Parse week-of-year with implicit day-of-week.

If %W is specified, assume Monday; if %U is specified, assume Sunday.

Fixes #1914.

d3.js

@@ -2539,7 +2539,8 @@
         if (i != string.length) return null;
         if ("p" in d) d.H = d.H % 12 + d.p * 12;
         var localZ = d.Z != null && d3_date !== d3_date_utc, date = new (localZ ? d3_date_utc : d3_date)();
-        if ("j" in d) date.setFullYear(d.y, 0, d.j); else if ("w" in d && ("W" in d || "U" in d)) {
+        if ("j" in d) date.setFullYear(d.y, 0, d.j); else if ("W" in d || "U" in d) {
+          if (!("w" in d)) d.w = "W" in d ? 1 : 0;
           date.setFullYear(d.y, 0, 1);
           date.setFullYear(d.y, 0, "W" in d ? (d.w + 6) % 7 + d.W * 7 - (date.getDay() + 5) % 7 : d.w + d.U * 7 - (date.getDay() + 6) % 7);
         } else date.setFullYear(d.y, d.m, d.d);

src/locale/time-format.js

@@ -54,7 +54,8 @@ function d3_locale_timeFormat(locale) {
 
       // Set year, month, date.
       if ("j" in d) date.setFullYear(d.y, 0, d.j);
-      else if ("w" in d && ("W" in d || "U" in d)) {
+      else if ("W" in d || "U" in d) {
+        if (!("w" in d)) d.w = "W" in d ? 1 : 0;
         date.setFullYear(d.y, 0, 1);
         date.setFullYear(d.y, 0, "W" in d
             ? (d.w + 6) % 7 + d.W * 7 - (date.getDay() + 5) % 7

test/time/format-test.js

@@ -222,6 +222,12 @@ suite.addBatch({
        assert.deepEqual(p("Sun 01 1995"), local(1995, 0, 1));
        assert.isNull(p("XXX 03 2010"));
      },
+     "assumes Sunday when parsing week number (Sunday) with no weekday": function(format) {
+       var p = format("%U %Y").parse;
+       assert.deepEqual(p("00 1990"), local(1989, 11, 31));
+       assert.deepEqual(p("05 1991"), local(1991,  1,  3));
+       assert.deepEqual(p("01 1995"), local(1995,  0,  1));
+     },
      "parses weekday, week number (Sunday) and year": function(format) {
        var p = format("%A %U %Y").parse;
        assert.deepEqual(p("Monday 00 1990"), local(1990, 0, 1));
@@ -256,6 +262,12 @@ suite.addBatch({
        assert.deepEqual(p("0 04 1991"), local(1991, 1, 3));
        assert.deepEqual(p("0 00 1995"), local(1995, 0, 1));
        assert.isNull(p("X 03 2010"));
+     },
+     "assumes Monday when parsing week number (Monday) with no weekday": function(format) {
+       var p = format("%W %Y").parse;
+       assert.deepEqual(p("01 1990"), local(1990, 0, 1));
+       assert.deepEqual(p("05 1991"), local(1991, 1, 4));
+       assert.deepEqual(p("01 1995"), local(1995, 0, 2));
      },
       "parses numeric date": function(format) {
         var p = format("%m/%d/%y").parse;