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// Copyright 2024 The Hugo Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package maps
import (
"slices"
"github.com/gohugoio/hugo/common/hashing"
)
// Ordered is a map that can be iterated in the order of insertion.
// Note that insertion order is not affected if a key is re-inserted into the map.
// In a nil map, all operations are no-ops.
// This is not thread safe.
type Ordered[K comparable, T any] struct {
// The keys in the order they were added.
keys []K
// The values.
values map[K]T
}
// NewOrdered creates a new Ordered map.
func NewOrdered[K comparable, T any]() *Ordered[K, T] {
return &Ordered[K, T]{values: make(map[K]T)}
}
// Set sets the value for the given key.
// Note that insertion order is not affected if a key is re-inserted into the map.
func (m *Ordered[K, T]) Set(key K, value T) {
if m == nil {
return
}
// Check if key already exists.
if _, found := m.values[key]; !found {
m.keys = append(m.keys, key)
}
m.values[key] = value
}
// Get gets the value for the given key.
func (m *Ordered[K, T]) Get(key K) (T, bool) {
if m == nil {
var v T
return v, false
}
value, found := m.values[key]
return value, found
}
// Has returns whether the given key exists in the map.
func (m *Ordered[K, T]) Has(key K) bool {
if m == nil {
return false
}
_, found := m.values[key]
return found
}
// Delete deletes the value for the given key.
func (m *Ordered[K, T]) Delete(key K) {
if m == nil {
return
}
delete(m.values, key)
for i, k := range m.keys {
if k == key {
m.keys = slices.Delete(m.keys, i, i+1)
break
}
}
}
// Clone creates a shallow copy of the map.
func (m *Ordered[K, T]) Clone() *Ordered[K, T] {
if m == nil {
return nil
}
clone := NewOrdered[K, T]()
for _, k := range m.keys {
clone.Set(k, m.values[k])
}
return clone
}
// Keys returns the keys in the order they were added.
func (m *Ordered[K, T]) Keys() []K {
if m == nil {
return nil
}
return m.keys
}
// Values returns the values in the order they were added.
func (m *Ordered[K, T]) Values() []T {
if m == nil {
return nil
}
var values []T
for _, k := range m.keys {
values = append(values, m.values[k])
}
return values
}
// Len returns the number of items in the map.
func (m *Ordered[K, T]) Len() int {
if m == nil {
return 0
}
return len(m.keys)
}
// Range calls f sequentially for each key and value present in the map.
// If f returns false, range stops the iteration.
// TODO(bep) replace with iter.Seq2 when we bump go Go 1.24.
func (m *Ordered[K, T]) Range(f func(key K, value T) bool) {
if m == nil {
return
}
for _, k := range m.keys {
if !f(k, m.values[k]) {
return
}
}
}
// Hash calculates a hash from the values.
func (m *Ordered[K, T]) Hash() (uint64, error) {
if m == nil {
return 0, nil
}
return hashing.Hash(m.values)
}
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