Add `year_format` option to date_select tag. This option makes it possible to customize year

names. Lambda should be passed to use this option. Example:

    date_select('user_birthday', '', start_year: 1998, end_year: 2000, year_format: ->year { "Heisei #{year - 1988}" })

The HTML produced:

    <select id="user_birthday__1i" name="user_birthday[(1i)]">
    <option value="1998">Heisei 10</option>
    <option value="1999">Heisei 11</option>
    <option value="2000">Heisei 12</option>
    </select>
    /* The rest is omitted */

1 files changed, 44 insertions, 1 deletions

diff --git a/actionview/lib/action_view/helpers/date_helper.rb b/actionview/lib/action_view/helpers/date_helper.rb
index 620e1e9f21..1622b9f680 100644
--- a/actionview/lib/action_view/helpers/date_helper.rb
+++ b/actionview/lib/action_view/helpers/date_helper.rb
@@ -850,7 +850,7 @@ module ActionView
             raise ArgumentError, "There are too many years options to be built. Are you sure you haven't mistyped something? You can provide the :max_years_allowed parameter."
           end
 
-          build_options_and_select(:year, val, options)
+          build_select(:year, build_year_options(val, options))
         end
       end
 
@@ -933,6 +933,21 @@ module ActionView
           end
         end
 
+        # Looks up year names by number.
+        #
+        #   year_name(1998) # => 1998
+        #
+        # If the <tt>:year_format</tt> option is passed:
+        #
+        #   year_name(1998) # => "Heisei 10"
+        def year_name(number)
+          if year_format_lambda = @options[:year_format]
+            year_format_lambda.call(number)
+          else
+            number
+          end
+        end
+
         def date_order
           @date_order ||= @options[:order] || translated_date_order
         end
@@ -995,6 +1010,34 @@ module ActionView
           (select_options.join("\n") + "\n").html_safe
         end
 
+        # Build select option HTML for year.
+        # If <tt>year_format</tt> option is not passed
+        #  build_year_options(1998, start: 1998, end: 2000)
+        #  => "<option value="1998" selected="selected">1998</option>
+        #      <option value="1999">1999</option>
+        #      <option value="2000">2000</option>"
+        #
+        # If <tt>year_format</tt> option is passed
+        #  build_year_options(1998, start: 1998, end: 2000, year_format: ->year { "Heisei #{ year - 1988 }" })
+        #  => "<option value="1998" selected="selected">Heisei 10</option>
+        #      <option value="1999">Heisei 11</option>
+        #      <option value="2000">Heisei 12</option>"
+        def build_year_options(selected, options = {})
+          start = options.delete(:start)
+          stop = options.delete(:end)
+          step = options.delete(:step)
+
+          select_options = []
+          start.step(stop, step) do |value|
+            tag_options = { value: value }
+            tag_options[:selected] = "selected" if selected == value
+            text = year_name(value)
+            select_options << content_tag("option".freeze, text, tag_options)
+          end
+
+          (select_options.join("\n") + "\n").html_safe
+        end
+
         # Builds select tag from date type and HTML select options.
         #  build_select(:month, "<option value="1">January</option>...")
         #  => "<select id="post_written_on_2i" name="post[written_on(2i)]">