Remove travis and replace badge with GH actions

Fix typos

.github/workflows/tests-workflow.yml

@@ -0,0 +1,47 @@
+name: qdate tests and dialyzer
+on: push
+
+jobs:
+  linux:
+    name: OTP ${{ matrix.otp_version }}
+    runs-on: ${{ matrix.os }}
+    continue-on-error: true
+
+    strategy:
+      matrix:
+        include:
+          - os: ubuntu-22.04
+            otp_version: '27.x'
+            rebar3_version: "3.24.0"
+          - os: ubuntu-22.04
+            otp_version: '27.x'
+            rebar3_version: "3.23.0"
+          - os: ubuntu-22.04
+            otp_version: '26.x'
+            rebar3_version: "3.22.1"
+          - os: ubuntu-22.04
+            otp_version: '25.x'
+            rebar3_version: "3.22.1"
+          - os: ubuntu-22.04
+            otp_version: '24.x'
+            rebar3_version: "3.22.1"
+          - os: ubuntu-20.04
+            otp_version: '23.x'
+            rebar3_version: "3.19.0"
+
+    steps:
+      - name: Install OTP ${{matrix.otp_version}}
+        uses: erlef/setup-beam@v1
+        with:
+          version-type: loose
+          otp-version: ${{ matrix.otp_version}}
+          rebar3-version: ${{ matrix.rebar3_version}}
+
+      - name: Checkout qdate
+        uses: actions/checkout@v4
+
+      - name: Run Tests
+        run: make test
+
+      - name: Run Dialyzer
+        run: make dialyzer

.gitignore

@@ -1,8 +1,10 @@
 *~
 *.beam
 *.sw?
+*.iml
 deps/
 ebin/
 .eunit/
+.idea/
 _build
-rebar.lock
+doc/

.travis.yml

@@ -1,11 +0,0 @@
-language: erlang
-script: "make test"
-otp_release:
-  - 17.4
-  - 17.1
-  - 17.0
-  - R16B
-  - R15B02
-  - R15B01
-  - R15B
-before_script: "sudo apt-get --yes --force-yes install libpam0g-dev"

CHANGELOG.markdown

@@ -1,8 +1,50 @@
-## 0.5.0 (in development)
+## 0.7.3
 
-* Update to rebar3 and add hex compatability. (@Licenser)
+* Remove the `?else` macro.
+
+## 0.7.2
+
+* Update the error message when qdate is not started with some better instructions.
+* Some minor updates for hex.pm
+* Removed the `erlnow()` warning
+* Fix some typos in the documentation
+* Update the makefile to use [rebar3.mk](https://rebar3.mk)
+* Skipped 0.7.1 only because there was a partially tagged 0.7.1 for a while,
+  but was never published to hex. Just to ensure upgrades are easier, I just skipped
+  a proper 0.7.1 release
+
+## 0.7.0
+
+* Re-introduce the qdate server for storing qdate timezones, formats, and parsers,
+  rather than overloading the `application` env vars (since the `application`
+  module only wants keys to be atoms).
+* Convert to using `qdate_localtime` 1.2.0 (which passes dialyzer checks)
+* `qdate` is passing dialyzer again
+
+## 0.6.0
+
+* Add `age` and `age_days` functions
+* Add option to preserve millisecond accuracy in date parsing and formatting (@Leonardb)
+
+
+## 0.5.0
+
+* Add `range_X` functions for getting a list of dates/times within a range
+  (such as `range_day/3` to get a range of days between a start and end date.
+* Add `beginning_X` functions to return the beginning of the provided precision
+  (minute, hour, day, week, month, or year)
++ Add `end_X` functions to return the last second of each time period (this is
+  just the opposite of `beginning_X`)
+* Add `between/[2,3,5]` functions for computing whether a date/time is between
+  two others.
+* Update to rebar3 and add hex compatibility. (@Licenser)
 * Properly add dependent apps to .app.src (@Licenser)
-* Remove R14 from travis testing.
+* Add an optional "relative date/time parser".
+* Fix: Ensure `get_timezone()` returns the default timezone (from config) if it
+  hasn't been set by `get_timezone()`
+* Fix UTC/GMT bug (@loudferret)
+* Fix Erlang 21 Stacktrace changes (@tnt-dev)
+* Set a better rebar2 version of erlware commons (@tnt-dev)
 
 ## 0.4.2
 

Makefile

@@ -1,21 +1,41 @@
-REBAR = $(shell pwd)/rebar3
-
 all: compile
 
-compile:
+# Check if rebar3.mk exists, and if not, download it
+ifeq ("$(wildcard rebar3.mk)","")
+$(shell curl -O https://raw.githubusercontent.com/choptastic/rebar3.mk/master/rebar3.mk)
+endif
+
+# rebar3.mk adds a new rebar3 rule to your Makefile
+# (see https://github.com/choptastic/rebar3.mk) for full info
+include rebar3.mk
+
+compile: rebar3
 	$(REBAR) compile
 
-update:
+update: rebar3
 	$(REBAR) update
 
-test: compile
+test:
-	$(REBAR) eunit
+	EUNIT=1 $(REBAR) compile
+	EUNIT=1 $(REBAR) eunit
 
-run:
+dialyzer: compile
+	DIALYZER=1 $(REBAR) dialyzer
+
+dev:
+	mkdir -p _checkouts
+	cd _checkouts; git clone https://github.com/choptastic/qdate_localtime
+
+
+run: rebar3
 	$(REBAR) shell
 
-publish:
+push_tags:
-	$(REBAR) as pkg upgrade
+	git push --tag
-	$(REBAR) as pkg hex publish
+
-	$(REBAR) upgrade
+pull_tags:
+	git pull --tag
+
+publish: rebar3 pull_tags
+	$(REBAR) hex publish
 

README.md

@@ -1,6 +1,6 @@
 # qdate - Erlang Date and Timezone Library
 
-[![Build Status](https://travis-ci.org/choptastic/qdate.png?branch=master)](https://travis-ci.org/choptastic/qdate)
+[![qdate tests and dialyzer](https://github.com/choptastic/qdate/actions/workflows/tests-workflow.yml/badge.svg)](https://github.com/choptastic/qdate/actions/workflows/tests-workflow.yml)
 
 ## Purpose
 
@@ -98,14 +98,16 @@ will infer the timezone in the following order.
     `set_timezone/1` only applies to that *specific* process. If none is
     specified.
   + If no timezone is specified for the process, `qdate` looks at the `qdate`
-    application variable `default_timezone`.
+	application variable `default_timezone`. `default_timezone` can be either a
+    hard-specified timezone, or a `{Module, Function}` tuple.  The tuple format
+    should return either a timezone or the atom `undefined`.
   + If no timezone is specified by either of the above, `qdate` assumes "GMT"
     for all dates.
   + A timezone value of `auto` will act as if no timezone is specified.
 
 #### Disambiguating Ambiguous Timezone Conversions
 
-Sometimes, when youre converting a datetime from one timezone to another, there
+Sometimes, when you're converting a datetime from one timezone to another, there
 are potentially two different results if the conversion happens to land on in a
 timezone that's in the middle of a Daylight Saving conversion.  For example,
 converting "11-Nov-2013 1:00:am" in "America/New York" to "GMT" could be both
@@ -190,24 +192,72 @@ ok
 
 `qdate` provides a few convenience functions for performing date comparisons.
 
-  + `compare(A, B)` - Like C's `strcmp`, returns:
+  + `compare(A, B) -> -1|0|1` - Like C's `strcmp`, returns:
     + `0`: `A` and `B` are exactly the same.
     + `-1`: `A` is less than (before) `B`.
     + `1`: `A` is greater than (after) `B`.
-  + `compare(A, Operator, B)` - Operator is an infix comparison operator, and
+  + `compare(A, Operator, B) -> true|false` - Operator is an infix comparison operator, and
-    the function will return true if:
+    the function will return a boolean. Will return `true` if:
     + `'='`, or `'=='` - `A` is the same time as `B`
     + `'/='`, or `'=/='` or `'!='` - `A` is not the same time as `B`
     + `'<'` - `A` is before `B`
     + `'>'` - `A` is after `B`
     + `'=<'` or `'<='` - `A` is before or equal to `B`
     + `'>='` or `'=>'` - `A` is after or equal to `B`
+  + `between(A, Date, B) -> true|false` - The provided `Date` is (inclusively)
+    between `A` and `B`. That is, `A =< Date =< B`.
+  + `between(A, B) -> true|false` - shortcut for `between(A, now(), B)`
+  + `between(A, Op1, Date, Op2, B) -> true|false` - the fully verbose option of
+    comparing between. `Op1` and `Op2` are custom operators. For example, if
+    you wanted to do an exclusive `between`, you can do:
+	`between(A, '<', Date, '<', B)`
 
 **Note 1:** `Operator` must be an atom.
 
 **Note 2:** These functions will properly compare times with different timezones
 (for example: `compare("12am CST",'==',"1am EST")` will properly return true)
 
