mod.rs

// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

//! Numeric traits and functions for the built-in numeric types.

#![stable(feature = "rust1", since = "1.0.0")]

use convert::{Infallible, TryFrom};
use fmt;
use intrinsics;
use ops;
use str::FromStr;

/// Provides intentionally-wrapped arithmetic on `T`.
///
/// Operations like `+` on `u32` values is intended to never overflow,
/// and in some debug configurations overflow is detected and results
/// in a panic. While most arithmetic falls into this category, some
/// code explicitly expects and relies upon modular arithmetic (e.g.,
/// hashing).
///
/// Wrapping arithmetic can be achieved either through methods like
/// `wrapping_add`, or through the `Wrapping<T>` type, which says that
/// all standard arithmetic operations on the underlying value are
/// intended to have wrapping semantics.
///
/// # Examples
///
/// ```
/// use std::num::Wrapping;
///
/// let zero = Wrapping(0u32);
/// let one = Wrapping(1u32);
///
/// assert_eq!(std::u32::MAX, (zero - one).0);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[derive(PartialEq, Eq, PartialOrd, Ord, Clone, Copy, Default, Hash)]
pub struct Wrapping<T>(#[stable(feature = "rust1", since = "1.0.0")]
                       pub T);

#[stable(feature = "rust1", since = "1.0.0")]
impl<T: fmt::Debug> fmt::Debug for Wrapping<T> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        self.0.fmt(f)
    }
}

#[stable(feature = "wrapping_display", since = "1.10.0")]
impl<T: fmt::Display> fmt::Display for Wrapping<T> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        self.0.fmt(f)
    }
}

#[stable(feature = "wrapping_fmt", since = "1.11.0")]
impl<T: fmt::Binary> fmt::Binary for Wrapping<T> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        self.0.fmt(f)
    }
}

#[stable(feature = "wrapping_fmt", since = "1.11.0")]
impl<T: fmt::Octal> fmt::Octal for Wrapping<T> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        self.0.fmt(f)
    }
}

#[stable(feature = "wrapping_fmt", since = "1.11.0")]
impl<T: fmt::LowerHex> fmt::LowerHex for Wrapping<T> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        self.0.fmt(f)
    }
}

#[stable(feature = "wrapping_fmt", since = "1.11.0")]
impl<T: fmt::UpperHex> fmt::UpperHex for Wrapping<T> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        self.0.fmt(f)
    }
}

mod wrapping;

// All these modules are technically private and only exposed for coretests:
pub mod flt2dec;
pub mod dec2flt;
pub mod bignum;
pub mod diy_float;

// `Int` + `SignedInt` implemented for signed integers
macro_rules! int_impl {
    ($SelfT:ty, $ActualT:ident, $UnsignedT:ty, $BITS:expr) => {
        /// Returns the smallest value that can be represented by this integer type.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(i8::min_value(), -128);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub const fn min_value() -> Self {
            !0 ^ ((!0 as $UnsignedT) >> 1) as Self
        }

        /// Returns the largest value that can be represented by this integer type.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(i8::max_value(), 127);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub const fn max_value() -> Self {
            !Self::min_value()
        }

        /// Converts a string slice in a given base to an integer.
        ///
        /// The string is expected to be an optional `+` or `-` sign
        /// followed by digits.
        /// Leading and trailing whitespace represent an error.
        /// Digits are a subset of these characters, depending on `radix`:
        ///
        /// * `0-9`
        /// * `a-z`
        /// * `A-Z`
        ///
        /// # Panics
        ///
        /// This function panics if `radix` is not in the range from 2 to 36.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(i32::from_str_radix("A", 16), Ok(10));
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn from_str_radix(src: &str, radix: u32) -> Result<Self, ParseIntError> {
            from_str_radix(src, radix)
        }

        /// Returns the number of ones in the binary representation of `self`.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let n = -0b1000_0000i8;
        ///
        /// assert_eq!(n.count_ones(), 1);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn count_ones(self) -> u32 { (self as $UnsignedT).count_ones() }

        /// Returns the number of zeros in the binary representation of `self`.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let n = -0b1000_0000i8;
        ///
        /// assert_eq!(n.count_zeros(), 7);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn count_zeros(self) -> u32 {
            (!self).count_ones()
        }

