Some time refactors to reuse code for the parser

src/time/time.cr

-require "./*"
+require "./**"
 
 lib C
   struct TimeSpec

src/time/time_format.cr

 struct TimeFormat
-  MONTH_NAMES = %w(January February March April May June July August September October November December)
-  DAY_NAMES = %w(Sunday Monday Tuesday Wednesday Thursday Friday Saturday)
-
   getter pattern
 
   def initialize(@pattern : String)
   end
 
+  def parse(string)
+    # TimeParser.new(pattern, string).parse
+  end
+
   def format(time : Time)
     String.build do |str|
       format time, str
@@ -14,237 +15,7 @@ struct TimeFormat
   end
 
   def format(time : Time, io : IO)
-    i = 0
-    bytesize = pattern.bytesize
-    str = pattern.cstr
-
-    while i < bytesize
-      byte = str[i]
-      case byte.chr
-      when '%'
-        i += 1
-        byte = str[i]
-        case byte.chr
-        when 'a'
-          percent_a time, io
-        when 'A'
-          io << day_name(time)
-        when 'b', 'h'
-          percent_b time, io
-        when 'c'
-          percent_a time, io
-          char ' ', io
-          percent_b time, io
-          char ' ', io
-          percent_e time, io
-          char ' ', io
-          percent_T time, io
-          char ' ', io
-          percent_Y time, io
-        when 'B'
-          io << month_name(time)
-        when 'C'
-          io << time.year / 100
-        when 'd'
-          pad2 time.day, '0', io
-        when 'D', 'x'
-          percent_m time, io
-          char '/', io
-          percent_d time, io
-          char '/', io
-          percent_y time, io
-        when 'e'
-          percent_e time, io
-        when 'F'
-          percent_Y time, io
-          char '-', io
-          percent_m time, io
-          char '-', io
-          percent_d time, io
-        when 'j'
-          pad3 time.day_of_year, '0', io
-        when 'H'
-          percent_H time, io
-        when 'I'
-          percent_I time, io
-        when 'k'
-          pad2 time.hour, ' ', io
-        when 'l'
-          pad2 (time.hour % 12), ' ', io
-        when 'L'
-          pad3 time.millisecond, '0', io
-        when 'm'
-          percent_m time, io
-        when 'M'
-          percent_M time, io
-        when 'p'
-          io << (time.hour < 12 ? "am" : "pm")
-        when 'P'
-          percent_P time, io
-        when 'r'
-          percent_I time, io
-          char ':', io
-          percent_M time, io
-          char ':', io
-          percent_S time, io
-          char ' ', io
-          percent_P time, io
-        when 'R'
-          percent_H time, io
-          char ':', io
-          percent_M time, io
-        when 'S'
-          percent_S time, io
-        when 'T'
-          percent_T time, io
-        when 'u'
-          v = time.day_of_week
-          v = 7 if v == 0
-          io << v
-        when 'w'
-          io << time.day_of_week
-        when 'X'
-          percent_T time, io
-        when 'y'
-          percent_y time, io
-        when 'Y'
-          percent_Y time, io
-        when '_'
-          i += 1
-          byte = str[i]
-          case byte.chr
-          when 'm'
-            pad2 time.month, ' ', io
-          else
-            char '%', io
-            char '_', io
-            io.write_byte byte
-          end
-        when '-'
-          i += 1
-          byte = str[i]
-          case byte.chr
-          when 'd'
-            io << time.day
-          when 'm'
-            io << time.month
-          else
-            char '%', io
-            char '-', io
-            io.write_byte byte
-          end
-        when '^'
-          i += 1
-          byte = str[i]
-          case byte.chr
-          when 'A'
-            io << day_name(time).upcase
-          when 'b', 'h'
-            io << short_month_name(time).upcase
-          when 'B'
-            io << month_name(time).upcase
-          else
-            char '%', io
-            char '^', io
-            io.write_byte byte
-          end
-        when '%'
-          char '%', io
-        else
-          char '%', io
-          io.write_byte byte
-        end
-      else
-        io.write_byte byte
-      end
-
-      i += 1
-    end
-  end
-
-  private def percent_a(time, io)
-    io << short_day_name(time)
-  end
-
-  private def percent_b(time, io)
-    io << short_month_name(time)
-  end
-
-  private def percent_d(time, io)
-    pad2 time.day, '0', io
-  end
-
-  private def percent_e(time, io)
-    pad2 time.day, ' ', io
-  end
-
-  private def percent_H(time, io)
-    pad2 time.hour, '0', io
-  end
-
-  private def percent_I(time, io)
-    pad2 (time.hour % 12), '0', io
-  end
-
-  private def percent_m(time, io)
-    pad2 time.month, '0', io
-  end
-
-  private def percent_M(time, io)
-    pad2 time.minute, '0', io
-  end
-
-  private def percent_P(time, io)
-    io << (time.hour < 12 ? "AM" : "PM")
-  end
-
-  private def percent_S(time, io)
-    pad2 time.second, '0', io
-  end
-
-  private def percent_T(time, io)
-    percent_H time, io
-    char ':', io
-    percent_M time, io
-    char ':', io
-    percent_S time, io
-  end
-
-  private def percent_y(time, io)
-    io << time.year % 100
-  end
-
-  private def percent_Y(time, io)
-    io << time.year
-  end
-
-  private def char(char, io)
-    io.write_byte char.ord.to_u8
-  end
-
-  private def month_name(time)
-    MONTH_NAMES[time.month]
-  end
-
-  private def short_month_name(time)
-    month_name(time)[0, 3]
-  end
-
-  private def day_name(time)
-    DAY_NAMES[time.day_of_week]
-  end
-
-  private def short_day_name(time)
-    day_name(time)[0, 3]
-  end
-
-  private def pad2(value, padding, io)
-    io.write_byte padding.ord.to_u8 if value < 10
-    io << value
-  end
-
-  private def pad3(value, padding, io)
-    io.write_byte padding.ord.to_u8 if value < 100
-    pad2 value, padding, io
+    formatter = Formatter.new(time, io)
+    formatter.visit(pattern)
   end
 end

