mirror of
https://github.com/superseriousbusiness/gotosocial.git
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374 lines
11 KiB
Go
374 lines
11 KiB
Go
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// Package orderedmap implements an ordered map, i.e. a map that also keeps track of
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// the order in which keys were inserted.
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//
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// All operations are constant-time.
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//
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// Github repo: https://github.com/wk8/go-ordered-map
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package orderedmap
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import (
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"fmt"
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"iter"
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list "github.com/bahlo/generic-list-go"
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)
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type Pair[K comparable, V any] struct {
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Key K
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Value V
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element *list.Element[*Pair[K, V]]
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}
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type OrderedMap[K comparable, V any] struct {
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pairs map[K]*Pair[K, V]
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list *list.List[*Pair[K, V]]
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}
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type initConfig[K comparable, V any] struct {
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capacity int
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initialData []Pair[K, V]
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}
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type InitOption[K comparable, V any] func(config *initConfig[K, V])
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// WithCapacity allows giving a capacity hint for the map, akin to the standard make(map[K]V, capacity).
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func WithCapacity[K comparable, V any](capacity int) InitOption[K, V] {
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return func(c *initConfig[K, V]) {
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c.capacity = capacity
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}
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}
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// WithInitialData allows passing in initial data for the map.
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func WithInitialData[K comparable, V any](initialData ...Pair[K, V]) InitOption[K, V] {
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return func(c *initConfig[K, V]) {
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c.initialData = initialData
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if c.capacity < len(initialData) {
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c.capacity = len(initialData)
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}
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}
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}
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// New creates a new OrderedMap.
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// options can either be one or several InitOption[K, V], or a single integer,
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// which is then interpreted as a capacity hint, à la make(map[K]V, capacity).
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func New[K comparable, V any](options ...any) *OrderedMap[K, V] {
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orderedMap := &OrderedMap[K, V]{}
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var config initConfig[K, V]
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for _, untypedOption := range options {
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switch option := untypedOption.(type) {
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case int:
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if len(options) != 1 {
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invalidOption()
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}
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config.capacity = option
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case InitOption[K, V]:
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option(&config)
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default:
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invalidOption()
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}
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}
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orderedMap.initialize(config.capacity)
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orderedMap.AddPairs(config.initialData...)
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return orderedMap
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}
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const invalidOptionMessage = `when using orderedmap.New[K,V]() with options, either provide one or several InitOption[K, V]; or a single integer which is then interpreted as a capacity hint, à la make(map[K]V, capacity).` //nolint:lll
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func invalidOption() { panic(invalidOptionMessage) }
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func (om *OrderedMap[K, V]) initialize(capacity int) {
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om.pairs = make(map[K]*Pair[K, V], capacity)
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om.list = list.New[*Pair[K, V]]()
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}
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// Get looks for the given key, and returns the value associated with it,
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// or V's nil value if not found. The boolean it returns says whether the key is present in the map.
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func (om *OrderedMap[K, V]) Get(key K) (val V, present bool) {
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if pair, present := om.pairs[key]; present {
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return pair.Value, true
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}
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return
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}
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// Load is an alias for Get, mostly to present an API similar to `sync.Map`'s.
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func (om *OrderedMap[K, V]) Load(key K) (V, bool) {
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return om.Get(key)
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}
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// Value returns the value associated with the given key or the zero value.
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func (om *OrderedMap[K, V]) Value(key K) (val V) {
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if pair, present := om.pairs[key]; present {
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val = pair.Value
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}
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return
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}
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// GetPair looks for the given key, and returns the pair associated with it,
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// or nil if not found. The Pair struct can then be used to iterate over the ordered map
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// from that point, either forward or backward.
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func (om *OrderedMap[K, V]) GetPair(key K) *Pair[K, V] {
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return om.pairs[key]
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}
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// Set sets the key-value pair, and returns what `Get` would have returned
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// on that key prior to the call to `Set`.
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func (om *OrderedMap[K, V]) Set(key K, value V) (val V, present bool) {
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if pair, present := om.pairs[key]; present {
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oldValue := pair.Value
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pair.Value = value
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return oldValue, true
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}
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pair := &Pair[K, V]{
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Key: key,
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Value: value,
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}
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pair.element = om.list.PushBack(pair)
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om.pairs[key] = pair
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return
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}
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// AddPairs allows setting multiple pairs at a time. It's equivalent to calling
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// Set on each pair sequentially.