        /// Returns the number of leading zeros in the binary representation
        /// of `self`.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let n = -1i16;
        ///
        /// assert_eq!(n.leading_zeros(), 0);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn leading_zeros(self) -> u32 {
            (self as $UnsignedT).leading_zeros()
        }

        /// Returns the number of trailing zeros in the binary representation
        /// of `self`.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let n = -4i8;
        ///
        /// assert_eq!(n.trailing_zeros(), 2);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn trailing_zeros(self) -> u32 {
            (self as $UnsignedT).trailing_zeros()
        }

        /// Shifts the bits to the left by a specified amount, `n`,
        /// wrapping the truncated bits to the end of the resulting integer.
        ///
        /// Please note this isn't the same operation as `<<`!
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let n = 0x0123456789ABCDEFi64;
        /// let m = -0x76543210FEDCBA99i64;
        ///
        /// assert_eq!(n.rotate_left(32), m);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn rotate_left(self, n: u32) -> Self {
            (self as $UnsignedT).rotate_left(n) as Self
        }

        /// Shifts the bits to the right by a specified amount, `n`,
        /// wrapping the truncated bits to the beginning of the resulting
        /// integer.
        ///
        /// Please note this isn't the same operation as `>>`!
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let n = 0x0123456789ABCDEFi64;
        /// let m = -0xFEDCBA987654322i64;
        ///
        /// assert_eq!(n.rotate_right(4), m);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn rotate_right(self, n: u32) -> Self {
            (self as $UnsignedT).rotate_right(n) as Self
        }

        /// Reverses the byte order of the integer.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let n: i16 = 0b0000000_01010101;
        /// assert_eq!(n, 85);
        ///
        /// let m = n.swap_bytes();
        ///
        /// assert_eq!(m, 0b01010101_00000000);
        /// assert_eq!(m, 21760);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn swap_bytes(self) -> Self {
            (self as $UnsignedT).swap_bytes() as Self
        }

        /// Converts an integer from big endian to the target's endianness.
        ///
        /// On big endian this is a no-op. On little endian the bytes are
        /// swapped.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let n = 0x0123456789ABCDEFi64;
        ///
        /// if cfg!(target_endian = "big") {
        ///     assert_eq!(i64::from_be(n), n)
        /// } else {
        ///     assert_eq!(i64::from_be(n), n.swap_bytes())
        /// }
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn from_be(x: Self) -> Self {
            if cfg!(target_endian = "big") { x } else { x.swap_bytes() }
        }

        /// Converts an integer from little endian to the target's endianness.
        ///
        /// On little endian this is a no-op. On big endian the bytes are
        /// swapped.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let n = 0x0123456789ABCDEFi64;
        ///
        /// if cfg!(target_endian = "little") {
        ///     assert_eq!(i64::from_le(n), n)
        /// } else {
        ///     assert_eq!(i64::from_le(n), n.swap_bytes())
        /// }
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn from_le(x: Self) -> Self {
            if cfg!(target_endian = "little") { x } else { x.swap_bytes() }
        }

        /// Converts `self` to big endian from the target's endianness.
        ///
        /// On big endian this is a no-op. On little endian the bytes are
        /// swapped.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let n = 0x0123456789ABCDEFi64;
        ///
        /// if cfg!(target_endian = "big") {
        ///     assert_eq!(n.to_be(), n)
        /// } else {
        ///     assert_eq!(n.to_be(), n.swap_bytes())
        /// }
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn to_be(self) -> Self { // or not to be?
            if cfg!(target_endian = "big") { self } else { self.swap_bytes() }
        }

        /// Converts `self` to little endian from the target's endianness.
        ///
        /// On little endian this is a no-op. On big endian the bytes are
        /// swapped.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let n = 0x0123456789ABCDEFi64;
        ///
        /// if cfg!(target_endian = "little") {
        ///     assert_eq!(n.to_le(), n)
        /// } else {
        ///     assert_eq!(n.to_le(), n.swap_bytes())
        /// }
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn to_le(self) -> Self {
            if cfg!(target_endian = "little") { self } else { self.swap_bytes() }
        }

        /// Checked integer addition. Computes `self + rhs`, returning `None`
        /// if overflow occurred.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(7i16.checked_add(32760), Some(32767));
        /// assert_eq!(8i16.checked_add(32760), None);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn checked_add(self, rhs: Self) -> Option<Self> {
            let (a, b) = self.overflowing_add(rhs);
            if b {None} else {Some(a)}
        }

