| use core::mem::size_of; |
| use core::num::Wrapping; |
| use core::{f32, f64}; |
| #[cfg(has_i128)] |
| use core::{i128, u128}; |
| use core::{i16, i32, i64, i8, isize}; |
| use core::{u16, u32, u64, u8, usize}; |
| |
| /// A generic trait for converting a value to a number. |
| /// |
| /// A value can be represented by the target type when it lies within |
| /// the range of scalars supported by the target type. |
| /// For example, a negative integer cannot be represented by an unsigned |
| /// integer type, and an `i64` with a very high magnitude might not be |
| /// convertible to an `i32`. |
| /// On the other hand, conversions with possible precision loss or truncation |
| /// are admitted, like an `f32` with a decimal part to an integer type, or |
| /// even a large `f64` saturating to `f32` infinity. |
| pub trait ToPrimitive { |
| /// Converts the value of `self` to an `isize`. If the value cannot be |
| /// represented by an `isize`, then `None` is returned. |
| #[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`. If the value cannot be |
| /// represented by an `i8`, then `None` is returned. |
| #[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`. If the value cannot be |
| /// represented by an `i16`, then `None` is returned. |
| #[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`. If the value cannot be |
| /// represented by an `i32`, then `None` is returned. |
| #[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`. If the value cannot be |
| /// represented by an `i64`, then `None` is returned. |
| fn to_i64(&self) -> Option<i64>; |
| |
| /// Converts the value of `self` to an `i128`. If the value cannot be |
| /// represented by an `i128` (`i64` under the default implementation), then |
| /// `None` is returned. |
| /// |
| /// This method is only available with feature `i128` enabled on Rust >= 1.26. |
| /// |
| /// The default implementation converts through `to_i64()`. Types implementing |
| /// this trait should override this method if they can represent a greater range. |
| #[inline] |
| #[cfg(has_i128)] |
| fn to_i128(&self) -> Option<i128> { |
| self.to_i64().map(From::from) |
| } |
| |
| /// Converts the value of `self` to a `usize`. If the value cannot be |
| /// represented by a `usize`, then `None` is returned. |
| #[inline] |
| fn to_usize(&self) -> Option<usize> { |
| self.to_u64().as_ref().and_then(ToPrimitive::to_usize) |
| } |
| |
| /// Converts the value of `self` to a `u8`. If the value cannot be |
| /// represented by a `u8`, then `None` is returned. |
| #[inline] |
| fn to_u8(&self) -> Option<u8> { |
| self.to_u64().as_ref().and_then(ToPrimitive::to_u8) |
| } |
| |
| /// Converts the value of `self` to a `u16`. If the value cannot be |
| /// represented by a `u16`, then `None` is returned. |
| #[inline] |
| fn to_u16(&self) -> Option<u16> { |
| self.to_u64().as_ref().and_then(ToPrimitive::to_u16) |
| } |
| |
| /// Converts the value of `self` to a `u32`. If the value cannot be |
| /// represented by a `u32`, then `None` is returned. |
| #[inline] |
| fn to_u32(&self) -> Option<u32> { |
| self.to_u64().as_ref().and_then(ToPrimitive::to_u32) |
| } |
| |
| /// Converts the value of `self` to a `u64`. If the value cannot be |
| /// represented by a `u64`, then `None` is returned. |
| fn to_u64(&self) -> Option<u64>; |
| |
| /// Converts the value of `self` to a `u128`. If the value cannot be |
| /// represented by a `u128` (`u64` under the default implementation), then |
| /// `None` is returned. |
| /// |
| /// This method is only available with feature `i128` enabled on Rust >= 1.26. |
| /// |
| /// The default implementation converts through `to_u64()`. Types implementing |
