Sample

In 2015/day_03.zig:

pub fn part1(input: []const u8) [:0]const u8 {
    _ = input;
    return "foo";
}

pub fn part2(input: []u8) !i32 {
    std.debug.print("All your codebase are belong to us.\n", .{});
    _ = input;
    return error.Overflow;
}

const std = @import("std");

(input/2015/day03.txt exists)

$ zig build solve -Dday=..3
[01/1] (43.3 µs)    foo
All your codebase are belong to us.
[01/2]  failed: Overflow
[02/1] (26.361 ms)  27
...
[03/2] (1.652 ms)   bar
Total elapsed solution time: 104.833 ms (excluding 1 failure)

Usage

You may delete any file other than build.zig.

The build script expects the following file layout:

input/
    YYYY/
        day01.txt
        day02.txt
        ...
YYYY/
    day_01.zig
    day_02.zig
    ...
build.zig

In each day_DD.zig, the solution program checks for and runs top-level pub functions named part1() and part2(), each of which must accept a slice of bytes ([]const u8 or []u8), which contains that day's input string as it appears in input/YYYY/day01.txt. You may safely mutate the slice. Do not free the slice. The solution functions may return any type printable with {any}, a type with a .format() method, a u8 string, or any of the previous options within an error union. If you return data by reference (e.g. a []const u8), do not keep it on the stack and do not free it from the heap (use static buffers or leak the memory).

zig build solve -Dday=... will run the solutions for any single day or range of days:

• -Dday=5: print output of day_05.part1(), if it is defined, print output of day_05.part2(), if it is defined
• -Dday=5..7: the same, for days 5, 6, and 7, serially
• -Dday=..7: the same, for days 1-7, serially

The results are printed directly to stdout.