move world-calendar logic in lib/dates.js to new 'calendars' component

- use Registry in lib.dates.js to invoke world-calendar logic on-demand.
plotly · alexcjohnson · Dec 9, 2016 · Dec 2, 2016 · Nov 30, 2016 · Nov 30, 2016
commit 31430999a77ab8af1d90fffa425260acb13cf16d
diff --git a/src/components/calendars/index.js b/src/components/calendars/index.js
@@ -0,0 +1,158 @@
+/**
+* Copyright 2012-2016, Plotly, Inc.
+* All rights reserved.
+*
+* This source code is licensed under the MIT license found in the
+* LICENSE file in the root directory of this source tree.
+*/
+
+'use strict';
+
+var calendars = require('world-calendars');
+
+var Lib = require('../../lib');
+var constants = require('../../constants/numerical');
+
+var EPOCHJD = constants.EPOCHJD;
+var ONEDAY = constants.ONEDAY;
+
+// each calendar needs its own default canonical tick. I would love to use
+// 2000-01-01 (or even 0000-01-01) for them all but they don't necessarily
+// all support either of those dates. Instead I'll use the most significant
+// number they *do* support, biased toward the present day.
+var CANONICAL_TICK = {
+    coptic: '2000-01-01',
+    discworld: '2000-01-01',
+    ethiopian: '2000-01-01',
+    hebrew: '5000-01-01',
+    islamic: '1000-01-01',
+    julian: '2000-01-01',
+    mayan: '5000-01-01',
+    nanakshahi: '1000-01-01',
+    nepali: '2000-01-01',
+    persian: '1000-01-01',
+    jalali: '1000-01-01',
+    taiwan: '1000-01-01',
+    thai: '2000-01-01',
+    ummalqura: '1400-01-01'
+};
+
+// Start on a Sunday - for week ticks
+// Discworld and Mayan calendars don't have 7-day weeks anyway so don't change them.
+// If anyone really cares we can customize the auto tick spacings for these calendars.
+var CANONICAL_SUNDAY = {
+    coptic: '2000-01-03',
+    discworld: '2000-01-01',
+    ethiopian: '2000-01-05',
+    hebrew: '5000-01-01',
+    islamic: '1000-01-02',
+    julian: '2000-01-03',
+    mayan: '5000-01-01',
+    nanakshahi: '1000-01-05',
+    nepali: '2000-01-05',
+    persian: '1000-01-01',
+    jalali: '1000-01-01',
+    taiwan: '1000-01-04',
+    thai: '2000-01-04',
+    ummalqura: '1400-01-06'
+};
+
+var DFLTRANGE = {
+    coptic: ['1700-01-01', '1701-01-01'],
+    discworld: ['1800-01-01', '1801-01-01'],
+    ethiopian: ['2000-01-01', '2001-01-01'],
+    hebrew: ['5700-01-01', '5701-01-01'],
+    islamic: ['1400-01-01', '1401-01-01'],
+    julian: ['2000-01-01', '2001-01-01'],
+    mayan: ['5200-01-01', '5201-01-01'],
+    nanakshahi: ['0500-01-01', '0501-01-01'],
+    nepali: ['2000-01-01', '2001-01-01'],
+    persian: ['1400-01-01', '1401-01-01'],
+    jalali: ['1400-01-01', '1401-01-01'],
+    taiwan: ['0100-01-01', '0101-01-01'],
+    thai: ['2500-01-01', '2501-01-01'],
+    ummalqura: ['1400-01-01', '1401-01-01']
+};
+
+/*
+ * convert d3 templates to world-calendars templates, so our users only need
+ * to know d3's specifiers. Map space padding to no padding, and unknown fields
+ * to an ugly placeholder
+ */
+var UNKNOWN = '##';
+var d3ToWorldCalendars = {
+    'd': {'0': 'dd', '-': 'd'}, // 2-digit or unpadded day of month
+    'a': {'0': 'D', '-': 'D'}, // short weekday name