+### Sorting
+
+`qdate` also provides a convenience functions for sorting lists of dates/times:
+
+  + `sort(List)` - Sort the list in ascending order of earliest to latest.
+  + `sort(Op, List)` - Sort the list where `Op` is one of the following:
+    + `'<'` or `'=<'` or `'<='` - Sort ascending
+    + `'>'` or `'>='` or `'=>'` - Sort descending
+  + `sort(Op, List, Opts)` - Sort the list according to the `Op`, with options provided in `Opts`. `Opts` is a proplist of the following options:
+    + `{non_dates, NonDates}` - Tells it how to handle non-dates.  `NonDates` can be any of the following:
+      + `back` **(default)** - put any non-dates at the end (the back) of the list
+      + `front` - put any non-dates at the beginning of the list
+      + `crash` - if there are any non-dates, crash.
+
+Example:
+
+```erlang
+	 1> Dates = ["non date string", <<"garbage">>,
+		1466200861, "2011-01-01", "7pm",
+		{{1999,6,21},{5,30,0}}, non_date_atom, {some_tuple,123}].
+	 2> qdate:sort('>=', Dates, [{non_dates, front}]).
+     [<<"garbage">>,"non date string",
+	  {some_tuple,123},
+	  non_date_atom,1466200861,"2011-01-01",
+	  {{1999,6,21},{5,30,0}},
+	  "7pm"]
+```
+
+**Note 1:** This sorting is optimized to be much faster than using a home-grown
+sort using the `compare` functions, as this normalizes the items in the list
+before comparing (so it's only really comparing integers, which is quite fast).
+
+**Note 2:** This is one of the few qdate functions that don't have the "Date"
+as the last argument. This follows the pattern in Erlang/OTP to put options as
+the last argument (for example, `re:run/3`)
+
+**Note 3:** You'll notice that qdate's sorting retains the original terms (in
+the example above, we compared a datetime tuple, unix timestamp, and two
+strings (along with a number of non-dates, which were just prepended to the
+front of the list).
+
 ### Timezone Functions
 
   + `set_timezone(Key, TZ)` - Set the timezone to TZ for the key `Key`
@@ -448,8 +498,31 @@ the crash.
 
 **Another Note:** Custom parsers are expected to return either:
   + A `datetime()` tuple. (ie {{2012,12,21},{14,45,23}}).
+  + An integer, which represents the Unix timestamp.
   + The atom `undefined` if this parser is not a match for the supplied value
 
+#### Included Parser: Relative Times
+
+`qdate` ships with an optional relative time parser. To speed up performance
+(since this parser uses regular expressions), this parser is disabled by
+default. But if you wish to use it, make sure you call
+`qdate:register_parser(parse_relative, fun qdate:parse_relative/1)`. 
+
+Doing this allows you to parse relative time strings of the following formats:
+
+  + "1 hour ago"
+  + "-15 minutes"
+  + "in 45 days"
+  + "+2 years"
+
+And doing so allows you to construct slightly more readable comparison calls
+for sometimes common comparisons. For example, the following two calls are identical:
+
+```erlang
+qdate:between("-15 minutes", Date, "+15 minutes").
+
+qdate:between(qdate:add_minutes(-15), Date, qdate:add_minutes(15)).
+```
 
 ### Registering Custom Formats
 
@@ -463,7 +536,7 @@ the crash.
 
 %% But, you don't have to: if that's a common format you use in your
 %% application, you can register your format with the `qdate` server, and then
-%% easiy refer to that format by its key.
+%% easily refer to that format by its key.
 
