Add AVLTree to docs

Author: eulerkochy

README.md

@@ -31,6 +31,7 @@ This package implements a variety of data structures, including
 -   SparseIntSet
 -   DiBitVector (in which each element can store two bits)
 -   Red Black Tree
+-	AVL Tree
 
 Resources
 ---------

docs/make.jl

@@ -26,6 +26,7 @@ makedocs(
         "sorted_containers.md",
         "dibit_vector.md",
         "red_black_tree.md",
+        "avl_tree.md",
     ],
     modules = [DataStructures],
     format = Documenter.HTML()

docs/src/avl_tree.md

@@ -0,0 +1,34 @@
+```@meta
+DocTestSetup = :(using DataStructures)
+```
+
+# AVL Tree
+
+The `AVLTree` type is an implementation of AVL Tree in Julia. It is a self-balancing binary search tree where balancing occurs based on the difference of height of the left subtree and the right subtree. Operations such as search, insert and delete can be done in `O(log n)` complexity, where `n` is the number of nodes in the `AVLTree`.
+
+Examples:
+
+```jldoctest
+julia> tree = AVLTree{Int}();
+
+julia> for k in 1:2:20
+           push!(tree, k)
+       end
+
+julia> haskey(tree, 3)
+true
+
+julia> tree[4]
+7
+
+julia> for k in 1:2:10
+           delete!(tree, k)
+       end
+
+julia> haskey(tree, 5)
+false
+```
+
+```@meta
+DocTestSetup = nothing
+```

docs/src/index.md

@@ -23,6 +23,7 @@ This package implements a variety of data structures, including
 -   SparseIntSet
 -   DiBitVector
 -   Red Black Tree
+-   AVL Tree
 
 ## Contents
 
@@ -48,6 +49,7 @@ Pages = [
     "sorted_containers.md",
     "sparse_int_set.md",
     "dibit_vector.md",
-    "red_black_tree.md"
+    "red_black_tree.md",
+    "avl_tree.md"
 ]
 ```

src/avl_tree.jl

@@ -111,7 +111,7 @@ Returns true if `key` is present in the `tree`, else returns false.
 """
 haskey(tree, key)
 
-function haskey(tree::AVLTree{K}, d::K) where K 
+function Base.haskey(tree::AVLTree{K}, d::K) where K 
     (tree.root == nothing) && return false
     node = search_node(tree, d)
     return (node.data == d)