enum_primitive/
cast.rs

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// Licensed under the Apache License, Version 2.0 or the MIT License.
// SPDX-License-Identifier: Apache-2.0 OR MIT
// Copyright Tock Contributors 2022.

use core::mem::size_of;
use core::num::Wrapping;

/// A generic trait for converting a value to a number.
pub trait ToPrimitive {
    /// Converts the value of `self` to an `isize`.
    #[inline]
    fn to_isize(&self) -> Option<isize> {
        self.to_i64().as_ref().and_then(ToPrimitive::to_isize)
    }

    /// Converts the value of `self` to an `i8`.
    #[inline]
    fn to_i8(&self) -> Option<i8> {
        self.to_i64().as_ref().and_then(ToPrimitive::to_i8)
    }

    /// Converts the value of `self` to an `i16`.
    #[inline]
    fn to_i16(&self) -> Option<i16> {
        self.to_i64().as_ref().and_then(ToPrimitive::to_i16)
    }

    /// Converts the value of `self` to an `i32`.
    #[inline]
    fn to_i32(&self) -> Option<i32> {
        self.to_i64().as_ref().and_then(ToPrimitive::to_i32)
    }

    /// Converts the value of `self` to an `i64`.
    fn to_i64(&self) -> Option<i64>;

    /// Converts the value of `self` to a `usize`.
    #[inline]
    fn to_usize(&self) -> Option<usize> {
        self.to_u64().as_ref().and_then(ToPrimitive::to_usize)
    }

    /// Converts the value of `self` to an `u8`.
    #[inline]
    fn to_u8(&self) -> Option<u8> {
        self.to_u64().as_ref().and_then(ToPrimitive::to_u8)
    }

    /// Converts the value of `self` to an `u16`.
    #[inline]
    fn to_u16(&self) -> Option<u16> {
        self.to_u64().as_ref().and_then(ToPrimitive::to_u16)
    }

    /// Converts the value of `self` to an `u32`.
    #[inline]
    fn to_u32(&self) -> Option<u32> {
        self.to_u64().as_ref().and_then(ToPrimitive::to_u32)
    }

    /// Converts the value of `self` to an `u64`.
    fn to_u64(&self) -> Option<u64>;
}

macro_rules! impl_to_primitive_int_to_int {
    ($SrcT:ident : $( $(#[$cfg:meta])* fn $method:ident -> $DstT:ident ; )*) => {$(
        #[inline]
        $(#[$cfg])*
        fn $method(&self) -> Option<$DstT> {
            let min = $DstT::MIN as $SrcT;
            let max = $DstT::MAX as $SrcT;
            if size_of::<$SrcT>() <= size_of::<$DstT>() || (min <= *self && *self <= max) {
                Some(*self as $DstT)
            } else {
                None
            }
        }
    )*}
}

macro_rules! impl_to_primitive_int_to_uint {
    ($SrcT:ident : $( $(#[$cfg:meta])* fn $method:ident -> $DstT:ident ; )*) => {$(
        #[inline]
        $(#[$cfg])*
        fn $method(&self) -> Option<$DstT> {
            let max = $DstT::MAX as $SrcT;
            if 0 <= *self && (size_of::<$SrcT>() <= size_of::<$DstT>() || *self <= max) {
                Some(*self as $DstT)
            } else {
                None
            }
        }
    )*}
}

macro_rules! impl_to_primitive_int {
    ($T:ident) => {
        impl ToPrimitive for $T {
            impl_to_primitive_int_to_int! { $T:
                fn to_isize -> isize;
                fn to_i8 -> i8;
                fn to_i16 -> i16;
                fn to_i32 -> i32;
                fn to_i64 -> i64;
            }

            impl_to_primitive_int_to_uint! { $T:
                fn to_usize -> usize;
                fn to_u8 -> u8;
                fn to_u16 -> u16;
                fn to_u32 -> u32;
                fn to_u64 -> u64;
            }
        }
    };
}

