Module date 

Calendar arithmetic for the date picker, ported from upstream’s datepicker.ts.

Dates are civil dates with no time zone, so no daylight-saving shift can turn midnight into the previous day; they cross the API as ISO YYYY-MM-DD. Day counts use Howard Hinnant’s days_from_civil, exact over the whole proleptic Gregorian range this type allows.

Structs

Date

A calendar date. Construction validates it, so every Date exists.

InvalidDate

The text or numbers do not name a real date.

Functions

days_in_month

Days in a month of a year.

key_target

Where a key moves focus from current, as upstream’s date grid does: arrows by a day (swapped in RTL) or a week, Home and End to the ends of the week, Page Up and Down by a month, or a year with Shift.

leading_blanks

How many blank cells come before the first of the month, given the first day of the week (0 = Sunday).