Zig

Bikram Sambat dates, conversion, arithmetic, formatting, parsing, ranges and fiscal years for Zig 0.17.0. The core and the patro are two modules of one package, released together from one tag. They compile the C amalgamation at a pinned tag, so the calendar data and the patro data are the same as every other port.

• nepdate is the core module.
• nepdate_patro is the patro module: tithi, public holidays and events for BS 2077-01-01 to 2084-08-20. It imports nepdate.
• There is no package registry. The release is a source archive whose hash you record in build.zig.zon.

Release candidate

This is 1.0.0-rc.1, the release candidate for the Zig package. The API is stable from 1.0 (hub ADR-0009).

Install

zig fetch --save https://github.com/sanamhub/nepdate-zig/archive/refs/tags/v1.0.0-rc.1.tar.gz

zig fetch adds the dependency and its hash to your build.zig.zon. Add both modules to your executable:

build.zig

const dep = b.dependency("nepdate", .{ .target = target, .optimize = optimize });
exe.root_module.addImport("nepdate", dep.module("nepdate"));
exe.root_module.addImport("nepdate_patro", dep.module("nepdate_patro"));

Quick start

const nepdate = @import("nepdate");

const date = try nepdate.Date.fromBs(2081, 4, 15);
var buffer: [16]u8 = undefined;
try date.write(&buffer);                    // 2081/04/15
const ad = date.englishDate();              // 2024-07-30
const long = try date.longAlloc(allocator, .{}); // Shrawan 15, 2081

A date is always a real day of the calendar, from BS 1901-01-01 to 2199-12-30 (AD 1844-04-11 to 2143-04-15). Construction validates the year, then the month, then the day, and returns an error union. There is no invalid or default value in the API.

Dates

const date = try nepdate.Date.fromBs(2081, 4, 32);
_ = date.year();        // 2081
_ = date.month();       // .shrawan
_ = date.day();         // 32
_ = date.dayOfWeek();   // .friday
_ = date.dayOfYear();   // 126
_ = date.monthLength(); // 32
_ = date.yearLength();  // 366

yearLength is the BS year length, 364 to 367 days, and replaces the C# IsLeapYear(). monthEndDate() replaces MonthEndDate().

Conversion and serialization

try nepdate.Date.fromGregorian(2024, 7, 30);
try nepdate.Date.fromYmd(20810415);
_ = (try nepdate.Date.fromBs(2081, 4, 15)).ymd(); // 20810415
const iso = try (try nepdate.Date.fromBs(2081, 4, 15)).toJsonAlloc(allocator);
_ = try nepdate.Date.fromJson(iso);

Batch conversion keeps input order and is all or nothing:

var out: [1]nepdate.Date = undefined;
_ = try nepdate.toNepaliDates(&.{.{ .year = 2024, .month = 7, .day = 30 }}, &out);

Arithmetic

const date = try nepdate.Date.fromBs(2081, 4, 32);
_ = try date.addDays(30);          // 2081-05-30
_ = try date.addMonths(2, .clamp); // 2081-06-30
_ = try date.addMonths(2, .spill); // 2081-07-02
_ = date.daysUntil(try nepdate.Date.fromBs(2081, 4, 16)); // 1

daysUntil is other - this; minus is the C# operator direction, this - other. Fractional months and days are not ported.

Formatting

const date = try nepdate.Date.fromBs(2081, 4, 15);
const short = try date.shortAlloc(allocator, .{ .order = .dmy, .separator = .dash }); // 15-04-2081
const unicode = try date.shortAlloc(allocator, .{ .lang = .ne });                     // २०८१/०४/१५
const long = try date.longAlloc(allocator, .{});                                      // Shrawan 15, 2081
const pattern = try date.formatAlloc(allocator, "MMMM d, yyyy", .en);                  // Shrawan 15, 2081

{f} in std.fmt writes YYYY/MM/DD. Functions that build text take an allocator or a caller buffer; nothing allocates behind your back.

Parsing

_ = try nepdate.Date.parse("2081/04/15");
_ = try nepdate.Date.parse("२०८१/०४/१५");
_ = try nepdate.Date.parseLenient("15 Shrawan 2081 B.S.");
_ = nepdate.Date.tryParse("2081/13/01"); // null

The strict parser accepts ASCII and Devanagari digits. The lenient parser accepts month names in English or Nepali, the day before the year, and era markers. Failures are named error values.

Ranges

const range = try nepdate.Range.of(
    try nepdate.Date.fromBs(2081, 4, 10),
    try nepdate.Date.fromBs(2081, 4, 20),
);
_ = range.length(); // 11
_ = range.contains(try nepdate.Date.fromBs(2081, 4, 15)); // true
const text = try range.formatAlloc(allocator); // 2081/04/10 - 2081/04/20

Ranges are inclusive and non-empty. They offer containment, overlap, adjacency, intersection, union, difference, month and fiscal-quarter splits, interval walks, working days and weekend days.

Fiscal year

const fy = nepdate.FiscalYear.containing(try nepdate.Date.fromBs(2082, 1, 15));
_ = fy.year; // 2081
var label_buffer: [39]u8 = undefined;
_ = try fy.label(&label_buffer, .en); // 2081/82

Today

The clock and the zone are arguments, never a hidden local setting.

const instant: i64 = 1722364200; // 2024-07-30 18:30 UTC
_ = try nepdate.Date.todayNepal(instant);      // 2081-04-16
_ = try nepdate.Date.today(0, instant);        // 2081-04-15
_ = try nepdate.Date.todayIn(.nepal, instant); // 2081-04-16

Patro

const patro = @import("nepdate_patro");

var events: [8]patro.Event = undefined;
const info = try patro.infoInto(try nepdate.Date.fromBs(2081, 1, 1), &events);
_ = info.tithiEn();         // Panchami
_ = info.is_public_holiday; // true
_ = info.events[0].english; // New Year

patro.info(allocator, date) allocates the event list and has a deinit; infoInto uses your buffer. The patro covers 2077-01-01 to 2084-08-20 and returns empty values outside that range.

Data and correctness

The tests assert every shared vector file, walk every supported day through Gregorian and YYYYMMDD, and check the vendored C files against their release tag. The details are in the port’s README and API.md.

Performance

B1 to B8 against the C core are in benchmarks.md. The numbers were taken on an idle machine, pinned to one performance core, and the idle check is recorded with the table.