 %% So let's take that format and register it
 16> qdate:register_format(longdate, "l, F jS, Y g:i A T").
@@ -619,25 +692,76 @@ ok
 %% that timezone to our intended timezone.
 ```
 
-## Date Arithmetic
+## Beginning or Ending of time periods (hours, days, years, weeks, etc)
 
-(not fully tested yet, but will have full tests for 0.4.0)
+qdate can determine beginnings and endings of time periods, like "beginning of the month"
+
+This is abstracted to `beginning_X` functions, which return a date/time format
+with the dates and times truncated to the specified level.
+
+   + `beginning_minute(Date)`
+   + `beginning_hour(Date)`
+   + `beginning_day(Date)`
+   + `beginning_month(Date)`
+   + `beginning_year(Date)`
+
+There are also 0-arity versions of the above, in which `Date` is assumed to be
+"right now". For example, calling `qdate:beginning_month()` would return
+midnight on the first day of the current month.
+
+#### Beginning of Week
+
+qdate can also do a special "beginning" case, particularly the "beginning of
+the week" calculation.  This has three forms, specifically:
+  
+   + `beginning_week()` - Returns first day of the current week.
+   + `beginning_week(Date)` - Assumes the beginning of the week is Monday
+     (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 the
+     integers 1-7 or the atom versions 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
+conventions, except return the last second of that time period.
+
+So `end_month("2016-01-05")` will return the unix timestamp representing
+"2016-01-31 11:59:59pm"
+
+
+## Date Arithmetic
 
 The current implementation of qdate's date arithmetic returns Unixtimes.
 
 There are 8 main functions for date arithmetic:
 
-	+ `add_seconds(Seconds, Date)`
+   + `add_seconds(Seconds, Date)`
-	+ `add_minutes(Minutes, Date)`
+   + `add_minutes(Minutes, Date)`
-	+ `add_hours(Hours, Date)`
+   + `add_hours(Hours, Date)`
-	+ `add_days(Days, Date)`
+   + `add_days(Days, Date)`
-	+ `add_weeks(Weeks, Date)`
+   + `add_weeks(Weeks, Date)`
-	+ `add_months(Months, Date)`
+   + `add_months(Months, Date)`
-	+ `add_years(Years, Date)`
+   + `add_years(Years, Date)`
-	+ `add_date(DateToAdd, Date)` - `DateToAdd` is a shortcut way of adding
+   + `add_date(DateToAdd, Date)` - `DateToAdd` is a shortcut way of adding
-	  numerous options. For example. `qdate:add_date({{1, 2, -3}, {-500, 20, 0}})`
+      numerous options. For example. `qdate:add_date({{1, 2, -3}, {-500, 20, 0}})`
-	  will add 1 year, add 2 months, subtract 3 days, subtract 500 hours, add 20
+      will add 1 year, add 2 months, subtract 3 days, subtract 500 hours, add 20
-	  minutes, and not make any changes to seconds.
+      minutes, and not make any changes to seconds.
 
 For the date arithmetic functions, `Date`, like all `qdate` functions, can be any
 format.
@@ -654,6 +778,89 @@ There are 7 other arithmetic functions that take a single argument, and these do
    + `add_months(Months)`
    + `add_years(Years)`
 
+## Date and Time Ranges
+
+qdate provides a number of `range` functions that give applicable dates/times
+within a start and end time. For example, "All days from 2015-01-01 to today",
+"every 3rd month from 2000-01-01 to 2009-12-31", or "every 15 minutes from
+midnight to 11:59pm on 2015-04-15".
+
+The functions are as follows:
+
+   + `range_seconds(Interval, Start, End)`
+   + `range_minutes(Interval, Start, End)`
+   + `range_hours(Interval, Start, End)`
+   + `range_days(Interval, Start, End)`
+   + `range_weeks(Interval, Start, End)`
+   + `range_months(Interval, Start, End)`
+   + `range_years(Interval, Start, End)`
+
+Where `Interval` is the number of seconds/days/years/etc.
+
+So for example:
+
+```erlang
+%% Get every 15th minute from "2015-04-15 12:00am to 2015-04-15 11:59am"
+> qdate:range_minutes(15, "2015-04-15 12:00am", "2015-04-15 11:59am").
+[1429056000,1429056900,1429057800,1429058700,1429059600,
+ 1429060500,1429061400,1429062300,1429063200,1429064100,
+ 1429065000,1429065900,1429066800,1429067700,1429068600,
+ 1429069500,1429070400,1429071300,1429072200,1429073100,
+ 1429074000,1429074900,1429075800,1429076700,1429077600,
+ 1429078500,1429079400,1429080300,1429081200|...]
+
+%% Get every day of April, 2014
+> qdate:range_days(1, "2014-04-01", "2014-04-30").
+[1396310400,1396396800,1396483200,1396569600,1396656000,
+ 1396742400,1396828800,1396915200,1397001600,1397088000,
+ 1397174400,1397260800,1397347200,1397433600,1397520000,
+ 1397606400,1397692800,1397779200,1397865600,1397952000,
+ 1398038400,1398124800,1398211200,1398297600,1398384000,
+ 1398470400,1398556800,1398643200,1398729600|...]
+```
+
+Note, that the return value (just like qdate's arithmetic functions) is a list
+of integers. These integers are unix timestamps and can be easily formatted
+with qdate:
+
+```erlang
+> Mins = qdate:range_minutes(15, "2015-04-15 12:00am", "2015-04-15 11:59am"),
+> [qdate:to_string("Y-m-d h:ia", M) || M <- Mins].
+["2015-04-15 00:00am","2015-04-15 00:15am",
+ "2015-04-15 00:30am","2015-04-15 00:45am",
+ "2015-04-15 01:00am","2015-04-15 01:15am",
+ "2015-04-15 01:30am","2015-04-15 01:45am",
+ "2015-04-15 02:00am","2015-04-15 02:15am",
+ "2015-04-15 02:30am","2015-04-15 02:45am",
+ "2015-04-15 03:00am","2015-04-15 03:15am",
+ "2015-04-15 03:30am","2015-04-15 03:45am",
+ "2015-04-15 04:00am","2015-04-15 04:15am",
+ "2015-04-15 04:30am","2015-04-15 04:45am",
+ "2015-04-15 05:00am","2015-04-15 05:15am",
+ "2015-04-15 05:30am","2015-04-15 05:45am",
+ "2015-04-15 06:00am","2015-04-15 06:15am",
+ "2015-04-15 06:30am","2015-04-15 06:45am",
+ [...]|...]
+```
+
+Also note that the range functions are *inclusive*.
+
+
+## Age Comparison
+
+There are two main comparisons right now, age in years, and age in days.
+
+  + `age(Date)` - Number of years since `Date`
+  + `age(FromDate, ToDate)` - Number of years between `FromDate` to `ToDate`
+  + `age_days(Date)` - Number of full days since `Date` (for example from `2pm` yesterday to `1:59pm` today is still 0.
+  + `age_days(FromDate, ToDate)` - Number of full days between `FromDate` and `ToDate`.
+
+## Configuration Sample
+
+There is a sample configuration file can be found in the root of the qdate
+directory. Or you can just [look at it
+here](https://github.com/choptastic/qdate/blob/master/qdate.config).
+
 ## Thanks
 
 A few shoutouts to [Dale Harvey](http://github.com/daleharvey) and the
@@ -680,7 +887,6 @@ See [CHANGELOG.markdown](https://github.com/choptastic/qdate/blob/master/CHANGEL
 + Make `qdate` backend-agnostic (allow specifying either ec_date or dh_date as
   the backend)
 + Add `-spec` and `-type` info for dialyzer
-+ Provide a sample qdate.config for users to see
 + Research the viability of [ezic](https://github.com/drfloob/ezic) for a
   timezone backend replacement for `erlang_localtime`.
 

qdate.config

@@ -0,0 +1,20 @@
+%% vim: ts=4 sw=4 et ft=erlang
+[{qdate, [
+    %% default_timezone can be one of two things:
+    %%   1) An actual timezone.  Either short-form like "GMT", "UTC", or a
+    %%      longer-form (but more likely to pick the correct daylight saving
+    %%      config timezone like "America/Chicago"
+    %%   2) A 2-tuple of {Module, Function}, which will be called as
+    %%      Module:Function() to determine the timezone (say you wanted to
+    %%      determine timezone based on some kind of environmental conditions)
+    {default_timezone, "GMT"},
+
+    %% See readme section here:
+    %% https://github.com/choptastic/qdate#about-backwards-compatibility-with-ec_date-and-deterministic-parsing
+    {deterministic_parsing, {zero, zero}},
+
+    %% Preserve Milliseconds in parsing
+    %% Changes the return for qdate:to_date to include any Ms value
+    %% and also changes the return of to_string to include the Ms value
+    {preserve_ms, false}
+]}].

rebar.config

@@ -2,25 +2,23 @@
 %% vim:ts=4 sw=4 et ft=erlang
 {cover_enabled, true}.
 
-%% For rebar2 compat
+{dialyzer, [
+    {exclude_apps, []},
+    {warnings, []}
+]}.
+
 {deps,
  [
-  %% This uses an older erlware_commons version so retain compatibility with
+  erlware_commons,
-  %% rebar2. v0.16.1 introduced a 'cf' dependency, which seems to cause
+  {qdate_localtime, "~> 1.2.0"}
-  %% breakage.
-  {erlware_commons,  ".*", {git, "git://github.com/erlware/erlware_commons.git",     {tag, "v0.15.0"}}},
-
-  %% We'll temporarily still use choptastic/erlang_localtime until
