add splaytree feature to tree

README.md

@@ -29,6 +29,7 @@ Implementation of various data structures and algorithms in Go.
     - [AVLTree](#avltree)
     - [BTree](#btree)
     - [BinaryHeap](#binaryheap)
+	- [SplayTree](#spalytree)
 - [Functions](#functions)
     - [Comparator](#comparator)
     - [Iterator](#iterator)
@@ -846,6 +847,100 @@ func main() {
 }
 ```
 
+#### SplayTree
+
+<b>A polymorphic splay tree implementation in Go(lang)</b>
+
+splay is defined around the <code>SplayTree</code> interface:  
+
+    type SplayTree interface {
+        SetRoot(n *Node)
+        GetRoot() *Node
+        Ord(key1, key2 interface{}) int
+    }
+
+Your <code>SplayTree</code> implementation must contain a <code>root *Node</code> where
+
+    type Node struct {
+        key    interface{}
+        value  interface{}
+        parent *Node
+        left   *Node
+        right  *Node
+    }
+
+<code>SetRoot</code> and <code>GetRoot</code> are the getter and setter for root, and <code>Ord</code> is a method for
+comparing keys must return 0 if key1 < key2, 1 if key1 == key2, or 2 if
+key1 > key2 (for whatever definitions of <, ==, and > apply to your key type).
+
+Here's an example assuming we have the splay directory in the same directory as
+our project (a very similar example is given in <i>example.go</i>):
+
+    package main
+
+    import (
+        "./splay"
+        "fmt"
+        "unicode/utf8"
+    )
+
+    type Tree struct {
+        root *splay.Node
+    }
+
+    func (T *Tree) SetRoot(n *splay.Node) {
+        T.root = n
+    }
+
+    func (T *Tree) GetRoot() *splay.Node {
+        return T.root
+    }
+
+    // This Splay Tree will use strings as keys and strings as values
+    // It returns 0, 1, or 2 based on the lexical comparison of the key strings
+    func (T *Tree) Ord(key1, key2 interface{}) int {
+        for i := 0; i < len(key1.(string)); {
+            c1, j := utf8.DecodeRuneInString(key1.(string)[i:])
+            c2, _ := utf8.DecodeRuneInString(key2.(string)[i:])
+            if c1 < c2 {
+                return 0
+            } else if c1 > c2 {
+                return 2
+            }
+            i += j
+        }
+        if len(key1.(string)) < len(key2.(string)) {
+            return 0
+        } else if len(key1.(string)) == len(key2.(string)) {
+            return 1
+        } else {
+            return 2
+        }
+    }
+
+    func main() {
+        T := new(Tree)
+
+        splay.Insert(T, "hello", "world")
+        splay.Insert(T, "foo", "bar")
+        splay.Insert(T, "what's your name", "buddy?")
+        splay.Insert(T, "Goku says", "Kamehameha")
+        err := splay.Insert(T, "foo", "foo")
+        fmt.Println(err)
+
+        v := splay.Find(T, "Goku says")
+        fmt.Println(v)
+
+        splay.Print(T)
+
+        splay.Delete(T, "foo")
+        err = splay.Delete(T, "foo")
+        fmt.Println(err)
+
+        splay.Print(T)
+    }
+
+
 ## Functions
 
 Various helper functions used throughout the library.