/
reflect.go
194 lines (162 loc) · 4.35 KB
/
reflect.go
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package rest
import (
"reflect"
)
type ReflectConsumer interface {
Consume(v reflect.Value)
ForIndex(index int) ReflectConsumer
ForField(field reflect.StructField) ReflectConsumer
ForKey(key string) ReflectConsumer
}
type ReflectShouldConsume func(t reflect.Type) bool
type ReflectIterator func(value reflect.Value, consumer ReflectConsumer)
type Reflector struct {
Iterators map[reflect.Type][]ReflectIterator
ShouldConsume ReflectShouldConsume
}
func NewReflector(should ReflectShouldConsume) *Reflector {
return &Reflector{
Iterators: make(map[reflect.Type][]ReflectIterator),
ShouldConsume: should,
}
}
func (r *Reflector) Consume(value any, consumer ReflectConsumer) {
reflectValue := reflect.ValueOf(value)
reflectType := reflectValue.Type()
iterators := r.getIterators(reflectType)
r.iterate(iterators, reflectValue, consumer)
}
func (r *Reflector) getIterators(t reflect.Type) []ReflectIterator {
iterators, exists := r.Iterators[t]
if exists {
return iterators
}
r.Iterators[t] = make([]ReflectIterator, 0)
pointerCanConsume := t.Kind() != reflect.Pointer && r.ShouldConsume(reflect.PointerTo(t))
if !pointerCanConsume && r.ShouldConsume(t) {
r.addIterator(t, r.consumeValue())
}
switch t.Kind() {
case reflect.Pointer:
r.addIterator(t, r.consumePointer(t.Elem()))
case reflect.Interface:
r.addIterator(t, r.consumeInterface(t.Elem()))
case reflect.Struct:
for i := 0; i < t.NumField(); i++ {
r.addIterator(t, r.consumeField(t, i))
}
case reflect.Array, reflect.Slice:
r.addIterator(t, r.consumeSlice(t.Elem()))
case reflect.Map:
r.addIterator(t, r.consumeMap(t.Elem()))
}
return r.Iterators[t]
}
func (r *Reflector) addIterator(t reflect.Type, iter ReflectIterator) {
if iter != nil {
r.Iterators[t] = append(r.Iterators[t], iter)
}
}
func (r *Reflector) iterate(iters []ReflectIterator, value reflect.Value, consumer ReflectConsumer) {
for _, i := range iters {
i(value, consumer)
}
}
func (r *Reflector) consumeValue() ReflectIterator {
return func(value reflect.Value, consumer ReflectConsumer) {
consumer.Consume(value)
}
}
func (r *Reflector) consumePointer(t reflect.Type) ReflectIterator {
iters := r.getIterators(t)
if len(iters) == 0 {
return nil
}
return func(value reflect.Value, consumer ReflectConsumer) {
if value.IsNil() {
return
}
r.iterate(iters, ref(value.Elem()), consumer)
}
}
func (r *Reflector) consumeInterface(t reflect.Type) ReflectIterator {
iters := r.getIterators(t)
if len(iters) == 0 {
return nil
}
return func(value reflect.Value, consumer ReflectConsumer) {
if value.IsNil() {
return
}
r.iterate(iters, ref(value.Elem()), consumer)
}
}
func (r *Reflector) consumeSlice(t reflect.Type) ReflectIterator {
iters := r.getIterators(t)
if len(iters) == 0 {
return nil
}
return func(value reflect.Value, consumer ReflectConsumer) {
if value.IsNil() {
return
}
slice := val(value)
for i := 0; i < slice.Len(); i++ {
item := ref(slice.Index(i))
if indexValidator := consumer.ForIndex(i); indexValidator != nil {
r.iterate(iters, item, indexValidator)
}
}
}
}
func (r *Reflector) consumeMap(t reflect.Type) ReflectIterator {
iters := r.getIterators(t)
if len(iters) == 0 {
return nil
}
return func(value reflect.Value, consumer ReflectConsumer) {
if value.IsNil() {
return
}
iter := value.MapRange()
for iter.Next() {
key := iter.Key()
value := ref(iter.Value())
if keyValidator := consumer.ForKey(key.String()); keyValidator != nil {
r.iterate(iters, value, keyValidator)
}
}
}
}
func (r *Reflector) consumeField(parent reflect.Type, fieldIndex int) ReflectIterator {
field := parent.Field(fieldIndex)
iters := r.getIterators(reflect.PointerTo(field.Type))
if len(iters) == 0 {
iters = r.getIterators(field.Type)
if len(iters) == 0 {
return nil
}
}
return func(value reflect.Value, consumer ReflectConsumer) {
fieldValue := ref(val(value).Field(fieldIndex))
if field.Anonymous {
r.iterate(iters, fieldValue, consumer)
} else {
if fieldValidator := consumer.ForField(field); fieldValidator != nil {
r.iterate(iters, fieldValue, fieldValidator)
}
}
}
}
func ref(value reflect.Value) reflect.Value {
if value.CanAddr() {
return value.Addr()
}
return value
}
func val(value reflect.Value) reflect.Value {
if value.Kind() == reflect.Pointer {
return value.Elem()
}
return value
}