src/time/time_format/formatter.cr

+require "pattern"
+
+struct TimeFormat
+  struct Formatter
+    include Pattern
+
+    getter io
+    getter time
+
+    def initialize(@time, @io)
+    end
+
+    def short_day_name
+      io << get_short_day_name
+    end
+
+    def day_name
+      io << get_day_name
+    end
+
+    def short_month_name
+      io << get_short_month_name
+    end
+
+    def month_name
+      io << get_month_name
+    end
+
+    def year_divided_by_100
+      io << time.year / 100
+    end
+
+    def day_of_month_zero_padded
+      pad2 time.day, '0'
+    end
+
+    def day_of_month_blank_padded
+      pad2 time.day, ' '
+    end
+
+    def hour_24_zero_padded
+      pad2 time.hour, '0'
+    end
+
+    def hour_12_zero_padded
+      pad2 (time.hour % 12), '0'
+    end
+
+    def day_of_year_zero_padded
+      pad3 time.day_of_year, '0'
+    end
+
+    def hour_24_blank_padded
+      pad2 time.hour, ' '
+    end
+
+    def hour_12_blank_padded
+      pad2 (time.hour % 12), ' '
+    end
+
+    def milliseconds
+      pad3 time.millisecond, '0'
+    end
+
+    def month_zero_padded
+      pad2 time.month, '0'
+    end
+
+    def minute_zero_padded
+      pad2 time.minute, '0'
+    end
+
+    def am_pm
+      io << (time.hour < 12 ? "am" : "pm")
+    end
+
+    def am_pm_upcase
+      io << (time.hour < 12 ? "AM" : "PM")
+    end
+
+    def second_zero_padded
+      pad2 time.second, '0'
+    end
+
+    def day_of_week_monday_1_7
+      v = time.day_of_week
+      v = 7 if v == 0
+      io << v
+    end
+
+    def day_of_week_sunday_0_6
+      io << time.day_of_week
+    end
+
+    def year_modulo_100
+      io << time.year % 100
+    end
+
+    def year
+      io << time.year
+    end
+
+    def month_blank_padded
+      pad2 time.month, ' '
+    end
+
+    def day
+      io << time.day
+    end
+
+    def month
+      io << time.month
+    end
+
+    def day_name_upcase
+      io << get_day_name.upcase
+    end
+
+    def short_month_name_upcase
+      io << get_short_month_name.upcase
+    end
+
+    def month_name_upcase
+      io << get_month_name.upcase
+    end
+
+    def byte(byte)
+      io.write_byte byte
+    end
+
+    def get_month_name
+      MONTH_NAMES[time.month]
+    end
+
+    def get_short_month_name
+      get_month_name[0, 3]
+    end
+
+    def get_day_name
+      DAY_NAMES[time.day_of_week]
+    end
+
+    def get_short_day_name
+      get_day_name[0, 3]
+    end
+
+    def pad2(value, padding)
+      io.write_byte padding.ord.to_u8 if value < 10
+      io << value
+    end
+
+    def pad3(value, padding)
+      io.write_byte padding.ord.to_u8 if value < 100
+      pad2 value, padding
+    end
+  end
+end