        /// Checked integer subtraction. Computes `self - rhs`, returning
        /// `None` if overflow occurred.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!((-127i8).checked_sub(1), Some(-128));
        /// assert_eq!((-128i8).checked_sub(1), None);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn checked_sub(self, rhs: Self) -> Option<Self> {
            let (a, b) = self.overflowing_sub(rhs);
            if b {None} else {Some(a)}
        }

        /// Checked integer multiplication. Computes `self * rhs`, returning
        /// `None` if overflow occurred.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(6i8.checked_mul(21), Some(126));
        /// assert_eq!(6i8.checked_mul(22), None);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn checked_mul(self, rhs: Self) -> Option<Self> {
            let (a, b) = self.overflowing_mul(rhs);
            if b {None} else {Some(a)}
        }

        /// Checked integer division. Computes `self / rhs`, returning `None`
        /// if `rhs == 0` or the division results in overflow.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!((-127i8).checked_div(-1), Some(127));
        /// assert_eq!((-128i8).checked_div(-1), None);
        /// assert_eq!((1i8).checked_div(0), None);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn checked_div(self, rhs: Self) -> Option<Self> {
            if rhs == 0 || (self == Self::min_value() && rhs == -1) {
                None
            } else {
                Some(unsafe { intrinsics::unchecked_div(self, rhs) })
            }
        }

        /// Checked integer remainder. Computes `self % rhs`, returning `None`
        /// if `rhs == 0` or the division results in overflow.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// use std::i32;
        ///
        /// assert_eq!(5i32.checked_rem(2), Some(1));
        /// assert_eq!(5i32.checked_rem(0), None);
        /// assert_eq!(i32::MIN.checked_rem(-1), None);
        /// ```
        #[stable(feature = "wrapping", since = "1.7.0")]
        #[inline]
        pub fn checked_rem(self, rhs: Self) -> Option<Self> {
            if rhs == 0 || (self == Self::min_value() && rhs == -1) {
                None
            } else {
                Some(unsafe { intrinsics::unchecked_rem(self, rhs) })
            }
        }

        /// Checked negation. Computes `-self`, returning `None` if `self ==
        /// MIN`.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// use std::i32;
        ///
        /// assert_eq!(5i32.checked_neg(), Some(-5));
        /// assert_eq!(i32::MIN.checked_neg(), None);
        /// ```
        #[stable(feature = "wrapping", since = "1.7.0")]
        #[inline]
        pub fn checked_neg(self) -> Option<Self> {
            let (a, b) = self.overflowing_neg();
            if b {None} else {Some(a)}
        }

        /// Checked shift left. Computes `self << rhs`, returning `None`
        /// if `rhs` is larger than or equal to the number of bits in `self`.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(0x10i32.checked_shl(4), Some(0x100));
        /// assert_eq!(0x10i32.checked_shl(33), None);
        /// ```
        #[stable(feature = "wrapping", since = "1.7.0")]
        #[inline]
        pub fn checked_shl(self, rhs: u32) -> Option<Self> {
            let (a, b) = self.overflowing_shl(rhs);
            if b {None} else {Some(a)}
        }

        /// Checked shift right. Computes `self >> rhs`, returning `None`
        /// if `rhs` is larger than or equal to the number of bits in `self`.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(0x10i32.checked_shr(4), Some(0x1));
        /// assert_eq!(0x10i32.checked_shr(33), None);
        /// ```
        #[stable(feature = "wrapping", since = "1.7.0")]
        #[inline]
        pub fn checked_shr(self, rhs: u32) -> Option<Self> {
            let (a, b) = self.overflowing_shr(rhs);
            if b {None} else {Some(a)}
        }

        /// Checked absolute value. Computes `self.abs()`, returning `None` if
        /// `self == MIN`.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// use std::i32;
        ///
        /// assert_eq!((-5i32).checked_abs(), Some(5));
        /// assert_eq!(i32::MIN.checked_abs(), None);
        /// ```
        #[stable(feature = "no_panic_abs", since = "1.13.0")]
        #[inline]
        pub fn checked_abs(self) -> Option<Self> {
            if self.is_negative() {
                self.checked_neg()
            } else {
                Some(self)
            }
        }

