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// SPDX-FileCopyrightText: 2025 Stefan Majewsky <majewsky@gmx.net>
// SPDX-License-Identifier: Apache-2.0
package refined
import (
"encoding/json"
"errors"
. "github.com/majewsky/gg/option"
)
type Scalar[S any, V any] struct {
value Option[V]
}
func (s Scalar[S, V]) Raw() V {
return s.value.UnwrapOrPanic("TODO 1")
}
func New[S IsAScalar[S, V], V any](value V) (S, error) {
var empty S
if empty.RefinedMatch(value) {
return empty.RefinedBuild(PreScalar[S, V]{value: Some(value)}), nil
} else {
return empty, errors.New("TODO 2")
}
}
func Literal[S IsAScalar[S, V], V any](value V) S {
s, err := New[S, V](value)
if err != nil {
panic(err.Error())
}
return s
}
func (s Scalar[S, V]) MarshalJSON() ([]byte, error) {
return json.Marshal(s.Raw())
}
func (s *Scalar[S, V]) UnmarshalJSON(buf []byte) error {
var value V
err := json.Unmarshal(buf, &value)
if err != nil {
return err
}
// We cannot directly call `New[S, V](value)` here because we cannot prove statically
// that `S` satisfies `IsAScalar[S, V]`.
var empty S
if r, ok := any(empty).(IsAScalar[S, V]); ok {
if r.RefinedMatch(value) {
*s = Scalar[S, V]{value: Some(value)}
return nil
} else {
return errors.New("TODO 3")
}
} else {
return errors.New("TODO 4")
}
}
type IsAScalar[S any, V any] interface {
// We need both steps separately. New() wants to have an S at the end, which goes through both steps.
// But Unmarshal...() wants to obtain a Scalar[S, V], so it only wants to use the first step.
RefinedMatch(V) bool
RefinedBuild(PreScalar[S, V]) S
}
type PreScalar[S any, V any] struct {
value Option[V]
}
func (p PreScalar[S, V]) Into() Scalar[S, V] {
if p.value.IsNone() {
panic("broken PreScalar object")
}
return Scalar[S, V](p)
}
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