add Rugged::Tree#each_blob and Rugged::Tree#each_tree

lib/rugged.rb

@@ -4,3 +4,4 @@
 require 'rugged/version'
 require 'rugged/repository'
 require 'rugged/walker'
+require 'rugged/tree'

lib/rugged/tree.rb

@@ -0,0 +1,13 @@
+module Rugged
+  class Tree
+    # Walks the tree but only yields blobs
+    def each_blob(mode=:postorder)
+      self.walk(mode) { |root, e| yield root, e if e[:type] == :blob }
+    end
+
+    # Walks the tree but only yields subtrees
+    def each_tree(mode=:postorder)
+      self.walk(mode) { |root, e| yield root, e if e[:type] == :tree }
+    end
+  end
+end

test/tree_test.rb

@@ -36,6 +36,14 @@
     assert enum.kind_of? Enumerable
   end
 
+  test "can walk the tree, yielding only trees" do
+    @tree.each_tree {|root, entry| assert_equal :tree, entry[:type]}
+  end
+
+  test "can walk the tree, yielding only blobs" do
+    @tree.each_blob {|root, entry| assert_equal :blob, entry[:type]}
+  end
+
   xtest "can write the tree data" do
   end