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// License: see LICENSE file at root directory of `master` branch

//! # Root

pub mod en;

/// # Plural
///
/// This trait is implemented for all integers and floats along with [`Lang`][::Lang].
///
/// [::Lang]: enum.Lang.html
pub trait Plural<N> {

    /// # Formats self based on input value `n`
    fn fmt(&self, n: N) -> &str;

}

/// # Languages
///
/// Variants are named after ISO 639-1 codes: <https://en.wikipedia.org/wiki/ISO_639-1>
///
/// ## Examples
///
/// ```
/// use plurals::{Lang, Plural};
///
/// const FOOT: Lang = Lang::En { singular: "foot", plural: "feet" };
///
/// assert_eq!(FOOT.fmt(0), "feet");
/// assert_eq!(FOOT.fmt(1), "foot");
/// assert_eq!(FOOT.fmt(2), "feet");
/// assert_eq!(FOOT.fmt(4), "feet");
/// ```
#[derive(Debug, Eq, PartialEq, Hash)]
pub enum Lang<'a> {

    /// # English
    En {

        /// # Singular form
        singular: &'a str,

        /// # Plural form
        plural: &'a str,

    },

}

macro_rules! impl_plural_for_languages_with_unsigned_integers {
    ($($ty: ty, $test_fn_name: tt,)+) => {
        $(
            #[test]
            fn $test_fn_name() {
                assert_eq!(<$ty>::min_value(), 0);
            }

            impl<'a> Plural<$ty> for Lang<'a> {

                fn fmt(&self, n: $ty) -> &str {
                    match self {
                        Lang::En { singular, plural } => match n {
                            1 => singular,
                            _ => plural,
                        },
                    }
                }

            }
        )+
    }
}

impl_plural_for_languages_with_unsigned_integers!(
    u8, test_impl_plural_for_languages_with_u8,
    u16, test_impl_plural_for_languages_with_u16,
    u32, test_impl_plural_for_languages_with_u32,
    u64, test_impl_plural_for_languages_with_u64,
    u128, test_impl_plural_for_languages_with_u128,
    usize, test_impl_plural_for_languages_with_usize,
);

macro_rules! impl_plural_for_languages_with_signed_integers {
    ($($ty: ty, $test_fn_name: tt,)+) => {
        $(
            #[test]
            fn $test_fn_name() {
                assert!(<$ty>::min_value() < 0);
            }

            impl<'a> Plural<$ty> for Lang<'a> {

                fn fmt(&self, n: $ty) -> &str {
                    match self {
                        Lang::En { singular, plural } => match n {
                            -1 | 1 => singular,
                            _ => plural,
                        },
                    }
                }

            }
        )+
    }
}

impl_plural_for_languages_with_signed_integers!(
    i8, test_impl_plural_for_languages_with_i8,
    i16, test_impl_plural_for_languages_with_i16,
    i32, test_impl_plural_for_languages_with_i32,
    i64, test_impl_plural_for_languages_with_i64,
    i128, test_impl_plural_for_languages_with_i128,
    isize, test_impl_plural_for_languages_with_isize,
);

macro_rules! impl_plural_for_languages_with_floats {
    ($($ty: ty, $test_fn_name: tt,)+) => {
        $(
            #[test]
            fn $test_fn_name() {
                assert!(<$ty>::from(1.0).is_sign_positive());
            }

            impl<'a> Plural<$ty> for Lang<'a> {

                fn fmt(&self, _: $ty) -> &str {
                    match self {
                        Lang::En { singular: _, plural } => plural,
                    }
                }

            }
        )+
    }
}

impl_plural_for_languages_with_floats!(
    f32, test_impl_plural_for_languages_with_f32,
    f64, test_impl_plural_for_languages_with_f64,
);