[GR-40333] Ruby 3.1 Add optional Hash argument to Enumerable#tally

PullRequest: truffleruby/3684

Author: andrykonchin

CHANGELOG.md

@@ -86,6 +86,7 @@ Compatibility:
 * Add `freeze` keyword argument to `Marshal.load` (#2733, @andrykonchin).
 * Add `Integer.try_convert` (#2733, @moste00, @eregon).
 * Support optional `:in` keyword argument for `Time.now` and `Time.new` (#2733, @andrykonchin).
+* Add optional `Hash` argument to `Enumerable#tally` (#2733, @andrykonchin).
 
 Performance:
 

spec/ruby/core/enumerable/tally_spec.rb

@@ -49,13 +49,26 @@
       enum.tally(hash).should equal(hash)
     end
 
+    it "calls #to_hash to convert argument to Hash implicitly if passed not a Hash" do
+      enum = EnumerableSpecs::Numerous.new('foo', 'bar', 'foo', 'baz')
+      object = Object.new
+      def object.to_hash; { 'foo' => 1 }; end
+      enum.tally(object).should == { 'foo' => 3, 'bar' => 1, 'baz' => 1}
+    end
+
     it "raises a FrozenError and does not update the given hash when the hash is frozen" do
       enum = EnumerableSpecs::Numerous.new('foo', 'bar', 'foo', 'baz')
       hash = { 'foo' => 1 }.freeze
       -> { enum.tally(hash) }.should raise_error(FrozenError)
       hash.should == { 'foo' => 1 }
     end
 
+    it "raises a FrozenError even if enumerable is empty" do
+      enum = EnumerableSpecs::Numerous.new()
+      hash = { 'foo' => 1 }.freeze
+      -> { enum.tally(hash) }.should raise_error(FrozenError)
+    end
+
     it "does not call given block" do
       enum = EnumerableSpecs::Numerous.new('foo', 'bar', 'foo', 'baz')
       enum.tally({ 'foo' => 1 }) { |v| ScratchPad << v }

spec/tags/core/enumerable/tally_tags.txt

@@ -284,17 +284,23 @@ def slice_when(&block)
     end
   end
 
-  def tally
-    h = {}
+  def tally(hash = undefined)
+    if Primitive.undefined?(hash)
+      hash = {}
+    else
+      hash = Truffle::Type.rb_convert_type(hash, Hash, :to_hash)
+      Primitive.check_frozen(hash)
+    end
+
     each do
       e = Primitive.single_block_arg
-      if h.key?(e)
-        h[e] += 1
+      if hash.key?(e)
+        hash[e] += 1
       else
-        h[e] = 1
+        hash[e] = 1
       end
     end
-    h
+    hash
   end
 
   def to_a(*args, **kwargs)