mirror of
https://github.com/golang/go
synced 2024-09-18 15:32:18 +00:00
96aecdcb36
Added test example orderedmap.go (binary search tree) that requires this fix (calling function compare in _Map). Also added new tests slices.go and metrics.go that just work. Change-Id: Ifa5f42ab6eee9aa54c40f0eca19e00a87f8f608a Reviewed-on: https://go-review.googlesource.com/c/go/+/301829 Trust: Dan Scales <danscales@google.com> Trust: Robert Griesemer <gri@golang.org> Reviewed-by: Robert Griesemer <gri@golang.org>
287 lines
7.1 KiB
Go
287 lines
7.1 KiB
Go
// run -gcflags=-G=3
|
|
|
|
// Copyright 2021 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
// Package orderedmap provides an ordered map, implemented as a binary tree.
|
|
package main
|
|
|
|
import (
|
|
"bytes"
|
|
"context"
|
|
"fmt"
|
|
"runtime"
|
|
)
|
|
|
|
type Ordered interface {
|
|
type int, int8, int16, int32, int64,
|
|
uint, uint8, uint16, uint32, uint64, uintptr,
|
|
float32, float64,
|
|
string
|
|
}
|
|
|
|
// _Map is an ordered map.
|
|
type _Map[K, V any] struct {
|
|
root *node[K, V]
|
|
compare func(K, K) int
|
|
}
|
|
|
|
// node is the type of a node in the binary tree.
|
|
type node[K, V any] struct {
|
|
key K
|
|
val V
|
|
left, right *node[K, V]
|
|
}
|
|
|
|
// _New returns a new map. It takes a comparison function that compares two
|
|
// keys and returns < 0 if the first is less, == 0 if they are equal,
|
|
// > 0 if the first is greater.
|
|
func _New[K, V any](compare func(K, K) int) *_Map[K, V] {
|
|
return &_Map[K, V]{compare: compare}
|
|
}
|
|
|
|
// _NewOrdered returns a new map whose key is an ordered type.
|
|
// This is like _New, but does not require providing a compare function.
|
|
// The map compare function uses the obvious key ordering.
|
|
func _NewOrdered[K Ordered, V any]() *_Map[K, V] {
|
|
return _New[K, V](func(k1, k2 K) int {
|
|
switch {
|
|
case k1 < k2:
|
|
return -1
|
|
case k1 == k2:
|
|
return 0
|
|
default:
|
|
return 1
|
|
}
|
|
})
|
|
}
|
|
|
|
// find looks up key in the map, returning either a pointer to the slot of the
|
|
// node holding key, or a pointer to the slot where should a node would go.
|
|
func (m *_Map[K, V]) find(key K) **node[K, V] {
|
|
pn := &m.root
|
|
for *pn != nil {
|
|
switch cmp := m.compare(key, (*pn).key); {
|
|
case cmp < 0:
|
|
pn = &(*pn).left
|
|
case cmp > 0:
|
|
pn = &(*pn).right
|
|
default:
|
|
return pn
|
|
}
|
|
}
|
|
return pn
|
|
}
|
|
|
|
// Insert inserts a new key/value into the map.
|
|
// If the key is already present, the value is replaced.
|
|
// Reports whether this is a new key.
|
|
func (m *_Map[K, V]) Insert(key K, val V) bool {
|
|
pn := m.find(key)
|
|
if *pn != nil {
|
|
(*pn).val = val
|
|
return false
|
|
}
|
|
*pn = &node[K, V]{key: key, val: val}
|
|
return true
|
|
}
|
|
|
|
// Find returns the value associated with a key, or the zero value
|
|
// if not present. The found result reports whether the key was found.
|
|
func (m *_Map[K, V]) Find(key K) (V, bool) {
|
|
pn := m.find(key)
|
|
if *pn == nil {
|
|
var zero V
|
|
return zero, false
|
|
}
|
|
return (*pn).val, true
|
|
}
|
|
|
|
// keyValue is a pair of key and value used while iterating.
|
|
type keyValue[K, V any] struct {
|
|
key K
|
|
val V
|
|
}
|
|
|
|
// iterate returns an iterator that traverses the map.
|
|
func (m *_Map[K, V]) Iterate() *_Iterator[K, V] {
|
|
sender, receiver := _Ranger[keyValue[K, V]]()
|
|
var f func(*node[K, V]) bool
|
|
f = func(n *node[K, V]) bool {
|
|
if n == nil {
|
|
return true
|
|
}
|
|
// Stop the traversal if Send fails, which means that
|
|
// nothing is listening to the receiver.
|
|
return f(n.left) &&
|
|
sender.Send(context.Background(), keyValue[K, V]{n.key, n.val}) &&
|
|
f(n.right)
|
|
}
|
|
go func() {
|
|
f(m.root)
|
|
sender.Close()
|
|
}()
|
|
return &_Iterator[K, V]{receiver}
|
|
}
|
|
|
|
// _Iterator is used to iterate over the map.
|
|
type _Iterator[K, V any] struct {
|
|
r *_Receiver[keyValue[K, V]]
|
|
}
|
|
|
|
// Next returns the next key and value pair, and a boolean that reports
|
|
// whether they are valid. If not valid, we have reached the end of the map.
