/// These macros are coppied from:
/// <https://github.com/dalek-cryptography/curve25519-dalek/blob/master/src/macros.rs>

/// Define borrow and non-borrow variants of `Add`.
macro_rules! define_add_variants {
    (LHS = $lhs:ty, RHS = $rhs:ty, Output = $out:ty) => {
        impl<'b> Add<&'b $rhs> for $lhs {
            type Output = $out;
            fn add(self, rhs: &'b $rhs) -> $out {
                &self + rhs
            }
        }

        impl<'a> Add<$rhs> for &'a $lhs {
            type Output = $out;
            fn add(self, rhs: $rhs) -> $out {
                self + &rhs
            }
        }

        impl Add<$rhs> for $lhs {
            type Output = $out;
            fn add(self, rhs: $rhs) -> $out {
                &self + &rhs
            }
        }
    };
}

/// Define non-borrow variants of `AddAssign`.
macro_rules! define_add_assign_variants {
    (LHS = $lhs:ty, RHS = $rhs:ty) => {
        impl AddAssign<$rhs> for $lhs {
            fn add_assign(&mut self, rhs: $rhs) {
                *self += &rhs;
            }
        }
    };
}

/// Define borrow and non-borrow variants of `Sub`.
macro_rules! define_sub_variants {
    (LHS = $lhs:ty, RHS = $rhs:ty, Output = $out:ty) => {
        impl<'b> Sub<&'b $rhs> for $lhs {
            type Output = $out;
            fn sub(self, rhs: &'b $rhs) -> $out {
                &self - rhs
            }
        }

        impl<'a> Sub<$rhs> for &'a $lhs {
            type Output = $out;
            fn sub(self, rhs: $rhs) -> $out {
                self - &rhs
            }
        }

        impl Sub<$rhs> for $lhs {
            type Output = $out;
            fn sub(self, rhs: $rhs) -> $out {
                &self - &rhs
            }
        }
    };
}

/// Define non-borrow variants of `SubAssign`.
macro_rules! define_sub_assign_variants {
    (LHS = $lhs:ty, RHS = $rhs:ty) => {
        impl SubAssign<$rhs> for $lhs {
            fn sub_assign(&mut self, rhs: $rhs) {
                *self -= &rhs;
            }
        }
    };
}

/// That `ensure` does not transform into a string representation like `failure::ensure` is doing.
#[allow(unused_macros)]
macro_rules! ensure {
    ($predicate:expr, $context_selector:expr) => {
        if !$predicate {
            return Err($context_selector.into());
        }
    };
}

/// Helper macro to assert that `predicate` is an `Error::from( $err)`.
#[allow(unused_macros)]
macro_rules! assert_err {
    ($predicate:expr, $err:expr) => {
        assert_eq!($predicate.expect_err("Error expected").kind(), &$err);
    };
}
