Allow Hash#transform_keys to take a hash argument

CHANGELOG.md

@@ -19,6 +19,7 @@ Compatibility:
 * `Module#attr_*` methods now return an array of method names (#2498, @gogainda).
 * Fixed `Socket#(local|remote)_address` to retrieve family and type from the file descriptor (#2444, @larskanis).
 * Add `Thread.ignore_deadlock` accessor (#2453).
+* Allow `Hash#transform_keys` to take a hash argument (@ccocchi, #2464).
 
 Performance:
 

spec/tags/core/hash/transform_keys_tags.txt

@@ -1,6 +1 @@
 fails:Hash#transform_keys! returns the processed keys and non evaluated keys if we broke from the block
-fails:Hash#transform_keys allows a hash argument
-fails:Hash#transform_keys allows a partial transformation of keys when using a hash argument
-fails:Hash#transform_keys allows a combination of hash and block argument
-fails:Hash#transform_keys! allows a hash argument
-fails:Hash#transform_keys! on frozen instance raises a FrozenError on hash argument

src/main/ruby/truffleruby/core/hash.rb

@@ -539,25 +539,47 @@ def transform_values!
     self
   end
 
-  def transform_keys
-    return to_enum(:transform_keys) { size } unless block_given?
-
+  def transform_keys(mapping = nil)
+    has_block = block_given?
     h = {}
-    each_pair do |key, value|
-      h[yield(key)] = value
+
+    if mapping
+      mapping = Truffle::Type.coerce_to(mapping, Hash, :to_hash)
+      each_pair do |key, value|
+        k = Primitive.hash_get_or_undefined(mapping, key)
+        k = has_block ? yield(key) : key if Primitive.undefined?(k)
+        h[k] = value
+      end
+    else
+      return to_enum(:transform_keys) { size } unless has_block
+
+      each_pair do |key, value|
+        h[yield(key)] = value
+      end
     end
+
     h
   end
 
-  def transform_keys!
-    return to_enum(:transform_keys!) { size } unless block_given?
+  def transform_keys!(mapping = nil)
+    has_block = block_given?
+    return to_enum(:transform_keys!) { size } unless mapping || has_block
 
     Primitive.check_frozen self
-
     h = {}
+
     begin
-      each_pair do |key, value|
-        h[yield(key)] = value
+      if mapping
+        mapping = Truffle::Type.coerce_to(mapping, Hash, :to_hash)
+        each_pair do |key, value|
+          k = Primitive.hash_get_or_undefined(mapping, key)
+          k = has_block ? yield(key) : key if Primitive.undefined?(k)
+          h[k] = value
+        end
+      else
+        each_pair do |key, value|
+          h[yield(key)] = value
+        end
       end
     ensure
       replace h

tool/jt.rb

@@ -1637,9 +1637,6 @@ def purge(path, *args)
 
   def untag(path, *args)
     require_ruby_launcher!
-    puts
-    puts "WARNING: untag is currently not very reliable - run `jt test #{[path,*args] * ' '}` after and manually annotate any new failures"
-    puts
     test_specs('untag', path, *args)
   end