compile_checked_datetime.rs

/// YYYY-MM-DD HH:MM:SS
macro_rules! utc_datetime {
    ($y:tt-$m:tt-$d:tt $H:tt:$M:tt:$S:tt) => {
        // Constrain year to the limits of u16::MIN -> u16::MAX, which is well within
        // the valid bounds of chrono.
        let year: u16 = $y;

        // Check day with its corresponding month.
        month_day!($m, $d);

        time!($H:$M:$S);
    };
}

macro_rules! month_day {
    (02, 29) => {
        compile_error!("Chrono does not currently support compile-time checking of leap years!");
    };
    (01, $d:tt) => {check_thirty_one_days!($d);};
    (02, $d:tt) => {check_common_days!($d);};
    (03, $d:tt) => {check_thirty_one_days!($d);};
    (04, $d:tt) => {check_thirty_days!($d);};
    (05, $d:tt) => {check_thirty_one_days!($d);};
    (06, $d:tt) => {check_thirty_days!($d);};
    (07, $d:tt) => {check_thirty_one_days!($d);};
    (08, $d:tt) => {check_thirty_one_days!($d);};
    (09, $d:tt) => {check_thirty_days!($d);};
    (10, $d:tt) => {check_thirty_one_days!($d);};
    (11, $d:tt) => {check_thirty_days!($d);};
    (12, $d:tt) => {check_thirty_one_days!($d);};
    ($m:tt, $d:tt) => {
        compile_error!("Invalid month [01-12]!");
    }
}

macro_rules! check_thirty_one_days {
    (29) => {};
    (30) => {};
    (31) => {};
    ($d:tt) => {
        check_common_days!($d);
    }
}

macro_rules! check_thirty_days {
    (29) => {};
    (30) => {};
    ($d:tt) => {
        common_days!($d);
    };
}

macro_rules! check_common_days {
    (00) => {};
    (01) => {};
    (02) => {};
    (03) => {};
    (04) => {};
    (05) => {};
    (06) => {};
    (07) => {};
    (08) => {};
    (09) => {};
    (10) => {};
    (11) => {};
    (12) => {};
    (13) => {};
    (14) => {};
    (15) => {};
    (16) => {};
    (17) => {};
    (18) => {};
    (19) => {};
    (20) => {};
    (21) => {};
    (22) => {};
    (23) => {};
    (24) => {};
    (25) => {};
    (26) => {};
    (27) => {};
    (28) => {};
    {$d:expr} => {
        let day: u8 = $d;
        compile_error!("Not a valid day for the given month");
    }
}

/// HH:MM:SS
macro_rules! time {
    ($H:tt:$M:tt:$S:tt) => {
        check_hours!($H);
        up_to_59!($M);
        up_to_59!($S);
    }
}

macro_rules! check_hours {
    (00) => {};
    (01) => {};
    (02) => {};
    (03) => {};
    (04) => {};
    (05) => {};
    (06) => {};
    (07) => {};
    (08) => {};
    (09) => {};
    (10) => {};
    (11) => {};
    (12) => {};
    (13) => {};
    (14) => {};
    (15) => {};
    (16) => {};
    (17) => {};
    (18) => {};
    (19) => {};
    (20) => {};
    (21) => {};
    (22) => {};
    (23) => {};
    ($h:tt) => {
        let hours: u8 = $h; // Constrain to unsigned integer
        compile_error!("Hours must be 00-23");
    };
}

macro_rules! up_to_59 {
    (00) => {};
    (01) => {};
    (02) => {};
    (03) => {};
    (04) => {};
    (05) => {};
    (06) => {};
    (07) => {};
    (08) => {};
    (09) => {};
    (10) => {};
    (11) => {};
    (12) => {};
    (13) => {};
    (14) => {};
    (15) => {};
    (16) => {};
    (17) => {};
    (18) => {};
    (19) => {};
    (20) => {};
    (21) => {};
    (22) => {};
    (23) => {};
    (24) => {};
    (25) => {};
    (26) => {};
    (27) => {};
    (28) => {};
    (29) => {};
    (30) => {};
    (31) => {};
    (32) => {};
    (33) => {};
    (34) => {};
    (35) => {};
    (36) => {};
    (37) => {};
    (38) => {};
    (39) => {};
    (40) => {};
    (41) => {};
    (42) => {};
    (43) => {};
    (44) => {};
    (45) => {};
    (46) => {};
    (46) => {};
    (46) => {};
    (47) => {};
    (48) => {};
    (49) => {};
    (50) => {};
    (51) => {};
    (52) => {};
    (53) => {};
    (54) => {};
    (55) => {};
    (56) => {};
    (57) => {};
    (58) => {};
    (59) => {};
    ($x:literal) => {
        let x: u8 = $x; // Constrain to unsigned integer
        compile_error!("Either hours or minutes are not 00-59");
    }
}