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

@@ -1,6 +1,10 @@
 *~
 *.beam
 *.sw?
+*.iml
 deps/
 ebin/
 .eunit/
+.idea/
+_build
+doc/

.travis.yml

@@ -1,10 +0,0 @@
-language: erlang
-script: "make test"
-otp_release:
-  - R16B
-  - R15B02
-  - R15B01
-  - R15B
-  - R14B03
-  - R14B02
-before_script: "sudo apt-get --yes --force-yes install libpam0g-dev"

CHANGELOG.markdown

@@ -0,0 +1,87 @@
+## 0.7.3
+
+* 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)
+* 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
+
+* Add partial support for `ec_date`'s 4-tuple subsecond accuracy time format.
+* Fix `erlware_commons` dependency to a rebar2-compatible version.
+
+## 0.4.1
+
+* Remove unnecessary `io:format` call.
+
+## 0.4.0
+
+* Remove dependency on a running server for tracking application state.
+  Instead, parsers and formats are registered to the application environment
+  vars (e.g. `application:get_env`), and timezones are registered to the
+  application environment or the process dictionary. A side-effect of this
+  change is that you can no longer query another process's timezone. 
+* Add basic date arithmetic (e.g. `qdate:add_hours/[1-2]`, etc).
+* Add `get_formats()` and `get_parsers()` to see list of registered formats and
+  parsers.
+* Fix bug related to relying on the application environment variable
+  `default_timezone`
+
+## 0.3.0
+
+* Add Timezone/Daylight Saving Disambiguation
+* Add the `auto` timezone shortcut
+* Fix rebar.config to allow for compilation on Erlang 17
+
+## 0.2.1
+
+* Fix allowing timezone names to be binary
+
+## 0.2.0
+
+* Adding `qdate:compare/2,3` for easily comparing dates
+
+## 0.1.0
+
+* Initial Release

Makefile

@@ -1,13 +1,41 @@
-all: get-deps compile
+all: compile
 
-get-deps:
-	./rebar get-deps
+# 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
 
-compile:
-	./rebar compile
+# rebar3.mk adds a new rebar3 rule to your Makefile
+# (see https://github.com/choptastic/rebar3.mk) for full info
+include rebar3.mk
 
-test: get-deps compile
-	./rebar skip_deps=true eunit
+compile: rebar3
+	$(REBAR) compile
+
+update: rebar3
+	$(REBAR) update
+
+test:
+	EUNIT=1 $(REBAR) compile
+	EUNIT=1 $(REBAR) eunit
+
+dialyzer: compile
+	DIALYZER=1 $(REBAR) dialyzer
+
+dev:
+	mkdir -p _checkouts
+	cd _checkouts; git clone https://github.com/choptastic/qdate_localtime
+
+
+run: rebar3
+	$(REBAR) shell
+
+push_tags:
+	git push --tag
+
+pull_tags:
+	git pull --tag
+
+publish: rebar3 pull_tags
+	$(REBAR) hex publish
 
-run:
-	erl -pa ebin/ deps/*/ebin/ -eval "application:start(qdate)"

README.md

@@ -1,6 +1,6 @@
-# qdate - A Wrapper for Erlang Date and Timezone Management
+# 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
 
@@ -21,12 +21,15 @@ benefits of `ec_date` and `erlang_localtime`, as well as extending the
 capabilities of both to provide for other needed tools found in a single
 module.
 
-`qdate` will provide, under the roof of a single module date and time formatting
-and parsing from and into:
+`qdate` provides date and time formatting and parsing from and into:
  + Formatting Strings
  + Erlang Date Format
  + Erlang Now Format
  + Unixtime integers
+ + Timezones
+
+And all this while dealing with timezone parsing, formatting, conversion
+and overall management.
 
 #### Acceptable Date Formats
 
@@ -65,10 +68,15 @@ T, Z, r, and c), `qdate` will handle them for us.
   + `to_now(Date)` - converts any date/time format to Erlang now format.
   + `to_unixtime(Date)` - converts any date/time format to a unixtime integer
 
+A **ToTimezone** value of the atom `auto` will automatically determine the
+timezone. For example, `to_date(Date, auto)` is exactly the same as
+`to_date(Date)`
+
 **A Note About Argument Order**: In all cases, `ToTimezone` is optional and if
 omitted, will be determined as described below in "Understanding Timezone
 Determining and Conversion". If `ToTimezone` is specified, it will always be
-immediately left of the `Date` argument. `Date` will always be the last
+immediately left of the `Disambiguate` argument (if it's specified), which is
+always immediately left of `Date` argument. `Date` will always be the last
 argument to any of the conversion and formatting functions.
 
