Add 'today' parameter to .parse method

Refs mojombo#295
This one allows Chronic.parse method to receive
`today: true` param alongside a string to parse to allow
parsing ambiguous week days by name. E.g.:

Time.now  			     #=> Sun Aug 27 23:18:25 PDT 2006
Chronic.parse('sunday') 	     #=> Sun Sep 03 12:00:00 PDT 2006
Chronic.parse('sunday', today: true) #=> Sun Aug 27 12:00:00 PDT 2006

README.md

@@ -40,6 +40,12 @@ Chronic.parse('6/4/2012', :endian_precedence => :little)
 
 Chronic.parse('INVALID DATE')
   #=> nil
+
+Chronic.parse('sunday')
+  #=> Sun Sep 03 12:00:00 PDT 2006
+
+Chronic.parse('sunday', today: true)
+  #=> Sun Aug 27 12:00:00 PDT 2006
 ```
 
 If the parser can find a date or time, either a Time or Chronic::Span

lib/chronic/handlers.rb

@@ -521,7 +521,9 @@ def get_anchor(tokens, options)
       when :last
         outer_span = head.next(:past)
       when :this
-        if options[:context] != :past and repeaters.size > 0
+        if options[:today]
+          outer_span = head.this(:today)
+        elsif options[:context] != :past and repeaters.size > 0
           outer_span = head.this(:none)
         else
           outer_span = head.this(options[:context])

lib/chronic/parser.rb

@@ -14,7 +14,8 @@ class Parser
       :guess => true,
       :ambiguous_time_range => 6,
       :endian_precedence    => [:middle, :little],
-      :ambiguous_year_future_bias => 50
+      :ambiguous_year_future_bias => 50,
+      :today => false
     }
 
     attr_accessor :now
@@ -54,6 +55,11 @@ class Parser
     #                 look x amount of years into the future and past. If the
     #                 two digit year is `now + x years` it's assumed to be the
     #                 future, `now - x years` is assumed to be the past.
+    #        :today - When true is given, Chronic will parse day name as current
+    #                 date if they are ambigious. For example, Chronic.parse("monday")
+    #                 on 02/09/2015 will give "2015-02-16 12:00:00" without :today flag,
+    #                 and "2015-02-09 12:00:00" with `today: true`.
+
     def initialize(options = {})
       @options = DEFAULT_OPTIONS.merge(options)
       @now = options.delete(:now) || Chronic.time_class.now

lib/chronic/repeaters/repeater_day_name.rb

@@ -11,13 +11,15 @@ def next(pointer)
       super
 
       direction = pointer == :future ? 1 : -1
+      direction = 0 if pointer == :today
+
+      day_num = symbol_to_number(@type)
+      raise ArgumentError, "It's not #{day_num.to_s} today" if pointer == :today && @now.wday != day_num
 
       unless @current_date
         @current_date = ::Date.new(@now.year, @now.month, @now.day)
         @current_date += direction
 
-        day_num = symbol_to_number(@type)
-
         while @current_date.wday != day_num
           @current_date += direction
         end

test/test_parsing.rb

@@ -1239,6 +1239,34 @@ def test_handle_rdn_rmn_od_sy
     assert_equal Time.local(2005, 12, 30, 12), time
   end
 
+  def test_get_anchor
+    time = parse_now("wednesday")
+    assert_equal Time.local(2006, 8, 23, 12), time
+
+    time = parse_now("this wednesday")
+    assert_equal Time.local(2006, 8, 23, 12), time
+
+    time = parse_now("wednesday at 16:30")
+    assert_equal Time.local(2006, 8, 23, 16, 30), time
+
+    time = parse_now("wednesday", today: true)
+    assert_equal Time.local(2006, 8, 16, 12), time
+
+    time = parse_now("this wednesday", today: true)
+    assert_equal Time.local(2006, 8, 16, 12), time
+
+    time = parse_now("wednesday at 16:00", today: true)
+    assert_equal Time.local(2006, 8, 16, 16), time
+
+    assert_raises(ArgumentError) do
+      parse_now("thursday at 16:00", today: true)
+    end
+
+    assert_raises(ArgumentError) do
+      parse_now("tuesday", today: true)
+    end
+  end
+
   def test_normalizing_day_portions
     assert_equal pre_normalize("8:00 pm February 11"), pre_normalize("8:00 p.m. February 11")
   end