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func (om *OrderedMap[K, V]) AddPairs(pairs ...Pair[K, V]) {
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for _, pair := range pairs {
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om.Set(pair.Key, pair.Value)
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}
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}
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// Store is an alias for Set, mostly to present an API similar to `sync.Map`'s.
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func (om *OrderedMap[K, V]) Store(key K, value V) (V, bool) {
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return om.Set(key, value)
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}
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// Delete removes the key-value pair, and returns what `Get` would have returned
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// on that key prior to the call to `Delete`.
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func (om *OrderedMap[K, V]) Delete(key K) (val V, present bool) {
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if pair, present := om.pairs[key]; present {
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om.list.Remove(pair.element)
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delete(om.pairs, key)
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return pair.Value, true
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}
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return
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}
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// Len returns the length of the ordered map.
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func (om *OrderedMap[K, V]) Len() int {
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if om == nil || om.pairs == nil {
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return 0
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}
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return len(om.pairs)
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}
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// Oldest returns a pointer to the oldest pair. It's meant to be used to iterate on the ordered map's
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// pairs from the oldest to the newest, e.g.:
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// for pair := orderedMap.Oldest(); pair != nil; pair = pair.Next() { fmt.Printf("%v => %v\n", pair.Key, pair.Value) }
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func (om *OrderedMap[K, V]) Oldest() *Pair[K, V] {
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if om == nil || om.list == nil {
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return nil
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}
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return listElementToPair(om.list.Front())
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}
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// Newest returns a pointer to the newest pair. It's meant to be used to iterate on the ordered map's
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// pairs from the newest to the oldest, e.g.:
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// for pair := orderedMap.Newest(); pair != nil; pair = pair.Prev() { fmt.Printf("%v => %v\n", pair.Key, pair.Value) }
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func (om *OrderedMap[K, V]) Newest() *Pair[K, V] {
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if om == nil || om.list == nil {
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return nil
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}
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return listElementToPair(om.list.Back())
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}
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// Next returns a pointer to the next pair.
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func (p *Pair[K, V]) Next() *Pair[K, V] {
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return listElementToPair(p.element.Next())
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}
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// Prev returns a pointer to the previous pair.
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func (p *Pair[K, V]) Prev() *Pair[K, V] {
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return listElementToPair(p.element.Prev())
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}
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func listElementToPair[K comparable, V any](element *list.Element[*Pair[K, V]]) *Pair[K, V] {
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if element == nil {
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return nil
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}
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return element.Value
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}
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// KeyNotFoundError may be returned by functions in this package when they're called with keys that are not present
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// in the map.
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type KeyNotFoundError[K comparable] struct {
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MissingKey K
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}
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func (e *KeyNotFoundError[K]) Error() string {
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return fmt.Sprintf("missing key: %v", e.MissingKey)
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}
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// MoveAfter moves the value associated with key to its new position after the one associated with markKey.
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// Returns an error iff key or markKey are not present in the map. If an error is returned,
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// it will be a KeyNotFoundError.
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func (om *OrderedMap[K, V]) MoveAfter(key, markKey K) error {
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elements, err := om.getElements(key, markKey)
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if err != nil {
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return err
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}
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om.list.MoveAfter(elements[0], elements[1])
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return nil
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}
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// MoveBefore moves the value associated with key to its new position before the one associated with markKey.
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// Returns an error iff key or markKey are not present in the map. If an error is returned,
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// it will be a KeyNotFoundError.
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func (om *OrderedMap[K, V]) MoveBefore(key, markKey K) error {
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elements, err := om.getElements(key, markKey)
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if err != nil {
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return err
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}
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om.list.MoveBefore(elements[0], elements[1])
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return nil
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}
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func (om *OrderedMap[K, V]) getElements(keys ...K) ([]*list.Element[*Pair[K, V]], error) {
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elements := make([]*list.Element[*Pair[K, V]], len(keys))
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for i, k := range keys {
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pair, present := om.pairs[k]
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if !present {
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return nil, &KeyNotFoundError[K]{k}
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}
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elements[i] = pair.element
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}
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return elements, nil
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}
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// MoveToBack moves the value associated with key to the back of the ordered map,
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// i.e. makes it the newest pair in the map.
