From 1cccb8392abb9c914ad81a6a7cb1072a32d4d83c Mon Sep 17 00:00:00 2001
From: Jesse Gumm <gumm@sigma-star.com>
Date: Sun, 4 Feb 2018 12:21:47 -0600
Subject: [PATCH] Add support for named days of the week in beginning_week

---
 README.markdown | 15 +++++++++++++--
 src/qdate.erl   | 19 +++++++++++++++++++
 2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/README.markdown b/README.markdown
index 21f0cf7..25b9e56 100644
--- a/README.markdown
+++ b/README.markdown
@@ -719,12 +719,23 @@ the week" calculation.  This has three forms, specifically:
      (chosen because Erlang's calendar:day_of_the_week uses 1=Monday and
      7=Sunday).
    + `beginning_week(DayOfWeek, Date)` - Calculates the beginning of the week
-     based on the provided `DayOfWeek`. Valid values for DayOfWeek are 1-7,
-     where 1=Monday, and 7=Sunday.
+     based on the provided `DayOfWeek`. Valid values for DayOfWeek are the
+     integers 1-7 or the atom verions of the days of the week. Specifically:
+	 
+     * Monday: `1 | monday | mon`
+     * Tuesday: `2 | tuesday | tue`
+     * Wednesday: `3 | wednesday | wed`
+     * Thursday: `4 | thursday | thu`
+     * Friday: `5 | friday | fri`
+     * Saturday: `6 | saturday | sat`
+     * Sunday: `7 | sunday | sun`
 
 These all return 12am on the day that is the first day of the week of the
 provided date.
 
+(My apologies to non-English speakers. I'm a lazy American who only speaks
+English, hence the Anglocentric day names).
+
 ### End of time period
 
 There are also the related `end_X` functions available, using the same
diff --git a/src/qdate.erl b/src/qdate.erl
index 39c3967..48e841e 100644
--- a/src/qdate.erl
+++ b/src/qdate.erl
@@ -407,6 +407,9 @@ beginning_week() ->
 beginning_week(Date) ->
     beginning_week(1, Date).
 
+beginning_week(BeginningDayOfWeek, Date) when is_atom(BeginningDayOfWeek) ->
+    DOW = weekday_map(BeginningDayOfWeek),
+    beginning_week(DOW, Date);
 beginning_week(BeginningDayOfWeek, Date0) when
         BeginningDayOfWeek >= 1,
         BeginningDayOfWeek =< 7,
@@ -424,6 +427,22 @@ beginning_week(BeginningDayOfWeek, Date0) when
             beginning_day(add_days(-Diff, Date))
     end.
 
+weekday_map(mon) -> 1;
+weekday_map(tue) -> 2;
+weekday_map(wed) -> 3;
+weekday_map(thu) -> 4;
+weekday_map(fri) -> 5;
+weekday_map(sat) -> 6;
+weekday_map(sun) -> 7;
+
+weekday_map(monday) -> 1;
+weekday_map(tuesday) -> 2;
+weekday_map(wednesday) -> 3;
+weekday_map(thursday) -> 4;
+weekday_map(friday) -> 5;
+weekday_map(saturday) -> 6;
+weekday_map(sunday) -> 7.
+
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %%%%%%%%%%%%%%%%%%%%%% End of Period (day/hour, etc)  %%%%%%%%%%%%%%%%%%%%%%%%%%
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%