sort map move to generics

collections/generics/sort_map.go

@@ -0,0 +1,86 @@
+package generics
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+
+	"golang.org/x/exp/constraints"
+	"golang.org/x/exp/slices"
+)
+
+type mapSorter[K constraints.Ordered, V any] struct {
+	keys []K
+	m    map[K]V
+}
+
+func NewSortMap[K constraints.Ordered, V any](m map[K]V) *mapSorter[K, V] {
+	return &mapSorter[K, V]{
+		m:    m,
+		keys: keys(m),
+	}
+}
+
+func (s *mapSorter[K, V]) Asc() *mapSorter[K, V] {
+	keys := s.keys
+	slices.Sort(keys)
+
+	return &mapSorter[K, V]{
+		m:    s.m,
+		keys: keys,
+	}
+}
+
+func (s *mapSorter[K, V]) Desc() *mapSorter[K, V] {
+	keys := s.keys
+
+	// slices.SortFunc(keys, func(a, b E) bool {
+	// 	return a > b
+	// })
+
+	sort.Slice(keys, func(i, j int) bool {
+		return keys[i] > keys[j]
+	})
+
+	return &mapSorter[K, V]{
+		m:    s.m,
+		keys: keys,
+	}
+}
+
+func (s *mapSorter[K, V]) Join(sep string, f func(k K, v V) string) string {
+	slice := make([]string, 0, len(s.m))
+	for _, k := range s.keys {
+		slice = append(slice, f(k, s.m[k]))
+	}
+
+	return strings.Join(slice, sep)
+}
+
+func (s *mapSorter[K, V]) Keys() []K {
+	return s.keys
+}
+
+func (s *mapSorter[K, V]) Values() []V {
+	ret := make([]V, 0, len(s.m))
+	for _, k := range s.keys {
+		ret = append(ret, s.m[k])
+	}
+
+	return ret
+}
+
+func (s *mapSorter[K, V]) String() string {
+	return fmt.Sprintf("map[%s]", s.Join(" ", func(k K, v V) string {
+		return fmt.Sprintf("%v:%v", k, v)
+	}))
+}
+
+func keys[K comparable, V any](m map[K]V) []K {
+	keys := make([]K, 0, len(m))
+	for k := range m {
+		keys = append(keys, k)
+	}
+
+	return keys
+}