[Platform] Make instances usable as Hash keys.

Fixes CocoaPods#109.

CHANGELOG.md

@@ -4,6 +4,10 @@
 
 ##### Enhancements
 
+* Make Platform instances usable as Hash keys.
+  [Eloy Durán](https://github.com/alloy)
+  [#109](https://github.com/CocoaPods/Core/pull/109)
+
 * Accept new sources for Pods when they are just redirects of the old one.  
   [Boris Bügling](https://github.com/neonichu)
   [#101](https://github.com/CocoaPods/Core/issues/101)

lib/cocoapods-core/platform.rb

@@ -86,6 +86,18 @@ def ==(other)
       end
     end
 
+    # (see #==)
+    alias_method :eql?, :==
+
+    # Hashes the instance by the platform name and deployment target.
+    #
+    # This adds support to make instances usable as Hash keys.
+    #
+    # @!visibility private
+    def hash
+      name.hash ^ deployment_target.hash
+    end
+
     # Checks whether a platform supports another one.
     #
     # In the context of operating system SDKs, a platform supports another

spec/platform_spec.rb

@@ -83,6 +83,18 @@ module Pod
         Platform.new(:ios, '5.0').requires_legacy_ios_archs?.should.be.false
       end
 
+      it 'is usable as hash keys' do
+        ios   = Platform.new(:ios)
+        osx   = Platform.new(:osx)
+        ios6  = Platform.new(:ios, '6.0')
+        ios61 = Platform.new(:ios, '6.1')
+        hash  = { ios => ios, osx => osx, ios6 => ios6, ios61 => ios61 }
+        hash[Platform.new(:ios)].should.be.eql ios
+        hash[Platform.new(:osx)].should.be.eql osx
+        hash[Platform.new(:ios, '6.0')].should.be.eql ios6
+        hash[Platform.new(:ios, '6.1')].should.be.eql ios61
+      end
+
     end
 
     describe 'Supporting other platforms' do