 #### Understanding Timezone Determining and Conversions
@@ -90,9 +98,88 @@ 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 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
+"5am" and "6am" in GMT, since "1am EST". This is a side effect of the
+"intelligence" of `qdate` - `qdate` would notice that 1am in New York is EST,
+and should be converted to "1am EST", and then do the conversion from "1am EST"
+to "GMT".  This can lead to confusion.
+
+Further, since `qdate` attempts to be "smart" about mistakenly entered
+timezones (ie, if you entered "2013-01-01 EDT", `qdate` knows that "EDT"
+(Eastern Daylight Time) doesn't apply to January first, so it *assumes* you
+meant "EST".
+
+**THE SOLUTION** to this tangled mess that we call Daylight Saving Time is to
+provide an option to disambiguate if you so desire. By default disambiguation
+is disabled, and `qdate` will just guess as to it's best choice. But if you so
+desire, you can make sure qdate does *both* conversions, and returns both.
+
+You can do this by passing a `Disambiguation` argument to `to_string`,
+`to_date`, `to_unixtime`, and `to_now`. `Disambiguation` can be an atom of the
+values:
+
+  + `prefer_standard` *(Default Behavior)*: If an ambiguous result occurs,
+    qdate will return the date in standard time rather than daylight time.
+  + `prefer_daylight`: If an ambiguous result occurs, qdate will return the
+    preferred daylight time.
+  + `both`: If an ambiguous result occurs, `qdate` will return the tuple:
+    `{ambiguous, DateStandard, DateDaylight}`, where `DateStandard` is the date
+	in Standard Time, and `DateDaylight` is the date in Daylight Saving Time.
+
+So the expanded conversions functions are:
+
+  + `to_date(ToTimezone, Disambiguate, Date)`
+  + `to_string(FormatString, ToTimezone, Disambiguate, Date)`
+  + `to_unixtime(Disambiguate, Date)`
+  + `to_now(Disambiguate, Date)`
+
+Examples:
+
+```erlang
+1> qdate:set_timezone("GMT").
+ok
+
+%% Here, converting GMT 2013-11-03 6AM to America/New York yields an ambiguous
+%% result
+2> qdate:to_date("America/New York", both, {{2013,11,3},{6,0,0}}).
+{ambiguous,{{2013,11,3},{1,0,0}},{{2013,11,3},{2,0,0}}}
+
+%% Let's just use daylight time
+3> qdate:to_date("America/New York", prefer_daylight, {{2013,11,3},{6,0,0}}).
+{{2013,11,3},{2,0,0}}
+
+%% Let's just use standard time (the default behavior)
+4> qdate:to_date("America/New York", prefer_standard, {{2013,11,3},{6,0,0}}).
+{{2013,11,3},{1,0,0}}
+
+5> qdate:set_timezone("America/New York").
+ok
+
+%% Switching from 1AM Eastern Time to GMT yields a potentially ambiguous result
+6> qdate:to_date("GMT", both, {{2013,11,3},{1,0,0}}).
+{ambiguous,{{2013,11,3},{6,0,0}},{{2013,11,3},{5,0,0}}}
+
+%% Use daylight time for conversion
+7> qdate:to_date("GMT", prefer_daylight, {{2013,11,3},{1,0,0}}).
+{{2013,11,3},{5,0,0}}
+
+%% Here we demonstrated that even if we ask for "both", if there is no
+%% ambiguity, the plain date is returned
+8> qdate:to_date("GMT", both, {{2013,11,3},{5,0,0}}).
+{{2013,11,3},{10,0,0}}
+```
 
 #### Conversion Functions provided for API compatibility with `ec_date`
 
@@ -101,6 +188,76 @@ will infer the timezone in the following order.
   + `format/1` - Same as `to_string/1`
   + `format/2` - Same as `to_string/2`
 
+### Date and Time Comparison
+
+`qdate` provides a few convenience functions for performing date comparisons.
+
+  + `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) -> true|false` - Operator is an infix comparison operator, and
+    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`
@@ -136,6 +293,7 @@ be attempted before engaging the `ec_date` parser.
     able to parse the string, then it should return `undefined`.
   + `deregister_parser(Key)` - If you previously registered a parser with the
     `qdate` server, you can deregister it by its `Key`.
+  + `get_parsers()` - Get the list of all registered parsers and their keys.
 
 ### Registering and Deregistering Formatters
   + `register_format(Key, FormatString)` - Register a formatting string with
@@ -143,6 +301,7 @@ be attempted before engaging the `ec_date` parser.
     formatting string.
   + `deregister_format(Key)` - Deregister the formatting string from the
     `qdate` server.
+  + `get_formats()` - Get the list of all registered formats and their keys.
 
