ISO 8601 year (%G and %g)

README.md

@@ -109,6 +109,8 @@ Returns a new formatter for the given string *specifier*. The specifier string m
 * `%d` - zero-padded day of the month as a decimal number [01,31].
 * `%e` - space-padded day of the month as a decimal number [ 1,31]; equivalent to `%_d`.
 * `%f` - microseconds as a decimal number [000000, 999999].
+* `%g` - ISO 8601 week-based year without century as a decimal number [00,99].
+* `%G` - ISO 8601 week-based year with century as a decimal number.
 * `%H` - hour (24-hour clock) as a decimal number [00,23].
 * `%I` - hour (12-hour clock) as a decimal number [01,12].
 * `%j` - day of the year as a decimal number [001,366].
@@ -136,9 +138,9 @@ Directives marked with an asterisk (\*) may be affected by the [locale definitio
 
 For `%U`, all days in a new year preceding the first Sunday are considered to be in week 0. For `%W`, all days in a new year preceding the first Monday are considered to be in week 0. Week numbers are computed using [*interval*.count](https://github.com/d3/d3-time/blob/master/README.md#interval_count). For example, 2015-52 and 2016-00 represent Monday, December 28, 2015, while 2015-53 and 2016-01 represent Monday, January 4, 2016. This differs from the [ISO week date](https://en.wikipedia.org/wiki/ISO_week_date) specification (`%V`), which uses a more complicated definition!
 
-For `%V`, per the [strftime man page](http://man7.org/linux/man-pages/man3/strftime.3.html):
+For `%V`,`%g` and `%G`, per the [strftime man page](http://man7.org/linux/man-pages/man3/strftime.3.html):
 
-> In this system, weeks start on a Monday, and are numbered from 01, for the first week, up to 52 or 53, for the last week.  Week 1 is the first week where four or more days fall within the new year (or, synonymously, week 01 is: the first week of the year that contains a Thursday; or, the week that has 4 January in it).
+> In this system, weeks start on a Monday, and are numbered from 01, for the first week, up to 52 or 53, for the last week.  Week 1 is the first week where four or more days fall within the new year (or, synonymously, week 01 is: the first week of the year that contains a Thursday; or, the week that has 4 January in it). If the ISO week number belongs to the previous or next year, that year is used instead.
 
 The `%` sign indicating a directive may be immediately followed by a padding modifier:
 

src/locale.js

@@ -63,6 +63,8 @@ export default function formatLocale(locale) {
     "d": formatDayOfMonth,
     "e": formatDayOfMonth,
     "f": formatMicroseconds,
+    "g": formatYearISO,
+    "G": formatFullYearISO,
     "H": formatHour24,
     "I": formatHour12,
     "j": formatDayOfYear,
@@ -96,6 +98,8 @@ export default function formatLocale(locale) {
     "d": formatUTCDayOfMonth,
     "e": formatUTCDayOfMonth,
     "f": formatUTCMicroseconds,
+    "g": formatUTCYearISO,
+    "G": formatUTCFullYearISO,
     "H": formatUTCHour24,
     "I": formatUTCHour12,
     "j": formatUTCDayOfYear,
@@ -129,6 +133,8 @@ export default function formatLocale(locale) {
     "d": parseDayOfMonth,
     "e": parseDayOfMonth,
     "f": parseMicroseconds,
+    "g": parseYear,
+    "G": parseFullYear,
     "H": parseHour24,
     "I": parseHour24,
     "j": parseDayOfYear,
@@ -550,9 +556,13 @@ function formatWeekNumberSunday(d, p) {
   return pad(timeSunday.count(timeYear(d) - 1, d), p, 2);
 }
 
-function formatWeekNumberISO(d, p) {
+function dISO(d) {
   var day = d.getDay();
-  d = (day >= 4 || day === 0) ? timeThursday(d) : timeThursday.ceil(d);
+  return (day >= 4 || day === 0) ? timeThursday(d) : timeThursday.ceil(d);
+}
+
+function formatWeekNumberISO(d, p) {
+  d = dISO(d);
   return pad(timeThursday.count(timeYear(d), d) + (timeYear(d).getDay() === 4), p, 2);
 }
 
@@ -568,10 +578,21 @@ function formatYear(d, p) {
   return pad(d.getFullYear() % 100, p, 2);
 }
 
+function formatYearISO(d, p) {
+  d = dISO(d);
+  return pad(d.getFullYear() % 100, p, 2);
+}
+
 function formatFullYear(d, p) {
   return pad(d.getFullYear() % 10000, p, 4);
 }
 
+function formatFullYearISO(d, p) {
+  var day = d.getDay();
+  d = (day >= 4 || day === 0) ? timeThursday(d) : timeThursday.ceil(d);
+  return pad(d.getFullYear() % 10000, p, 4);
+}
+
 function formatZone(d) {
   var z = d.getTimezoneOffset();
   return (z > 0 ? "-" : (z *= -1, "+"))
@@ -624,9 +645,13 @@ function formatUTCWeekNumberSunday(d, p) {
   return pad(utcSunday.count(utcYear(d) - 1, d), p, 2);
 }
 
