From 2de042b741957f1e06fdfb6e3cf9c8219ce4c655 Mon Sep 17 00:00:00 2001
From: Paul Buetow <paul@buetow.org>
Date: Sun, 4 Oct 2020 11:18:04 +0100
Subject: Add elementary set ds

---
 set/elementary.go | 76 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 set/tree.go       |  7 +++++
 tree/tree.go      |  7 -----
 3 files changed, 83 insertions(+), 7 deletions(-)
 create mode 100644 set/elementary.go
 create mode 100644 set/tree.go
 delete mode 100644 tree/tree.go

diff --git a/set/elementary.go b/set/elementary.go
new file mode 100644
index 0000000..63a3fd8
--- /dev/null
+++ b/set/elementary.go
@@ -0,0 +1,76 @@
+package set
+
+type ElementaryElem struct {
+	key  int
+	val  interface{}
+	next *ElementaryElem
+}
+
+type Elementary struct {
+	root *ElementaryElem
+}
+
+func NewElementary() *Elementary {
+	return &Elementary{}
+}
+
+func (s Elementary) Empty() bool {
+	return s.root == nil
+}
+
+func (s Elementary) Set(key int, val interface{}) {
+	if s.Empty() {
+		s.root = &ElementaryElem{key, val, nil}
+		return
+	}
+
+	elem := s.root
+
+	for {
+		if elem.key == key {
+			elem.val = val
+			return
+		}
+		if elem.next == nil {
+			elem.next = &ElementaryElem{key, val, nil}
+			return
+		}
+		elem = elem.next
+	}
+}
+
+func (s Elementary) Get(key int) interface{} {
+	elem := s.root
+
+	for elem != nil {
+		if elem.key == key {
+			return elem.val
+		}
+		elem = elem.next
+	}
+
+	return nil
+}
+
+func (s Elementary) Del(key int) interface{} {
+	if s.Empty() {
+		return nil
+	}
+
+	if s.root.key == key {
+		defer func() { s.root = nil }()
+		return s.root.val
+	}
+
+	elem := s.root
+
+	for elem.next != nil {
+		if elem.next.key == key {
+			defer func() { elem.next = elem.next.next }()
+			return elem.next.val
+		}
+		elem = elem.next
+	}
+
+	return nil
+}
diff --git a/set/tree.go b/set/tree.go
new file mode 100644
index 0000000..2f34cc8
--- /dev/null
+++ b/set/tree.go
@@ -0,0 +1,7 @@
+package tree
+
+type Tree interface {
+	Empty() bool
+	Insert(key int, val interface{})
+	Search(key int) interface{}
+}
diff --git a/tree/tree.go b/tree/tree.go
deleted file mode 100644
index 2f34cc8..0000000
--- a/tree/tree.go
+++ /dev/null
@@ -1,7 +0,0 @@
-package tree
-
-type Tree interface {
-	Empty() bool
-	Insert(key int, val interface{})
-	Search(key int) interface{}
-}
-- 
cgit v1.2.3