impl_to_primitive_int!(isize);
impl_to_primitive_int!(i8);
impl_to_primitive_int!(i16);
impl_to_primitive_int!(i32);
impl_to_primitive_int!(i64);

macro_rules! impl_to_primitive_uint_to_int {
    ($SrcT:ident : $( $(#[$cfg:meta])* fn $method:ident -> $DstT:ident ; )*) => {$(
        #[inline]
        $(#[$cfg])*
        fn $method(&self) -> Option<$DstT> {
            let max = $DstT::MAX as $SrcT;
            if size_of::<$SrcT>() < size_of::<$DstT>() || *self <= max {
                Some(*self as $DstT)
            } else {
                None
            }
        }
    )*}
}

macro_rules! impl_to_primitive_uint_to_uint {
    ($SrcT:ident : $( $(#[$cfg:meta])* fn $method:ident -> $DstT:ident ; )*) => {$(
        #[inline]
        $(#[$cfg])*
        fn $method(&self) -> Option<$DstT> {
            let max = $DstT::MAX as $SrcT;
            if size_of::<$SrcT>() <= size_of::<$DstT>() || *self <= max {
                Some(*self as $DstT)
            } else {
                None
            }
        }
    )*}
}

macro_rules! impl_to_primitive_uint {
    ($T:ident) => {
        impl ToPrimitive for $T {
            impl_to_primitive_uint_to_int! { $T:
                fn to_isize -> isize;
                fn to_i8 -> i8;
                fn to_i16 -> i16;
                fn to_i32 -> i32;
                fn to_i64 -> i64;
            }

            impl_to_primitive_uint_to_uint! { $T:
                fn to_usize -> usize;
                fn to_u8 -> u8;
                fn to_u16 -> u16;
                fn to_u32 -> u32;
                fn to_u64 -> u64;
            }
        }
    };
}

impl_to_primitive_uint!(usize);
impl_to_primitive_uint!(u8);
impl_to_primitive_uint!(u16);
impl_to_primitive_uint!(u32);
impl_to_primitive_uint!(u64);

/// A generic trait for converting a number to a value.
pub trait FromPrimitive: Sized {
    /// Convert an `isize` to return an optional value of this type. If the
    /// value cannot be represented by this value, then `None` is returned.
    #[inline]
    fn from_isize(n: isize) -> Option<Self> {
        n.to_i64().and_then(FromPrimitive::from_i64)
    }

    /// Convert an `i8` to return an optional value of this type. If the
    /// type cannot be represented by this value, then `None` is returned.
    #[inline]
    fn from_i8(n: i8) -> Option<Self> {
        FromPrimitive::from_i64(From::from(n))
    }

    /// Convert an `i16` to return an optional value of this type. If the
    /// type cannot be represented by this value, then `None` is returned.
    #[inline]
    fn from_i16(n: i16) -> Option<Self> {
        FromPrimitive::from_i64(From::from(n))
    }

    /// Convert an `i32` to return an optional value of this type. If the
    /// type cannot be represented by this value, then `None` is returned.
    #[inline]
    fn from_i32(n: i32) -> Option<Self> {
        FromPrimitive::from_i64(From::from(n))
    }

    /// Convert an `i64` to return an optional value of this type. If the
    /// type cannot be represented by this value, then `None` is returned.
    fn from_i64(n: i64) -> Option<Self>;

    /// Convert a `usize` to return an optional value of this type. If the
    /// type cannot be represented by this value, then `None` is returned.
    #[inline]
    fn from_usize(n: usize) -> Option<Self> {
        n.to_u64().and_then(FromPrimitive::from_u64)
    }

    /// Convert an `u8` to return an optional value of this type. If the
    /// type cannot be represented by this value, then `None` is returned.
    #[inline]
    fn from_u8(n: u8) -> Option<Self> {
        FromPrimitive::from_u64(From::from(n))
    }