        /// Saturating integer addition. Computes `self + rhs`, saturating at
        /// the numeric bounds instead of overflowing.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(100i8.saturating_add(1), 101);
        /// assert_eq!(100i8.saturating_add(127), 127);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn saturating_add(self, rhs: Self) -> Self {
            match self.checked_add(rhs) {
                Some(x) => x,
                None if rhs >= 0 => Self::max_value(),
                None => Self::min_value(),
            }
        }

        /// Saturating integer subtraction. Computes `self - rhs`, saturating
        /// at the numeric bounds instead of overflowing.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(100i8.saturating_sub(127), -27);
        /// assert_eq!((-100i8).saturating_sub(127), -128);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn saturating_sub(self, rhs: Self) -> Self {
            match self.checked_sub(rhs) {
                Some(x) => x,
                None if rhs >= 0 => Self::min_value(),
                None => Self::max_value(),
            }
        }

        /// Saturating integer multiplication. Computes `self * rhs`,
        /// saturating at the numeric bounds instead of overflowing.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// use std::i32;
        ///
        /// assert_eq!(100i32.saturating_mul(127), 12700);
        /// assert_eq!((1i32 << 23).saturating_mul(1 << 23), i32::MAX);
        /// assert_eq!((-1i32 << 23).saturating_mul(1 << 23), i32::MIN);
        /// ```
        #[stable(feature = "wrapping", since = "1.7.0")]
        #[inline]
        pub fn saturating_mul(self, rhs: Self) -> Self {
            self.checked_mul(rhs).unwrap_or_else(|| {
                if (self < 0 && rhs < 0) || (self > 0 && rhs > 0) {
                    Self::max_value()
                } else {
                    Self::min_value()
                }
            })
        }

        /// Wrapping (modular) addition. Computes `self + rhs`,
        /// wrapping around at the boundary of the type.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(100i8.wrapping_add(27), 127);
        /// assert_eq!(100i8.wrapping_add(127), -29);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn wrapping_add(self, rhs: Self) -> Self {
            unsafe {
                intrinsics::overflowing_add(self, rhs)
            }
        }

        /// Wrapping (modular) subtraction. Computes `self - rhs`,
        /// wrapping around at the boundary of the type.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(0i8.wrapping_sub(127), -127);
        /// assert_eq!((-2i8).wrapping_sub(127), 127);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn wrapping_sub(self, rhs: Self) -> Self {
            unsafe {
                intrinsics::overflowing_sub(self, rhs)
            }
        }

        /// Wrapping (modular) multiplication. Computes `self *
        /// rhs`, wrapping around at the boundary of the type.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(10i8.wrapping_mul(12), 120);
        /// assert_eq!(11i8.wrapping_mul(12), -124);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn wrapping_mul(self, rhs: Self) -> Self {
            unsafe {
                intrinsics::overflowing_mul(self, rhs)
            }
        }

        /// Wrapping (modular) division. Computes `self / rhs`,
        /// wrapping around at the boundary of the type.
        ///
        /// The only case where such wrapping can occur is when one
        /// divides `MIN / -1` on a signed type (where `MIN` is the
        /// negative minimal value for the type); this is equivalent
        /// to `-MIN`, a positive value that is too large to represent
        /// in the type. In such a case, this function returns `MIN`
        /// itself.
        ///
        /// # Panics
        ///
        /// This function will panic if `rhs` is 0.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(100u8.wrapping_div(10), 10);
        /// assert_eq!((-128i8).wrapping_div(-1), -128);
        /// ```
        #[stable(feature = "num_wrapping", since = "1.2.0")]
        #[inline]
        pub fn wrapping_div(self, rhs: Self) -> Self {
            self.overflowing_div(rhs).0
        }

        /// Wrapping (modular) remainder. Computes `self % rhs`,
        /// wrapping around at the boundary of the type.
        ///
        /// Such wrap-around never actually occurs mathematically;
        /// implementation artifacts make `x % y` invalid for `MIN /
        /// -1` on a signed type (where `MIN` is the negative
        /// minimal value). In such a case, this function returns `0`.
        ///
        /// # Panics
        ///
        /// This function will panic if `rhs` is 0.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(100i8.wrapping_rem(10), 0);
        /// assert_eq!((-128i8).wrapping_rem(-1), 0);
        /// ```
        #[stable(feature = "num_wrapping", since = "1.2.0")]
        #[inline]
        pub fn wrapping_rem(self, rhs: Self) -> Self {
            self.overflowing_rem(rhs).0
        }