| /// this trait should override this method if they can represent a greater range. |
| #[inline] |
| #[cfg(has_i128)] |
| fn to_u128(&self) -> Option<u128> { |
| self.to_u64().map(From::from) |
| } |
| |
| /// Converts the value of `self` to an `f32`. Overflows may map to positive |
| /// or negative inifinity, otherwise `None` is returned if the value cannot |
| /// be represented by an `f32`. |
| #[inline] |
| fn to_f32(&self) -> Option<f32> { |
| self.to_f64().as_ref().and_then(ToPrimitive::to_f32) |
| } |
| |
| /// Converts the value of `self` to an `f64`. Overflows may map to positive |
| /// or negative inifinity, otherwise `None` is returned if the value cannot |
| /// be represented by an `f64`. |
| /// |
| /// The default implementation tries to convert through `to_i64()`, and |
| /// failing that through `to_u64()`. Types implementing this trait should |
| /// override this method if they can represent a greater range. |
| #[inline] |
| fn to_f64(&self) -> Option<f64> { |
| match self.to_i64() { |
| Some(i) => i.to_f64(), |
| None => self.to_u64().as_ref().and_then(ToPrimitive::to_f64), |
| } |
| } |
| } |
| |
| 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; |
| #[cfg(has_i128)] |
| fn to_i128 -> i128; |
| } |
| |
| impl_to_primitive_int_to_uint! { $T: |
| fn to_usize -> usize; |
| fn to_u8 -> u8; |
| fn to_u16 -> u16; |
| fn to_u32 -> u32; |
| fn to_u64 -> u64; |
| #[cfg(has_i128)] |
| fn to_u128 -> u128; |
| } |
| |
| #[inline] |
| fn to_f32(&self) -> Option<f32> { |
| Some(*self as f32) |
| } |
| #[inline] |
| fn to_f64(&self) -> Option<f64> { |
| Some(*self as f64) |
| } |
| } |
| }; |
| } |
| |
| impl_to_primitive_int!(isize); |
| impl_to_primitive_int!(i8); |
| impl_to_primitive_int!(i16); |
| impl_to_primitive_int!(i32); |
| impl_to_primitive_int!(i64); |
| #[cfg(has_i128)] |
| impl_to_primitive_int!(i128); |
| |
| macro_rules! impl_to_primitive_uint_to_int { |
| ($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; |
| #[cfg(has_i128)] |
| fn to_i128 -> i128; |
| } |
| |
| impl_to_primitive_uint_to_uint! { $T: |
| fn to_usize -> usize; |
| fn to_u8 -> u8; |
| fn to_u16 -> u16; |
| fn to_u32 -> u32; |
| fn to_u64 -> u64; |
| #[cfg(has_i128)] |
| fn to_u128 -> u128; |
| } |
| |
| #[inline] |
| fn to_f32(&self) -> Option<f32> { |
| Some(*self as f32) |
| } |
| #[inline] |
| fn to_f64(&self) -> Option<f64> { |
| Some(*self as f64) |
| } |
| } |
| }; |
| } |
| |
| impl_to_primitive_uint!(usize); |
| impl_to_primitive_uint!(u8); |
| impl_to_primitive_uint!(u16); |
| impl_to_primitive_uint!(u32); |
| impl_to_primitive_uint!(u64); |
| #[cfg(has_i128)] |
| impl_to_primitive_uint!(u128); |
| |
| macro_rules! impl_to_primitive_float_to_float { |
| ($SrcT:ident : $( fn $method:ident -> $DstT:ident ; )*) => {$( |
| #[inline] |
| fn $method(&self) -> Option<$DstT> { |
| // We can safely cast all values, whether NaN, +-inf, or finite. |
| // Finite values that are reducing size may saturate to +-inf. |
| Some(*self as $DstT) |
| } |
| )*} |
| } |
| |
| #[cfg(has_to_int_unchecked)] |
| macro_rules! float_to_int_unchecked { |
| // SAFETY: Must not be NaN or infinite; must be representable as the integer after truncating. |
| // We already checked that the float is in the exclusive range `(MIN-1, MAX+1)`. |
| ($float:expr => $int:ty) => { |
| unsafe { $float.to_int_unchecked::<$int>() } |
| }; |
| } |
| |
| #[cfg(not(has_to_int_unchecked))] |
| macro_rules! float_to_int_unchecked { |
| ($float:expr => $int:ty) => { |
| $float as $int |
| }; |
| } |
| |
| macro_rules! impl_to_primitive_float_to_signed_int { |
| ($f:ident : $( $(#[$cfg:meta])* fn $method:ident -> $i:ident ; )*) => {$( |
