Allow graphs to add vertices. Part of vertex operations for #3 and cl…

…oses #1

lib/abstract_graph/composition.rb

@@ -2,6 +2,7 @@
 
 require "abstract_graph/composition/vertex"
 require "abstract_graph/composition/edge"
+require "abstract_graph/composition/uniquenamecollection"
 
 module AbstractGraph
   module Composition

lib/abstract_graph/composition/uniquenamecollection.rb

@@ -0,0 +1,17 @@
+# required in "abstract_graph/composition"
+
+module AbstractGraph
+  module Composition
+
+    # public UniqueNameCollection class
+    # Note that the collection of this
+    #   class must implement #name
+    class UniqueNameCollection
+      attr_accessor :collection
+
+    end
+  end
+end
+
+require "abstract_graph/composition/uniquenamecollection/initialize"
+require "abstract_graph/composition/uniquenamecollection/add"

lib/abstract_graph/composition/uniquenamecollection/add.rb

@@ -0,0 +1,19 @@
+# required in "abstract_graph/composition/uniquenamecollection"
+
+module AbstractGraph
+  module Composition
+    class UniqueNameCollection
+
+      # adds an object o into the collection
+      # p: Object o that implements #name
+      def add( o )
+        if @collection[o.name]
+          raise IndexError
+        else
+          @collection[o.name] = o
+        end
+      end
+
+    end
+  end
+end

lib/abstract_graph/composition/uniquenamecollection/initialize.rb

@@ -0,0 +1,13 @@
+# required in "abstract_graph/composition/uniquenamecollection"
+
+module AbstractGraph
+  module Composition
+    class UniqueNameCollection
+
+      def initialize
+        @collection = Hash.new
+      end
+
+    end
+  end
+end

lib/abstract_graph/graph.rb

@@ -2,10 +2,17 @@
 
 module AbstractGraph
 
-    # public Graph class
-    class Graph
-    end
+  # public Graph class
+  class Graph
+
+    # Add the vertex and edge classes
+    include Composition
+
+    attr_accessor :vertices
+
+  end
 
 end
 
 require "abstract_graph/graph/initialize"
+require "abstract_graph/graph/add_vertex"

lib/abstract_graph/graph/add_vertex.rb

@@ -0,0 +1,16 @@
+# required in "abstract_graph/graph"
+
+module AbstractGraph
+  class Graph
+
+    # add a vertex named s to the graph
+    # p: String s represents the name of the wanted vertex
+    def add_vertex( s )
+      # create the vertex
+      vertex = Vertex.new s
+      @vertices.add vertex
+      self
+    end
+
+  end
+end

lib/abstract_graph/graph/initialize.rb

@@ -6,6 +6,8 @@ class Graph
     # public constructor
     def initialize
 
+      @vertices = UniqueNameCollection.new
+
     end
 
   end

spec/abstract_graph/composition/uniquenamecollection/add_spec.rb

@@ -0,0 +1,40 @@
+require 'spec_helper'
+
+module AbstractGraph
+  module Composition
+    describe UniqueNameCollection do
+
+      before(:each) do
+
+        @collection = UniqueNameCollection.new
+      end
+
+      describe "#add(Object)" do
+
+        it "tracks an object that has implemented #name" do
+          dummy = Dummy.new
+          dummy.name = "Hello"
+          @collection.add dummy
+        end
+
+        it "doesn't allow us to add the same object twice" do
+          dummy = Dummy.new
+          dummy.name = "Hello"
+          @collection.add dummy
+          expect { @collection.add dummy }.to raise_error
+        end
+
+        it "doesn't allow two objects to have the same name" do
+          dummy = Dummy.new
+          dummy2 = Dummy.new
+          dummy.name = "Hello"
+          dummy2.name = "Hello"
+          @collection.add dummy
+          expect { @collection.add dummy2 }.to raise_error
+        end
+
+      end
+
+    end
+  end
+end

spec/abstract_graph/composition/uniquenamecollection/initialize_spec.rb

@@ -0,0 +1,21 @@
+require 'spec_helper'
+
+module AbstractGraph
+  module Composition
+    describe UniqueNameCollection do
+
+      before (:each) do
+        @collection = UniqueNameCollection.new
+      end
+
+      describe "#new" do
+
+        it "returns an object of class UniqueNameCollection" do
+          @collection.should be_an_instance_of(UniqueNameCollection)
+        end
+
+      end
+
+    end
+  end
+end

spec/abstract_graph/composition/uniquenamecollection_spec.rb

@@ -0,0 +1,8 @@
+require 'spec_helper'
+
+module AbstractGraph
+  module Composition
+    describe UniqueNameCollection do
+    end
+  end
+end

spec/abstract_graph/graph/add_vertex_spec.rb

@@ -0,0 +1,29 @@
+require 'spec_helper'
+
+module AbstractGraph
+  describe Graph do
+
+    before :each do
+      @graph = Graph.new
+    end
+
+    describe "#add_vertex(String)" do
+
+      it "returns an object of class Graph" do
+        @graph.add_vertex( "MyVertex" ).should be_an_instance_of(Graph)
+      end
+
+      it "throws an exception when adding vertex of existing name" do
+        @graph.add_vertex( "MyVertex" )
+        expect { @graph.add_vertex( "MyVertex" ) }.to raise_error
+      end
+
+      it "allows two different graphs to have the same names" do
+        graph2 = Graph.new
+        @graph.add_vertex( "MyVertex" )
+        expect { graph2.add_vertex( "MyVertex" ) }.to_not raise_error
+      end
+
+    end
+  end
+end

spec/dummy_helper.rb

@@ -0,0 +1,4 @@
+# simple class that implements #name
+class Dummy
+  attr_accessor :name
+end

spec/spec_helper.rb

@@ -1,3 +1,4 @@
+require 'dummy_helper'
 require 'rspec'
 require 'abstract_graph'