tree.rb in sycamore-0.3.1

- old
+ new

@@ -63,13 +63,20 @@
 
     ##
     # Creates a new empty Tree.
     #
     def initialize
-      @data = Hash.new
     end
 
+    protected def data
+      @data ||= Hash.new
+    end
+
+    protected def clear_data
+      @data = nil
+    end
+
     ##
     # Creates a new Tree and initializes it with the given data.
     #
     # @param (see #add)
     # @return [Tree]
@@ -216,42 +223,42 @@
     end
 
     alias << add
 
     protected def add_node(node)
-      @data[node] ||= Nothing
+      data[node] ||= Nothing
 
       self
     end
 
     ##
     # @api private
     #
     def clear_child_of_node(node)
-      @data[valid_node! node] = Nothing
+      data[valid_node! node] = Nothing
 
       self
     end
 
     ##
     # @api private
     #
     def add_node_with_empty_child(node)
       valid_node! node
 
-      if @data.fetch(node, Nothing).nothing?
-        @data[node] = new_child(node)
+      if data.fetch(node, Nothing).nothing?
+        data[node] = new_child(node)
       end
 
       self
     end
 
     private def add_child(node, children)
       return add_node(node) if Nothing.like?(children)
 
       add_node_with_empty_child(node)
-      @data[node] << children
+      data[node] << children
 
       self
     end
 
     private def add_tree(tree)
@@ -327,11 +334,11 @@
     end
 
     alias >> delete
 
     protected def delete_node(node)
-      @data.delete(node)
+      data.delete(node)
 
       self
     end
 
     protected def delete_tree(tree)
@@ -489,11 +496,11 @@
     #   tree.size  # => 3
     #   tree.clear
     #   tree.size  # => 0
     #
     def clear
-      @data.clear
+      data.clear
 
       self
     end
 
     ##
@@ -507,11 +514,11 @@
     #   tree.to_h  # => {foo: {bar: []}}
     #   tree.compact
     #   tree.to_h  # => {foo: :bar}
     #
     def compact
-      @data.each do |node, child| case
+      data.each do |node, child| case
           when child.nothing? then next
           when child.empty?   then clear_child_of_node(node)
           else child.compact
         end
       end
@@ -533,11 +540,11 @@
     #   tree = Tree[foo: [:bar, :baz]]
     #   tree.nodes        # => [:foo]
     #   tree[:foo].nodes  # => [:bar, :baz]
     #
     def nodes
-      @data.keys
+      data.keys
     end
 
     alias keys nodes  # Hash compatibility
 
 
@@ -603,11 +610,11 @@
     # @todo Should we differentiate the case of a leaf and a not present node? How?
     #
     def child_of(node)
       valid_node! node
 
-      Nothing.like?(child = @data[node]) ? Absence.at(self, node) : child
+      Nothing.like?(child = data[node]) ? Absence.at(self, node) : child
     end
 
     ##
     # The child tree of a node at a path.
     #
@@ -682,11 +689,11 @@
     #
     def fetch(node, *default, &block)
       return fetch_path(node, *default, &block) if node.is_a? Path
       valid_node! node
 
-      child = @data.fetch(node, *default, &block)
+      child = data.fetch(node, *default, &block)
       if child.equal? Nothing
         child = case
           when block_given?    then yield
           when !default.empty? then default.first
           else raise ChildError, "node #{node.inspect} has no child tree"
@@ -752,11 +759,11 @@
     #   > b
     #
     def each_node(&block)
       return enum_for(__callee__) unless block_given?
 
-      @data.each_key(&block)
+      data.each_key(&block)
 
       self
     end
 
     alias each_key each_node  # Hash compatibility
@@ -781,11 +788,11 @@
     #   > b => #<Tree: Nothing>
     #
     def each_pair(&block)
       return enum_for(__callee__) unless block_given?
 
-      @data.each_pair(&block)
+      data.each_pair(&block)
 
       self
     end
 
     alias each each_pair
@@ -868,11 +875,11 @@
     #  Tree[1 => 2].include_node? Sycamore::Path[1,2]  # => true
     #
     def include_node?(node)
       return include_path?(node) if node.is_a? Path
 
-      @data.include?(node)
+      data.include?(node)
     end
 
     alias member?  include_node?  # Hash compatibility
     alias has_key? include_node?  # Hash compatibility
     alias key?     include_node?  # Hash compatibility
@@ -952,11 +959,11 @@
     #   tree.delete("a")
     #   tree.size  # => 3
     #   tree["e"].size  # => 2
     #
     def size
-      @data.size
+      data.size
     end
 
     ##
     # The number of {#nodes nodes} in this tree and all of their children.
     #
@@ -969,11 +976,11 @@
     #   tree.total_size  # => 7
     #   tree["e"].total_size  # => 2
     #
     def total_size
       total = size
-      @data.each { |_, child| total += child.total_size }
+      data.each { |_, child| total += child.total_size }
       total
     end
 
     alias tsize total_size
 
@@ -999,11 +1006,11 @@
     # @example
     #   Tree.new.empty?    # => true
     #   Tree[a: 1].empty?  # => false
     #
     def empty?
-      @data.empty?
+      data.empty?
     end
 
     alias blank? empty?
 
     ##
@@ -1144,11 +1151,11 @@
     # A hash code of this tree.
     #
     # @return [Fixnum]
     #
     def hash
-      @data.hash ^ self.class.hash
+      data.hash ^ self.class.hash
     end
 
     ##
     # Checks if this tree has the same content as another tree.
     #
@@ -1163,11 +1170,11 @@
     #   tree1.eql? tree2  # => false
     #   tree1.eql? tree3  # => true
     #   tree1.eql? tree4  # => false
     #
     def eql?(other)
-      (other.instance_of?(self.class) and @data.eql?(other.data)) or
+      (other.instance_of?(self.class) and data.eql?(other.data)) or
         (other.instance_of?(Absence) and other.eql?(self))
     end
 
     ##
     # Checks if this tree has the same content as another tree, but ignores empty child trees.
@@ -1337,11 +1344,11 @@
       return {} if empty?
 
       # not the nicest, but fastest way to inject on hashes, as noted here:
       # http://stackoverflow.com/questions/3230863/ruby-rails-inject-on-hashes-good-style
       hash = {}
-      @data.each do |node, child|
+      data.each do |node, child|
         hash[node] = child.to_native_object(*args)
       end
 
       hash
     end
@@ -1442,20 +1449,20 @@
     ##
     # Clones the whole tree.
     #
     def initialize_clone(other)
       super
-      @data = Hash.new
+      clear_data
       add other
     end
 
     ##
     # Deep freezes the whole tree.
     #
     # @see http://ruby-doc.org/core/Object.html#method-i-freeze
     #
     def freeze
-      @data.freeze
+      data.freeze
       each { |_, child| child.freeze }
       super
     end
 
   end  # Tree