| #[inline] |
| $(#[$cfg])* |
| fn $method(&self) -> Option<$i> { |
| // Float as int truncates toward zero, so we want to allow values |
| // in the exclusive range `(MIN-1, MAX+1)`. |
| if size_of::<$f>() > size_of::<$i>() { |
| // With a larger size, we can represent the range exactly. |
| const MIN_M1: $f = $i::MIN as $f - 1.0; |
| const MAX_P1: $f = $i::MAX as $f + 1.0; |
| if *self > MIN_M1 && *self < MAX_P1 { |
| return Some(float_to_int_unchecked!(*self => $i)); |
| } |
| } else { |
| // We can't represent `MIN-1` exactly, but there's no fractional part |
| // at this magnitude, so we can just use a `MIN` inclusive boundary. |
| const MIN: $f = $i::MIN as $f; |
| // We can't represent `MAX` exactly, but it will round up to exactly |
| // `MAX+1` (a power of two) when we cast it. |
| const MAX_P1: $f = $i::MAX as $f; |
| if *self >= MIN && *self < MAX_P1 { |
| return Some(float_to_int_unchecked!(*self => $i)); |
| } |
| } |
| None |
| } |
| )*} |
| } |
| |
| macro_rules! impl_to_primitive_float_to_unsigned_int { |
| ($f:ident : $( $(#[$cfg:meta])* fn $method:ident -> $u:ident ; )*) => {$( |
| #[inline] |
| $(#[$cfg])* |
| fn $method(&self) -> Option<$u> { |
| // Float as int truncates toward zero, so we want to allow values |
| // in the exclusive range `(-1, MAX+1)`. |
| if size_of::<$f>() > size_of::<$u>() { |
| // With a larger size, we can represent the range exactly. |
| const MAX_P1: $f = $u::MAX as $f + 1.0; |
| if *self > -1.0 && *self < MAX_P1 { |
| return Some(float_to_int_unchecked!(*self => $u)); |
| } |
| } else { |
| // We can't represent `MAX` exactly, but it will round up to exactly |
| // `MAX+1` (a power of two) when we cast it. |
| // (`u128::MAX as f32` is infinity, but this is still ok.) |
| const MAX_P1: $f = $u::MAX as $f; |
| if *self > -1.0 && *self < MAX_P1 { |
| return Some(float_to_int_unchecked!(*self => $u)); |
| } |
| } |
| None |
| } |
| )*} |
| } |
| |
| macro_rules! impl_to_primitive_float { |
| ($T:ident) => { |
| impl ToPrimitive for $T { |
| impl_to_primitive_float_to_signed_int! { $T: |
| fn to_isize -> isize; |
| fn to_i8 -> i8; |
| fn to_i16 -> i16; |
| fn to_i32 -> i32; |
| fn to_i64 -> i64; |
| #[cfg(has_i128)] |
| fn to_i128 -> i128; |
| } |
| |
| impl_to_primitive_float_to_unsigned_int! { $T: |
| fn to_usize -> usize; |
| fn to_u8 -> u8; |
| fn to_u16 -> u16; |
| fn to_u32 -> u32; |
| fn to_u64 -> u64; |
| #[cfg(has_i128)] |
| fn to_u128 -> u128; |
| } |
| |
| impl_to_primitive_float_to_float! { $T: |
| fn to_f32 -> f32; |
| fn to_f64 -> f64; |
| } |
| } |
| }; |
| } |
| |
| impl_to_primitive_float!(f32); |
| impl_to_primitive_float!(f64); |
| |
| /// A generic trait for converting a number to a value. |
| /// |
| /// A value can be represented by the target type when it lies within |
| /// the range of scalars supported by the target type. |
| /// For example, a negative integer cannot be represented by an unsigned |
| /// integer type, and an `i64` with a very high magnitude might not be |
| /// convertible to an `i32`. |
| /// On the other hand, conversions with possible precision loss or truncation |
| /// are admitted, like an `f32` with a decimal part to an integer type, or |
| /// even a large `f64` saturating to `f32` infinity. |
| pub trait FromPrimitive: Sized { |
| /// Converts an `isize` to return an optional value of this type. If the |
| /// value cannot be represented by this type, then `None` is returned. |
| #[inline] |
| fn from_isize(n: isize) -> Option<Self> { |
| n.to_i64().and_then(FromPrimitive::from_i64) |
| } |
| |
| /// Converts an `i8` to return an optional value of this type. If the |
| /// value cannot be represented by this type, then `None` is returned. |
