5 files changed, 107 insertions, 4 deletions
diff --git a/Library/Homebrew/formula.rb b/Library/Homebrew/formula.rb
index 6ad5eae3a..07fcc5a67 100644
--- a/Library/Homebrew/formula.rb
+++ b/Library/Homebrew/formula.rb
@@ -10,6 +10,7 @@ require 'build_options'
 require 'formulary'
 require 'software_spec'
 require 'install_renamed'
+require 'pkg_version'
 
 class Formula
   include FileUtils
@@ -18,7 +19,7 @@ class Formula
 
   attr_reader :name, :path, :homepage, :build
   attr_reader :stable, :bottle, :devel, :head, :active_spec
-  attr_reader :revision
+  attr_reader :pkg_version, :revision
 
   # The current working directory during builds and tests.
   # Will only be non-nil inside #stage and #test.
@@ -55,6 +56,7 @@ class Formula
     @active_spec = determine_active_spec
     validate_attributes :url, :name, :version
     @build = determine_build_options
+    @pkg_version = PkgVersion.new(version, revision)
 
     @pin = FormulaPin.new(self)
 
@@ -152,7 +154,7 @@ class Formula
     Keg.new(installed_prefix).version
   end
 
-  def prefix(v=version)
+  def prefix(v=pkg_version)
     Pathname.new("#{HOMEBREW_CELLAR}/#{name}/#{v}")
   end
   def rack; prefix.parent end
diff --git a/Library/Homebrew/keg.rb b/Library/Homebrew/keg.rb
index 42e960ad9..f46c23cfc 100644
--- a/Library/Homebrew/keg.rb
+++ b/Library/Homebrew/keg.rb
@@ -101,8 +101,8 @@ class Keg < Pathname
   end
 
   def version
-    require 'version'
-    Version.new(basename.to_s)
+    require 'pkg_version'
+    PkgVersion.parse(basename.to_s)
   end
 
   def basename
diff --git a/Library/Homebrew/pkg_version.rb b/Library/Homebrew/pkg_version.rb
new file mode 100644
index 000000000..3d81df261
--- /dev/null
+++ b/Library/Homebrew/pkg_version.rb
@@ -0,0 +1,35 @@
+require 'version'
+
+class PkgVersion < Version
+  attr_reader :version, :revision
+
+  RX = /\A(.+?)(?:_(\d+))?\z/
+
+  def self.parse(path)
+    _, version, revision = *path.match(RX)
+    new(version, revision)
+  end
+
+  def initialize(version, revision)
+    super(version)
+
+    if head?
+      @revision = 0
+    else
+      @revision = revision.to_i
+    end
+  end
+
+  def to_s
+    if revision > 0
+      "#{version}_#{revision}"
+    else
+      version
+    end
+  end
+  alias_method :to_str, :to_s
+
+  def <=>(other)
+    super.nonzero? || revision <=> other.revision
+  end
+end
diff --git a/Library/Homebrew/test/test_formula.rb b/Library/Homebrew/test/test_formula.rb
index dd4f9a3e3..9c168e1e6 100644
--- a/Library/Homebrew/test/test_formula.rb
+++ b/Library/Homebrew/test/test_formula.rb
@@ -24,6 +24,11 @@ class FormulaTests < Test::Unit::TestCase
     assert_kind_of Pathname, f.prefix
   end
 
+  def test_revised_prefix
+    f = Class.new(TestBall) { revision 1 }.new
+    assert_equal HOMEBREW_CELLAR/f.name/'0.1_1', f.prefix
+  end
+
   def test_installed?
     f = TestBall.new
     f.stubs(:installed_prefix).returns(stub(:directory? => false))
@@ -233,4 +238,29 @@ class FormulaTests < Test::Unit::TestCase
       assert_equal 'foo', f.class.send(spec).deps.first.name
     end
   end
+
+  def test_simple_version
+    assert_equal PkgVersion.parse('1.0'), formula { url 'foo-1.0.bar' }.pkg_version
+  end
+
+  def test_version_with_revision
+    f = formula do
+      url 'foo-1.0.bar'
+      revision 1
+    end
+
+    assert_equal PkgVersion.parse('1.0_1'), f.pkg_version
+  end
+
+  def test_head_ignores_revisions
+    ARGV.stubs(:build_head?).returns(true)
+
+    f = formula do
+      url 'foo-1.0.bar'
+      revision 1
+      head 'foo'
+    end
+
+    assert_equal PkgVersion.parse('HEAD'), f.pkg_version
+  end
 end
diff --git a/Library/Homebrew/test/test_pkg_version.rb b/Library/Homebrew/test/test_pkg_version.rb
new file mode 100644
index 000000000..d78007dcf
--- /dev/null
+++ b/Library/Homebrew/test/test_pkg_version.rb
@@ -0,0 +1,36 @@
+require 'testing_env'
+require 'pkg_version'
+
+class PkgVersionTests < Test::Unit::TestCase
+  def v(version)
+    PkgVersion.parse(version)
+  end
+
+  def test_parse
+    assert_equal PkgVersion.new("1.0", 1), PkgVersion.parse("1.0_1")
+    assert_equal PkgVersion.new("1.0", 1), PkgVersion.parse("1.0_1")
+    assert_equal PkgVersion.new("1.0", 0), PkgVersion.parse("1.0")
+    assert_equal PkgVersion.new("1.0", 0), PkgVersion.parse("1.0_0")
+    assert_equal PkgVersion.new("2.1.4", 0), PkgVersion.parse("2.1.4_0")
+    assert_equal PkgVersion.new("2.1.4_1", 0), PkgVersion.parse("2.1.4_1_0")
+    assert_equal PkgVersion.new("1.0.1e", 1), PkgVersion.parse("1.0.1e_1")
+  end
+
+  def test_comparison
+    assert_operator v("1.0_0"), :==, v("1.0")
+    assert_operator v("1.0_1"), :==, v("1.0_1")
+    assert_operator v("1.1"), :>, v("1.0_1")
+    assert_operator v("1.0_0"), :==, v("1.0")
+    assert_operator v("1.0_1"), :<, v("2.0_1")
+    assert_operator v("HEAD"), :>, v("1.0")
+    assert_operator v("1.0"), :<, v("HEAD")
+  end
+
+  def test_to_s
+    assert_equal "1.0", PkgVersion.new("1.0", 0).to_s
+    assert_equal "1.0_1", PkgVersion.new("1.0", 1).to_s
+    assert_equal "1.0", PkgVersion.new("1.0", 0).to_s
+    assert_equal "1.0", PkgVersion.new("1.0", 0).to_s
+    assert_equal "HEAD", PkgVersion.new("HEAD", 1).to_s
+  end
+end