Add Explode and Filter to optional.Optional.

pkg/optional/optional.go

@@ -68,6 +68,14 @@ type Optional[V any] interface {
 
 	// OrElseGet returns the value contained in the Optional if the Optional is not empty, or the result of the provided function otherwise.
 	OrElseGet(func() V) V
+
+	// Explode returns the value contained in the Optional and an indicator of whether the Optional is empty.
+	// If the Optional is empty, the value returned is the zero value of type V.
+	Explode() (V, bool)
+
+	// Filter returns an Optional containing the value contained in the Optional if the provided predicate returns true for that value.
+	// If the Optional is empty, an empty Optional is returned.
+	Filter(func(V) bool) Optional[V]
 }
 
 // None is an Optional that represents the absence of a value.
@@ -83,6 +91,15 @@ func (n None[V]) Get() V {
 	return zero
 }
 
+func (n None[V]) Explode() (V, bool) {
+	var zero V
+	return zero, false
+}
+
+func (n None[V]) Filter(_ func(V) bool) Optional[V] {
+	return n
+}
+
 func (n None[V]) IfPresent(_ func(V)) bool {
 	return false
 }
@@ -118,6 +135,21 @@ func (s Some[V]) Present() bool {
 	return true
 }
 
+func (s Some[V]) Get() V {
+	return s.Value
+}
+
+func (s Some[V]) Explode() (V, bool) {
+	return s.Value, true
+}
+
+func (s Some[V]) Filter(f func(V) bool) Optional[V] {
+	if f(s.Value) {
+		return s
+	}
+	return Empty[V]()
+}
+
 func (s Some[V]) IfPresent(f func(V)) bool {
 	f(s.Value)
 	return true
@@ -140,10 +172,6 @@ func (s Some[V]) OrElseGet(_ func() V) V {
 	return s.Value
 }
 
-func (s Some[V]) Get() V {
-	return s.Value
-}
-
 func (s Some[V]) String() string {
 	return fmt.Sprintf("Some(%#v)", s.Value)
 }

pkg/optional/optional_test.go

@@ -67,6 +67,71 @@ func TestMap(t *testing.T) {
 	})
 }
 
+func TestPresent(t *testing.T) {
+	t.Run("Some", func(t *testing.T) {
+		o := Of(42)
+		if !o.Present() {
+			t.Errorf("expected Present() to be true")
+		}
+	})
+
+	t.Run("None", func(t *testing.T) {
+		o := Empty[int]()
+		if o.Present() {
+			t.Errorf("expected Present() to be false")
+		}
+	})
+}
+
+func TestExplode(t *testing.T) {
+	t.Run("Some", func(t *testing.T) {
+		o := Of(42)
+		if v, ok := o.Explode(); !ok || v != 42 {
+			t.Errorf("expected Explode() to return (42, true)")
+		}
+	})
+
+	t.Run("None", func(t *testing.T) {
+		o := Empty[int]()
+		if v, ok := o.Explode(); ok || v != 0 {
+			t.Errorf("expected Explode() to return (0, false)")
+		}
+	})
+}
+
+func TestFilter(t *testing.T) {
+	t.Run("Some", func(t *testing.T) {
+		o := Of(42)
+
+		o2 := o.Filter(func(i int) bool { return i == 42 })
+		if !o2.Present() {
+			t.Errorf("expected Present() to be true")
+		}
+		if o2.Get() != 42 {
+			t.Errorf("expected Get() to return 42")
+		}
+
+		o3 := o.Filter(func(i int) bool { return i != 42 })
+		if o3.Present() {
+			t.Errorf("expected Present() to be false")
+		}
+	})
+
+	t.Run("None", func(t *testing.T) {
+		o := Empty[int]()
+
+		o2 := o.Filter(func(i int) bool { return i == 42 })
+		if o2.Present() {
+			t.Errorf("expected Present() to be false")
+		}
+
+		o3 := o.Filter(func(i int) bool { return i != 42 })
+		if o3.Present() {
+			t.Errorf("expected Present() to be false")
+		}
+	})
+}
+
 func TestIfPresent(t *testing.T) {
 	t.Run("Some", func(t *testing.T) {
 		var called bool