add {Array|Hash|String}.try_convert

2 files changed, 25 insertions, 0 deletions

diff --git a/mrbgems/mruby-hash-ext/mrblib/hash.rb b/mrbgems/mruby-hash-ext/mrblib/hash.rb
index f72cb54e8..2727e1f65 100644
--- a/mrbgems/mruby-hash-ext/mrblib/hash.rb
+++ b/mrbgems/mruby-hash-ext/mrblib/hash.rb
@@ -62,6 +62,25 @@ class Hash
 
   ##
   # call-seq:
+  #     Hash.try_convert(obj) -> hash or nil
+  #
+  # Try to convert <i>obj</i> into a hash, using to_hash method.
+  # Returns converted hash or nil if <i>obj</i> cannot be converted
+  # for any reason.
+  #
+  #     Hash.try_convert({1=>2})   # => {1=>2}
+  #     Hash.try_convert("1=>2")   # => nil
+  #
+  def self.try_convert(obj)
+    if obj.respond_to?(:to_hash)
+      obj.to_hash
+    else
+      nil
+    end
+  end
+
+  ##
+  # call-seq:
   #     hsh.merge!(other_hash)                                 -> hsh
   #     hsh.merge!(other_hash){|key, oldval, newval| block}    -> hsh
   #
diff --git a/mrbgems/mruby-hash-ext/test/hash.rb b/mrbgems/mruby-hash-ext/test/hash.rb
index 4a2251b6c..8b6b2e5b9 100644
--- a/mrbgems/mruby-hash-ext/test/hash.rb
+++ b/mrbgems/mruby-hash-ext/test/hash.rb
@@ -39,6 +39,12 @@ assert('Hash.[] "c_key", "c_value"') do
   end
 end
 
+assert('Hash.try_convert') do
+  assert_nil Hash.try_convert(nil)
+  assert_nil Hash.try_convert("{1=>2}")
+  assert_equal({1=>2}, Hash.try_convert({1=>2}))
+end
+
 assert('Hash#merge!') do
   a = { 'abc_key' => 'abc_value', 'cba_key' => 'cba_value' }
   b = { 'cba_key' => 'XXX',  'xyz_key' => 'xyz_value' }