core: Modify plugin interfaces and API for hosts

lib/vagrant/plugin/v2/components.rb

@@ -26,6 +26,16 @@ module Vagrant
         # @return [Hash<Symbol, Registry>]
         attr_reader :guest_capabilities
 
+        # This contains all the hosts and their parents.
+        #
+        # @return [Registry<Symbol, Array<Class, Symbol>>]
+        attr_reader :hosts
+
+        # This contains all the registered host capabilities.
+        #
+        # @return [Hash<Symbol, Registry>]
+        attr_reader :host_capabilities
+
         # This contains all the provider plugins by name, and returns
         # the provider class and options.
         #
@@ -44,6 +54,8 @@ module Vagrant
           @configs = Hash.new { |h, k| h[k] = Registry.new }
           @guests  = Registry.new
           @guest_capabilities = Hash.new { |h, k| h[k] = Registry.new }
+          @hosts   = Registry.new
+          @host_capabilities = Hash.new { |h, k| h[k] = Registry.new }
           @providers = Registry.new
           @synced_folders = Registry.new
         end

lib/vagrant/plugin/v2/manager.rb

@@ -88,18 +88,33 @@ module Vagrant
 
           results
         end
-
-        # This returns all registered host classes.
+        # This returns all the registered guests.
         #
         # @return [Hash]
         def hosts
           Registry.new.tap do |result|
             @registered.each do |plugin|
-              result.merge!(plugin.host)
+              result.merge!(plugin.components.hosts)
             end
           end
         end
 
+        # This returns all the registered host capabilities.
+        #
+        # @return [Hash]
+        def host_capabilities
+          results = Hash.new { |h, k| h[k] = Registry.new }
+
+          @registered.each do |plugin|
+            plugin.components.host_capabilities.each do |host, caps|
+              results[host].merge!(caps)
+            end
+          end
+
+          results
+        end
+
+
         # This returns all registered providers.
         #
         # @return [Hash]

lib/vagrant/plugin/v2/plugin.rb

@@ -135,7 +135,7 @@ module Vagrant
         #
         # @param [String] name Name of the guest.
         # @param [String] parent Name of the parent guest (if any)
-        def self.guest(name=UNSET_VALUE, parent=nil, &block)
+        def self.guest(name, parent=nil, &block)
           components.guests.register(name.to_sym) do
             parent = parent.to_sym if parent
 
@@ -160,14 +160,26 @@ module Vagrant
         # the given key.
         #
         # @param [String] name Name of the host.
-        def self.host(name=UNSET_VALUE, &block)
-          data[:hosts] ||= Registry.new
+        # @param [String] parent Name of the parent host (if any)
+        def self.host(name, parent=nil, &block)
+          components.hosts.register(name.to_sym) do
+            parent = parent.to_sym if parent
 
-          # Register a new host class only if a name was given
-          data[:hosts].register(name.to_sym, &block) if name != UNSET_VALUE
+            [block.call, parent]
+          end
+          nil
+        end
 
-          # Return the registry
-          data[:hosts]
+        # Defines a capability for the given host. The block should return
+        # a class/module that has a method with the capability name, ready
+        # to be executed. This means that if it is an instance method,
+        # the block should return an instance of the class.
+        #
+        # @param [String] host The name of the host
+        # @param [String] cap The name of the capability
+        def self.host_capability(host, cap, &block)
+          components.host_capabilities[host.to_sym].register(cap.to_sym, &block)
+          nil
         end
 
         # Registers additional providers to be available.

test/unit/vagrant/plugin/v2/manager_test.rb

@@ -126,15 +126,32 @@ describe Vagrant::Plugin::V2::Manager do
     end
 
     pB = plugin do |p|
-      p.host("bar") { "baz" }
+      p.host("bar", "foo") { "baz" }
     end
 
     instance.register(pA)
     instance.register(pB)
 
     instance.hosts.to_hash.length.should == 2
-    instance.hosts[:foo].should == "bar"
-    instance.hosts[:bar].should == "baz"
+    instance.hosts[:foo].should == ["bar", nil]
+    instance.hosts[:bar].should == ["baz", :foo]
+  end
+
+  it "should enumerate registered host capabilities" do
+    pA = plugin do |p|
+      p.host_capability("foo", "foo") { "bar" }
+    end
+
+    pB = plugin do |p|
+      p.host_capability("bar", "foo") { "baz" }
+    end
+
+    instance.register(pA)
+    instance.register(pB)
+
+    instance.host_capabilities.length.should == 2
+    instance.host_capabilities[:foo][:foo].should == "bar"
+    instance.host_capabilities[:bar][:foo].should == "baz"
   end
 
   it "should enumerate registered provider classes" do

test/unit/vagrant/plugin/v2/plugin_test.rb

@@ -192,7 +192,7 @@ describe Vagrant::Plugin::V2::Plugin do
         host("foo") { "bar" }
       end
 
-      plugin.host[:foo].should == "bar"
+      plugin.components.hosts[:foo].should == ["bar", nil]
     end
 
     it "should lazily register host classes" do
@@ -214,6 +214,16 @@ describe Vagrant::Plugin::V2::Plugin do
     end
   end
 
+  describe "host capabilities" do
+    it "should register host capabilities" do
+      plugin = Class.new(described_class) do
+        host_capability("foo", "bar") { "baz" }
+      end
+
+      plugin.components.host_capabilities[:foo][:bar].should == "baz"
+    end
+  end
+
   describe "providers" do
     it "should register provider classes" do
       plugin = Class.new(described_class) do