-  %% https://github.com/dmitryme/erlang_localtime/pull/24 gets merged. Then we
-  %% can switch to the mainline repo
-  {erlang_localtime, ".*", {git, "git://github.com/choptastic/erlang_localtime.git", {branch, master}}}
  ]}.
 
-%% for rebar3
+{project_plugins, [rebar3_ex_doc]}.
-{profiles,
+
- [{pkg,
+{hex, [{doc, ex_doc}]}.
-   [{deps,
+
-     [
+{ex_doc, [
-      erlware_commons,
+          {source_url, <<"https://github.com/choptastic/qdate">>},
-      erlang_localtime
+          {extras, [<<"README.md">>, <<"LICENSE.md">>]},
-     ]}]}]}.
+          {main, <<"readme">>}]}.
+

rebar.config.script

@@ -0,0 +1,15 @@
+%% -*- mode: erlang -*-
+%% -*- tab-width: 4;erlang-indent-level: 4;indent-tabs-mode: nil -*-
+%% ex: ts=4 sw=4 sts ft=erlang et
+
+case erlang:function_exported(rebar3, main, 1) of
+    true -> % rebar3
+        CONFIG;
+    false -> % rebar 2.x or older
+        %% Rebuild deps, possibly including those that have been moved to
+        %% profiles
+        [{deps, [
+            {erlware_commons, "", {git, "https://github.com/erlware/erlware_commons", {tag, "v1.5.0"}}}, %% this is the version of erlware_commons that works until erlware tags a new version
+            {qdate_localtime, "", {git, "https://github.com/choptastic/qdate_localtime", {tag, "1.1.0"}}}
+        ]} | lists:keydelete(deps, 1, CONFIG)]
+end.

rebar.lock

@@ -0,0 +1,14 @@
+{"1.2.0",
+[{<<"cf">>,{pkg,<<"cf">>,<<"0.3.1">>},1},
+ {<<"erlware_commons">>,{pkg,<<"erlware_commons">>,<<"1.6.0">>},0},
+ {<<"qdate_localtime">>,{pkg,<<"qdate_localtime">>,<<"1.2.1">>},0}]}.
+[
+{pkg_hash,[
+ {<<"cf">>, <<"5CB902239476E141EA70A740340233782D363A31EEA8AD37049561542E6CD641">>},
+ {<<"erlware_commons">>, <<"E0DA62F91E65DEFAE28BB450DDC3C24E85ECB99B926F857CDC6ED8E7DD7076B4">>},
+ {<<"qdate_localtime">>, <<"72E1034DC6B7FEE8F588281EDDD0BD0DC5260005D758052F50634D265D382C18">>}]},
+{pkg_hash_ext,[
+ {<<"cf">>, <<"315E8D447D3A4B02BCDBFA397AD03BBB988A6E0AA6F44D3ADD0F4E3C3BF97672">>},
+ {<<"erlware_commons">>, <<"B57C299C39A2992A8C413F9D2C1B8A20061310FB4432B0EEE5E4C4DF7AAA0AA3">>},
+ {<<"qdate_localtime">>, <<"1109958D205C65C595C8C5694CB83EBAF2DBE770CF902E4DCE8AFB2C4123764D">>}]}
+].

src/qdate.app.src

@@ -1,17 +1,17 @@
 {application, qdate,
  [
   {description, "Simple Date and Timezone handling for Erlang"},
-  {vsn, "0.4.2"},
+  {vsn, git},
   {registered, []},
   {applications, [
                   kernel,
-                  erlang_localtime,
+                  stdlib,
-                  erlware_commons,
+                  qdate_localtime,
-                  stdlib
+                  erlware_commons
                  ]},
-  {modules, [qdate, qdate_srv]},
+  {modules, [qdate, qdate_srv, qdate_sup, qdate_app]},
   {env, []},
-  {contributors, ["Jesse Gumm"]},
   {licenses, ["MIT"]},
+  {mod, {qdate_app, []}},
   {links, [{"Github", "https://github.com/choptastic/qdate"}]}
  ]}.

src/qdate.erl

@@ -1,9 +1,11 @@
 % vim: ts=4 sw=4 et
-% Copyright (c) 2013 Jesse Gumm
+% Copyright (c) 2013-2023 Jesse Gumm
 % See LICENSE for licensing information.
 %
 -module(qdate).
 
+%-compile(export_all).
+
 -export([
     start/0,
     stop/0
@@ -24,9 +26,50 @@
     unixtime/0
 ]).
 
+-export([
+    beginning_minute/1,
+    beginning_minute/0,
+    beginning_hour/1,
+    beginning_hour/0,
+    beginning_day/1,
+    beginning_day/0,
+    beginning_week/0,
+    beginning_week/1,
+    beginning_week/2,
+    beginning_month/1,
+    beginning_month/0,
+    beginning_year/1,
+    beginning_year/0
+]).
+
+-export([
+     end_minute/1,
+     end_minute/0,
+     end_hour/1,
+     end_hour/0,
+     end_day/1,
+     end_day/0,
+     end_week/0,
+     end_week/1,
+     end_week/2,
+     end_month/1,
+     end_month/0,
+     end_year/1,
+     end_year/0
+]).
+
 -export([
     compare/2,
-    compare/3
+    compare/3,
+    between/2,
+    between/3,
+    between/5
+]).
+
+-export([
+    sort/1,
+    sort/2,
+    sort/3
 ]).
 
 -export([
@@ -44,9 +87,29 @@
     add_months/1,
     add_years/2,
     add_years/1,
+    add_unit/2,
+    add_unit/3,
     add_date/2
 ]).
 
+-export([
+    range/4,
+    range_seconds/3,
+    range_minutes/3,
+    range_hours/3,
+    range_days/3,
+    range_weeks/3,
+    range_months/3,
+    range_years/3
+]).
+
+-export([
+    age/1,
+    age/2,
+    age_days/1,
+    age_days/2
+]).
+
 -export([
     register_parser/2,
     register_parser/1,
@@ -66,6 +129,9 @@
     clear_timezone/1
 ]).
 
+-export([
+    parse_relative/1
+]).
 
 %% Exported for API compatibility with ec_date
 -export([
@@ -74,28 +140,32 @@
     parse/1
 ]).
 
+-type qdate() :: any().
+-type datetime() :: {{integer(), integer(), integer()}, {integer(), integer(), integer()}} |
+                    {{integer(), integer(), integer()}, {integer(), integer(), integer(), integer()}}.
+-type erlnow() :: {integer(), integer(), integer()}.
+-type binary_or_string() :: binary() | string().
+-type disambiguate() :: prefer_standard | prefer_daylight | both.
+
+%% erlang:get_stacktrace/0 is deprecated in OTP 21
+-ifndef(OTP_RELEASE).
+-define(WITH_STACKTRACE(T, R, S), T:R -> S = erlang:get_stacktrace(), ).
+-else.
+-define(WITH_STACKTRACE(T, R, S), T:R:S ->).
+-endif.
+
 %% This the value in gregorian seconds for jan 1st 1970, 12am
 %% It's used to convert to and from unixtime, since unixtime starts 
 %% 1970-01-01 12:00am
 -define(UNIXTIME_BASE,62167219200).
 
-%% This is the timezone only if the qdate application variable 
-%% "default_timezone" isn't set or is set to undefined.
-%% It's recommended that your app sets the var in a config, or at least using
-%%
-%%      application:set_env(qdate, default_timezone, "GMT").
-%%
--define(DEFAULT_TZ, case application:get_env(qdate, default_timezone) of 
-                        undefined -> "GMT";
-                        {ok, TZ} -> TZ 
-                    end).
 
 -define(DETERMINE_TZ, determine_timezone()).
 -define(DEFAULT_DISAMBIG, prefer_standard).
--define(else, true).
+
 
 start() ->
-    application:load(qdate).
+    application:ensure_all_started(qdate).
 
 stop() ->
     ok.
@@ -109,6 +179,7 @@ to_string(Format, Date) ->
 to_string(Format, ToTZ, Date) ->
     to_string(Format, ToTZ, ?DEFAULT_DISAMBIG, Date).
 
+-spec to_string(Format :: any(), ToTZ :: any(), Disambiguate :: disambiguate(), Date :: qdate()) -> binary_or_string() | {ambiguous, binary_or_string() , binary_or_string()}.
 to_string(FormatKey, ToTZ, Disambiguate, Date) when is_atom(FormatKey) orelse is_tuple(FormatKey) ->
     Format = case qdate_srv:get_format(FormatKey) of
         undefined -> throw({undefined_format_key,FormatKey});
@@ -175,7 +246,13 @@ to_string_worker([$r | RestFormat], ToTZ, Disamb, Date) ->
     to_string_worker(NewFormat, ToTZ, Disamb, Date) ++ to_string_worker(RestFormat, ToTZ, Disamb, Date);
 to_string_worker([$c | RestFormat], ToTZ, Disamb, Date) ->
     Format1 = "Y-m-d",
-    Format2 = "H:i:sP",
+    Format2 = case Date of
+                  {_, {_,_,_,_}} ->
+                      %% Have milliseconds
+                      "H:i:s.fP";
+                  _ ->
+                      "H:i:sP"
+              end,
     to_string_worker(Format1, ToTZ, Disamb, Date) 
             ++ "T" 
             ++ to_string_worker(Format2, ToTZ, Disamb, Date) 
@@ -226,6 +303,7 @@ to_date(RawDate) ->
 to_date(ToTZ, RawDate) ->
     to_date(ToTZ, ?DEFAULT_DISAMBIG, RawDate).
 
+-spec to_date(ToTZ :: any(), Disambiguate :: disambiguate(), RawDate :: any()) -> {ambiguous, datetime(), datetime()} | datetime().
 to_date(ToTZ, Disambiguate, RawDate) when is_binary(RawDate) ->
     to_date(ToTZ, Disambiguate, binary_to_list(RawDate));
 to_date(ToTZ, Disambiguate, RawDate) when is_binary(ToTZ) ->
@@ -240,9 +318,13 @@ to_date(ToTZ, Disambiguate, RawDate)  ->
         {ParsedDate,ParsedTZ} ->
             {ParsedDate,ParsedTZ}
     end,
+    PreserveMs = preserve_ms(),
     try raw_to_date(RawDate3) of
         D={{_,_,_},{_,_,_}} ->
             date_tz_to_tz(D, Disambiguate, FromTZ, ToTZ);
+        {{Year, Month, Date},{Hour,Minute,Second,Millis}} when PreserveMs ->
+            {ODate, {OHour,OMinute,OSecond}} = date_tz_to_tz({{Year, Month, Date},{Hour,Minute,Second}}, Disambiguate, FromTZ, ToTZ),
+            {ODate, {OHour,OMinute,OSecond, Millis}};
         {{Year, Month, Date},{Hour,Minute,Second,_Millis}} ->
             date_tz_to_tz({{Year, Month, Date},{Hour,Minute,Second}}, Disambiguate, FromTZ, ToTZ)
     catch