|
|
func (it *_Iterator[K, V]) Next() (K, V, bool) {
|
|
keyval, ok := it.r.Next(context.Background())
|
|
if !ok {
|
|
var zerok K
|
|
var zerov V
|
|
return zerok, zerov, false
|
|
}
|
|
return keyval.key, keyval.val, true
|
|
}
|
|
|
|
func TestMap() {
|
|
m := _New[[]byte, int](bytes.Compare)
|
|
|
|
if _, found := m.Find([]byte("a")); found {
|
|
panic(fmt.Sprintf("unexpectedly found %q in empty map", []byte("a")))
|
|
}
|
|
if !m.Insert([]byte("a"), 'a') {
|
|
panic(fmt.Sprintf("key %q unexpectedly already present", []byte("a")))
|
|
}
|
|
if !m.Insert([]byte("c"), 'c') {
|
|
panic(fmt.Sprintf("key %q unexpectedly already present", []byte("c")))
|
|
}
|
|
if !m.Insert([]byte("b"), 'b') {
|
|
panic(fmt.Sprintf("key %q unexpectedly already present", []byte("b")))
|
|
}
|
|
if m.Insert([]byte("c"), 'x') {
|
|
panic(fmt.Sprintf("key %q unexpectedly not present", []byte("c")))
|
|
}
|
|
|
|
if v, found := m.Find([]byte("a")); !found {
|
|
panic(fmt.Sprintf("did not find %q", []byte("a")))
|
|
} else if v != 'a' {
|
|
panic(fmt.Sprintf("key %q returned wrong value %c, expected %c", []byte("a"), v, 'a'))
|
|
}
|
|
if v, found := m.Find([]byte("c")); !found {
|
|
panic(fmt.Sprintf("did not find %q", []byte("c")))
|
|
} else if v != 'x' {
|
|
panic(fmt.Sprintf("key %q returned wrong value %c, expected %c", []byte("c"), v, 'x'))
|
|
}
|
|
|
|
if _, found := m.Find([]byte("d")); found {
|
|
panic(fmt.Sprintf("unexpectedly found %q", []byte("d")))
|
|
}
|
|
|
|
gather := func(it *_Iterator[[]byte, int]) []int {
|
|
var r []int
|
|
for {
|
|
_, v, ok := it.Next()
|
|
if !ok {
|
|
return r
|
|
}
|
|
r = append(r, v)
|
|
}
|
|
}
|
|
got := gather(m.Iterate())
|
|
want := []int{'a', 'b', 'x'}
|
|
if !_SliceEqual(got, want) {
|
|
panic(fmt.Sprintf("Iterate returned %v, want %v", got, want))
|
|
}
|
|
}
|
|
|
|
func main() {
|
|
TestMap()
|
|
}
|
|
|
|
// _Equal reports whether two slices are equal: the same length and all
|
|
// elements equal. All floating point NaNs are considered equal.
|
|
func _SliceEqual[Elem comparable](s1, s2 []Elem) bool {
|
|
if len(s1) != len(s2) {
|
|
return false
|
|
}
|
|
for i, v1 := range s1 {
|
|
v2 := s2[i]
|
|
if v1 != v2 {
|
|
isNaN := func(f Elem) bool { return f != f }
|
|
if !isNaN(v1) || !isNaN(v2) {
|
|
return false
|
|
}
|
|
}
|
|
}
|
|
return true
|
|
}
|
|
|
|
// Ranger returns a Sender and a Receiver. The Receiver provides a
|
|
// Next method to retrieve values. The Sender provides a Send method
|
|
// to send values and a Close method to stop sending values. The Next
|
|
// method indicates when the Sender has been closed, and the Send
|
|
// method indicates when the Receiver has been freed.
|
|
//
|
|
// This is a convenient way to exit a goroutine sending values when
|
|
// the receiver stops reading them.
|
|
func _Ranger[Elem any]() (*_Sender[Elem], *_Receiver[Elem]) {
|
|
c := make(chan Elem)
|
|
d := make(chan struct{})
|
|
s := &_Sender[Elem]{
|
|
values: c,
|
|
done: d,
|
|
}
|
|
r := &_Receiver[Elem] {
|
|
values: c,
|
|
done: d,
|
|
}
|
|
runtime.SetFinalizer(r, (*_Receiver[Elem]).finalize)
|
|
return s, r
|
|
}
|
|
|
|
// A _Sender is used to send values to a Receiver.
|
|
type _Sender[Elem any] struct {
|
|
values chan<- Elem
|
|
done <-chan struct{}
|
|
}
|
|
|
|
// Send sends a value to the receiver. It reports whether the value was sent.
|
|
// The value will not be sent if the context is closed or the receiver
|
|
// is freed.
|
|
func (s *_Sender[Elem]) Send(ctx context.Context, v Elem) bool {
|
|
select {
|
|
case <-ctx.Done():
|
|
return false
|
|
case s.values <- v:
|
|
return true
|
|
case <-s.done:
|
|
return false
|
|
}
|
|
}
|
|
|
|
// Close tells the receiver that no more values will arrive.
|
|
// After Close is called, the _Sender may no longer be used.
|
|
func (s *_Sender[Elem]) Close() {
|
|
close(s.values)
|
|
}
|
|
|
|
// A _Receiver receives values from a _Sender.
|
|
type _Receiver[Elem any] struct {
|
|
values <-chan Elem
|
|
done chan<- struct{}
|
|
}
|
|
|
|
// Next returns the next value from the channel. The bool result indicates
|
|
// whether the value is valid.
|
|
func (r *_Receiver[Elem]) Next(ctx context.Context) (v Elem, ok bool) {
|
|
select {
|
|
case <-ctx.Done():
|
|
case v, ok = <-r.values:
|
|
}
|
|
return v, ok
|
|
}
|
|
|
|
// finalize is a finalizer for the receiver.
|
|
func (r *_Receiver[Elem]) finalize() {
|
|
close(r.done)
|
|
}
|