go-mixed/collections/generics/sort_map.go

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
}