        /// Wrapping (modular) negation. Computes `-self`,
        /// wrapping around at the boundary of the type.
        ///
        /// The only case where such wrapping can occur is when one
        /// negates `MIN` on a signed type (where `MIN` is the
        /// negative minimal value for the type); this is a positive
        /// value that is too large to represent in the type. In such
        /// a case, this function returns `MIN` itself.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(100i8.wrapping_neg(), -100);
        /// assert_eq!((-128i8).wrapping_neg(), -128);
        /// ```
        #[stable(feature = "num_wrapping", since = "1.2.0")]
        #[inline]
        pub fn wrapping_neg(self) -> Self {
            self.overflowing_neg().0
        }

        /// Panic-free bitwise shift-left; yields `self << mask(rhs)`,
        /// where `mask` removes any high-order bits of `rhs` that
        /// would cause the shift to exceed the bitwidth of the type.
        ///
        /// Note that this is *not* the same as a rotate-left; the
        /// RHS of a wrapping shift-left is restricted to the range
        /// of the type, rather than the bits shifted out of the LHS
        /// being returned to the other end. The primitive integer
        /// types all implement a `rotate_left` function, which may
        /// be what you want instead.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!((-1i8).wrapping_shl(7), -128);
        /// assert_eq!((-1i8).wrapping_shl(8), -1);
        /// ```
        #[stable(feature = "num_wrapping", since = "1.2.0")]
        #[inline]
        pub fn wrapping_shl(self, rhs: u32) -> Self {
            unsafe {
                intrinsics::unchecked_shl(self, (rhs & ($BITS - 1)) as $SelfT)
            }
        }

        /// Panic-free bitwise shift-right; yields `self >> mask(rhs)`,
        /// where `mask` removes any high-order bits of `rhs` that
        /// would cause the shift to exceed the bitwidth of the type.
        ///
        /// Note that this is *not* the same as a rotate-right; the
        /// RHS of a wrapping shift-right is restricted to the range
        /// of the type, rather than the bits shifted out of the LHS
        /// being returned to the other end. The primitive integer
        /// types all implement a `rotate_right` function, which may
        /// be what you want instead.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!((-128i8).wrapping_shr(7), -1);
        /// assert_eq!((-128i8).wrapping_shr(8), -128);
        /// ```
        #[stable(feature = "num_wrapping", since = "1.2.0")]
        #[inline]
        pub fn wrapping_shr(self, rhs: u32) -> Self {
            unsafe {
                intrinsics::unchecked_shr(self, (rhs & ($BITS - 1)) as $SelfT)
            }
        }

        /// Wrapping (modular) absolute value. Computes `self.abs()`,
        /// wrapping around at the boundary of the type.
        ///
        /// The only case where such wrapping can occur is when one takes
        /// the absolute value of the negative minimal value for the type
        /// this is a positive value that is too large to represent in the
        /// type. In such a case, this function returns `MIN` itself.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(100i8.wrapping_abs(), 100);
        /// assert_eq!((-100i8).wrapping_abs(), 100);
        /// assert_eq!((-128i8).wrapping_abs(), -128);
        /// assert_eq!((-128i8).wrapping_abs() as u8, 128);
        /// ```
        #[stable(feature = "no_panic_abs", since = "1.13.0")]
        #[inline]
        pub fn wrapping_abs(self) -> Self {
            if self.is_negative() {
                self.wrapping_neg()
            } else {
                self
            }
        }

        /// Calculates `self` + `rhs`
        ///
        /// Returns a tuple of the addition along with a boolean indicating
        /// whether an arithmetic overflow would occur. If an overflow would
        /// have occurred then the wrapped value is returned.
        ///
        /// # Examples
        ///
        /// Basic usage
        ///
        /// ```
        /// use std::i32;
        ///
        /// assert_eq!(5i32.overflowing_add(2), (7, false));
        /// assert_eq!(i32::MAX.overflowing_add(1), (i32::MIN, true));
        /// ```
        #[inline]
        #[stable(feature = "wrapping", since = "1.7.0")]
        pub fn overflowing_add(self, rhs: Self) -> (Self, bool) {
            let (a, b) = unsafe {
                intrinsics::add_with_overflow(self as $ActualT,
                                              rhs as $ActualT)
            };
            (a as Self, b)
        }

