Potential form

lib/verb.rb

@@ -40,13 +40,13 @@ class KanaKanji
 end
 
 class Verb
-  attr_reader :dict_kanji, :dict_kana, :definition_english, :dict
+  attr_reader :dict_kanji, :dict_kana, :definition, :dict
 
-  def initialize(dict_kanji, dict_kana, definition_english)
+  def initialize(dict_kanji, dict_kana, definition)
     @dict_kanji = dict_kanji || dict_kana
     @dict_kana = dict_kana
     @dict = KanaKanji.new dict_kana, dict_kanji
-    @definition_english = definition_english
+    @definition = definition
   end
 
   def last_character(new_form=nil)
@@ -96,6 +96,10 @@ class Verb
   def desire
     stem + "たい"
   end
+
+  def potential
+    IchidanVerb.new(potential_starter.kanji, potential_starter.kana, "to be able #{definition}")
+  end
 end
 
 class IchidanVerb < Verb
@@ -110,6 +114,10 @@ class IchidanVerb < Verb
   def te
     all_but_last_character + "て"
   end
+
+  def potential_starter
+    stem + "られる"
+  end
 end
 
 class GodanVerb < Verb
@@ -125,6 +133,10 @@ class GodanVerb < Verb
     all_but_last_character + last_character("a") + "ない"
   end
 
+  def potential_starter
+    all_but_last_character + last_character("e") + "る"
+  end
+
   def te
     all_but_last_character + case last_character
                              when "う"
@@ -165,5 +177,9 @@ class SuruVerb < Verb
   def te
     prefix + "して"
   end
+
+  def potential_starter
+    prefix + "できる"
+  end
 end
 

test/test_verb.rb

@@ -138,4 +138,15 @@ class TestVerb < Minitest::Test
     assert_equal "勉強したい", @benkyousuru.desire.kanji
     assert_equal "べんきょうしたい", @benkyousuru.desire.kana
   end
+
+  def test_potential
+    assert_equal "見られる", @miru.potential.dictionary.kanji
+    assert_equal "みられる", @miru.potential.dictionary.kana
+    assert_equal "飲める", @nomu.potential.dictionary.kanji
+    assert_equal "のめる", @nomu.potential.dictionary.kana
+    assert_equal "できる", @suru.potential.dictionary.kanji
+    assert_equal "できる", @suru.potential.dictionary.kana
+    assert_equal "勉強できる", @benkyousuru.potential.dictionary.kanji
+    assert_equal "べんきょうできる", @benkyousuru.potential.dictionary.kana
+  end
 end