Module: RiCal::CoreExtensions::Time::Calculations
Overview

©2009 Rick DeNatale

All rights reserved. Refer to the file README.txt for the license
Provide calculation methods for use by the RiCal gem This module is included by Time, Date, and DateTime
Class Method Summary collapse

.convert_wday(wday) ⇒ Object
Convert the receivers wday to RFC 2445 format.

.iso_week_one(year, wkst) ⇒ Object
Return the date on which the first iso week with a given starting week day occurs for a given iso year.
Instance Method Summary collapse

#days_in_month ⇒ Object
Return the number of days in the month which includes the receiver.

#iso_week_num(wkst) ⇒ Object
 return the iso week number of the receiver == parameter wkst

an integer representing the day of the week on which weeks are deemed to start.

#iso_weeks_in_year(wkst) ⇒ Object
 return the number of weeks in the the iso year containing the receiver == parameter wkst

an integer representing the day of the week on which weeks are deemed to start.

#iso_year(wkst) ⇒ Object
 return the iso year of the receiver == parameter wkst

an integer representing the day of the week on which weeks are deemed to start.

#iso_year_and_week_num(wkst) ⇒ Object
:nodoc:.

#iso_year_and_week_one_start(wkst) ⇒ Object
Return an array containing the iso year and iso week number for the receiver.

#iso_year_start(wkst) ⇒ Object
 return the first day of the iso year of the receiver == parameter wkst

an integer representing the day of the week on which weeks are deemed to start.

#leap_year? ⇒ Boolean
A predicate method used to determine if the receiver is within a leap year.
Class Method Details
.convert_wday(wday) ⇒ Object
Convert the receivers wday to RFC 2445 format. Whereas the Ruby time/date classes use 0 to represent Sunday, RFC 2445 uses 7.
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# File 'lib/ri_cal/core_extensions/time/calculations.rb', line 79 def self.convert_wday(wday) wday == 0 ? 7 : wday end 
.iso_week_one(year, wkst) ⇒ Object
Return the date on which the first iso week with a given starting week day occurs for a given iso year
From RFC 2445 page 43: A week is defined as a seven day period, starting on the day of the week defined to be the week start (see WKST). Week number one of the calendar year is the first week which contains at least four (4) days in that calendar year.
parameters
 year

the iso year
 wkst

an integer representing the day of the week on which weeks are deemed to start. This uses
the ruby convention where 0 represents Sunday.
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# File 'lib/ri_cal/core_extensions/time/calculations.rb', line 35 def self.iso_week_one(year, wkst) # # Note that wkst uses the ruby definition, with Sunday = 0 # # A good article about calculating ISO week number is at # http://www.boyet.com/Articles/PublishedArticles/CalculatingtheISOweeknumb.html # # RFC 2445 generalizes the notion of ISO week by allowing the start of the week to vary. # In order to adopt the algorithm in the referenced article, we must determine, for each # wkst value, the day in January which must be contained in week 1 of the year. # # For a given wkst week 1 for a year is the first week which # 1) Starts with a day with a wday of wkst # 2) Contains a majority (4 or more) of days in that year # # If end of prior Dec, start of Jan Week 1 starts on For WKST = # MO TU WE TH FR SA SU MO TU WE TH FR SA SU MO TU WE TH FR SA SU # 01 02 03 04 05 06 07 08 09 10 11 12 13 14 0107 0208 0309 0410 0511 0612 0713 # 31 01 02 03 04 05 06 07 08 09 10 11 12 13 3106 0107 0208 0309 0410 0511 0612 # 30 31 01 02 03 04 05 06 07 08 09 10 11 12 3005 3106 0107 0208 0309 0410 0511 # 29 30 31 01 02 03 04 05 06 07 08 09 10 11 2904 3005 3106 0107 0208 0309 0410 # 28 29 30 31 01 02 03 04 05 06 07 08 09 10 0410 2904 3005 3106 0107 0208 0309 # 27 28 29 30 31 01 02 03 04 05 06 07 08 09 0309 0410 2904 3005 3106 0107 0208 # 26 27 28 29 30 31 01 02 03 04 05 06 07 08 0208 0309 0410 2904 3005 3106 0107 # 25 26 27 28 29 30 31 01 02 03 04 05 06 07 0107 0208 0309 0410 2904 3005 3106 # Week 1 must contain 4 4 4 4 ? ? ? # # So for a wkst of FR, SA, or SU, there is no date which MUST be contained in the 1st week # We'll have to brute force that if (1..4).include?(wkst) # return the date of the wkst day which is less than or equal to jan4th jan4th = ::Date.new(year, 1, 4) result = jan4th  (convert_wday(jan4th.wday)  convert_wday(wkst)) else # return the date of the wkst day which is greater than or equal to Dec 31 of the prior year dec29th = ::Date.new(year1, 12, 29) result = dec29th + convert_wday(wkst)  convert_wday(dec29th.wday) end result end 
Instance Method Details
#days_in_month ⇒ Object
Return the number of days in the month which includes the receiver
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# File 'lib/ri_cal/core_extensions/time/calculations.rb', line 16 def days_in_month raw = [0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31][self.month] self.month == 2 && leap_year? ? raw + 1 : raw end 
#iso_week_num(wkst) ⇒ Object
return the iso week number of the receiver
parameter
 wkst