        /// Calculates `self` - `rhs`
        ///
        /// Returns a tuple of the subtraction along with a boolean indicating
        /// whether an arithmetic overflow would occur. If an overflow would
        /// have occurred then the wrapped value is returned.
        ///
        /// # Examples
        ///
        /// Basic usage
        ///
        /// ```
        /// use std::i32;
        ///
        /// assert_eq!(5i32.overflowing_sub(2), (3, false));
        /// assert_eq!(i32::MIN.overflowing_sub(1), (i32::MAX, true));
        /// ```
        #[inline]
        #[stable(feature = "wrapping", since = "1.7.0")]
        pub fn overflowing_sub(self, rhs: Self) -> (Self, bool) {
            let (a, b) = unsafe {
                intrinsics::sub_with_overflow(self as $ActualT,
                                              rhs as $ActualT)
            };
            (a as Self, b)
        }

        /// Calculates the multiplication of `self` and `rhs`.
        ///
        /// Returns a tuple of the multiplication along with a boolean
        /// indicating whether an arithmetic overflow would occur. If an
        /// overflow would have occurred then the wrapped value is returned.
        ///
        /// # Examples
        ///
        /// Basic usage
        ///
        /// ```
        /// assert_eq!(5i32.overflowing_mul(2), (10, false));
        /// assert_eq!(1_000_000_000i32.overflowing_mul(10), (1410065408, true));
        /// ```
        #[inline]
        #[stable(feature = "wrapping", since = "1.7.0")]
        pub fn overflowing_mul(self, rhs: Self) -> (Self, bool) {
            let (a, b) = unsafe {
                intrinsics::mul_with_overflow(self as $ActualT,
                                              rhs as $ActualT)
            };
            (a as Self, b)
        }

        /// Calculates the divisor when `self` is divided by `rhs`.
        ///
        /// Returns a tuple of the divisor along with a boolean indicating
        /// whether an arithmetic overflow would occur. If an overflow would
        /// occur then self is returned.
        ///
        /// # Panics
        ///
        /// This function will panic if `rhs` is 0.
        ///
        /// # Examples
        ///
        /// Basic usage
        ///
        /// ```
        /// use std::i32;
        ///
        /// assert_eq!(5i32.overflowing_div(2), (2, false));
        /// assert_eq!(i32::MIN.overflowing_div(-1), (i32::MIN, true));
        /// ```
        #[inline]
        #[stable(feature = "wrapping", since = "1.7.0")]
        pub fn overflowing_div(self, rhs: Self) -> (Self, bool) {
            if self == Self::min_value() && rhs == -1 {
                (self, true)
            } else {
                (self / rhs, false)
            }
        }

        /// Calculates the remainder when `self` is divided by `rhs`.
        ///
        /// Returns a tuple of the remainder after dividing along with a boolean
        /// indicating whether an arithmetic overflow would occur. If an
        /// overflow would occur then 0 is returned.
        ///
        /// # Panics
        ///
        /// This function will panic if `rhs` is 0.
        ///
        /// # Examples
        ///
        /// Basic usage
        ///
        /// ```
        /// use std::i32;
        ///
        /// assert_eq!(5i32.overflowing_rem(2), (1, false));
        /// assert_eq!(i32::MIN.overflowing_rem(-1), (0, true));
        /// ```
        #[inline]
        #[stable(feature = "wrapping", since = "1.7.0")]
        pub fn overflowing_rem(self, rhs: Self) -> (Self, bool) {
            if self == Self::min_value() && rhs == -1 {
                (0, true)
            } else {
                (self % rhs, false)
            }
        }

        /// Negates self, overflowing if this is equal to the minimum value.
        ///
        /// Returns a tuple of the negated version of self along with a boolean
        /// indicating whether an overflow happened. If `self` is the minimum
        /// value (e.g. `i32::MIN` for values of type `i32`), then the minimum
        /// value will be returned again and `true` will be returned for an
        /// overflow happening.
        ///
        /// # Examples
        ///
        /// Basic usage
        ///
        /// ```
        /// use std::i32;
        ///
        /// assert_eq!(2i32.overflowing_neg(), (-2, false));
        /// assert_eq!(i32::MIN.overflowing_neg(), (i32::MIN, true));
        /// ```
        #[inline]
        #[stable(feature = "wrapping", since = "1.7.0")]
        pub fn overflowing_neg(self) -> (Self, bool) {
            if self == Self::min_value() {
                (Self::min_value(), true)
            } else {
                (-self, false)
            }
        }