@@ -279,9 +361,10 @@ get_deterministic_datetime() ->
 to_unixtime(Date) ->
     to_unixtime(?DEFAULT_DISAMBIG, Date).
 
+-spec to_unixtime(Disamb :: disambiguate(), qdate()) -> {ambiguous, integer(), integer()} | integer().
 to_unixtime(_, Unixtime) when is_integer(Unixtime) ->
     Unixtime;
-to_unixtime(_, {MegaSecs,Secs,_}) ->
+to_unixtime(_, {MegaSecs,Secs,_}) when is_integer(MegaSecs), is_integer(Secs) ->
     MegaSecs*1000000 + Secs;
 to_unixtime(Disamb, ToParse) ->
     %% We want to treat all unixtimes as GMT
@@ -300,11 +383,12 @@ unixtime() ->
 to_now(Date) ->
     to_now(?DEFAULT_DISAMBIG, Date).
 
+-spec to_now(Disamb :: disambiguate(), qdate()) -> erlnow() | {ambiguous, erlnow(), erlnow()}.
 to_now(_, Now = {_,_,_}) ->
     Now;
 to_now(Disamb, ToParse) ->
     case to_unixtime(Disamb, ToParse) of
-        {ambiguous, Standard, Daylight} ->
+        {ambiguous, Standard, Daylight} when is_integer(Standard), is_integer(Daylight) ->
             {ambiguous, 
                 unixtime_to_now(Standard),
                 unixtime_to_now(Daylight)};
@@ -313,10 +397,144 @@ to_now(Disamb, ToParse) ->
     end.
 
 
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Beginning/Truncation  %%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+beginning_minute() ->
+    beginning_minute({date(),time()}).
+
+beginning_minute(Date) ->
+    {{Y,M,D},{H,I,_}} = to_date(Date),
+    {{Y,M,D},{H,I,0}}.
+
+beginning_hour() ->
+    beginning_hour({date(),time()}).
+
+beginning_hour(Date) ->
+    {{Y,M,D},{H,_,_}} = to_date(Date),
+    {{Y,M,D},{H,0,0}}.
+
+beginning_day() ->
+    beginning_day(unixtime()).
+
+beginning_day(Date) ->
+    {{Y,M,D},{_,_,_}} = to_date(Date),
+    {{Y,M,D},{0,0,0}}.
+
+beginning_month() ->
+    beginning_month({date(),time()}).
+
+beginning_month(Date) ->
+    {{Y,M,_},{_,_,_}} = to_date(Date),
+    {{Y,M,1},{0,0,0}}.
+
+beginning_year() ->
+    beginning_year({date(),time()}).
+
+beginning_year(Date) ->
+    {{Y,_,_},{_,_,_}} = to_date(Date),
+    {{Y,1,1},{0,0,0}}.
+
+beginning_week() ->
+    beginning_week({date(), time()}).
+
+%% 1 = Monday, 7 = Sunday
+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,
+        is_integer(BeginningDayOfWeek) ->
+    {DateOnly, _} = Date = to_date(Date0),
+    CurDOW = calendar:day_of_the_week(DateOnly),
+    if
+        CurDOW==BeginningDayOfWeek ->
+            {DateOnly, {0,0,0}};
+        CurDOW > BeginningDayOfWeek->
+            Diff = CurDOW - BeginningDayOfWeek,
+            beginning_day(add_days(-Diff, Date));
+        CurDOW < BeginningDayOfWeek ->
+            Diff = 7 - (BeginningDayOfWeek - CurDOW),
+            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)  %%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+
+end_minute() ->
+    end_minute({date(),time()}).
+
+end_minute(Date) ->
+    {{Y,M,D},{H,I,_}} = to_date(Date),
+    {{Y,M,D},{H,I,59}}.
+
+end_hour() ->
+    end_hour({date(),time()}).
+
+end_hour(Date) ->
+    {{Y,M,D},{H,_,_}} = to_date(Date),
+    {{Y,M,D},{H,59,59}}.
+
+end_day() ->
+    end_day({date(),time()}).
+
+end_day(Date) ->
+    {{Y,M,D},_} = to_date(Date),
+    {{Y,M,D},{23,59,59}}.
+
+end_month() ->
+    end_month({date(), time()}).
+
+end_month(Date) ->
+    Beginning = beginning_month(Date),
+    add_seconds(-1, add_months(1, Beginning)).
+
+end_year() ->
+    end_year({date(),time()}).
+
+end_year(Date) ->
+    {{Y,_,_},_} = to_date(Date),
+    {{Y,12,31},{23,59,59}}.
+
+end_week() ->
+    end_week({date(), time()}).
+
+end_week(Date) ->
+    end_week(1, Date).
+
+end_week(BeginningDayOfWeek, Date) ->
+    Beginning = beginning_week(BeginningDayOfWeek, Date),
+    PlusWeek = add_weeks(1, Beginning),
+    add_seconds(-1, PlusWeek).
+
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%    Comparisons     %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
+-spec compare(A :: qdate(), B :: qdate()) -> integer().
 compare(A, B) ->
     NowA = to_now(A),
     NowB = to_now(B),
@@ -326,6 +544,7 @@ compare(A, B) ->
         NowA > NowB -> 1
     end.
 
+-spec compare(A :: qdate(), Op :: atom(), B :: qdate()) -> boolean().
 compare(A, Op, B) ->
     Comp = compare(A, B),
     case Op of
@@ -336,15 +555,93 @@ compare(A, Op, B) ->
         '=/='   -> Comp =/= 0;
         '/='    -> Comp =/= 0;
 
+        'before'-> Comp =:= -1;
         '<'     -> Comp =:= -1;
         '<='    -> Comp =:= -1 orelse Comp =:= 0;
         '=<'    -> Comp =:= -1 orelse Comp =:= 0;
 
+        'after' -> Comp =:= 1;
         '>'     -> Comp =:= 1;
         '>='    -> Comp =:= 1 orelse Comp =:= 0;
         '=>'    -> Comp =:= 1 orelse Comp =:= 0
     end.
 
+between(A, B) ->
+    between(A, unixtime(), B).
+
+between(A, Date, B) ->
+    between(A, '=<', Date, '=<', B).
+
+between(A, Op1, Date, Op2, B) ->
+    compare(A, Op1, Date) andalso compare(Date, Op2, B).
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%    Sorting    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+sort(List) ->
+    sort('=<', List).
+
+sort(Op, List) ->
+    sort(Op, List, [{non_dates, back}]).
+
+sort(Op, List, Opts) ->
+    NonDateOpt = proplists:get_value(non_dates, Opts, back),
+    WithNorm = add_sort_normalization(List, NonDateOpt),
+    SortFun = make_sort_fun(Op, NonDateOpt),
+    Sorted = lists:sort(SortFun, WithNorm),
+    strip_sort_normalization(Sorted).
+
+%% Normalization pre-processes the dates (converting them to unixtimes for easy
+%% comparison, and also tags non-dates (dates that crashed during parsing) as such
+add_sort_normalization(List, NonDateOpt) ->
+    lists:map(fun(Date) ->
+        Sortable = try to_unixtime(Date)
+                   catch _:_ when NonDateOpt=/=crash ->
+                        {non_date, Date}
+                   end,
+        {Sortable, Date}
+    end, List).
+
+%% Remove the normalization tag to return the original term
+strip_sort_normalization(List) ->
+    [Date || {_, Date} <- List].
+
+-spec make_sort_fun(Op :: atom(), NonDateOpt :: front | back) -> fun().
+make_sort_fun(Op, NonDateOpt) ->
+    DateComp = sort_op_comp_fun(Op),
+    
+    fun({{non_date, A}, _}, {{non_date, B},_}) ->
+            DateComp(A,B);
+       ({{non_date, _}, _}, _) when NonDateOpt == front ->
+            true;
+       ({{non_date, _}, _}, _) when NonDateOpt == back ->
+            false;
+       (_, {{non_date, _}, _}) when NonDateOpt == front ->
+            false;
+       (_, {{non_date, _}, _}) when NonDateOpt == back ->
+            true;
+       (A, B) ->
+            DateComp(A, B)
+    end.
+   
+sort_op_comp_fun(Op) ->
+    fun(A, B) ->
+        case Op of
+            'before'-> A < B;
+            '<'     -> A < B;
+            '<='    -> A =< B;
+            '=<'    -> A =< B;
+
+            'after' -> A > B;
+            '>'     -> A > B;
+            '>='    -> A >= B;
+            '=>'    -> A >= B
+        end
+    end.
+
+
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%    Date Math       %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -405,6 +702,48 @@ add_years(Years, Date) ->
 add_years(Years) ->
     add_years(Years, os:timestamp()).
 
+-type unit() :: second | seconds |
+                minute | minutes |
+                hour | hours |
+                day | days |
+                week | weeks |
+                month | months |
+                year | years.
+
+-spec add_unit(Unit :: unit(), Value :: integer(), Date :: qdate()) -> qdate().
+add_unit(second, Value, Date) ->
+    add_unit(seconds, Value, Date);
+add_unit(seconds, Value, Date) ->
+    add_seconds(Value, Date);
+add_unit(minute, Value, Date) ->
+    add_unit(minutes, Value, Date);
+add_unit(minutes, Value, Date) ->
+    add_minutes(Value, Date);
+add_unit(hour, Value, Date) ->
+    add_unit(hours, Value, Date);
+add_unit(hours, Value, Date) ->
+    add_hours(Value, Date);
+add_unit(day, Value, Date) ->
+    add_unit(days, Value, Date);
+add_unit(days, Value, Date) ->
+    add_days(Value, Date);
+add_unit(week, Value, Date) ->
+    add_unit(weeks, Value, Date);
+add_unit(weeks, Value, Date) ->
+    add_weeks(Value, Date);
+add_unit(month, Value, Date) ->
+    add_unit(months, Value, Date);
+add_unit(months, Value, Date) ->
+    add_months(Value, Date);
+add_unit(year, Value, Date) ->
+    add_unit(years, Value, Date);
+add_unit(years, Value, Date) ->
+    add_years(Value, Date).
+
+add_unit(Unit, Value) ->
+    add_unit(Unit, Value, os:timestamp()).
+
+