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// Returns an error iff key is not present in the map. If an error is returned,
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// it will be a KeyNotFoundError.
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func (om *OrderedMap[K, V]) MoveToBack(key K) error {
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_, err := om.GetAndMoveToBack(key)
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return err
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}
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// MoveToFront moves the value associated with key to the front of the ordered map,
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// i.e. makes it the oldest pair in the map.
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// Returns an error iff key is not present in the map. If an error is returned,
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// it will be a KeyNotFoundError.
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func (om *OrderedMap[K, V]) MoveToFront(key K) error {
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_, err := om.GetAndMoveToFront(key)
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return err
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}
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// GetAndMoveToBack combines Get and MoveToBack in the same call. If an error is returned,
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// it will be a KeyNotFoundError.
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func (om *OrderedMap[K, V]) GetAndMoveToBack(key K) (val V, err error) {
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if pair, present := om.pairs[key]; present {
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val = pair.Value
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om.list.MoveToBack(pair.element)
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} else {
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err = &KeyNotFoundError[K]{key}
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}
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return
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}
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// GetAndMoveToFront combines Get and MoveToFront in the same call. If an error is returned,
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// it will be a KeyNotFoundError.
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func (om *OrderedMap[K, V]) GetAndMoveToFront(key K) (val V, err error) {
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if pair, present := om.pairs[key]; present {
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val = pair.Value
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om.list.MoveToFront(pair.element)
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} else {
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err = &KeyNotFoundError[K]{key}
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}
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return
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}
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// FromOldest returns an iterator over all the key-value pairs in the map, starting from the oldest pair.
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func (om *OrderedMap[K, V]) FromOldest() iter.Seq2[K, V] {
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return func(yield func(K, V) bool) {
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for pair := om.Oldest(); pair != nil; pair = pair.Next() {
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if !yield(pair.Key, pair.Value) {
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return
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}
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}
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}
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}
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// FromNewest returns an iterator over all the key-value pairs in the map, starting from the newest pair.
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func (om *OrderedMap[K, V]) FromNewest() iter.Seq2[K, V] {
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return func(yield func(K, V) bool) {
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for pair := om.Newest(); pair != nil; pair = pair.Prev() {
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if !yield(pair.Key, pair.Value) {
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return
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}
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}
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}
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}
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// KeysFromOldest returns an iterator over all the keys in the map, starting from the oldest pair.
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func (om *OrderedMap[K, V]) KeysFromOldest() iter.Seq[K] {
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return func(yield func(K) bool) {
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for pair := om.Oldest(); pair != nil; pair = pair.Next() {
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if !yield(pair.Key) {
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return
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}
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}
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}
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}
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// KeysFromNewest returns an iterator over all the keys in the map, starting from the newest pair.
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func (om *OrderedMap[K, V]) KeysFromNewest() iter.Seq[K] {
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return func(yield func(K) bool) {
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for pair := om.Newest(); pair != nil; pair = pair.Prev() {
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if !yield(pair.Key) {
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return
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}
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}
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}
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}
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// ValuesFromOldest returns an iterator over all the values in the map, starting from the oldest pair.
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func (om *OrderedMap[K, V]) ValuesFromOldest() iter.Seq[V] {
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return func(yield func(V) bool) {
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for pair := om.Oldest(); pair != nil; pair = pair.Next() {
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if !yield(pair.Value) {
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return
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}
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}
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}
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}
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// ValuesFromNewest returns an iterator over all the values in the map, starting from the newest pair.
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func (om *OrderedMap[K, V]) ValuesFromNewest() iter.Seq[V] {
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return func(yield func(V) bool) {
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for pair := om.Newest(); pair != nil; pair = pair.Prev() {
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if !yield(pair.Value) {
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return
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}
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}
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}
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}
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// From creates a new OrderedMap from an iterator over key-value pairs.
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func From[K comparable, V any](i iter.Seq2[K, V]) *OrderedMap[K, V] {
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oMap := New[K, V]()
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for k, v := range i {
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oMap.Set(k, v)
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}
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return oMap
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}
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