Merge pull request #10 from goctus/issue/#7

Add `NativeMap`

pkg/map.go

@@ -24,6 +24,10 @@
 
 package collection
 
+import "errors"
+
+var ErrNotFound = errors.New("key not found")
+
 // Map is an associated collection.
 type Map[K any, V any] interface {
 	Collecton[K, V]

pkg/native_map.go

@@ -0,0 +1,72 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2023-present goctus
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package collection
+
+import option "github.com/goctus/option/pkg"
+
+// NativeMap is Map that uses Go's map.
+type NativeMap[K, V any] struct {
+	origin map[any]V
+}
+
+// NewNativeMap creates a new NativeMap.
+func NewNativeMap[K, V any](origin map[any]V) NativeMap[K, V] {
+	return NativeMap[K, V]{origin}
+}
+
+func (nm NativeMap[K, V]) Size() int {
+	return len(nm.origin)
+}
+
+func (nm NativeMap[K, V]) Found(key K) option.Option[V] {
+	value, ok := nm.origin[key]
+	if !ok {
+		return option.NewNone[V](ErrNotFound)
+	}
+	return option.NewSome(value)
+}
+
+func (nm NativeMap[K, V]) With(key K, value V) Map[K, V] {
+	copy := nm.clone()
+	copy[key] = value
+	return NativeMap[K, V]{copy}
+}
+
+func (nm NativeMap[K, V]) Without(key K) Map[K, V] {
+	if _, contains := nm.origin[key]; !contains {
+		return nm
+	}
+	copy := nm.clone()
+	delete(copy, key)
+	return NativeMap[K, V]{copy}
+}
+
+func (nm NativeMap[K, V]) clone() (result map[any]V) {
+	result = make(map[any]V)
+	for k, v := range nm.origin {
+		result[k] = v
+	}
+	return
+}