src/time/time_format/pattern.cr

+struct TimeFormat
+  module Pattern
+    MONTH_NAMES = %w(January February March April May June July August September October November December)
+    DAY_NAMES = %w(Sunday Monday Tuesday Wednesday Thursday Friday Saturday)
+
+    def visit(pattern)
+      i = 0
+      bytesize = pattern.bytesize
+      str = pattern.cstr
+
+      while i < bytesize
+        byte = str[i]
+        case byte.chr
+        when '%'
+          i += 1
+          byte = str[i]
+          case byte.chr
+          when 'a'
+            short_day_name
+          when 'A'
+            day_name
+          when 'b', 'h'
+            short_month_name
+          when 'c'
+            date_and_time
+          when 'B'
+            month_name
+          when 'C'
+            year_divided_by_100
+          when 'd'
+            day_of_month_zero_padded
+          when 'D', 'x'
+            date
+          when 'e'
+            day_of_month_blank_padded
+          when 'F'
+            iso_8601_date
+          when 'j'
+            day_of_year_zero_padded
+          when 'H'
+            hour_24_zero_padded
+          when 'I'
+            hour_12_zero_padded
+          when 'k'
+            hour_24_blank_padded
+          when 'l'
+            hour_12_blank_padded
+          when 'L'
+            milliseconds
+          when 'm'
+            month_zero_padded
+          when 'M'
+            minute_zero_padded
+          when 'p'
+            am_pm
+          when 'P'
+            am_pm_upcase
+          when 'r'
+            twelve_hour_time
+          when 'R'
+            twenty_four_hour_time
+          when 'S'
+            second_zero_padded
+          when 'T'
+            twenty_four_hour_time_with_seconds
+          when 'u'
+            day_of_week_monday_1_7
+          when 'w'
+            day_of_week_sunday_0_6
+          when 'X'
+            twenty_four_hour_time_with_seconds
+          when 'y'
+            year_modulo_100
+          when 'Y'
+            year
+          when '_'
+            i += 1
+            byte = str[i]
+            case byte.chr
+            when 'm'
+              month_blank_padded
+            else
+              char '%'
+              char '_'
+              byte byte
+            end
+          when '-'
+            i += 1
+            byte = str[i]
+            case byte.chr
+            when 'd'
+              day
+            when 'm'
+              month
+            else
+              char '%'
+              char '-'
+              byte byte
+            end
+          when '^'
+            i += 1
+            byte = str[i]
+            case byte.chr
+            when 'A'
+              day_name_upcase
+            when 'b', 'h'
+              short_month_name_upcase
+            when 'B'
+              month_name_upcase
+            else
+              char '%'
+              char '^'
+              byte byte
+            end
+          when '%'
+            char '%'
+          else
+            char '%'
+            byte byte
+          end
+        else
+          byte byte
+        end
+
+        i += 1
+      end
+    end
+
+    def char(char)
+      byte char.ord.to_u8
+    end
+
+    def date_and_time
+      short_day_name
+      char ' '
+      short_month_name
+      char ' '
+      day_of_month_blank_padded
+      char ' '
+      twenty_four_hour_time_with_seconds
+      char ' '
+      year
+    end
+
+    def date
+      month_zero_padded
+      char '/'
+      day_of_month_zero_padded
+      char '/'
+      year_modulo_100
+    end
+
+    def iso_8601_date
+      year
+      char '-'
+      month_zero_padded
+      char '-'
+      day_of_month_zero_padded
+    end
+
+    def twelve_hour_time
+      hour_12_zero_padded
+      char ':'
+      minute_zero_padded
+      char ':'
+      second_zero_padded
+      char ' '
+      am_pm_upcase
+    end
+
+    def twenty_four_hour_time
+      hour_24_zero_padded
+      char ':'
+      minute_zero_padded
+    end
+
+    def twenty_four_hour_time_with_seconds
+      hour_24_zero_padded
+      char ':'
+      minute_zero_padded
+      char ':'
+      second_zero_padded
+    end
+  end
+end