first-commit

modules/optional/option.go

@@ -0,0 +1,69 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package optional
+
+import "strconv"
+
+// Option is a generic type that can hold a value of type T or be empty (None).
+//
+// It must use the slice type to work with "chi" form values binding:
+// * non-existing value are represented as an empty slice (None)
+// * existing value is represented as a slice with one element (Some)
+// * multiple values are represented as a slice with multiple elements (Some), the Value is the first element (not well-defined in this case)
+type Option[T any] []T
+
+func None[T any]() Option[T] {
+	return nil
+}
+
+func Some[T any](v T) Option[T] {
+	return Option[T]{v}
+}
+
+func FromPtr[T any](v *T) Option[T] {
+	if v == nil {
+		return None[T]()
+	}
+	return Some(*v)
+}
+
+func FromMapLookup[K comparable, V any](m map[K]V, k K) Option[V] {
+	if v, ok := m[k]; ok {
+		return Some(v)
+	}
+	return None[V]()
+}
+
+func FromNonDefault[T comparable](v T) Option[T] {
+	var zero T
+	if v == zero {
+		return None[T]()
+	}
+	return Some(v)
+}
+
+func (o Option[T]) Has() bool {
+	return o != nil
+}
+
+func (o Option[T]) Value() T {
+	var zero T
+	return o.ValueOrDefault(zero)
+}
+
+func (o Option[T]) ValueOrDefault(v T) T {
+	if o.Has() {
+		return o[0]
+	}
+	return v
+}
+
+// ParseBool get the corresponding optional.Option[bool] of a string using strconv.ParseBool
+func ParseBool(s string) Option[bool] {
+	v, e := strconv.ParseBool(s)
+	if e != nil {
+		return None[bool]()
+	}
+	return Some(v)
+}