| #[inline] |
| fn from_i8(n: i8) -> Option<Self> { |
| FromPrimitive::from_i64(From::from(n)) |
| } |
| |
| /// Converts an `i16` to return an optional value of this type. If the |
| /// value cannot be represented by this type, then `None` is returned. |
| #[inline] |
| fn from_i16(n: i16) -> Option<Self> { |
| FromPrimitive::from_i64(From::from(n)) |
| } |
| |
| /// Converts an `i32` to return an optional value of this type. If the |
| /// value cannot be represented by this type, then `None` is returned. |
| #[inline] |
| fn from_i32(n: i32) -> Option<Self> { |
| FromPrimitive::from_i64(From::from(n)) |
| } |
| |
| /// Converts an `i64` to return an optional value of this type. If the |
| /// value cannot be represented by this type, then `None` is returned. |
| fn from_i64(n: i64) -> Option<Self>; |
| |
| /// Converts an `i128` to return an optional value of this type. If the |
| /// value cannot be represented by this type, then `None` is returned. |
| /// |
| /// This method is only available with feature `i128` enabled on Rust >= 1.26. |
| /// |
| /// The default implementation converts through `from_i64()`. Types implementing |
| /// this trait should override this method if they can represent a greater range. |
| #[inline] |
| #[cfg(has_i128)] |
| fn from_i128(n: i128) -> Option<Self> { |
| n.to_i64().and_then(FromPrimitive::from_i64) |
| } |
| |
| /// Converts a `usize` to return an optional value of this type. If the |
| /// value cannot be represented by this type, then `None` is returned. |
| #[inline] |
| fn from_usize(n: usize) -> Option<Self> { |
| n.to_u64().and_then(FromPrimitive::from_u64) |
| } |
| |
| /// Converts an `u8` to return an optional value of this type. If the |
| /// value cannot be represented by this type, then `None` is returned. |
| #[inline] |
| fn from_u8(n: u8) -> Option<Self> { |
| FromPrimitive::from_u64(From::from(n)) |
| } |
| |
| /// Converts an `u16` to return an optional value of this type. If the |
| /// value cannot be represented by this type, then `None` is returned. |
| #[inline] |
| fn from_u16(n: u16) -> Option<Self> { |
| FromPrimitive::from_u64(From::from(n)) |
| } |
| |
| /// Converts an `u32` to return an optional value of this type. If the |
| /// value cannot be represented by this type, then `None` is returned. |
| #[inline] |
| fn from_u32(n: u32) -> Option<Self> { |
| FromPrimitive::from_u64(From::from(n)) |
| } |
| |
| /// Converts an `u64` to return an optional value of this type. If the |
| /// value cannot be represented by this type, then `None` is returned. |
| fn from_u64(n: u64) -> Option<Self>; |
| |
| /// Converts an `u128` to return an optional value of this type. If the |
| /// value cannot be represented by this type, then `None` is returned. |
| /// |
| /// This method is only available with feature `i128` enabled on Rust >= 1.26. |
| /// |
| /// The default implementation converts through `from_u64()`. Types implementing |
| /// this trait should override this method if they can represent a greater range. |
| #[inline] |
| #[cfg(has_i128)] |
| fn from_u128(n: u128) -> Option<Self> { |
| n.to_u64().and_then(FromPrimitive::from_u64) |
| } |
| |
| /// Converts a `f32` to return an optional value of this type. If the |
| /// value cannot be represented by this type, then `None` is returned. |
| #[inline] |
| fn from_f32(n: f32) -> Option<Self> { |
| FromPrimitive::from_f64(From::from(n)) |
| } |
| |
| /// Converts a `f64` to return an optional value of this type. If the |
| /// value cannot be represented by this type, then `None` is returned. |
| /// |
| /// The default implementation tries to convert through `from_i64()`, and |
