started by copying from https://sourcegraph.com/github.com/timtadh/data-structures@master/-/tree/tree/bptree

weed/util/bptree/bpmap.go

@@ -0,0 +1,77 @@
+package bptree
+
+import (
+	"fmt"
+)
+
+/* A BpMap is a B+Tree with support for duplicate keys disabled. This makes it
+ * behave like a regular Map rather than a MultiMap.
+ */
+type BpMap BpTree
+
+func NewBpMap(node_size int) *BpMap {
+	return &BpMap{
+		root: NewLeaf(node_size, true),
+		size: 0,
+	}
+}
+
+func (self *BpMap) Size() int {
+	return (*BpTree)(self).Size()
+}
+
+func (self *BpMap) Has(key Hashable) bool {
+	return (*BpTree)(self).Has(key)
+}
+
+func (self *BpMap) Put(key Hashable, value interface{}) (err error) {
+	had := self.Has(key)
+	new_root, err := self.root.put(key, value)
+	if err != nil {
+		return err
+	}
+	self.root = new_root
+	if !had {
+		self.size += 1
+	}
+	return nil
+}
+
+func (self *BpMap) Get(key Hashable) (value interface{}, err error) {
+	j, l := self.root.get_start(key)
+	if l.keys[j].Equals(key) {
+		return l.values[j], nil
+	}
+	return nil, fmt.Errorf("key not found: %s", key)
+}
+
+func (self *BpMap) Remove(key Hashable) (value interface{}, err error) {
+	value, err = self.Get(key)
+	if err != nil {
+		return nil, err
+	}
+	ns := self.root.NodeSize()
+	new_root, err := self.root.remove(key, func(value interface{}) bool { return true })
+	if err != nil {
+		return nil, err
+	}
+	if new_root == nil {
+		self.root = NewLeaf(ns, true)
+	} else {
+		self.root = new_root
+	}
+	self.size--
+	return value, nil
+}
+
+func (self *BpMap) Keys() (ki KIterator) {
+	return (*BpTree)(self).Keys()
+}
+
+func (self *BpMap) Values() (vi Iterator) {
+	return (*BpTree)(self).Values()
+}
+
+func (self *BpMap) Iterate() (kvi KVIterator) {
+	return (*BpTree)(self).Iterate()
+}