add {Array|Hash|String}.try_convert

2 files changed, 47 insertions, 0 deletions

diff --git a/mrbgems/mruby-array-ext/mrblib/array.rb b/mrbgems/mruby-array-ext/mrblib/array.rb
index 35be79339..f19581cdc 100644
--- a/mrbgems/mruby-array-ext/mrblib/array.rb
+++ b/mrbgems/mruby-array-ext/mrblib/array.rb
@@ -1,6 +1,31 @@
 class Array
   ##
   # call-seq:
+  #    Array.try_convert(obj) -> array or nil
+  #
+  # Tries to convert +obj+ into an array, using +to_ary+ method.
+  # converted array or +nil+ if +obj+ cannot be converted for any reason.
+  # This method can be used to check if an argument is an array.
+  #
+  #    Array.try_convert([1])   #=> [1]
+  #    Array.try_convert("1")   #=> nil
+  #
+  #    if tmp = Array.try_convert(arg)
+  #      # the argument is an array
+  #    elsif tmp = String.try_convert(arg)
+  #      # the argument is a string
+  #    end
+  #
+  def self.try_convert(obj)
+    if obj.respond_to?(:to_ary)
+      obj.to_ary
+    else
+      nil
+    end
+  end
+
+  ##
+  # call-seq:
   #    ary.uniq!                -> ary or nil
   #    ary.uniq! { |item| ... } -> ary or nil
   #
@@ -709,4 +734,14 @@ class Array
     end
     nil
   end
+
+  ##
+  #  call-seq:
+  #     ary.to_ary -> ary
+  #
+  #  Returns +self+.
+  #
+  def to_ary
+    self
+  end
 end
diff --git a/mrbgems/mruby-array-ext/test/array.rb b/mrbgems/mruby-array-ext/test/array.rb
index 6c2f52379..f17cb80e1 100644
--- a/mrbgems/mruby-array-ext/test/array.rb
+++ b/mrbgems/mruby-array-ext/test/array.rb
@@ -1,6 +1,13 @@
 ##
 # Array(Ext) Test
 
+assert("Array.try_convert") do
+  assert_nil Array.try_convert(0)
+  assert_nil Array.try_convert(nil)
+  assert_equal [], Array.try_convert([])
+  assert_equal [1,2,3], Array.try_convert([1,2,3])
+end
+
 assert("Array#assoc") do
   s1 = [ "colors", "red", "blue", "green" ]
   s2 = [ "letters", "a", "b", "c" ]
@@ -298,3 +305,8 @@ assert("Array#index (block)") do
   assert_nil (1..10).to_a.index { |i| i % 5 == 0 and i % 7 == 0 }
   assert_equal 34, (1..100).to_a.index { |i| i % 5 == 0 and i % 7 == 0 }
 end
+
+assert("Array#to_ary") do
+  assert_equal [], [].to_ary
+  assert_equal [1,2,3], [1,2,3].to_ary
+end