil
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if sv.IsNil() {
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return ErrCanNotIterateNilPointer
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}
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// solve the reference
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st = st.Elem()
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sv = sv.Elem()
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if st.Kind() != reflect.Struct {
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return fmt.Errorf("f should be a struct, %s given", st)
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}
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for i := 0; i < sv.NumField(); i++ {
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fv := sv.Field(i)
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ft := st.Field(i)
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// skip unexported fields
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if !st.Field(i).IsExported() {
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continue
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}
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if children && isStructPtr(ft.Type) && !fv.IsNil() {
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// recursive iterate the struct field
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if err := IterateFieldsByTag(fv.Interface(), tagName, false, cb); err != nil {
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return fmt.Errorf("unable to iterate struct fields over the type %v: %v", ft, err)
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}
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}
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tag, ok := ft.Tag.Lookup(tagName)
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if !ok {
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continue
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}
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// call the iterator
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if err := cb(tag, ft, fv); err != nil {
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return err
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}
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}
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return nil
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}
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