    /// Convert an `u16` to return an optional value of this type. If the
    /// type cannot be represented by this value, then `None` is returned.
    #[inline]
    fn from_u16(n: u16) -> Option<Self> {
        FromPrimitive::from_u64(From::from(n))
    }

    /// Convert an `u32` to return an optional value of this type. If the
    /// type cannot be represented by this value, then `None` is returned.
    #[inline]
    fn from_u32(n: u32) -> Option<Self> {
        FromPrimitive::from_u64(From::from(n))
    }

    /// Convert an `u64` to return an optional value of this type. If the
    /// type cannot be represented by this value, then `None` is returned.
    fn from_u64(n: u64) -> Option<Self>;
}

macro_rules! impl_from_primitive {
    ($T:ty, $to_ty:ident) => {
        #[allow(deprecated)]
        impl FromPrimitive for $T {
            #[inline]
            fn from_isize(n: isize) -> Option<$T> {
                n.$to_ty()
            }
            #[inline]
            fn from_i8(n: i8) -> Option<$T> {
                n.$to_ty()
            }
            #[inline]
            fn from_i16(n: i16) -> Option<$T> {
                n.$to_ty()
            }
            #[inline]
            fn from_i32(n: i32) -> Option<$T> {
                n.$to_ty()
            }
            #[inline]
            fn from_i64(n: i64) -> Option<$T> {
                n.$to_ty()
            }

            #[inline]
            fn from_usize(n: usize) -> Option<$T> {
                n.$to_ty()
            }
            #[inline]
            fn from_u8(n: u8) -> Option<$T> {
                n.$to_ty()
            }
            #[inline]
            fn from_u16(n: u16) -> Option<$T> {
                n.$to_ty()
            }
            #[inline]
            fn from_u32(n: u32) -> Option<$T> {
                n.$to_ty()
            }
            #[inline]
            fn from_u64(n: u64) -> Option<$T> {
                n.$to_ty()
            }
        }
    };
}

impl_from_primitive!(isize, to_isize);
impl_from_primitive!(i8, to_i8);
impl_from_primitive!(i16, to_i16);
impl_from_primitive!(i32, to_i32);
impl_from_primitive!(i64, to_i64);
impl_from_primitive!(usize, to_usize);
impl_from_primitive!(u8, to_u8);
impl_from_primitive!(u16, to_u16);
impl_from_primitive!(u32, to_u32);
impl_from_primitive!(u64, to_u64);

macro_rules! impl_to_primitive_wrapping {
    ($( $(#[$cfg:meta])* fn $method:ident -> $i:ident ; )*) => {$(
        #[inline]
        $(#[$cfg])*
        fn $method(&self) -> Option<$i> {
            (self.0).$method()
        }
    )*}
}

impl<T: ToPrimitive> ToPrimitive for Wrapping<T> {
    impl_to_primitive_wrapping! {
        fn to_isize -> isize;
        fn to_i8 -> i8;
        fn to_i16 -> i16;
        fn to_i32 -> i32;
        fn to_i64 -> i64;

        fn to_usize -> usize;
        fn to_u8 -> u8;
        fn to_u16 -> u16;
        fn to_u32 -> u32;
        fn to_u64 -> u64;
    }
}

macro_rules! impl_from_primitive_wrapping {
    ($( $(#[$cfg:meta])* fn $method:ident ( $i:ident ); )*) => {$(
        #[inline]
        $(#[$cfg])*
        fn $method(n: $i) -> Option<Self> {
            T::$method(n).map(Wrapping)
        }
    )*}
}

impl<T: FromPrimitive> FromPrimitive for Wrapping<T> {
    impl_from_primitive_wrapping! {
        fn from_isize(isize);
        fn from_i8(i8);
        fn from_i16(i16);
        fn from_i32(i32);
        fn from_i64(i64);
        fn from_usize(usize);
        fn from_u8(u8);
        fn from_u16(u16);
        fn from_u32(u32);
        fn from_u64(u64);
    }
}