bbgo_origin/pkg/dynamic/iterate.go

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