 add_date({{AddY, AddM, AddD}, {AddH, AddI, AddS}}, Date) ->
     {{Y, M, D}, {H, I, S}} = to_date(Date),
     Date1 = fix_maybe_improper_date({{Y+AddY, M+AddM, D+AddD}, {H, I, S}}),
@@ -420,12 +759,22 @@ fix_maybe_improper_date({Date0, Time}) ->
     Date = fmid(Date0),
     {Date, Time}.
 
+
+%% Originally, this function didn't recurse.  Here's the story.  Some numbers,
+%% like M = 12 (December) or M = -11 (January) would trigger an overflow or
+%% underflow, resulting in fix_year_month returning something nonsensical like
+%% {2018, 13}.  I added some extra clauses to special treat those "overflow but
+%% shouldn't" situations, but realized it was just cleaner to recurse, calling
+%% fix_year_month on the calculated result, knowing that the numbers will
+%% normalize on their own. So for all the clauses of fix_year_month, we recurse
+%% as a sanity check, eventually only returning the result of the "Everything
+%% Looks good" clause at the bottom.
 fix_year_month({Y, M}) when M > 12 ->
     YearsOver = M div 12,
-    {Y + YearsOver, M-(YearsOver*12)};
+    fix_year_month({Y + YearsOver, M-(YearsOver*12)});
 fix_year_month({Y, M}) when M < 1 ->
     YearsUnder = (abs(M-1) div 12) + 1,
-    {Y - YearsUnder, M+(YearsUnder*12)};
+    fix_year_month({Y - YearsUnder, M+(YearsUnder*12)});
 fix_year_month({Y, M}) ->
     {Y, M}.
     
@@ -460,6 +809,170 @@ fmid({Y, M, D}) when D < 1 ->
 fmid(Date) ->
     Date.
 
+age(Birth) ->
+    age(Birth, os:timestamp()).
+
+age(Birth, Now) ->
+    %% B=Birth
+    {{BY, BM, BD}, _} = to_date(Birth),
+    %% C=Current
+    {{CY, CM, CD}, _} = to_date(Now),
+    if
+        (CM > BM);
+        (CM == BM andalso CD >= BD)
+            -> CY - BY;
+        true ->
+            (CY - BY) - 1
+    end.
+
+age_days(Birth) ->
+    age_days(Birth, os:timestamp()).
+
+age_days(Birth, Now) ->
+    case {to_date(Birth), to_date(Now)} of
+        {{SameDay, _}, {SameDay, _}} ->
+            0;
+        {{BirthDate, BirthTime}, {NowDate, NowTime}} ->
+            BirthDays = calendar:date_to_gregorian_days(BirthDate),
+            NowDays = calendar:date_to_gregorian_days(NowDate),
+            DiffDays = NowDays - BirthDays,
+            if
+                NowTime >= BirthTime ->
+                    DiffDays;
+                true ->
+                    DiffDays-1
+            end
+    end.
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%      Ranges        %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+range(seconds, Interval, Start, Finish) ->
+    range_inner(fun add_seconds/2, Interval, Start, Finish);
+range(minutes, Interval, Start, Finish) ->
+    range_inner(fun add_minutes/2, Interval, Start, Finish);
+range(hours, Interval, Start, Finish) ->
+    range_inner(fun add_hours/2, Interval, Start, Finish);
+range(days, Interval, Start, Finish) ->
+    range_inner(fun add_days/2, Interval, Start, Finish);
+range(weeks, Interval, Start, Finish) ->
+    range_inner(fun add_weeks/2, Interval, Start, Finish);
+range(months, Interval, Start, Finish) ->
+    range_inner(fun add_months/2, Interval, Start, Finish);
+range(years, Interval, Start, Finish) ->
+    range_inner(fun add_years/2, Interval, Start, Finish).
+
+range_inner(IntervalFun, Interval, Start, Finish) when Interval > 0 ->
+    %% If Interval>0, then we're ascending, and we want to compare start/end
+    %% dates normally
+    CompareFun = fun(S, F) -> compare(S, F) end,
+    range_normalizer(IntervalFun, Interval, CompareFun, Start, Finish);
+range_inner(IntervalFun, Interval, Start, Finish) when Interval < 0 ->
+    %% If Interval<0, then we're descending, and we want to compare start/end
+    %% dates backwards (we want to end when the Start Date is Lower than
+    %% Finish)
+    CompareFun = fun(S, F) -> compare(F, S) end,
+    range_normalizer(IntervalFun, Interval, CompareFun, Start, Finish);
+range_inner(_, Interval, _, _) when Interval==0 ->
+    throw(interval_cannot_be_zero).
+
+range_normalizer(IntervalFun, Interval, CompareFun, Start0, Finish0) ->
+    %% Convert dates to unixtime for speed's sake
+    Start = to_unixtime(Start0),
+    Finish = to_unixtime(Finish0),
+    %% Prepare the incrementer, so we just need to pass the date to the incrementer.
+    Incrementer = fun(D) -> IntervalFun(Interval, D) end,
+    range_worker(Incrementer, CompareFun, Start, Finish).
+
+range_worker(Incrementer, CompareFun, Start, Finish) ->
+    case CompareFun(Start, Finish) of
+        0 -> [Finish]; %% Equal, so we add our Finish value
+        1 -> []; %% Start is after Finish, so we add nothing
+        -1 -> %% Start is before Finish, so we include it, and recurse
+            NextDay = Incrementer(Start),
+            [Start | range_worker(Incrementer, CompareFun, NextDay, Finish)]
+    end.
+
+range_seconds(Interval, Start, Finish) ->
+    range(seconds, Interval, Start, Finish).
+
+range_minutes(Interval, Start, Finish) ->
+    range(minutes, Interval, Start, Finish).
+
+range_hours(Interval, Start, Finish) ->
+    range(hours, Interval, Start, Finish).
+
+range_days(Interval, Start, Finish) ->
+    range(days, Interval, Start, Finish).
+
+range_weeks(Interval, Start, Finish) ->
+    range(weeks, Interval, Start, Finish).
+
+range_months(Interval, Start, Finish) ->
+    range(months, Interval, Start, Finish).
+
+range_years(Interval, Start, Finish) ->
+    range(years, Interval, Start, Finish).
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%  Relative Date Parsing  %%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+parse_relative({relative, Date, Relation}) when is_atom(Relation) ->
+    parse_relative({relative, Date, atom_to_list(Relation)});
+parse_relative({relative, Date, Relation}) when is_list(Relation); is_binary(Relation) ->
+    case parse_actual_relation(Relation) of
+        undefined -> undefined;
+        {OpStr, NumStr, UnitStr} ->
+	    {Num, Unit} = normalize_relative_matches(OpStr, NumStr, UnitStr),
+	    add_unit(Unit, Num, Date)
+    end;
+parse_relative(now) ->
+    unixtime();
+parse_relative("now") ->
+    unixtime();
+parse_relative(<<"now">>) ->
+    unixtime();
+parse_relative(Relation) when is_list(Relation); is_binary(Relation) ->
+    parse_relative({relative, unixtime(), Relation});
+parse_relative(_) ->
+    undefined.
+
+
+%% I would do this function recursively, but the return order of arguments
+%% inconsistent, so I just leave it like this. It's a little nasty to have the
+%% nested case expressions, but I can deal with it.
+parse_actual_relation(Relation) ->
+    PrefixRE = "^(\\-|\\+|in)\\s?(\\d+) (second|minute|hour|day|week|month|year)s?$",
+    SuffixRE = "^(\\d+) (second|minute|hour|day|week|month|year)s?\\s?(ago|from now)?$",
+    case re:run(Relation, PrefixRE, [{capture, all_but_first, list}]) of
+        nomatch ->
+            case re:run(Relation, SuffixRE, [{capture, all_but_first, list}]) of
+                nomatch -> undefined;
+                {match, [NumStr, UnitStr, OpStr]} ->
+                    {OpStr, NumStr, UnitStr}
+            end;
+        {match, [OpStr, NumStr, UnitStr]} ->
+            {OpStr, NumStr, UnitStr}
+    end.
+
+normalize_relative_matches(OpStr, NumStr, UnitStr) ->
+    Op = normalize_relative_op(OpStr),
+    Num = list_to_integer(Op ++ NumStr),
+    Unit = list_to_existing_atom(UnitStr),
+    {Num, Unit}.
+
+normalize_relative_op(Op) ->
+    case Op of
+        "+"         -> "+";
+        "-"         -> "-";
+        "ago"       -> "-";
+        "from now"  -> "+";
+        "in"        -> "+"
+    end.
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%   Timezone Stuff   %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -471,6 +984,7 @@ get_timezone_shift(TZ, Disambiguate, Date) ->
         {error,T} -> {error,T};
         {Sh, _} when Disambiguate==prefer_standard -> Sh;
         {_, Sh} when Disambiguate==prefer_daylight -> Sh;
+        0 -> {'+', 0, 0};
         Sh -> Sh
     end.
 
@@ -488,6 +1002,8 @@ extract_timezone(DateString) when is_list(DateString) ->
     end;
 extract_timezone(Date={{_,_,_},{_,_,_}}) ->
     {Date, ?DETERMINE_TZ};
+extract_timezone(Rel={relative, _, _}) ->
+    {Rel, "GMT"};
 extract_timezone(Now={_,_,_}) ->
     {Now, "GMT"};
 extract_timezone({MiscDate,TZ}) ->
@@ -523,15 +1039,33 @@ extract_timezone_helper(RevDate, [TZ | TZs]) when length(RevDate) >= length(TZ)
 extract_timezone_helper(RevDate, [_TZ | TZs]) ->
     extract_timezone_helper(RevDate, TZs).
 
