Added back Hash::Iterator because it's used in C-API.

kernel/common/hash.rb

@@ -29,6 +29,35 @@ def match?(key, key_hash)
     end
   end
 
+  # An external iterator that returns only entry chains from the
+  # Hash storage, never nil bins. While somewhat following the API
+  # of Enumerator, it is named Iterator because it does not provide
+  # <code>#each</code> and should not conflict with +Enumerator+ in
+  # MRI 1.8.7+. Returned by <code>Hash#to_iter</code>.
+
+  class Iterator
+    attr_reader :index
+
+    def initialize(entries, capacity)
+      @entries  = entries
+      @capacity = capacity
+      @index    = -1
+    end
+
+    # Returns the next object or +nil+.
+    def next(entry)
+      if entry and entry = entry.link
+        return entry
+      end
+
+      while (@index += 1) < @capacity
+        if entry = @entries[@index]
+          return entry
+        end
+      end
+    end
+  end
+
   # Hash methods
 
   attr_reader :size
@@ -646,6 +675,11 @@ def to_a
     ary
   end
 
+  # Returns an external iterator for the bins. See +Iterator+
+  def to_iter
+    Iterator.new @entries, @capacity
+  end
+
   def to_hash
     self
   end

kernel/common/hash19.rb

@@ -84,6 +84,26 @@ def remove
     end
   end
 
+  # An external iterator that returns entries in insertion order.  While
+  # somewhat following the API of Enumerator, it is named Iterator because it
+  # does not provide <code>#each</code> and should not conflict with
+  # +Enumerator+ in MRI 1.8.7+. Returned by <code>Hash#to_iter</code>.
+
+  class Iterator
+    def initialize(state)
+      @state = state
+    end
+
+    # Returns the next object or +nil+.
+    def next(entry)
+      if entry
+        return entry if entry = entry.next
+      else
+        return @state.head
+      end
+    end
+  end
+
   # Hash methods
 
   attr_reader :size
@@ -732,6 +752,11 @@ def to_a
     ary
   end
 
+  # Returns an external iterator for the bins. See +Iterator+
+  def to_iter
+    Iterator.new @state
+  end
+
   def to_hash
     self
   end

kernel/common/hash_hamt.rb

@@ -290,6 +290,25 @@ def delete(key, key_hash)
     end
   end
 
+  # An external iterator that returns entries in insertion order.  While
+  # somewhat following the API of Enumerator, it is named Iterator because it
+  # does not provide <code>#each</code> and should not conflict with
+  # +Enumerator+ in MRI 1.8.7+. Returned by <code>Hash#to_iter</code>.
+
+  class Iterator
+    def initialize(state)
+      @state = state
+    end
+
+    # Returns the next object or +nil+.
+    def next(entry)
+      if entry
+        return entry if entry = entry.next
+      else
+        return @state.head
+      end
+    end
+  end
 
   # Hash methods
 
@@ -778,6 +797,11 @@ def to_a
     ary
   end
 
+  # Returns an external iterator for the bins. See +Iterator+
+  def to_iter
+    Iterator.new @state
+  end
+
   def to_hash
     self
   end

spec/core/hash/iterator/index_spec.rb

@@ -0,0 +1,23 @@
+require File.expand_path('../../../../spec_helper', __FILE__)
+
+with_feature :hash_bucket do
+  describe "Hash::Iterator#index" do
+    ruby_version_is ""..."1.9" do
+      it "returns the index of the last object returned by #next" do
+        h = Hash.new
+        a = Hash::Bucket.new 1, 2, 3
+        b = Hash::Bucket.new 4, 5, 6
+        e = h.instance_variable_get :@entries
+        e[2] = a
+        e[4] = b
+
+        iter = h.to_iter
+
+        (entry = iter.next(entry)).should == a
+        (entry = iter.next(entry)).should == b
+
+        iter.index.should == 4
+      end
+    end
+  end
+end

spec/core/hash/iterator/new_spec.rb

@@ -0,0 +1,16 @@
+require File.expand_path('../../../../spec_helper', __FILE__)
+
+with_feature :hash_bucket do
+  describe "Hash::Iterator.new" do
+    ruby_version_is ""..."1.9" do
+      it "initializes the iterator" do
+        h = Hash[:a => 1, :b => 2]
+        entries = h.instance_variable_get :@entries
+        iter = h.to_iter
+        iter.instance_variable_get(:@entries).should == entries
+        iter.instance_variable_get(:@capacity).should == entries.size
+        iter.instance_variable_get(:@index).should == -1
+      end
+    end
+  end
+end

spec/core/hash/iterator/next_spec.rb

@@ -0,0 +1,59 @@
+require File.expand_path('../../../../spec_helper', __FILE__)
+
+with_feature :hash_bucket do
+  describe "Hash::Iterator#next" do
+    before :each do
+      ScratchPad.record []
+    end
+
+    ruby_version_is ""..."1.9" do
+      it "returns each non-nil entry from the storage vector" do
+        h = Hash.new
+        a = Hash::Bucket.new 1, 2, 3
+        b = Hash::Bucket.new 4, 5, 6
+        c = Hash::Bucket.new 7, 8, 9
+        e = h.instance_variable_get :@entries
+        e[2] = a
+        e[4] = b
+        e[7] = c
+
+        iter = h.to_iter
+
+        while entry = iter.next(entry)
+          ScratchPad << entry
+        end
+        ScratchPad.recorded.should == [a, b, c]
+      end
+    end
+
+    ruby_version_is "1.9" do
+      it "returns each entry in the Hash" do
+        h = Hash[:a, 1, :b, 2, :c, 3]
+        iter = h.to_iter
+
+        while entry = iter.next(entry)
+          ScratchPad << entry.key
+        end
+        ScratchPad.recorded.should == [:a, :b, :c]
+      end
+    end
+  end
+end
+
+with_feature :hash_hamt do
+  describe "Hash::Iterator#next" do
+    before :each do
+      ScratchPad.record []
+    end
+
+    it "returns each entry in the Hash" do
+      h = Hash[:a, 1, :b, 2, :c, 3]
+      iter = h.to_iter
+
+      while entry = iter.next(entry)
+        ScratchPad << entry.key
+      end
+      ScratchPad.recorded.should == [:a, :b, :c]
+    end
+  end
+end