add {Array|Hash|String}.try_convert

6 files changed, 98 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
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' }
diff --git a/mrbgems/mruby-string-ext/mrblib/string.rb b/mrbgems/mruby-string-ext/mrblib/string.rb
index 4c8a2ce3b..c699e13b7 100644
--- a/mrbgems/mruby-string-ext/mrblib/string.rb
+++ b/mrbgems/mruby-string-ext/mrblib/string.rb
@@ -1,6 +1,25 @@
 class String
 
   ##
+  #  call-seq:
+  #     String.try_convert(obj) -> string or nil
+  #
+  # Try to convert <i>obj</i> into a String, using to_str method.
+  # Returns converted string or nil if <i>obj</i> cannot be converted
+  # for any reason.
+  #
+  #     String.try_convert("str")     #=> "str"
+  #     String.try_convert(/re/)      #=> nil
+  #
+  def self.try_convert(obj)
+    if obj.respond_to?(:to_str)
+      obj.to_str
+    else
+      nil
+    end
+  end
+
+  ##
   # call-seq:
   #    string.clear    ->  string
   #
diff --git a/mrbgems/mruby-string-ext/test/string.rb b/mrbgems/mruby-string-ext/test/string.rb
index 8324a1613..37a5d28cf 100644
--- a/mrbgems/mruby-string-ext/test/string.rb
+++ b/mrbgems/mruby-string-ext/test/string.rb
@@ -3,6 +3,13 @@
 
 UTF8STRING = ("\343\201\202".size == 1)
 
+assert('String.try_convert') do
+  assert_nil String.try_convert(nil)
+  assert_nil String.try_convert(:foo)
+  assert_equal "", String.try_convert("")
+  assert_equal "1,2,3", String.try_convert("1,2,3")
+end
+
 assert('String#getbyte') do
   str1 = "hello"
   bytes1 = [104, 101, 108, 108, 111]