an integer representing the day of the week on which weeks are deemed to start. This uses
the ruby convention where 0 represents Sunday.
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# File 'lib/ri_cal/core_extensions/time/calculations.rb', line 131 def iso_week_num(wkst) iso_year_and_week_num(wkst)[1] end 
#iso_weeks_in_year(wkst) ⇒ Object
return the number of weeks in the the iso year containing the receiver
parameter
 wkst

an integer representing the day of the week on which weeks are deemed to start. This uses
the ruby convention where 0 represents Sunday.
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# File 'lib/ri_cal/core_extensions/time/calculations.rb', line 117 def iso_weeks_in_year(wkst) iso_year, week_one_start = *iso_year_and_week_one_start(wkst) probe_date = week_one_start + (7*52) if probe_date.iso_year(wkst) == iso_year 53 else 52 end end 
#iso_year(wkst) ⇒ Object
return the iso year of the receiver
parameter
 wkst

an integer representing the day of the week on which weeks are deemed to start. This uses
the ruby convention where 0 represents Sunday.
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# File 'lib/ri_cal/core_extensions/time/calculations.rb', line 139 def iso_year(wkst) iso_year_and_week_num(wkst)[0] end 
#iso_year_and_week_num(wkst) ⇒ Object
:nodoc:
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# File 'lib/ri_cal/core_extensions/time/calculations.rb', line 108 def iso_year_and_week_num(wkst) #:nodoc: iso_year, week_one_start = *iso_year_and_week_one_start(wkst) [iso_year, (::Date.new(self.year, self.month, self.mday)  week_one_start).to_i / 7 + 1] end 
#iso_year_and_week_one_start(wkst) ⇒ Object
Return an array containing the iso year and iso week number for the receiver. Note that the iso year may be the year before or after the calendar year containing the receiver.
parameter
 wkst

an integer representing the day of the week on which weeks are deemed to start. This uses
the ruby convention where 0 represents Sunday.
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# File 'lib/ri_cal/core_extensions/time/calculations.rb', line 88 def iso_year_and_week_one_start(wkst) iso_year = self.year date = ::Date.new(self.year, self.month, self.mday) if (date >= ::Date.new(iso_year, 12, 29)) week_one_start = Calculations.iso_week_one(iso_year + 1, wkst) if date < week_one_start week_one_start = Calculations.iso_week_one(iso_year, wkst) else iso_year += 1 end else week_one_start = Calculations.iso_week_one(iso_year, wkst) if (date < week_one_start) iso_year = 1 week_one_start = Calculations.iso_week_one(iso_year, wkst) end end [iso_year, week_one_start] end 
#iso_year_start(wkst) ⇒ Object
return the first day of the iso year of the receiver
parameter
 wkst

an integer representing the day of the week on which weeks are deemed to start. This uses
the ruby convention where 0 represents Sunday.
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# File 'lib/ri_cal/core_extensions/time/calculations.rb', line 147 def iso_year_start(wkst) iso_year_and_week_one_start(wkst)[1] end 
#leap_year? ⇒ Boolean
A predicate method used to determine if the receiver is within a leap year
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# File 'lib/ri_cal/core_extensions/time/calculations.rb', line 11 def leap_year? year % 4 == 0 && (year % 400 == 0  year % 100 != 0) end 