-function formatUTCWeekNumberISO(d, p) {
+function UTCdISO(d) {
   var day = d.getUTCDay();
-  d = (day >= 4 || day === 0) ? utcThursday(d) : utcThursday.ceil(d);
+  return (day >= 4 || day === 0) ? utcThursday(d) : utcThursday.ceil(d);
+}
+
+function formatUTCWeekNumberISO(d, p) {
+  d = UTCdISO(d);
   return pad(utcThursday.count(utcYear(d), d) + (utcYear(d).getUTCDay() === 4), p, 2);
 }
 
@@ -642,10 +667,21 @@ function formatUTCYear(d, p) {
   return pad(d.getUTCFullYear() % 100, p, 2);
 }
 
+function formatUTCYearISO(d, p) {
+  d = UTCdISO(d);
+  return pad(d.getUTCFullYear() % 100, p, 2);
+}
+
 function formatUTCFullYear(d, p) {
   return pad(d.getUTCFullYear() % 10000, p, 4);
 }
 
+function formatUTCFullYearISO(d, p) {
+  var day = d.getUTCDay();
+  d = (day >= 4 || day === 0) ? utcThursday(d) : utcThursday.ceil(d);
+  return pad(d.getUTCFullYear() % 10000, p, 4);
+}
+
 function formatUTCZone() {
   return "+0000";
 }

test/format-test.js

@@ -110,6 +110,22 @@ tape("timeFormat(\"%e\")(date) formats space-padded dates", function(test) {
   test.end();
 });
 
+tape("timeFormat(\"%g\")(date) formats zero-padded two-digit ISO 8601 years", function (test) {
+  var f = timeFormat.timeFormat("%g");
+  test.equal(f(date.local(2018, 11, 30, 0)), "18"); // Sunday
+  test.equal(f(date.local(2018, 11, 31, 0)), "19"); // Monday
+  test.equal(f(date.local(2019, 0, 1, 0)), "19");
+  test.end();
+});
+
+tape("timeFormat(\"%G\")(date) formats zero-padded four-digit ISO 8601 years", function (test) {
+  var f = timeFormat.timeFormat("%G");
+  test.equal(f(date.local(2018, 11, 30, 0)), "2018"); // Sunday
+  test.equal(f(date.local(2018, 11, 31, 0)), "2019"); // Monday
+  test.equal(f(date.local(2019, 0, 1, 0)), "2019");
+  test.end();
+});
+
 tape("timeFormat(\"%H\")(date) formats zero-padded hours (24)", function(test) {
   var f = timeFormat.timeFormat("%H");
   test.equal(f(date.local(1990, 0, 1,  0)), "00");

test/parse-test.js

@@ -72,13 +72,39 @@ tape("timeParse(\"%w %U %Y\")(date) parses numeric weekday (Sunday), week number
   test.end();
 });
 
-tape("timeParse(\"%w %V %Y\")(date) parses numeric weekday, week number (ISO) and year", function(test) {
-  var p = timeFormat.timeParse("%w %V %Y");
+tape("timeParse(\"%w %V %G\")(date) parses numeric weekday, week number (ISO) and corresponding year", function(test) {
+  var p = timeFormat.timeParse("%w %V %G");
   test.deepEqual(p("1 01 1990"), date.local(1990,  0,  1));
   test.deepEqual(p("0 05 1991"), date.local(1991,  1,  3));
   test.deepEqual(p("4 53 1992"), date.local(1992, 11, 31));
   test.deepEqual(p("0 52 1994"), date.local(1995,  0,  1));
   test.deepEqual(p("0 01 1995"), date.local(1995,  0,  8));
+  test.deepEqual(p("1 01 2018"), date.local(2018,  0,  1));
+  test.deepEqual(p("1 01 2019"), date.local(2018,  11,  31));
+  test.end();
+});
+
+tape("timeParse(\"%w %V %g\")(date) parses numeric weekday, week number (ISO) and corresponding two-digits year", function(test) {
+  var p = timeFormat.timeParse("%w %V %g");
+  test.deepEqual(p("1 01 90"), date.local(1990,  0,  1));
+  test.deepEqual(p("0 05 91"), date.local(1991,  1,  3));
+  test.deepEqual(p("4 53 92"), date.local(1992, 11, 31));
+  test.deepEqual(p("0 52 94"), date.local(1995,  0,  1));
+  test.deepEqual(p("0 01 95"), date.local(1995,  0,  8));
+  test.deepEqual(p("1 01 18"), date.local(2018,  0,  1));
+  test.deepEqual(p("1 01 19"), date.local(2018, 11, 31));
+  test.end();
+});
+
+tape("timeParse(\"%V %g\")(date) parses week number (ISO) and corresponding two-digits year", function(test) {
+  var p = timeFormat.timeParse("%V %g");
+  test.deepEqual(p("01 90"), date.local(1990,  0,  1));
+  test.deepEqual(p("05 91"), date.local(1991,  0, 28));
+  test.deepEqual(p("53 92"), date.local(1992, 11, 28));
+  test.deepEqual(p("52 94"), date.local(1994, 11, 26));
+  test.deepEqual(p("01 95"), date.local(1995,  0,  2));
+  test.deepEqual(p("01 18"), date.local(2018,  0,  1));
+  test.deepEqual(p("01 19"), date.local(2018, 11, 31));
   test.end();
 });
 

test/utcFormat-test.js

@@ -98,6 +98,22 @@ tape("utcFormat(\"%e\")(date) formats space-padded dates", function(test) {
   test.end();
 });
 