+    'A': {'0': 'DD', '-': 'DD'}, // full weekday name
+    'j': {'0': 'oo', '-': 'o'}, // 3-digit or unpadded day of the year
+    'W': {'0': 'ww', '-': 'w'}, // 2-digit or unpadded week of the year (Monday first)
+    'm': {'0': 'mm', '-': 'm'}, // 2-digit or unpadded month number
+    'b': {'0': 'M', '-': 'M'}, // short month name
+    'B': {'0': 'MM', '-': 'MM'}, // full month name
+    'y': {'0': 'yy', '-': 'yy'}, // 2-digit year (map unpadded to zero-padded)
+    'Y': {'0': 'yyyy', '-': 'yyyy'}, // 4-digit year (map unpadded to zero-padded)
+    'U': UNKNOWN, // Sunday-first week of the year
+    'w': UNKNOWN, // day of the week [0(sunday),6]
+    // combined format, we replace the date part with the world-calendar version
+    // and the %X stays there for d3 to handle with time parts
+    '%c': {'0': 'D M m %X yyyy', '-': 'D M m %X yyyy'},
+    '%x': {'0': 'mm/dd/yyyy', '-': 'mm/dd/yyyy'}
+};
+
+function worldCalFmt(fmt, x, calendar) {
+    var dateJD = Math.floor(x + 0.05 / ONEDAY) + EPOCHJD,
+        cDate = getCal(calendar).fromJD(dateJD),
+        i = 0,
+        modifier, directive, directiveLen, directiveObj, replacementPart;
+    while((i = fmt.indexOf('%', i)) !== -1) {
+        modifier = fmt.charAt(i + 1);
+        if(modifier === '0' || modifier === '-' || modifier === '_') {
+            directiveLen = 3;
+            directive = fmt.charAt(i + 1);
+            if(modifier === '_') modifier = '-';
+        }
+        else {
+            directive = modifier;
+            modifier = '0';
+            directiveLen = 2;
+        }
+        directiveObj = d3ToWorldCalendars[directive];
+        if(!directiveObj) {
+            i += directiveLen;
+        }
+        else {
+            // code is recognized as a date part but world-calendars doesn't support it
+            if(directiveObj === UNKNOWN) replacementPart = UNKNOWN;
+
+            // format the cDate according to the translated directive
+            else replacementPart = cDate.formatDate(directiveObj[modifier]);
+
+            fmt = fmt.substr(0, i) + replacementPart + fmt.substr(i + directiveLen);
+            i += replacementPart.length;
+        }
+    }
+    return fmt;
+}
+
+// cache world calendars, so we don't have to reinstantiate
+// during each date-time conversion
+var allCals = {};
+function getCal(calendar) {
+    var calendarObj = allCals[calendar];
+    if(calendarObj) return calendarObj;
+
+    calendarObj = allCals[calendar] = calendars.instance(calendar);
+    return calendarObj;
+}
+
+module.exports = {
+    moduleType: 'component',
+    name: 'calendars',
+
+    CANONICAL_SUNDAY: CANONICAL_SUNDAY,
+    CANONICAL_TICK: CANONICAL_TICK,
+    DFLTRANGE: DFLTRANGE,
+
+    getCal: getCal,
+    worldCalFmt: worldCalFmt
+};
diff --git a/src/constants/numerical.js b/src/constants/numerical.js
@@ -36,5 +36,11 @@ module.exports = {
     ONEDAY: 86400000,
     ONEHOUR: 3600000,
     ONEMIN: 60000,
-    ONESEC: 1000
+    ONESEC: 1000,
+
+    /*
+     * For fast conversion btwn world calendars and epoch ms, the Julian Day Number
+     * of the unix epoch. From calendars.instance().newDate(1970, 1, 1).toJD()
+     */
+    EPOCHJD: 2440587.5
 };