sparql.rs

macro_rules! select_variables (
    () => {""};
    ($head:ident $($tail:ident)*) => {
        concat!(" ?", stringify!($head), select_variables!($($tail)*));
        };
);

macro_rules! fmt(
    ($a:tt) => {stringify!($a)};
    (?$a:tt) => {concat!("?", stringify!($a))};
);

macro_rules! single_statement(
    ($a:tt $b:tt $c:tt) => {concat!(fmt!($a), " ", fmt!($b), " ", fmt!($c), ".\n");};
    (?$a:tt $b:tt $c:tt) => {concat!(fmt!(?$a), " ", fmt!($b), " ", fmt!($c), ".\n");};
    ($a:tt ?$b:tt $c:tt) => {concat!(fmt!($a), " ", fmt!(?$b), " ", fmt!($c), ".\n");};
    ($a:tt $b:tt ?$c:tt) => {concat!(fmt!($a), " ", fmt!($b), " ", fmt!(?$c), ".\n");};
    (?$a:tt ?$b:tt $c:tt) => {concat!(fmt!(?$a), " ", fmt!(?$b), " ", fmt!($c), ".\n");};
    (?$a:tt $b:tt $c:tt) => {concat!(fmt!(?$a), " ", fmt!($b), " ", fmt!(?$c), ".\n");};
    ($a:tt ?$b:tt ?$c:tt) => {concat!(fmt!($a), " ", fmt!(?$b), " ", fmt!(?$c), ".\n");};
    (?$a:tt ?$b:tt ?$c:tt) => {concat!(fmt!(?$a), " ", fmt!(?$b), " ", fmt!(?$c), ".\n");};
);


macro_rules! statement(
    () => {""};
    ($a:tt $b:tt $c:tt. $($tail:tt)*) => {concat!(single_statement!($a $b $c), statement!($($tail)*));};
    (?$a:tt $b:tt $c:tt. $($tail:tt)*) => {concat!(single_statement!(?$a $b $c), statement!($($tail)*));};
    ($a:tt ?$b:tt $c:tt. $($tail:tt)*) => {concat!(single_statement!($a ?$b $c), statement!($($tail)*));};
    ($a:tt $b:tt ?$c:tt. $($tail:tt)*) => {concat!(single_statement!($a $b ?$c), statement!($($tail)*));};
    (?$a:tt ?$b:tt $c:tt. $($tail:tt)*) => {concat!(single_statement!(?$a ?$b $c), statement!($($tail)*));};
    (?$a:tt $b:tt $c:tt. ?$($tail:tt)*) => {concat!(single_statement!(?$a $b ?$c), statement!($($tail)*));};
    ($a:tt ?$b:tt ?$c:tt. $($tail:tt)*) => {concat!(single_statement!($a ?$b ?$c), statement!($($tail)*));};
    (?$a:tt ?$b:tt ?$c:tt. $($tail:tt)*) => {concat!(single_statement!(?$a ?$b ?$c), statement!($($tail)*));};
);

macro_rules! select(
    ($($var:tt),* where $($statement:tt)*) => {
        concat!(
            "SELECT",
            select_variables!($($var)*),
            "\nWHERE\n",
            statement!($($statement)*),
            "SERVICE wikibase:label { bd:serviceParam wikibase:language \"en\". }"

        );
    };
);