 ### About backwards compatibility with `ec_date` and deterministic parsing
 
@@ -339,8 +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
 
@@ -354,7 +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").
@@ -510,6 +692,175 @@ ok
 %% that timezone to our intended timezone.
 ```
 
+## Beginning or Ending of time periods (hours, days, years, weeks, etc)
+
+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_minutes(Minutes, Date)`
+   + `add_hours(Hours, Date)`
+   + `add_days(Days, Date)`
+   + `add_weeks(Weeks, Date)`
+   + `add_months(Months, Date)`
+   + `add_years(Years, Date)`
+   + `add_date(DateToAdd, Date)` - `DateToAdd` is a shortcut way of adding
+      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
+      minutes, and not make any changes to seconds.
+
+For the date arithmetic functions, `Date`, like all `qdate` functions, can be any
+format.
+
+### Date Arithmetic from "now"
+
+There are 7 other arithmetic functions that take a single argument, and these do arithmetic from "now." For example, `add_years(4)` is a shortcut for `add_years(4, os:timestamp())`.
+
+   + `add_seconds(Seconds)`
+   + `add_minutes(Minutes)`
+   + `add_hours(Hours)`
+   + `add_days(Days)`
+   + `add_weeks(Weeks)`
+   + `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
@@ -518,12 +869,24 @@ A few shoutouts to [Dale Harvey](http://github.com/daleharvey) and the
 package. Without the hard work of all involved in those projects, `qdate` would
 not exist.
 
+### Thanks to Additional Contributors
+
++ [Mark Allen](https://github.com/mrallen1)
++ [Christopher Phillips](https://github.com/lostcolony)
++ [Nicholas Lundgaard](https://github.com/nlundgaard-al)
++ [Alejandro Ramallo](https://github.com/aramallo)
++ [Heinz Gies](https://github.com/Licenser)
+
+
+## Changelog
+
+See [CHANGELOG.markdown](https://github.com/choptastic/qdate/blob/master/CHANGELOG.markdown)
+
 ## TODO
 
 + Make `qdate` backend-agnostic (allow specifying either ec_date or dh_date as
   the backend)
 + Add `-spec` and `-type` info for dialyzer
-+ Add date and time arithmetic.
 + 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

@@ -1,13 +1,24 @@
-% vim:ts=4 sw=4 et ft=erlang
-{require_otp_vsn, "R13B04|R14|R15|R16"}.
-
+%% -*- erlang -*-
+%% vim:ts=4 sw=4 et ft=erlang
 {cover_enabled, true}.
 
-%{erl_opts, [debug_info,{i,"site/include"}]}.
-
-{deps_dir, ["deps"]}.
-
-{deps, [
-    {erlware_commons, ".*", {git, "git://github.com/erlware/erlware_commons.git", "HEAD"}},
-    {erlang_localtime, ".*", {git, "git://github.com/choptastic/erlang_localtime.git", "HEAD"}}
+{dialyzer, [
+    {exclude_apps, []},
+    {warnings, []}
 ]}.
+
+{deps,
+ [
+  erlware_commons,
+  {qdate_localtime, "~> 1.2.0"}
+ ]}.
+
+{project_plugins, [rebar3_ex_doc]}.
+
+{hex, [{doc, ex_doc}]}.
+
+{ex_doc, [
+          {source_url, <<"https://github.com/choptastic/qdate">>},
+          {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

@@ -1,12 +1,17 @@
 {application, qdate,
  [
   {description, "Simple Date and Timezone handling for Erlang"},
-  {vsn, "0.1.0"},
+  {vsn, git},
   {registered, []},
   {applications, [
                   kernel,
-                  stdlib
+                  stdlib,
+                  qdate_localtime,
+                  erlware_commons
                  ]},
-  {mod, { qdate_app, []}},
-  {env, []}
+  {modules, [qdate, qdate_srv, qdate_sup, qdate_app]},
+  {env, []},
+  {licenses, ["MIT"]},
+  {mod, {qdate_app, []}},
+  {links, [{"Github", "https://github.com/choptastic/qdate"}]}
  ]}.

src/qdate_app.erl

@@ -1,7 +1,3 @@
-% vim: ts=4 sw=4 et
-% Copyright (c) 2013 Jesse Gumm
-% See LICENSE for licensing information.
-
 -module(qdate_app).
 
 -behaviour(application).
@@ -9,12 +5,11 @@
 %% Application callbacks
