* object.c: Add NilClass#to_h [Feature ruby#6276]

  [ref ruby#5008] [rubyspec:dc5ecddbd608]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@35340 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

NEWS

@@ -43,6 +43,10 @@ with all sufficient information, see the ChangeLog file.
       * added LoadError#path method to return the file name that could not be
         loaded.
 
+  * NilClass
+    * added method:
+      * added nil.to_h which returns {}
+
   * Signal
     * incompatible changes:
       * Signal.trap raises ArgumentError when :SEGV, :BUS, :ILL, :FPE, :VTALRM

object.c

@@ -1057,6 +1057,23 @@ nil_to_a(VALUE obj)
     return rb_ary_new2(0);
 }
 
+/*
+ * Document-method: to_h
+ *
+ *  call-seq:
+ *     nil.to_h    -> {}
+ *
+ *  Always returns an empty hash.
+ *
+ *     nil.to_h   #=> {}
+ */
+
+static VALUE
+nil_to_h(VALUE obj)
+{
+    return rb_hash_new();
+}
+
 /*
  *  call-seq:
  *    nil.inspect  -> "nil"
@@ -2896,6 +2913,7 @@ Init_Object(void)
     rb_define_method(rb_cNilClass, "to_f", nil_to_f, 0);
     rb_define_method(rb_cNilClass, "to_s", nil_to_s, 0);
     rb_define_method(rb_cNilClass, "to_a", nil_to_a, 0);
+    rb_define_method(rb_cNilClass, "to_h", nil_to_h, 0);
     rb_define_method(rb_cNilClass, "inspect", nil_inspect, 0);
     rb_define_method(rb_cNilClass, "&", false_and, 1);
     rb_define_method(rb_cNilClass, "|", false_or, 1);