containers: Add a 'SortedMap' type

1 files changed, 76 insertions, 0 deletions

diff --git a/lib/containers/sortedmap.go b/lib/containers/sortedmap.go
new file mode 100644
index 0000000..b759fa3
--- /dev/null
+++ b/lib/containers/sortedmap.go
@@ -0,0 +1,76 @@
+// Copyright (C) 2022  Luke Shumaker <lukeshu@lukeshu.com>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package containers
+
+import (
+	"errors"
+)
+
+type orderedKV[K Ordered[K], V any] struct {
+	K K
+	V V
+}
+
+type SortedMap[K Ordered[K], V any] struct {
+	inner RBTree[K, orderedKV[K, V]]
+}
+
+func (m *SortedMap[K, V]) init() {
+	if m.inner.KeyFn == nil {
+		m.inner.KeyFn = m.keyFn
+	}
+}
+
+func (m *SortedMap[K, V]) keyFn(kv orderedKV[K, V]) K {
+	return kv.K
+}
+
+func (m *SortedMap[K, V]) Delete(key K) {
+	m.init()
+	m.inner.Delete(key)
+}
+
+func (m *SortedMap[K, V]) Load(key K) (value V, ok bool) {
+	m.init()
+	node := m.inner.Lookup(key)
+	if node == nil {
+		var zero V
+		return zero, false
+	}
+	return node.Value.V, true
+}
+
+var errStop = errors.New("stop")
+
+func (m *SortedMap[K, V]) Range(f func(key K, value V) bool) {
+	m.init()
+	_ = m.inner.Walk(func(node *RBNode[orderedKV[K, V]]) error {
+		if f(node.Value.K, node.Value.V) {
+			return nil
+		} else {
+			return errStop
+		}
+	})
+}
+
+func (m *SortedMap[K, V]) Subrange(rangeFn func(K, V) int, handleFn func(K, V) bool) {
+	m.init()
+	kvs := m.inner.SearchRange(func(kv orderedKV[K, V]) int {
+		return rangeFn(kv.K, kv.V)
+	})
+	for _, kv := range kvs {
+		if !handleFn(kv.K, kv.V) {
+			break
+		}
+	}
+}
+
+func (m *SortedMap[K, V]) Store(key K, value V) {
+	m.init()
+	m.inner.Insert(orderedKV[K, V]{
+		K: key,
+		V: value,
+	})
+}