| /// failing that through `from_u64()`. Types implementing this trait should |
| /// override this method if they can represent a greater range. |
| #[inline] |
| fn from_f64(n: f64) -> Option<Self> { |
| match n.to_i64() { |
| Some(i) => FromPrimitive::from_i64(i), |
| None => n.to_u64().and_then(FromPrimitive::from_u64), |
| } |
| } |
| } |
| |
| 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.$to_ty() |
| } |
| #[cfg(has_i128)] |
| #[inline] |
| fn from_i128(n: i128) -> Option<$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.$to_ty() |
| } |
| #[cfg(has_i128)] |
| #[inline] |
| fn from_u128(n: u128) -> Option<$T> { |
| n.$to_ty() |
| } |
| |
| #[inline] |
| fn from_f32(n: f32) -> Option<$T> { |
| n.$to_ty() |
| } |
| #[inline] |
| fn from_f64(n: f64) -> Option<$T> { |
| n.$to_ty() |
| } |
| } |
| }; |
| } |
| |
| impl_from_primitive!(isize, to_isize); |
| impl_from_primitive!(i8, to_i8); |
| impl_from_primitive!(i16, to_i16); |
| impl_from_primitive!(i32, to_i32); |
| impl_from_primitive!(i64, to_i64); |
| #[cfg(has_i128)] |
| impl_from_primitive!(i128, to_i128); |
| impl_from_primitive!(usize, to_usize); |
| impl_from_primitive!(u8, to_u8); |
| impl_from_primitive!(u16, to_u16); |
| impl_from_primitive!(u32, to_u32); |
| impl_from_primitive!(u64, to_u64); |
| #[cfg(has_i128)] |
| impl_from_primitive!(u128, to_u128); |
| impl_from_primitive!(f32, to_f32); |
| impl_from_primitive!(f64, to_f64); |
| |
| macro_rules! impl_to_primitive_wrapping { |
| ($( $(#[$cfg:meta])* fn $method:ident -> $i:ident ; )*) => {$( |
| #[inline] |
| $(#[$cfg])* |
| fn $method(&self) -> Option<$i> { |
| (self.0).$method() |
| } |
| )*} |
| } |
| |
| impl<T: ToPrimitive> ToPrimitive for Wrapping<T> { |
| impl_to_primitive_wrapping! { |
| fn to_isize -> isize; |
| fn to_i8 -> i8; |
| fn to_i16 -> i16; |
| fn to_i32 -> i32; |
| fn to_i64 -> i64; |
| #[cfg(has_i128)] |
| fn to_i128 -> i128; |
| |
| fn to_usize -> usize; |
| fn to_u8 -> u8; |
| fn to_u16 -> u16; |
| fn to_u32 -> u32; |
| fn to_u64 -> u64; |
| #[cfg(has_i128)] |
| fn to_u128 -> u128; |
| |
| fn to_f32 -> f32; |
| fn to_f64 -> f64; |
| } |
| } |
| |
| macro_rules! impl_from_primitive_wrapping { |
| ($( $(#[$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); |
| #[cfg(has_i128)] |
| fn from_i128(i128); |
| |
| fn from_usize(usize); |
| fn from_u8(u8); |
| fn from_u16(u16); |
| fn from_u32(u32); |
| fn from_u64(u64); |
| #[cfg(has_i128)] |
| fn from_u128(u128); |
| |
| fn from_f32(f32); |
| fn from_f64(f64); |
| } |
| } |
| |
| /// Cast from one machine scalar to another. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// # use num_traits as num; |
| /// let twenty: f32 = num::cast(0x14).unwrap(); |
| /// assert_eq!(twenty, 20f32); |
| /// ``` |
| /// |
| #[inline] |
| pub fn cast<T: NumCast, U: NumCast>(n: T) -> Option<U> { |
| NumCast::from(n) |
| } |
| |
| /// An interface for casting between machine scalars. |
| pub trait NumCast: Sized + ToPrimitive { |
| /// Creates a number from another value that can be converted into |
| /// a primitive via the `ToPrimitive` trait. If the source value cannot be |
| /// represented by the target type, then `None` is returned. |
| /// |
| /// A value can be represented by the target type when it lies within |
| /// the range of scalars supported by the target type. |
| /// For example, a negative integer cannot be represented by an unsigned |
| /// integer type, and an `i64` with a very high magnitude might not be |
| /// convertible to an `i32`. |
| /// On the other hand, conversions with possible precision loss or truncation |
| /// are admitted, like an `f32` with a decimal part to an integer type, or |