+preserve_ms() ->
+    application:get_env(qdate, preserve_ms, false).
+
+%% This is the timezone only if the qdate application variable 
+%% "default_timezone" isn't set or is set to undefined.
+%% It's recommended that your app sets the var in a config, or at least using
+%%
+%%      application:set_env(qdate, default_timezone, "GMT").
+%%
+default_timezone() ->
+    case application:get_env(qdate, default_timezone) of 
+        undefined -> "GMT";
+        {ok, {Mod, Fun}} -> Mod:Fun();
+        {ok, TZ} -> TZ 
+    end.
+
 determine_timezone() ->
     case qdate_srv:get_timezone() of
-        undefined -> ?DEFAULT_TZ;
+        undefined -> default_timezone();
         TZ -> TZ
     end.
 
 %% If FromTZ is an integer, then it's an integer that represents the number of minutes
 %% relative to GMT. So we convert the date to GMT based on that number, then we can
 %% do the other timezone conversion.
+-spec date_tz_to_tz(Date :: datetime(), Disambiguate :: disambiguate(), FromTZ :: any(), ToTZ :: any()) ->
+    datetime() | {ambiguous, datetime(), datetime()}.
 date_tz_to_tz(Date, Disambiguate, FromTZ, ToTZ) when is_integer(FromTZ) ->
     NewDate = localtime:adjust_datetime(Date, FromTZ),
     date_tz_to_tz(NewDate, Disambiguate, "GMT", ToTZ);
@@ -546,13 +1080,14 @@ date_tz_to_tz(Date, Disambiguate, FromTZ, ToTZ) ->
             date_tz_to_tz_both(Date, FromTZ, ToTZ)
     end.
 
+-spec date_tz_to_tz_both(Date :: datetime(), FromTZ :: string(), ToTZ :: string()) -> datetime() | {ambiguous, datetime(), datetime()}.
 date_tz_to_tz_both(Date, FromTZ, ToTZ) ->
     Standard = localtime:local_to_local(Date, FromTZ, ToTZ),
     Daylight = localtime:local_to_local_dst(Date, FromTZ, ToTZ),
     if
         Standard=:=Daylight ->
             Standard;
-        ?else -> 
+        true -> 
             {ambiguous, Standard, Daylight}
     end.           
 
@@ -568,7 +1103,7 @@ set_timezone(Key,TZ) ->
     qdate_srv:set_timezone(Key, TZ).
 
 get_timezone() ->
-    qdate_srv:get_timezone().
+    ?DETERMINE_TZ.
 
 get_timezone(Key) ->
     qdate_srv:get_timezone(Key).
@@ -619,6 +1154,8 @@ try_parsers(_RawDate,[]) ->
     undefined;
 try_parsers(RawDate,[{ParserKey,Parser}|Parsers]) ->
     try Parser(RawDate) of
+        Timestamp when is_integer(Timestamp) ->
+            {Timestamp, "GMT"};
         {{_,_,_},{_,_,_}} = DateTime ->
             {DateTime,undefined};
         {DateTime={{_,_,_},{_,_,_}},Timezone} ->
@@ -628,8 +1165,8 @@ try_parsers(RawDate,[{ParserKey,Parser}|Parsers]) ->
         Other ->
             throw({invalid_parser_return_value,[{parser_key,ParserKey},{return,Other}]})
     catch
-        Error:Reason -> 
+        ?WITH_STACKTRACE(Error, Reason, Stacktrace)
-            throw({error_in_parser,[{error,{Error,Reason}},{parser_key,ParserKey}]})
+            throw({error_in_parser,[{error,{Error,Reason}},{parser_key,ParserKey}, {stacktrace, Stacktrace}]})
     end.
 
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
@@ -648,7 +1185,7 @@ deregister_format(Key) ->
 
 
 unixtime_to_now(T) when is_integer(T) ->
-    MegaSec = floor(T/1000000),
+    MegaSec = flooring(T/1000000),
     Secs = T - MegaSec*1000000,
     {MegaSec,Secs,0}.
 
@@ -656,10 +1193,10 @@ unixtime_to_date(T) ->
     Now = unixtime_to_now(T),
     calendar:now_to_datetime(Now).
 
-floor(N) when N >= 0 ->
+flooring(N) when N >= 0 ->
-    trunc(N);
+    erlang:trunc(N);
-floor(N) when N < 0 ->
+flooring(N) when N < 0 ->
-    Int = trunc(N),
+    Int = erlang:trunc(N),
     if
         Int==N -> Int;
         true -> Int-1
@@ -669,6 +1206,8 @@ floor(N) when N < 0 ->
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%  TESTS  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 
+-ifdef(EUNIT).
+
 -include_lib("eunit/include/eunit.hrl").
 
 %% emulates as if a forum-type website has a Site tz, and a user-specified tz
@@ -696,6 +1235,30 @@ tz_test_() ->
         end
     }.
 
+tz_preserve_ms_true_test_() ->
+    {
+        setup,
+        fun start_test/0,
+        fun stop_test/1,
+        fun(SetupData) ->
+            {inorder,[
+                preserve_ms_true_tests(SetupData)
+            ]}
+        end
+    }.
+
+tz_preserve_ms_false_test_() ->
+    {
+        setup,
+        fun start_test/0,
+        fun stop_test/1,
+        fun(SetupData) ->
+            {inorder,[
+                preserve_ms_false_tests(SetupData)
+            ]}
+        end
+    }.
+
 test_deterministic_parser(_) ->
     {inorder, [
         ?_assertEqual(ok, application:set_env(qdate, deterministic_parsing, {now, now})),
@@ -754,6 +1317,20 @@ tz_tests(_) ->
         ?_assertEqual({{2013,3,6},{18,0,0}}, to_date("GMT","3/7/2013 12:00am +0600")),
         ?_assertEqual({{2013,3,6},{12,0,0}}, to_date("CST","3/7/2013 12:00am +0600")),
 
+        %% These next two test check to make sure that the tz database properly
+        %% interprets GMT+/-X timezones (an earlier issue with
+        %% erlang_localtime's tz database had it incrementing/decrementing the
+        %% minute field rather than hours.
+        %%
+        %% It also ensures that GMT+/-X handling is interpreted the way you'd
+        %% intuitively expect, rather than the POSIX way, which is, quite
+        %% frankly, broken.
+        ?_assertEqual({{2013,3,7},{10,0,0}}, to_date("GMT-0","3/7/2013 10:00am GMT")),
+        ?_assertEqual({{2013,3,7},{10,0,0}}, to_date("GMT+0","3/7/2013 10:00am GMT")),
+        ?_assertEqual({{2013,3,7},{9,0,0}}, to_date("GMT-1","3/7/2013 10:00am GMT")),
+        ?_assertEqual({{2013,3,7},{11,0,0}}, to_date("GMT+1","3/7/2013 10:00am GMT")),
+
+
         %% parsing, then reformatting the same time with a different timezone using the php "r" (rfc2822)
         ?_assertEqual("Thu, 07 Mar 2013 12:15:00 -0600",
             to_string("r","CST",to_string("r","EST",{{2013,3,7},{13,15,0}}))),
@@ -769,8 +1346,13 @@ tz_tests(_) ->
         ?_assertEqual(555555555,to_unixtime("1987-08-10 00:59:15 GMT")),
         ?_assertEqual({555,555555,0},to_now("1987-08-10 00:59:15 GMT")),
         ?_assertEqual(ok, set_timezone("GMT")),
-        ?_assertEqual({{1970, 1, 1}, {1, 0, 0}}, to_date("CET", "1970-01-01T00:00:00Z"))
+        ?_assertEqual({{1970, 1, 1}, {1, 0, 0}}, to_date("CET", "1970-01-01T00:00:00Z")),
-
+        ?_assertEqual(ok, set_timezone("UTC")),
+        ?_assertEqual(1521945120, to_unixtime("2018-3-25T2:32:00")),
+        ?_assertEqual(true, between("-1 seconds", os:timestamp(), "+1 seconds")),
+        ?_assertEqual(true, between("60 hours ago", unixtime(), "in 15 days")),
+        ?_assertEqual(false, between("+1 seconds", qdate:to_string("n/j/Y g:ia"), "+2 seconds")),
+        ?_assertEqual(false, between("5 seconds ago","1 second ago"))
     ]}.
 
 
@@ -836,22 +1418,81 @@ arith_tests(_) ->
         ?_assertEqual({{2015,1,31},{23,59,59}}, to_date(add_months(1, {{2014,12,31},{23,59,59}}))),
         ?_assertEqual({{2015,2,28},{0,0,0}}, to_date(add_months(2, {{2014,12,31},{0,0,0}}))),
         ?_assertEqual({{2016,2,28},{0,0,0}}, to_date(add_years(1, {{2015,2,28},{0,0,0}}))),
+
+        ?_assertEqual({{2017,2,1},{0,0,0}}, to_date(add_months(-11, {{2018,1,1},{0,0,0}}))),
+        ?_assertEqual({{2017,1,1},{0,0,0}}, to_date(add_months(-12, {{2018,1,1},{0,0,0}}))),
+        ?_assertEqual({{2016,12,1},{0,0,0}}, to_date(add_months(-13, {{2018,1,1},{0,0,0}}))),
+
+        ?_assertEqual({{2018,12,1},{0,0,0}}, to_date(add_months(11, {{2018,1,1},{0,0,0}}))),
+        ?_assertEqual({{2019,1,1},{0,0,0}}, to_date(add_months(12, {{2018,1,1},{0,0,0}}))),
+        ?_assertEqual({{2019,2,1},{0,0,0}}, to_date(add_months(13, {{2018,1,1},{0,0,0}}))),
+
+        ?_assertEqual({{2018,1,1},{0,0,0}}, to_date(add_months(-11, {{2018,12,1},{0,0,0}}))),
+        ?_assertEqual({{2017,12,1},{0,0,0}}, to_date(add_months(-12, {{2018,12,1},{0,0,0}}))),
+        ?_assertEqual({{2017,11,1},{0,0,0}}, to_date(add_months(-13, {{2018,12,1},{0,0,0}}))),
+
+        ?_assertEqual({{2019,11,1},{0,0,0}}, to_date(add_months(11, {{2018,12,1},{0,0,0}}))),
+        ?_assertEqual({{2019,12,1},{0,0,0}}, to_date(add_months(12, {{2018,12,1},{0,0,0}}))),
+        ?_assertEqual({{2020,1,1},{0,0,0}}, to_date(add_months(13, {{2018,12,1},{0,0,0}}))),
+
+
         ?_assertEqual({{2014,2,28},{0,0,0}}, to_date(add_months(-24, {{2016,2,29},{0,0,0}}))),
+        ?_assertEqual({{2018,12,15},{0,0,0}}, to_date(add_months(24, {{2016,12,15},{0,0,0}}))),