+tape("timeFormat(\"%g\")(date) formats zero-padded two-digit ISO 8601 years", function (test) {
+  var f = timeFormat.utcFormat("%g");
+  test.equal(f(date.utc(2018, 11, 30, 0)), "18"); // Sunday
+  test.equal(f(date.utc(2018, 11, 31, 0)), "19"); // Monday
+  test.equal(f(date.utc(2019, 0, 1, 0)), "19");
+  test.end();
+});
+
+tape("utcFormat(\"%G\")(date) formats zero-padded four-digit ISO 8601 years", function (test) {
+  var f = timeFormat.utcFormat("%G");
+  test.equal(f(date.utc(2018, 11, 30, 0)), "2018"); // Sunday
+  test.equal(f(date.utc(2018, 11, 31, 0)), "2019"); // Monday
+  test.equal(f(date.utc(2019, 0, 1, 0)), "2019");
+  test.end();
+});
+
 tape("utcFormat(\"%H\")(date) formats zero-padded hours (24)", function(test) {
   var f = timeFormat.utcFormat("%H");
   test.equal(f(date.utc(1990, 0, 1,  0)), "00");

test/utcParse-test.js

@@ -150,6 +150,19 @@ tape("utcParse(\"%w %V %Y\")(date) parses numeric weekday, week number (ISO) and
   test.end();
 });
 
+tape("utcParse(\"%w %V %G\")(date) parses numeric weekday, week number (ISO) and corresponding year", function(test) {
+  var p = timeFormat.utcParse("%w %V %G");
+  test.deepEqual(p("1 01 1990"), date.utc(1990,  0,  1));
+  test.deepEqual(p("0 05 1991"), date.utc(1991,  1,  3));
+  test.deepEqual(p("4 53 1992"), date.utc(1992, 11, 31));
+  test.deepEqual(p("0 52 1994"), date.utc(1995,  0,  1));
+  test.deepEqual(p("0 01 1995"), date.utc(1995,  0,  8));
+  test.deepEqual(p("1 01 2018"), date.utc(2018, 0, 1));
+  test.deepEqual(p("1 01 2019"), date.utc(2018, 11, 31));
+  test.equal(p("X 03 2010"), null);
+  test.end();
+});
+
 tape("utcParse(\"%V %Y\")(date) week number (ISO) and year", function(test) {
   var p = timeFormat.utcParse("%V %Y");
   test.deepEqual(p("01 1990"), date.utc(1990,  0,  1));
@@ -163,6 +176,36 @@ tape("utcParse(\"%V %Y\")(date) week number (ISO) and year", function(test) {
   test.end();
 });
 
+tape("utcParse(\"%V %g\")(date) week number (ISO) and corresponding two-digits year", function(test) {
+  var p = timeFormat.utcParse("%V %g");
+  test.deepEqual(p("01 90"), date.utc(1990,  0,  1));
+  test.deepEqual(p("05 91"), date.utc(1991,  0, 28));
+  test.deepEqual(p("53 92"), date.utc(1992, 11, 28));
+  test.deepEqual(p("01 93"), date.utc(1993,  0,  4));
+  test.deepEqual(p("01 95"), date.utc(1995, 0, 2));
+  test.deepEqual(p("01 18"), date.utc(2018, 0, 1));
+  test.deepEqual(p("01 19"), date.utc(2018, 11, 31));
+  test.deepEqual(p("00 95"), null);
+  test.deepEqual(p("54 95"), null);
+  test.deepEqual(p("X 95"), null);
+  test.end();
+});
+
+tape("utcParse(\"%V %G\")(date) week number (ISO) and corresponding year", function(test) {
+  var p = timeFormat.utcParse("%V %G");
+  test.deepEqual(p("01 1990"), date.utc(1990,  0,  1));
+  test.deepEqual(p("05 1991"), date.utc(1991,  0, 28));
+  test.deepEqual(p("53 1992"), date.utc(1992, 11, 28));
+  test.deepEqual(p("01 1993"), date.utc(1993,  0,  4));
+  test.deepEqual(p("01 1995"), date.utc(1995, 0, 2));
+  test.deepEqual(p("01 2018"), date.utc(2018, 0, 1));
+  test.deepEqual(p("01 2019"), date.utc(2018, 11, 31));
+  test.deepEqual(p("00 1995"), null);
+  test.deepEqual(p("54 1995"), null);
+  test.deepEqual(p("X 1995"), null);
+  test.end();
+});
+
 tape("utcParse(\"%Q\")(date) parses UNIX timestamps", function(test) {
   var p = timeFormat.utcParse("%Q");
   test.deepEqual(p("0"), date.utc(1970, 0, 1));