| /// even a large `f64` saturating to `f32` infinity. |
| fn from<T: ToPrimitive>(n: T) -> Option<Self>; |
| } |
| |
| macro_rules! impl_num_cast { |
| ($T:ty, $conv:ident) => { |
| impl NumCast for $T { |
| #[inline] |
| #[allow(deprecated)] |
| fn from<N: ToPrimitive>(n: N) -> Option<$T> { |
| // `$conv` could be generated using `concat_idents!`, but that |
| // macro seems to be broken at the moment |
| n.$conv() |
| } |
| } |
| }; |
| } |
| |
| impl_num_cast!(u8, to_u8); |
| impl_num_cast!(u16, to_u16); |
| impl_num_cast!(u32, to_u32); |
| impl_num_cast!(u64, to_u64); |
| #[cfg(has_i128)] |
| impl_num_cast!(u128, to_u128); |
| impl_num_cast!(usize, to_usize); |
| impl_num_cast!(i8, to_i8); |
| impl_num_cast!(i16, to_i16); |
| impl_num_cast!(i32, to_i32); |
| impl_num_cast!(i64, to_i64); |
| #[cfg(has_i128)] |
| impl_num_cast!(i128, to_i128); |
| impl_num_cast!(isize, to_isize); |
| impl_num_cast!(f32, to_f32); |
| impl_num_cast!(f64, to_f64); |
| |
| impl<T: NumCast> NumCast for Wrapping<T> { |
| fn from<U: ToPrimitive>(n: U) -> Option<Self> { |
| T::from(n).map(Wrapping) |
| } |
| } |
| |
| /// A generic interface for casting between machine scalars with the |
| /// `as` operator, which admits narrowing and precision loss. |
| /// Implementers of this trait `AsPrimitive` should behave like a primitive |
| /// numeric type (e.g. a newtype around another primitive), and the |
| /// intended conversion must never fail. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// # use num_traits::AsPrimitive; |
| /// let three: i32 = (3.14159265f32).as_(); |
| /// assert_eq!(three, 3); |
| /// ``` |
| /// |
| /// # Safety |
| /// |
| /// **In Rust versions before 1.45.0**, some uses of the `as` operator were not entirely safe. |
| /// In particular, it was undefined behavior if |
| /// a truncated floating point value could not fit in the target integer |
| /// type ([#10184](https://github.com/rust-lang/rust/issues/10184)). |
| /// |
| /// ```ignore |
| /// # use num_traits::AsPrimitive; |
| /// let x: u8 = (1.04E+17).as_(); // UB |
| /// ``` |
| /// |
| pub trait AsPrimitive<T>: 'static + Copy |
| where |
| T: 'static + Copy, |
| { |
| /// Convert a value to another, using the `as` operator. |
| fn as_(self) -> T; |
| } |
| |
| macro_rules! impl_as_primitive { |
| (@ $T: ty => $(#[$cfg:meta])* impl $U: ty ) => { |
| $(#[$cfg])* |
| impl AsPrimitive<$U> for $T { |
| #[inline] fn as_(self) -> $U { self as $U } |
| } |
| }; |
| (@ $T: ty => { $( $U: ty ),* } ) => {$( |
| impl_as_primitive!(@ $T => impl $U); |
| )*}; |
| ($T: ty => { $( $U: ty ),* } ) => { |
| impl_as_primitive!(@ $T => { $( $U ),* }); |
| impl_as_primitive!(@ $T => { u8, u16, u32, u64, usize }); |
| impl_as_primitive!(@ $T => #[cfg(has_i128)] impl u128); |
| impl_as_primitive!(@ $T => { i8, i16, i32, i64, isize }); |
| impl_as_primitive!(@ $T => #[cfg(has_i128)] impl i128); |
| }; |
| } |
| |
| impl_as_primitive!(u8 => { char, f32, f64 }); |
| impl_as_primitive!(i8 => { f32, f64 }); |
| impl_as_primitive!(u16 => { f32, f64 }); |
| impl_as_primitive!(i16 => { f32, f64 }); |
| impl_as_primitive!(u32 => { f32, f64 }); |
| impl_as_primitive!(i32 => { f32, f64 }); |
| impl_as_primitive!(u64 => { f32, f64 }); |
| impl_as_primitive!(i64 => { f32, f64 }); |
| #[cfg(has_i128)] |
| impl_as_primitive!(u128 => { f32, f64 }); |
| #[cfg(has_i128)] |
| impl_as_primitive!(i128 => { f32, f64 }); |
| impl_as_primitive!(usize => { f32, f64 }); |
| impl_as_primitive!(isize => { f32, f64 }); |
| impl_as_primitive!(f32 => { f32, f64 }); |
| impl_as_primitive!(f64 => { f32, f64 }); |
| impl_as_primitive!(char => { char }); |
| impl_as_primitive!(bool => {}); |