        /// Shifts self left by `rhs` bits.
        ///
        /// Returns a tuple of the shifted version of self along with a boolean
        /// indicating whether the shift value was larger than or equal to the
        /// number of bits. If the shift value is too large, then value is
        /// masked (N-1) where N is the number of bits, and this value is then
        /// used to perform the shift.
        ///
        /// # Examples
        ///
        /// Basic usage
        ///
        /// ```
        /// assert_eq!(0x10i32.overflowing_shl(4), (0x100, false));
        /// assert_eq!(0x10i32.overflowing_shl(36), (0x100, true));
        /// ```
        #[inline]
        #[stable(feature = "wrapping", since = "1.7.0")]
        pub fn overflowing_shl(self, rhs: u32) -> (Self, bool) {
            (self.wrapping_shl(rhs), (rhs > ($BITS - 1)))
        }

        /// Shifts self right by `rhs` bits.
        ///
        /// Returns a tuple of the shifted version of self along with a boolean
        /// indicating whether the shift value was larger than or equal to the
        /// number of bits. If the shift value is too large, then value is
        /// masked (N-1) where N is the number of bits, and this value is then
        /// used to perform the shift.
        ///
        /// # Examples
        ///
        /// Basic usage
        ///
        /// ```
        /// assert_eq!(0x10i32.overflowing_shr(4), (0x1, false));
        /// assert_eq!(0x10i32.overflowing_shr(36), (0x1, true));
        /// ```
        #[inline]
        #[stable(feature = "wrapping", since = "1.7.0")]
        pub fn overflowing_shr(self, rhs: u32) -> (Self, bool) {
            (self.wrapping_shr(rhs), (rhs > ($BITS - 1)))
        }

        /// Computes the absolute value of `self`.
        ///
        /// Returns a tuple of the absolute version of self along with a
        /// boolean indicating whether an overflow happened. If self is the
        /// minimum value (e.g. i32::MIN for values of type i32), then the
        /// minimum value will be returned again and true will be returned for
        /// an overflow happening.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(10i8.overflowing_abs(), (10,false));
        /// assert_eq!((-10i8).overflowing_abs(), (10,false));
        /// assert_eq!((-128i8).overflowing_abs(), (-128,true));
        /// ```
        #[stable(feature = "no_panic_abs", since = "1.13.0")]
        #[inline]
        pub fn overflowing_abs(self) -> (Self, bool) {
            if self.is_negative() {
                self.overflowing_neg()
            } else {
                (self, false)
            }
        }

        /// Raises self to the power of `exp`, using exponentiation by squaring.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let x: i32 = 2; // or any other integer type
        ///
        /// assert_eq!(x.pow(4), 16);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        #[rustc_inherit_overflow_checks]
        pub fn pow(self, mut exp: u32) -> Self {
            let mut base = self;
            let mut acc = 1;

            while exp > 1 {
                if (exp & 1) == 1 {
                    acc = acc * base;
                }
                exp /= 2;
                base = base * base;
            }

            // Deal with the final bit of the exponent separately, since
            // squaring the base afterwards is not necessary and may cause a
            // needless overflow.
            if exp == 1 {
                acc = acc * base;
            }

            acc
        }

        /// Computes the absolute value of `self`.
        ///
        /// # Overflow behavior
        ///
        /// The absolute value of `i32::min_value()` cannot be represented as an
        /// `i32`, and attempting to calculate it will cause an overflow. This
        /// means that code in debug mode will trigger a panic on this case and
        /// optimized code will return `i32::min_value()` without a panic.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(10i8.abs(), 10);
        /// assert_eq!((-10i8).abs(), 10);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        #[rustc_inherit_overflow_checks]
        pub fn abs(self) -> Self {
            if self.is_negative() {
                // Note that the #[inline] above means that the overflow
                // semantics of this negation depend on the crate we're being
                // inlined into.
                -self
            } else {
                self
            }
        }

        /// Returns a number representing sign of `self`.
        ///
        /// - `0` if the number is zero
        /// - `1` if the number is positive
        /// - `-1` if the number is negative
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(10i8.signum(), 1);
        /// assert_eq!(0i8.signum(), 0);
        /// assert_eq!((-10i8).signum(), -1);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn signum(self) -> Self {
            match self {
                n if n > 0 =>  1,
                0          =>  0,
                _          => -1,
            }
        }

