Revise ISO parser, add common formats (#20)

* prep common formats

* update readme

* draft new iso parser

* add modifier for a, A, b, B directives, add j directive

* update changelog

CHANGELOG.md

@@ -13,6 +13,24 @@ Types of changes
 
 ## Unreleased
 
+## 2024-10-03, v0.3.2
+
+### Added
+
+- ISO8601 parser:
+  - '-' as a year-month or month-day separator now optional
+  - ':' as a hour-minute or minute-second separator now optional
+  - capability to parse day-of-year (ordinal; 'yyyy-ooo' format)
+- Datetime from string / Parser:
+  - 'j' directive to parse day-of-year
+- Datetime to string / Formatter:
+  - 's' directive to get Unix time in seconds
+  - ':a', ':A', ':b', ':B' (modifier option) to get English day / month names, independent of locale
+
+### Changed
+
+- internal: ISO8601 parser revised
+
 ## 2024-09-30, v0.3.1
 
 ### Added

README.md

@@ -7,7 +7,10 @@
 **Datetime with Timezones in Zig.** Opinionated, and mostly for learning purposes.
 
 - [API overview](https://github.com/FObersteiner/zdt/wiki/API-overview)
-- [Demo](https://github.com/FObersteiner/zdt/blob/master/examples/ex_demo.zig):
+- [Roadmap](https://github.com/FObersteiner/zdt/wiki/Roadmap)
+- Contributions: Welcome!
+
+### [Demo](https://github.com/FObersteiner/zdt/blob/master/examples/ex_demo.zig)
 
 ```zig
   // need an allocator for the time zones since the size of the rule-files varies
@@ -69,7 +72,7 @@ See [changelog](https://github.com/FObersteiner/zdt/blob/master/change.log)
 
 ## Zig version
 
-This library is developed with Zig `0.14.0-dev` aka 'master', might not compile with older versions. As of 2024-09-20, Zig-0.13 stable or higher should work.
+This library is developed with Zig `0.14.0-dev` aka 'master', might not compile with older versions. As of 2024-10-01, Zig-0.13 stable or higher should work.
 
 ## IANA timezone database version
 

lib/Datetime.zig

@@ -485,6 +485,10 @@ pub fn weekday(dt: Datetime) Weekday {
     return std.meta.intToEnum(Weekday, dt.weekdayNumber()) catch unreachable;
 }
 
+pub fn monthEnum(dt: Datetime) Month {
+    return std.meta.intToEnum(Month, dt.month) catch unreachable;
+}
+
 /// Number of the weekday starting at 0 == Sunday (strftime/strptime: %w).
 pub fn weekdayNumber(dt: Datetime) u8 {
     const days = cal.dateToRD([3]u16{ dt.year, dt.month, dt.day });
@@ -497,10 +501,6 @@ pub fn weekdayIsoNumber(dt: Datetime) u8 {
     return cal.ISOweekdayFromUnixdays(days);
 }
 
-pub fn monthEnum(dt: Datetime) Month {
-    return std.meta.intToEnum(Month, dt.month) catch unreachable;
-}
-
 /// Roll datetime forward to the specified next weekday. Makes a new datetime.
 pub fn nextWeekday(dt: Datetime, d: Weekday) Datetime {
     var daysdiff: i8 = 0;
@@ -582,6 +582,13 @@ pub fn fromString(string: []const u8, directives: []const u8) !Datetime {
 
 /// Make a datetime from a string with an ISO8601-compatibel format.
 pub fn fromISO8601(string: []const u8) !Datetime {
+    // 9 digits of fractional seconds and hh:mm:ss UTC offset: 38 characters
+    if (string.len > 38)
+        return error.InvalidFormat;
+    // last character must be Z (UTC) or a digit
+    if (string[string.len - 1] != 'Z' and !std.ascii.isDigit(string[string.len - 1])) {
+        return error.InvalidFormat;
+    }
     var idx: usize = 0; // assume datetime starts at beginning of string
     return try Datetime.fromFields(try str.parseISO8601(string, &idx));
 }

lib/Formats.zig

@@ -0,0 +1,5 @@
+//! common datetime formats
+
+pub const DateOnly = "%Y-%m-%d";
+pub const TimeOnly = "%H:%M:%S";
+pub const DateTime = "%Y-%m-%d %H:%M:%S";