Initial implementation of ObservableArray

opal/vienna/observable_array.rb

@@ -0,0 +1,74 @@
+require 'vienna/observable'
+
+module ObservableArray
+  def self.infect(array)
+    class << array
+      alias :old_push :<<
+      alias :old_clear :clear
+      alias :old_insert :insert
+    end
+
+    array.extend self
+    array.extend Vienna::Observable
+  end
+
+  def content
+    self
+  end
+
+  def array_content_did_change(idx, remove, added)
+    if observers = @array_observers
+      observers.each do |obj|
+        obj.array_did_change(self, idx, remove, added)
+
+      end
+    end
+
+    attribute_did_change :size
+    attribute_did_change :content
+    attribute_did_change :empty?
+  end
+
+  def add_array_observer(object)
+    (@array_observers ||= []) << object
+  end
+
+  def <<(obj)
+    size = length
+    old_push obj
+
+    array_content_did_change size, 0, 1
+    self
+  end
+
+  def insert(idx, object)
+    if idx > length
+      raise ArgumentError, 'out of range'
+    end
+
+    old_insert idx, object
+
+    array_content_did_change idx, 0, 1
+    self
+  end
+
+  def clear
+    length = self.length
+    old_clear
+
+    array_content_did_change 0, length, 0
+    self
+  end
+end
+
+class Array
+  def add_observer(attribute, &blk)
+    ObservableArray.infect(self)
+    add_observer(attribute, &blk)
+  end
+
+  def add_array_observer(object)
+    ObservableArray.infect(self)
+    add_array_observer(object)
+  end
+end