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e36aeda | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 | // Copyright 2019 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.
// This file is like map.go, but instead of importing chans, it contains
// the necessary functionality at the end of the file.
// Package orderedmap provides an ordered map, implemented as a binary tree.
package orderedmap
// 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.
func New[K, V any](compare func(K, K) int) *Map[K, V] {
return &Map[K, V]{compare: compare}
}
// find looks up key in the map, and returns either a pointer
// to the node holding key, or a pointer to the location where
// such 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.
// Returns true if this is a new key, false if already present.
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 zero 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 // see the discussion of zero values, above
return zero, false
}
return (*pn).val, true
}
// keyValue is a pair of key and value used when iterating.
type keyValue[K, V any] struct {
key K
val V
}
// InOrder returns an iterator that does an in-order traversal of the map.
func (m *Map[K, V]) InOrder() *Iterator[K, V] {
sender, receiver := chans_Ranger[keyValue[K, V]]()
var f func(*node[K, V]) bool
f = func(n *node[K, V]) bool {
if n == nil {
return true
}
// Stop sending values if sender.Send returns false,
// meaning that nothing is listening at the receiver end.
return f(n.left) &&
sender.Send(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 *chans_Receiver[keyValue[K, V]]
}
// Next returns the next key and value pair, and a boolean indicating
// whether they are valid or whether we have reached the end.
func (it *Iterator[K, V]) Next() (K, V, bool) {
keyval, ok := it.r.Next()
if !ok {
var zerok K
var zerov V
return zerok, zerov, false
}
return keyval.key, keyval.val, true
}
// chans
func chans_Ranger[T any]() (*chans_Sender[T], *chans_Receiver[T])
// A sender is used to send values to a Receiver.
type chans_Sender[T any] struct {
values chan<- T
done <-chan bool
}
func (s *chans_Sender[T]) Send(v T) bool {
select {
case s.values <- v:
return true
case <-s.done:
return false
}
}
func (s *chans_Sender[T]) Close() {
close(s.values)
}
type chans_Receiver[T any] struct {
values <-chan T
done chan<- bool
}
func (r *chans_Receiver[T]) Next() (T, bool) {
v, ok := <-r.values
return v, ok
}
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