extracted parsing/translating logic into another class to avoid addin…

…g private methods to Date and Time

lib/stamp.rb

@@ -1,43 +1,9 @@
+require "stamp/translator"
 require "stamp/version"
 require "date"
 require "time"
 
 module Stamp
-  MONTHNAMES_REGEXP      = /^(#{Date::MONTHNAMES.compact.join('|')})$/i
-  ABBR_MONTHNAMES_REGEXP = /^(#{Date::ABBR_MONTHNAMES.compact.join('|')})$/i
-  DAYNAMES_REGEXP        = /^(#{Date::DAYNAMES.join('|')})$/i
-  ABBR_DAYNAMES_REGEXP   = /^(#{Date::ABBR_DAYNAMES.join('|')})$/i
-
-  ONE_DIGIT_REGEXP       = /^\d{1}$/
-  TWO_DIGIT_REGEXP       = /^\d{2}$/
-  FOUR_DIGIT_REGEXP      = /^\d{4}$/
-
-  TIME_REGEXP            = /(\d{1,2})(:)(\d{2})(\s*)(:)?(\d{2})?(\s*)?([ap]m)?/i
-
-  MERIDIAN_LOWER_REGEXP  = /^(a|p)m$/
-  MERIDIAN_UPPER_REGEXP  = /^(A|P)M$/
-
-  # Disambiguate based on value
-  OBVIOUS_YEARS          = 60..99
-  OBVIOUS_MONTHS         = 12
-  OBVIOUS_DAYS           = 28..31
-  OBVIOUS_24_HOUR        = 13..23
-
-  TWO_DIGIT_DATE_SUCCESSION = {
-    '%m' => '%d',
-    '%b' => '%d',
-    '%B' => '%d',
-    '%d' => '%y',
-    '%e' => '%y'
-  }
-
-  TWO_DIGIT_TIME_SUCCESSION = {
-    '%H' => '%M',
-    '%I' => '%M',
-    '%l' => '%M',
-    '%M' => '%S'
-  }
-
   # Formats a date/time using a human-friendly example as a template.
   #
   # @param  [String] example a human-friendly date/time example
@@ -60,101 +26,7 @@ def stamp(example)
   # @example
   #   Date.today.strftime_format("Jan 1, 1999") #=> "%b %e, %Y"
   def strftime_format(example)
-    # extract any substrings that look like times, like "23:59" or "8:37 am"
-    before, time_example, after = example.partition(TIME_REGEXP)
-
-    # transform any date tokens to strftime directives
-    words = strftime_directives(before.split(/\b/)) do |token, previous_directive|
-      strftime_date_directive(token, previous_directive)
-    end
-
-    # transform the example time string to strftime directives
-    unless time_example.empty?
-      time_parts = time_example.scan(TIME_REGEXP).first
-      words += strftime_directives(time_parts) do |token, previous_directive|
-        strftime_time_directive(token, previous_directive)
-      end
-    end
-
-    # recursively process any remaining text
-    words << strftime_format(after) unless after.empty?
-    words.join
-  end
-
-  private
-
-  # Transforms tokens that look like date/time parts to strftime directives.
-  def strftime_directives(tokens)
-    previous_directive = nil
-    tokens.map do |token|
-      directive = yield(token, previous_directive)
-      previous_directive = directive unless directive.nil?
-      directive || token
-    end
-  end
-
-  def strftime_time_directive(token, previous_directive)
-    case token
-    when MERIDIAN_LOWER_REGEXP
-      if RUBY_VERSION =~ /^1.8/ && self.is_a?(Time)
-        # 1.8.7 doesn't implement %P
-        self.strftime("%p").downcase
-      else
-        '%P'
-      end
-
-    when MERIDIAN_UPPER_REGEXP
-      '%p'
-
-    when TWO_DIGIT_REGEXP
-      TWO_DIGIT_TIME_SUCCESSION[previous_directive] ||
-        case token.to_i
-        when OBVIOUS_24_HOUR
-          '%H' # 24-hour clock
-        else
-          '%I' # 12-hour clock with leading zero
-        end
-
-    when ONE_DIGIT_REGEXP
-      '%l' # hour without leading zero
-    end
-  end
-
-  def strftime_date_directive(token, previous_directive)
-    case token
-    when MONTHNAMES_REGEXP
-      '%B'
-
-    when ABBR_MONTHNAMES_REGEXP
-      '%b'
-
-    when DAYNAMES_REGEXP
-      '%A'
-
-    when ABBR_DAYNAMES_REGEXP
-      '%a'
-
-    when FOUR_DIGIT_REGEXP
-      '%Y'
-
-    when TWO_DIGIT_REGEXP
-      # try to discern obvious intent based on the example value
-      case token.to_i
-      when OBVIOUS_YEARS
-        '%y'
-      when OBVIOUS_MONTHS
-        '%m'
-      when OBVIOUS_DAYS
-        '%d'
-      else
-        # the intent isn't obvious based on the example value, so try to
-        # disambiguate based on context
-        TWO_DIGIT_DATE_SUCCESSION[previous_directive] || '%m'
-      end
-
-    when ONE_DIGIT_REGEXP
-      '%e' # day without leading zero
-    end
+    Stamp::StrftimeTranslator.new(self).translate(example)
   end
 end
 

