WIP11

Signed-off-by: Koichi Shiraishi <zchee.io@gmail.com>

Author: zchee

generics.go

@@ -0,0 +1,195 @@
+package protocol
+
+import (
+	"bytes"
+	"fmt"
+)
+
+// Nil represents a empty sturct that is provides nil type.
+type Nil struct{}
+
+var (
+	trueBytes  = []byte("true")
+	falseBytes = []byte("false")
+	nullBytes  = []byte("null")
+)
+
+// OneOf represents a JSON-unmarshals as either a T or a U.
+type OneOf[T, U any] struct {
+	// The underlying value
+	value any
+}
+
+var (
+	_ Marshaler   = (*OneOf[any, any])(nil)
+	_ Unmarshaler = (*OneOf[any, any])(nil)
+)
+
+// Any returns the underlying value.
+func (o *OneOf[T, U]) Any() any {
+	if o == nil {
+		return nil
+	}
+	return o.value
+}
+
+// MarshalJSON implements [Marshaler].
+func (o *OneOf[T, U]) MarshalJSON() ([]byte, error) {
+	if o == nil {
+		return nullBytes, nil
+	}
+	return marshal(o.value)
+}
+
+// UnmarshalJSON implements [Unmarshaler].
+func (o *OneOf[T, U]) UnmarshalJSON(data []byte) error {
+	if bytes.Equal(data, nullBytes) {
+		return nil
+	}
+
+	// Try to unmarshal as T
+	var valueT T
+	errT := unmarshal(data, &valueT)
+	if errT == nil {
+		o.value = valueT
+		return nil
+	}
+
+	// Try to unmarshal as U
+	var valueU U
+	errU := unmarshal(data, &valueU)
+	if errU == nil {
+		o.value = valueU
+		return nil
+	}
+
+	return fmt.Errorf("cannot unmarshal to either type: %v or %v", errT, errU)
+}
+
+// OneOf3 represents a JSON-unmarshals as either a T, U or V.
+type OneOf3[T, U, V any] struct {
+	// The underlying value
+	value any
+}
+
+var (
+	_ Marshaler   = (*OneOf3[any, any, any])(nil)
+	_ Unmarshaler = (*OneOf3[any, any, any])(nil)
+)
+
+// Any returns the underlying value.
+func (o *OneOf3[T, U, V]) Any() any {
+	if o == nil {
+		return nil
+	}
+	return o.value
+}
+
+// MarshalJSON implements [Marshaler].
+func (o *OneOf3[T, U, V]) MarshalJSON() ([]byte, error) {
+	if o == nil {
+		return nullBytes, nil
+	}
+	return marshal(o.value)
+}
+
+// UnmarshalJSON implements [Unmarshaler].
+func (o *OneOf3[T, U, V]) UnmarshalJSON(data []byte) error {
+	if bytes.Equal(data, nullBytes) {
+		return nil
+	}
+
+	// Try to unmarshal as T
+	var valueT T
+	errT := unmarshal(data, &valueT)
+	if errT == nil {
+		o.value = valueT
+		return nil
+	}
+
+	// Try to unmarshal as U
+	var valueU U
+	errU := unmarshal(data, &valueU)
+	if errU == nil {
+		o.value = valueU
+		return nil
+	}
+
+	// Try to unmarshal as V
+	var valueV V
+	errV := unmarshal(data, &valueV)
+	if errV == nil {
+		o.value = valueV
+		return nil
+	}
+
+	return fmt.Errorf("cannot unmarshal to either type: %v or %v or %v", errT, errU, errV)
+}
+
+// OneOf4 represents a JSON-unmarshals as either a T, U, V or V.
+type OneOf4[T, U, V, Y any] struct {
+	// The underlying value
+	value any
+}
+
+var (
+	_ Marshaler   = (*OneOf4[any, any, any, any])(nil)
+	_ Unmarshaler = (*OneOf4[any, any, any, any])(nil)
+)
+
+// Any returns the underlying value.
+func (o *OneOf4[T, U, V, Y]) Any() any {
+	if o == nil {
+		return nil
+	}
+	return o.value
+}
+
+// MarshalJSON implements [Marshaler].
+func (o *OneOf4[T, U, V, Y]) MarshalJSON() ([]byte, error) {
+	if o == nil {
+		return nullBytes, nil
+	}
+	return marshal(o.value)
+}
+
+// UnmarshalJSON implements [Unmarshaler].
+func (o *OneOf4[T, U, V, Y]) UnmarshalJSON(data []byte) error {
+	if bytes.Equal(data, nullBytes) {
+		return nil
+	}
+
+	// Try to unmarshal as T
+	var valueT T
+	errT := unmarshal(data, &valueT)
+	if errT == nil {
+		o.value = valueT
+		return nil
+	}
+
+	// Try to unmarshal as U
+	var valueU U
+	errU := unmarshal(data, &valueU)
+	if errU == nil {
+		o.value = valueU
+		return nil
+	}
+
+	// Try to unmarshal as V
+	var valueV V
+	errV := unmarshal(data, &valueV)
+	if errV == nil {
+		o.value = valueV
+		return nil
+	}
+
+	// Try to unmarshal as V
+	var valueY Y
+	errY := unmarshal(data, &valueY)
+	if errY == nil {
+		o.value = valueV
+		return nil
+	}
+
+	return fmt.Errorf("cannot unmarshal to either type: %v or %v or %v or %v", errT, errU, errV, errY)
+}

protocol.go

@@ -13,6 +13,12 @@ import (
 	"go.lsp.dev/jsonrpc2"
 )
 
+// Marshaler is the interface implemented by types that
+// can marshal themselves into valid JSON.
+type Marshaler interface {
+	MarshalJSON() ([]byte, error)
+}
+
 // MarshalFunc function type of marshal JSON data.
 //
 // Default is used [json.Marshal].
@@ -24,6 +30,15 @@ func RegiserMarshaler(fn MarshalFunc) {
 	marshal = fn
 }
 
+// Unmarshaler is the interface implemented by types
+// that can unmarshal a JSON description of themselves.
+// The input can be assumed to be a valid encoding of
+// a JSON value. UnmarshalJSON must copy the JSON data
+// if it wishes to retain the data after returning.
+type Unmarshaler interface {
+	UnmarshalJSON([]byte) error
+}
+
 // UnmarshalFunc function type of unmarshal JSON data.
 //
 // Default is used [json.Unmarshal].