From a720c2c16b442b668db465fbbc70740cfc7ddee4 Mon Sep 17 00:00:00 2001
From: Keuin <keuinx@gmail.com>
Date: Thu, 8 Sep 2022 00:31:26 +0800
Subject: Load config from file or cli.

---
 common/orelse.go | 49 +++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 45 insertions(+), 4 deletions(-)

(limited to 'common/orelse.go')

diff --git a/common/orelse.go b/common/orelse.go
index a96bde7..29e3dc7 100644
--- a/common/orelse.go
+++ b/common/orelse.go
@@ -1,20 +1,61 @@
 package common
 
-type Opt[T any] struct {
+import "reflect"
+
+type Opt[T any] interface {
+	OrElse(thing T) T
+}
+
+type OptError[T any] struct {
 	thing T
 	err   error
 }
 
-func Optional[T any](thing T, err error) Opt[T] {
-	return Opt[T]{
+type OptNull[T any] struct {
+	ptr *T
+}
+
+type OptZero[T any] struct {
+	thing T
+}
+
+func (o OptNull[T]) OrElse(thing T) T {
+	if o.ptr != nil {
+		return *o.ptr
+	}
+	return thing
+}
+
+func Errorable[T any](thing T, err error) Opt[T] {
+	return OptError[T]{
 		thing: thing,
 		err:   err,
 	}
 }
 
-func (o Opt[T]) OrElse(thing T) T {
+func (o OptError[T]) OrElse(thing T) T {
 	if o.err != nil {
 		return thing
 	}
 	return o.thing
 }
+
+func Nullable[T any](ptr *T) Opt[T] {
+	return OptNull[T]{
+		ptr: ptr,
+	}
+}
+
+func Zeroable[T any](thing T) Opt[T] {
+	return OptZero[T]{
+		thing: thing,
+	}
+}
+
+func (o OptZero[T]) OrElse(thing T) T {
+	var zero T
+	if reflect.DeepEqual(zero, o.thing) {
+		return thing
+	}
+	return o.thing
+}
-- 
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