Merge pull request #12 from github/feat-add-compare

feat: add .compare(a, b), .rcompare(a, b)

README.md

@@ -29,6 +29,8 @@ VersionSorter.rsort(versions)  #=> reverse sorted array
 
 VersionSorter.sort!(versions)  # sort array in place
 VersionSorter.rsort!(versions) # reverse sort array in place
+
+VersionSorter.compare(version_a, version_b) #=> positive or negative number depending on which way to sort 
 ```
 
 <http://github.com/blog/521-speedy-version-sorting>

ext/version_sorter/version_sorter.c

@@ -232,11 +232,20 @@ rb_version_sort_r_bang(VALUE rb_self, VALUE rb_versions)
 	return rb_version_sort_1(rb_self, rb_versions, version_compare_cb_r);
 }
 
+static VALUE
+rb_version_compare(VALUE rb_self, VALUE rb_version_a, VALUE rb_version_b)
+{
+	struct version_number *version_a = parse_version_number(StringValuePtr(rb_version_a));
+	struct version_number *version_b = parse_version_number(StringValuePtr(rb_version_b));
+	return INT2NUM(version_compare_cb(&version_a, &version_b));
+}
+
 void Init_version_sorter(void)
 {
 	VALUE rb_mVersionSorter = rb_define_module("VersionSorter");
 	rb_define_module_function(rb_mVersionSorter, "sort", rb_version_sort, 1);
 	rb_define_module_function(rb_mVersionSorter, "rsort", rb_version_sort_r, 1);
 	rb_define_module_function(rb_mVersionSorter, "sort!", rb_version_sort_bang, 1);
 	rb_define_module_function(rb_mVersionSorter, "rsort!", rb_version_sort_r_bang, 1);
+	rb_define_module_function(rb_mVersionSorter, "compare", rb_version_compare, 2);
 }

test/version_sorter_test.rb

@@ -21,6 +21,10 @@ def test_sorts_versions_correctly
 
   def test_sorts_versions_like_rubygems
     versions = %w(1.0.9.b 1.0.9 1.0.10 2.0 3.1.4.2 1.0.9a 2.0rc2 2.0-rc1)
+    if (Gem.rubygems_version < Gem::Version.new('2.1.0')) 
+      # Old versions of RubyGems cannot parse semver versions like `2.0-rc1`
+      versions.pop()
+    end
     sorted_versions = versions.sort_by { |v| Gem::Version.new(v) }
 
     assert_equal sorted_versions, VersionSorter.sort(versions)
@@ -91,6 +95,12 @@ def test_rsort_block
     assert_equal [@version10, @version2, @version1], sorted
   end
 
+  def test_compare
+    assert VersionSorter.compare("10.0", "1.0") > 0
+    assert VersionSorter.compare("10.0", "12.0") < 0
+    assert_equal 0, VersionSorter.compare("12.0", "12.0")
+  end
+
   def shuffle(array)
     array, result = array.dup, []
     result << array.delete_at(rand(array.size)) until array.size.zero?