 -export([start/2, stop/1]).
 
-%% ===================================================================
-%% Application callbacks
-%% ===================================================================
-
 start(_StartType, _StartArgs) ->
     qdate_sup:start_link().
 
+
 stop(_State) ->
     ok.
+
+

src/qdate_srv.erl

@@ -1,22 +1,10 @@
 % vim: ts=4 sw=4 et
-% Copyright (c) 2013 Jesse Gumm
+% Copyright (c) 2013-2021 Jesse Gumm
 % See LICENSE for licensing information.
 
 -module(qdate_srv).
 -behaviour(gen_server).
 
--define(SRV, ?MODULE).
-
--export([
-    start_link/0,
-    init/1,
-    handle_call/3,
-    handle_cast/2,
-    handle_info/2,
-    code_change/3,
-    terminate/2
-]).
-
 -export([
     set_timezone/1,
     set_timezone/2,
@@ -33,133 +21,172 @@
 
     register_format/2,
     get_format/1,
-    deregister_format/1
+    deregister_format/1,
+    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}).
+
+-define(TZTAG, qdate_tz).
+-define(TZKEY(Name), {?TZTAG, Name}).
+-define(PARSERTAG, qdate_parser).
+-define(PARSERKEY(Name), {?PARSERTAG, Name}).
+-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
 
-start_link() ->
-    gen_server:start_link({local, ?SRV}, ?MODULE, [], []).
-
 set_timezone(TZ) ->
-    set_timezone(self(),TZ).
+    put_pd(?TZTAG, TZ).
 
-set_timezone(Key,TZ) ->
-    ok = gen_server:call(?SRV,{set_timezone,Key,TZ}).
+set_timezone(Key, TZ) ->
+    set_env(?TZKEY(Key), TZ).
 
 get_timezone() ->
-    get_timezone(self()).
+    get_pd(?TZTAG).
 
 get_timezone(Key) ->
-    gen_server:call(?SRV,{get_timezone,Key}).
+    get_env(?TZKEY(Key)).
 
 clear_timezone() ->
-    clear_timezone(self()).
+    unset_pd(?TZTAG).
 
 clear_timezone(Key) ->
-    ok = gen_server:call(?SRV, {clear_timezone, Key}).
+    unset_env(?TZKEY(Key)).
 
 register_parser(Parser) when is_function(Parser,1) ->
     register_parser(erlang:make_ref(),Parser).
 
 register_parser(Key,Parser) when is_function(Parser,1) ->
-    Key = gen_server:call(?SRV,{register_parser,Key,Parser}).
+    set_env(?PARSERKEY(Key), Parser).
 
 deregister_parser(Key) ->
-    ok = gen_server:call(?SRV,{deregister_parser,Key}).
+    unset_env(?PARSERKEY(Key)).
 
 deregister_parsers() ->
-    ok = gen_server:call(?SRV,{deregister_parsers}).
+    [deregister_parser(Key) || {Key, _} <- get_parsers()].
 
 get_parsers() ->
-    gen_server:call(?SRV,{get_parsers}).    
+    get_all_env(?PARSERTAG). 
 
-register_format(Key,Format) ->
-    ok = gen_server:call(?SRV,{register_format,Key,Format}).
+register_format(Key, Format) ->
+    set_env(?FORMATKEY(Key), Format).
 
 get_format(Key) ->
-    gen_server:call(?SRV,{get_format,Key}).
+    get_env(?FORMATKEY(Key)).
 
 deregister_format(Key) ->
-    ok = gen_server:call(?SRV,{deregister_format,Key}).
+    unset_env(?FORMATKEY(Key)).
    
-
-%% SERVER FUNCTIONS
-
--record(state, {tz, parsers, formats}).
-
-init(_) ->
-    State = #state{tz=dict:new(),parsers=dict:new(),formats=dict:new()},
-    {ok, State}.
-
-handle_cast(_,State) ->
-    {noreply, State}.
-
-handle_info({'DOWN', MonitorRef, process, Pid, _Reason}, State) ->
-    erlang:demonitor(MonitorRef),
-    NewTZ = dict:erase(Pid, State#state.tz),
-    NewParsers = dict:erase(Pid, State#state.parsers),
-    NewFormats = dict:erase(Pid, State#state.formats),
-    NewState = State#state{tz=NewTZ, parsers=NewParsers, formats=NewFormats},   
-    {noreply, NewState };
-handle_info(_, State) ->
-    {noreply, State}.
-
-handle_call({set_timezone,Key,TZ}, _From, State) ->
-    monitor_if_pid(Key),
-    NewTZ = dict:store(Key, TZ, State#state.tz),
-    NewState = State#state{tz=NewTZ},
-    {reply, ok, NewState};
-handle_call({clear_timezone,Key},_From, State) ->
-    NewTZ = dict:erase(Key, State#state.tz),
-    NewState = State#state{tz=NewTZ},
