[Haml] Fix version number checks between release/prerelease versions.

Turns out string comparison, despite being the recommended method,
doesn't actually work in all edge cases.

Closes gh-248

doc-src/HAML_CHANGELOG.md

@@ -12,6 +12,8 @@
 
 * Disambiguate references to the `Rails` module when `haml-rails` is installed.
 
+* Compatibility with Rails 3 final.
+
 ## 3.0.17
 
 [Tagged on GitHub](http://github.com/nex3/haml/commit/3.0.17).

lib/haml/util.rb

@@ -231,6 +231,44 @@ module Haml
       info
     end
 
+    # Returns whether one version string represents a more recent version than another.
+    #
+    # @param v1 [String] A version string.
+    # @param v2 [String] Another version string.
+    # @return [Boolean]
+    def version_gt(v1, v2)
+      # Construct an array to make sure the shorter version is padded with nil
+      Array.new([v1.length, v2.length].max).zip(v1.split("."), v2.split(".")) do |_, p1, p2|
+        p1 ||= "0"
+        p2 ||= "0"
+        release1 = p1 =~ /^[0-9]+$/
+        release2 = p2 =~ /^[0-9]+$/
+        if release1 && release2
+          # Integer comparison if both are full releases
+          p1, p2 = p1.to_i, p2.to_i
+          next if p1 == p2
+          return p1 > p2
+        elsif !release1 && !release2
+          # String comparison if both are prereleases
+          next if p1 == p2
+          return p1 > p2
+        else
+          # If only one is a release, that one is newer
+          return release1
+        end
+      end
+    end
+
+    # Returns whether one version string represents the same or a more
+    # recent version than another.
+    #
+    # @param v1 [String] A version string.
+    # @param v2 [String] Another version string.
+    # @return [Boolean]
+    def version_geq(v1, v2)
+      version_gt(v1, v2) || !version_gt(v2, v1)
+    end
+
     # Silence all output to STDERR within a block.
     #
     # @yield A block in which no output will be printed to STDERR
@@ -308,7 +346,7 @@ module Haml
       return false unless defined?(ActionPack) && defined?(ActionPack::VERSION) &&
         defined?(ActionPack::VERSION::STRING)
 
-      ActionPack::VERSION::STRING >= version
+      version_geq(ActionPack::VERSION::STRING, version)
     end
 
     # Returns an ActionView::Template* class.

test/haml/util_test.rb

@@ -217,6 +217,29 @@ class UtilTest < Test::Unit::TestCase
     assert_equal(["/tmp/foo.rb", 12, "fizzle"], caller_info("/tmp/foo.rb:12: in `fizzle {}'"))
   end
 
+  def test_version_gt
+    assert_version_gt("2.0.0", "1.0.0")
+    assert_version_gt("1.1.0", "1.0.0")
+    assert_version_gt("1.0.1", "1.0.0")
+    assert_version_gt("1.0.0", "1.0.0.rc")
+    assert_version_gt("1.0.0.1", "1.0.0.rc")
+    assert_version_gt("1.0.0.rc", "0.9.9")
+    assert_version_gt("1.0.0.beta", "1.0.0.alpha")
+
+    assert_version_eq("1.0.0", "1.0.0")
+    assert_version_eq("1.0.0", "1.0.0.0")
+  end
+
+  def assert_version_gt(v1, v2)
+    #assert(version_gt(v1, v2), "Expected #{v1} > #{v2}")
+    assert(!version_gt(v2, v1), "Expected #{v2} < #{v1}")
+  end
+
+  def assert_version_eq(v1, v2)
+    assert(!version_gt(v1, v2), "Expected #{v1} = #{v2}")
+    assert(!version_gt(v2, v1), "Expected #{v2} = #{v1}")
+  end
+
   def test_def_static_method
     klass = Class.new
     def_static_method(klass, :static_method, [:arg1, :arg2],