lib/stamp/translator.rb

@@ -0,0 +1,139 @@
+module Stamp
+  class StrftimeTranslator
+    MONTHNAMES_REGEXP      = /^(#{Date::MONTHNAMES.compact.join('|')})$/i
+    ABBR_MONTHNAMES_REGEXP = /^(#{Date::ABBR_MONTHNAMES.compact.join('|')})$/i
+    DAYNAMES_REGEXP        = /^(#{Date::DAYNAMES.join('|')})$/i
+    ABBR_DAYNAMES_REGEXP   = /^(#{Date::ABBR_DAYNAMES.join('|')})$/i
+
+    ONE_DIGIT_REGEXP       = /^\d{1}$/
+    TWO_DIGIT_REGEXP       = /^\d{2}$/
+    FOUR_DIGIT_REGEXP      = /^\d{4}$/
+
+    TIME_REGEXP            = /(\d{1,2})(:)(\d{2})(\s*)(:)?(\d{2})?(\s*)?([ap]m)?/i
+
+    MERIDIAN_LOWER_REGEXP  = /^(a|p)m$/
+    MERIDIAN_UPPER_REGEXP  = /^(A|P)M$/
+
+    # Disambiguate based on value
+    OBVIOUS_YEARS          = 60..99
+    OBVIOUS_MONTHS         = 12
+    OBVIOUS_DAYS           = 28..31
+    OBVIOUS_24_HOUR        = 13..23
+
+    TWO_DIGIT_DATE_SUCCESSION = {
+      '%m' => '%d',
+      '%b' => '%d',
+      '%B' => '%d',
+      '%d' => '%y',
+      '%e' => '%y'
+    }
+
+    TWO_DIGIT_TIME_SUCCESSION = {
+      '%H' => '%M',
+      '%I' => '%M',
+      '%l' => '%M',
+      '%M' => '%S'
+    }
+
+    def initialize(target_date_or_time)
+      @target = target_date_or_time
+    end
+
+    def translate(example)
+      # extract any substrings that look like times, like "23:59" or "8:37 am"
+      before, time_example, after = example.partition(TIME_REGEXP)
+
+      # transform any date tokens to strftime directives
+      words = strftime_directives(before.split(/\b/)) do |token, previous_directive|
+        strftime_date_directive(token, previous_directive)
+      end
+
+      # transform the example time string to strftime directives
+      unless time_example.empty?
+        time_parts = time_example.scan(TIME_REGEXP).first
+        words += strftime_directives(time_parts) do |token, previous_directive|
+          strftime_time_directive(token, previous_directive)
+        end
+      end
+
+      # recursively process any remaining text
+      words << translate(after) unless after.empty?
+      words.join
+    end
+
+    # Transforms tokens that look like date/time parts to strftime directives.
+    def strftime_directives(tokens)
+      previous_directive = nil
+      tokens.map do |token|
+        directive = yield(token, previous_directive)
+        previous_directive = directive unless directive.nil?
+        directive || token
+      end
+    end
+
+    def strftime_time_directive(token, previous_directive)
+      case token
+      when MERIDIAN_LOWER_REGEXP
+        if RUBY_VERSION =~ /^1.8/ && @target.is_a?(Time)
+          # 1.8.7 doesn't implement %P
+          @target.strftime("%p").downcase
+        else
+          '%P'
+        end
+
+      when MERIDIAN_UPPER_REGEXP
+        '%p'
+
+      when TWO_DIGIT_REGEXP
+        TWO_DIGIT_TIME_SUCCESSION[previous_directive] ||
+          case token.to_i
+          when OBVIOUS_24_HOUR
+            '%H' # 24-hour clock
+          else
+            '%I' # 12-hour clock with leading zero
+          end
+
+      when ONE_DIGIT_REGEXP
+        '%l' # hour without leading zero
+      end
+    end
+
+    def strftime_date_directive(token, previous_directive)
+      case token
+      when MONTHNAMES_REGEXP
+        '%B'
+
+      when ABBR_MONTHNAMES_REGEXP
+        '%b'
+
+      when DAYNAMES_REGEXP
+        '%A'
+
+      when ABBR_DAYNAMES_REGEXP
+        '%a'
+
+      when FOUR_DIGIT_REGEXP
+        '%Y'
+
+      when TWO_DIGIT_REGEXP
+        # try to discern obvious intent based on the example value
+        case token.to_i
+        when OBVIOUS_YEARS
+          '%y'
+        when OBVIOUS_MONTHS
+          '%m'
+        when OBVIOUS_DAYS
+          '%d'
+        else
+          # the intent isn't obvious based on the example value, so try to
+          # disambiguate based on context
+          TWO_DIGIT_DATE_SUCCESSION[previous_directive] || '%m'
+        end
+
+      when ONE_DIGIT_REGEXP
+        '%e' # day without leading zero
+      end
+    end
+
+  end
+end