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use paste::paste;

/// The CastIntoAs trait for simple convert self value between integer types with possible overflow.
/// - No generic data type used in the trait definition.
/// - Easy implementation when used as a super trait.
///
/// # Usage
/// Basic use of the trait.
///
/// ```
/// use num_convert::CastIntoAs;
/// assert_eq!(<u16 as CastIntoAs>::into_u8(255_u16), 255_u8);
/// assert_eq!(258_u16.into_u8(), 2_u8);
/// ```
///
/// # Examples
///
/// ```
/// # use num_convert::CastIntoAs;
/// assert_eq!(128_u8.into_i8(), -128_i8);
/// assert_eq!(512_u16.into_u8(), 0_u8);
/// ```
pub trait CastIntoAs {
    /// Converts the value of self to i8. Overflow possible during conversion.
    fn into_i8(self) -> i8;

    /// Converts the value of self to i16. Overflow possible during conversion.
    fn into_i16(self) -> i16;

    /// Converts the value of self to i32. Overflow possible during conversion.
    fn into_i32(self) -> i32;

    /// Converts the value of self to i64. Overflow possible during conversion.
    fn into_i64(self) -> i64;

    /// Converts the value of self to isize. Overflow possible during conversion.
    fn into_isize(self) -> isize;

    /// Converts the value of self to i128. Overflow possible during conversion.
    fn into_i128(self) -> i128;

    /// Converts the value of self to u8. Overflow possible during conversion.
    fn into_u8(self) -> u8;

    /// Converts the value of self to u16. Overflow possible during conversion.
    fn into_u16(self) -> u16;

    /// Converts the value of self to u32. Overflow possible during conversion.
    fn into_u32(self) -> u32;

    /// Converts the value of self to u64. Overflow possible during conversion.
    fn into_u64(self) -> u64;

    /// Converts the value of self to usize. Overflow possible during conversion.
    fn into_usize(self) -> usize;

    /// Converts the value of self to u128.
    fn into_u128(self) -> u128;
}

macro_rules! cast_into_as_impls {
    ($($from_type:ty),+; $type:ty ) => {
        impl CastIntoAs for $type {
            paste!{
                #[inline]
                fn [<into_$type>](self) -> $type {
                    self
                }
            }

            $(
                paste!{
                    #[inline]
                    fn [<into_$from_type>](self) -> $from_type {
                        self as $from_type
                    }
                }
            )*
        }
    }
}

cast_into_as_impls! { i16, i32, i64, isize, i128, u8, u16, u32, u64, usize, u128; i8 }
cast_into_as_impls! { i8, i32, i64, isize, i128, u8, u16, u32, u64, usize, u128; i16 }
cast_into_as_impls! { i8, i16, i64, isize, i128, u8, u16, u32, u64, usize, u128; i32 }
cast_into_as_impls! { i8, i16, i32, isize, i128, u8, u16, u32, u64, usize, u128; i64 }
cast_into_as_impls! { i8, i16, i32, i64, i128, u8, u16, u32, u64, usize, u128; isize }
cast_into_as_impls! { i8, i16, i32, i64, isize, u8, u16, u32, u64, usize, u128; i128 }
cast_into_as_impls! { i8, i16, i32, i64, isize, i128, u16, u32, u64, usize, u128; u8 }
cast_into_as_impls! { i8, i16, i32, i64, isize, i128, u8, u32, u64, usize, u128; u16 }
cast_into_as_impls! { i8, i16, i32, i64, isize, i128, u8, u16, u64, usize, u128; u32 }
cast_into_as_impls! { i8, i16, i32, i64, isize, i128, u8, u16, u32, usize, u128; u64 }
cast_into_as_impls! { i8, i16, i32, i64, isize, i128, u8, u16, u32, u64, u128; usize }
cast_into_as_impls! { i8, i16, i32, i64, isize, i128, u8, u16, u32, u64, usize; u128 }