-    {reply, ok, NewState};
-handle_call({get_timezone,Key},_From, State) ->
-    Reply = case dict:find(Key, State#state.tz) of
-        error -> undefined;
-        {ok,TZ} -> TZ
-    end,
-    {reply, Reply, State};
-
-handle_call({register_parser,Key,Parser},_From,State) ->
-    NewParsers = dict:store(Key, Parser, State#state.parsers),
-    NewState = State#state{parsers=NewParsers},
-    {reply, Key, NewState};
-handle_call({get_parsers},_From,State) ->
-    Reply = dict:to_list(State#state.parsers),
-    {reply, Reply, State};
-handle_call({deregister_parser,Key},_From,State) ->
-    NewParsers = dict:erase(Key, State#state.parsers),
-    NewState = State#state{parsers=NewParsers},
-    {reply, ok, NewState};
-handle_call({deregister_parsers},_From,State) ->
-    NewState = State#state{parsers=dict:new()},
-    {reply, ok, NewState};
-
-handle_call({register_format,Key,Format},_From,State) ->
-    NewFormats = dict:store(Key, Format, State#state.formats),
-    NewState = State#state{formats=NewFormats},
-    {reply, ok, NewState};
-handle_call({get_format,Key},_From,State) ->
-    Reply = case dict:find(Key, State#state.formats) of
-        error -> undefined;
-        {ok, Format} -> Format
-    end,
-    {reply, Reply,State};
-handle_call({deregister_format,Key},_From,State) ->
-    NewFormats = dict:erase(Key, State#state.formats),
-    NewState = State#state{formats=NewFormats},
-    {reply, ok, NewState}.
-
-terminate(_Reason, _State) ->
-    ok.
-
-code_change(_OldVersion, State, _Extra) ->
-    {ok, State}.
+get_formats() ->
+    get_all_env(?FORMATTAG).
 
 %% PRIVATE TOOLS
 
-monitor_if_pid(Key) when is_pid(Key) ->
-    erlang:monitor(process,Key);
-monitor_if_pid(_) ->
-    do_nothing.
+%% App Vars
+
+set_env(Key, Val) ->
+    gen_server:call(?SERVER, {set, ?KEY(Key), Val}).
+
+get_env(Key) ->
+    get_env(Key, undefined).
+
+get_env(Key, Default) ->
+    case ets:lookup(?TABLE, ?KEY(Key)) of
+        [{__Key, Val}] -> Val;
+        [] -> Default
+    end.
+
+unset_env(Key) ->
+    gen_server:call(?SERVER, {unset, ?KEY(Key)}).
+
+get_all_env(FilterTag) ->
+    try ets:tab2list(?TABLE) of
+        All ->
+            [{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
+
+get_pd(Key) ->
+    erlang:get(?KEY(Key)).
+
+put_pd(Key, Val) ->
+    erlang:put(?KEY(Key), Val),
+    ok.
+
+unset_pd(Key) ->
+    put_pd(Key, undefined).
+
+
+
+
+
+

src/qdate_sup.erl

@@ -1,7 +1,3 @@
-% vim: ts=4 sw=4 et
-% Copyright (c) 2013 Jesse Gumm
-% See LICENSE for licensing information.
-
 -module(qdate_sup).
 
 -behaviour(supervisor).
@@ -12,21 +8,25 @@
 %% Supervisor callbacks
 -export([init/1]).
 
-%% Helper macro for declaring children of supervisor
--define(CHILD(I, Type), {I, {I, start_link, []}, permanent, 5000, Type, [I]}).
-
-%% ===================================================================
-%% API functions
-%% ===================================================================
+-define(SERVER, ?MODULE).
 
 start_link() ->
-    supervisor:start_link({local, ?MODULE}, ?MODULE, []).
-
-%% ===================================================================
-%% Supervisor callbacks
-%% ===================================================================
+        supervisor:start_link({local, ?SERVER}, ?MODULE, []).
 
 init([]) ->
-    Server = ?CHILD(qdate_srv, worker),
-    {ok, { {one_for_one, 5, 10}, [Server]} }.
+
+        SupFlags = #{},
+
+        ChildSpec = #{
+            id=>qdate_srv,
+            start=>{qdate_srv, start_link, []}
+        },
+
+        {ok, {SupFlags, [ChildSpec]}}.
+
+%%%===================================================================
+%%% Internal functions
+%%%===================================================================
+
+