         ?_assertEqual({{2012,2,29},{0,0,0}}, to_date(add_months(-48, {{2016,2,29},{0,0,0}}))),
         ?_assertEqual({{2016,2,29},{0,0,0}}, to_date(add_months(-1, {{2016,3,31},{0,0,0}}))),
         ?_assertEqual({{2017,2,28},{0,0,0}}, to_date(add_years(1, {{2016,2,29},{0,0,0}}))),
         ?_assertEqual({{2015,3,1},{0,0,0}}, to_date(add_days(1, {{2015,2,28},{0,0,0}}))),
-        ?_assertEqual({{2015,3,3},{0,0,0}}, to_date(add_days(3, {{2015,2,28},{0,0,0}})))
+        ?_assertEqual({{2015,3,3},{0,0,0}}, to_date(add_days(3, {{2015,2,28},{0,0,0}}))),
+        ?_assertEqual({{2017,1,2},{0,0,0}}, beginning_week({{2017,1,2},{0,0,0}})),
+        ?_assertEqual({{2017,1,2},{0,0,0}}, beginning_week({{2017,1,3},{0,0,0}})),
+        ?_assertEqual({{2017,1,3},{0,0,0}}, beginning_week(2, {{2017,1,4},{0,0,0}})),
+        ?_assertEqual({{2016,12,29},{0,0,0}}, beginning_week(4, {{2017,1,4},{0,0,0}})),
+        ?_assertEqual({{2016,12,31},{0,0,0}}, beginning_week(6, {{2017,1,6},{0,0,0}})),
+        ?_assertEqual({{2017,1,1},{0,0,0}}, beginning_week(7, {{2017,1,6},{0,0,0}})),
+
+        ?_assertEqual(0, age("1981-01-15", "1981-12-31")),
+        ?_assertEqual(39, age("1981-01-15", "2020-01-15")),
+        ?_assertEqual(39, age("1981-01-15", "2020-01-15 12am")),
+        ?_assertEqual(38, age("1981-01-15", "2020-01-14")),
+        ?_assertEqual(38, age("1981-01-15", "2020-01-14 11:59pm")),
+
+        %% checking pre-unix-epoch
+        ?_assertEqual(100, age("1901-01-01","2001-01-01")),
+        ?_assertEqual(20, age("1900-01-01", "1920-01-01")),
+        
+        ?_assertEqual(0, age_days("2020-11-20 12am","2020-11-20 11:59:59pm")),
+        ?_assertEqual(1, age_days("2020-11-19 11:59:59pm","2020-11-20 11:59:59pm")),
+        ?_assertEqual(7, age_days("2020-11-20","2020-11-27")),
+        ?_assertEqual(7, age_days("2020-11-27","2020-12-04"))
+
     ]}.
 
+preserve_ms_true_tests(_) ->
+    application:set_env(qdate, preserve_ms, true),
+    {inorder, [
+      ?_assertEqual({{2021,5,8},{23,0,16,472000}}, qdate:to_date(<<"UTC">>,<<"2021-5-09 0:0:16.472+01:00">>)),
+      ?_assertEqual(<<"2021-05-08T23:00:16.472000+00:00">>, qdate:to_string(<<"Y-m-d\\TH:i:s.fP">>, <<"UTC">>,<<"2021-5-09 0:0:16.472+01:00">>)),
+      ?_assertEqual(<<"2021-05-08T23:00:16+00:00">>, qdate:to_string(<<"Y-m-d\\TH:i:sP">>, <<"UTC">>,<<"2021-5-09 0:0:16.472+01:00">>)),
+      ?_assertEqual(<<"2021-05-08T23:00:16.472000+00:00">>, qdate:to_string(<<"c">>, <<"UTC">>,<<"2021-5-09 0:0:16.472+01:00">>))
+    ]}.
+
+preserve_ms_false_tests(_) ->
+    application:set_env(qdate, preserve_ms, false),
+    {inorder, [
+        ?_assertEqual({{2021,5,8},{23,0,16}}, qdate:to_date(<<"UTC">>,<<"2021-5-09 0:0:16.472+01:00">>)),
+        ?_assertEqual(<<"2021-05-08T23:00:16.0+00:00">>, qdate:to_string(<<"Y-m-d\\TH:i:s.fP">>, <<"UTC">>,<<"2021-5-09 0:0:16.472+01:00">>)),
+        ?_assertEqual(<<"2021-05-08T23:00:16+00:00">>, qdate:to_string(<<"Y-m-d\\TH:i:sP">>, <<"UTC">>,<<"2021-5-09 0:0:16.472+01:00">>)),
+        ?_assertEqual(<<"2021-05-08T23:00:16+00:00">>, qdate:to_string(<<"c">>, <<"UTC">>,<<"2021-5-09 0:0:16.472+01:00">>))
+    ]}.
 
 start_test() ->
-    application:start(qdate),
+    qdate:start(),
     set_timezone(?SELF_TZ),
     set_timezone(?SITE_KEY,?SITE_TZ),
     set_timezone(?USER_KEY,?USER_TZ),
     register_parser(compressed,fun compressed_parser/1),
     register_parser(microsoft_date,fun microsoft_parser/1),
+    register_parser(parse_relative, fun parse_relative/1),
     register_format(shortdate,"n/j/Y"),
     register_format(longdate,"n/j/Y g:ia").
 
@@ -873,7 +1514,7 @@ compressed_parser(_) ->
 
 microsoft_parser(FloatDate) when is_float(FloatDate) ->
     try
-        DaysSince1900 = floor(FloatDate),
+        DaysSince1900 = flooring(FloatDate),
         Days0to1900 = calendar:date_to_gregorian_days(1900,1,1),
         GregorianDays = Days0to1900 + DaysSince1900,
         Date = calendar:gregorian_days_to_date(GregorianDays),
@@ -890,3 +1531,5 @@ microsoft_parser(_) ->
 
 stop_test(_) ->
     ok.
+
+-endif.

src/qdate_app.erl

@@ -0,0 +1,15 @@
+-module(qdate_app).
+
+-behaviour(application).
+
+%% Application callbacks
+-export([start/2, stop/1]).
+
+start(_StartType, _StartArgs) ->
+    qdate_sup:start_link().
+
+
+stop(_State) ->
+    ok.
+
+

src/qdate_srv.erl

@@ -1,12 +1,9 @@
 % vim: ts=4 sw=4 et
-% Copyright (c) 2013-2015 Jesse Gumm
+% Copyright (c) 2013-2021 Jesse Gumm
 % See LICENSE for licensing information.
-%
-% NOTE: You'll probably notice that this isn't *actually* a server.  It *used*
-% to be a server, but is now instead just where we interact with the qdate
-% application environment.  Anyway, sorry for the confusion.
 
 -module(qdate_srv).
+-behaviour(gen_server).
 
 -export([
     set_timezone/1,
@@ -28,6 +25,19 @@
     get_formats/0
 ]).
 
+
+%% API
+-export([start_link/0]).
+
+%% gen_server callbacks
+-export([init/1,
+         handle_call/3,
+         handle_cast/2,
+         handle_info/2,
+         terminate/2,
+         code_change/3]).
+
+
 %% Simple wrappers for unique keys
 -define(BASETAG, qdate_var).
 -define(KEY(Name), {?BASETAG, Name}).
@@ -39,6 +49,42 @@
 -define(FORMATTAG, qdate_format).
 -define(FORMATKEY(Name), {?FORMATTAG, Name}).
 
+-define(SERVER, ?MODULE).
+-define(TABLE, ?MODULE).
+
+-record(state, {}).
+
+start_link() ->
+    gen_server:start_link({local, ?SERVER}, ?MODULE, [], []).
+
+init([]) ->
+    error_logger:info_msg("Creating qdate ETS Table: ~p",[?TABLE]),
+    ?TABLE = ets:new(?TABLE, [public, {read_concurrency, true}, named_table]),
+    {ok, #state{}}.
+
+handle_call({set, Key, Val}, _From, State) ->
+    ets:insert(?TABLE, {Key, Val}),
+    {reply, ok, State};
+handle_call({unset, Key}, _From, State) ->
+    ets:delete(?TABLE, Key),
+    {reply, ok, State};
+handle_call(_, _From, State) ->
+    {reply, invalid_request, State}.
+
+handle_cast(_Msg, State) ->
+        {noreply, State}.
+
+handle_info(_Info, State) ->
+        {noreply, State}.
+
+terminate(_Reason, _State) ->
+        ok.
+
+code_change(_OldVsn, State, _Extra) ->
+        {ok, State}.
+
+
+
 %% PUBLIC API FUNCTIONS
 
 set_timezone(TZ) ->
@@ -91,26 +137,41 @@ get_formats() ->
 %% App Vars
 
 set_env(Key, Val) ->
-    application:set_env(qdate, ?KEY(Key), Val).
+    gen_server:call(?SERVER, {set, ?KEY(Key), Val}).
 
 get_env(Key) ->
     get_env(Key, undefined).
 
 get_env(Key, Default) ->
-    %% Soon, this can just be replaced with application:get_env/3
+    case ets:lookup(?TABLE, ?KEY(Key)) of
-    %% which was introduced in R16B.
+        [{__Key, Val}] -> Val;
-    case application:get_env(qdate, ?KEY(Key)) of
+        [] -> Default
-        undefined -> Default;
-        {ok, Val} -> Val
     end.
 
 unset_env(Key) ->
-    application:unset_env(qdate, ?KEY(Key)).
+    gen_server:call(?SERVER, {unset, ?KEY(Key)}).
 
 get_all_env(FilterTag) ->
-    All = application:get_all_env(qdate),
+    try ets:tab2list(?TABLE) of
-    %% Maybe this is a little nasty.
+        All ->
-    [{Key, V} || {{?BASETAG, {Tag, Key}}, V} <- All, Tag==FilterTag].
+            [{Key, V} || {{?BASETAG, {Tag, Key}}, V} <- All, Tag==FilterTag]
+    catch
+        error:badarg:S ->
+            Msg = maybe_start_msg(),
+            logger:error(Msg),
+          
+            error({qdate_get_all_env_failed, #{
+                original_error => {error, badarg, S}
+            }})
+    end.
+
+maybe_start_msg() ->
+    "Attempting to read qdate environment failed (qdate_srv:get_all_env/1).\n"
+    "qdate may not have been started properly.\n"
+    "Please ensure qdate is started properly by either:\n"
+    "* Putting qdate in the 'applications' key in your .app.src or .app file, or\n"
+    "* Starting it manually with application:ensure_all_started(qdate) or qdate:start().".
+
 
 %% ProcDic Vars
 
@@ -123,3 +184,9 @@ put_pd(Key, Val) ->
 
 unset_pd(Key) ->
     put_pd(Key, undefined).
+
+
+
+
+
+

src/qdate_sup.erl

@@ -0,0 +1,32 @@
+-module(qdate_sup).
+
+-behaviour(supervisor).
+
+%% API
+-export([start_link/0]).
+
+%% Supervisor callbacks
+-export([init/1]).
+
+-define(SERVER, ?MODULE).
+
+start_link() ->
+        supervisor:start_link({local, ?SERVER}, ?MODULE, []).
+
+init([]) ->
+
+        SupFlags = #{},
+
+        ChildSpec = #{
+            id=>qdate_srv,
+            start=>{qdate_srv, start_link, []}
+        },
+
+        {ok, {SupFlags, [ChildSpec]}}.
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+
+
+