        /// Returns `true` if `self` is positive and `false` if the number
        /// is zero or negative.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert!(10i8.is_positive());
        /// assert!(!(-10i8).is_positive());
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn is_positive(self) -> bool { self > 0 }

        /// Returns `true` if `self` is negative and `false` if the number
        /// is zero or positive.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert!((-10i8).is_negative());
        /// assert!(!10i8.is_negative());
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn is_negative(self) -> bool { self < 0 }
    }
}

#[lang = "i8"]
impl i8 {
    int_impl! { i8, i8, u8, 8 }
}

#[lang = "i16"]
impl i16 {
    int_impl! { i16, i16, u16, 16 }
}

#[lang = "i32"]
impl i32 {
    int_impl! { i32, i32, u32, 32 }
}

#[lang = "i64"]
impl i64 {
    int_impl! { i64, i64, u64, 64 }
}

#[lang = "i128"]
impl i128 {
    int_impl! { i128, i128, u128, 128 }
}

#[cfg(target_pointer_width = "16")]
#[lang = "isize"]
impl isize {
    int_impl! { isize, i16, u16, 16 }
}

#[cfg(target_pointer_width = "32")]
#[lang = "isize"]
impl isize {
    int_impl! { isize, i32, u32, 32 }
}

#[cfg(target_pointer_width = "64")]
#[lang = "isize"]
impl isize {
    int_impl! { isize, i64, u64, 64 }
}

// `Int` + `UnsignedInt` implemented for unsigned integers
macro_rules! uint_impl {
    ($SelfT:ty, $ActualT:ty, $BITS:expr) => {
        /// Returns the smallest value that can be represented by this integer type.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(u8::min_value(), 0);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub const fn min_value() -> Self { 0 }

        /// Returns the largest value that can be represented by this integer type.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(u8::max_value(), 255);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub const fn max_value() -> Self { !0 }

        /// Converts a string slice in a given base to an integer.
        ///
        /// The string is expected to be an optional `+` sign
        /// followed by digits.
        /// Leading and trailing whitespace represent an error.
        /// Digits are a subset of these characters, depending on `radix`:
        ///
        /// * `0-9`
        /// * `a-z`
        /// * `A-Z`
        ///
        /// # Panics
        ///
        /// This function panics if `radix` is not in the range from 2 to 36.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(u32::from_str_radix("A", 16), Ok(10));
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn from_str_radix(src: &str, radix: u32) -> Result<Self, ParseIntError> {
            from_str_radix(src, radix)
        }

        /// Returns the number of ones in the binary representation of `self`.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let n = 0b01001100u8;
        ///
        /// assert_eq!(n.count_ones(), 3);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn count_ones(self) -> u32 {
            unsafe { intrinsics::ctpop(self as $ActualT) as u32 }
        }

        /// Returns the number of zeros in the binary representation of `self`.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let n = 0b01001100u8;
        ///
        /// assert_eq!(n.count_zeros(), 5);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn count_zeros(self) -> u32 {
            (!self).count_ones()
        }

        /// Returns the number of leading zeros in the binary representation
        /// of `self`.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let n = 0b0101000u16;
        ///
        /// assert_eq!(n.leading_zeros(), 10);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn leading_zeros(self) -> u32 {
            unsafe { intrinsics::ctlz(self as $ActualT) as u32 }
        }

        /// Returns the number of trailing zeros in the binary representation
        /// of `self`.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let n = 0b0101000u16;
        ///
        /// assert_eq!(n.trailing_zeros(), 3);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn trailing_zeros(self) -> u32 {
            // As of LLVM 3.6 the codegen for the zero-safe cttz8 intrinsic
            // emits two conditional moves on x86_64. By promoting the value to
            // u16 and setting bit 8, we get better code without any conditional
            // operations.
            // FIXME: There's a LLVM patch (http://reviews.llvm.org/D9284)
            // pending, remove this workaround once LLVM generates better code
            // for cttz8.
            unsafe {
                if $BITS == 8 {
                    intrinsics::cttz(self as u16 | 0x100) as u32
                } else {
                    intrinsics::cttz(self) as u32
                }
            }
        }

        /// Shifts the bits to the left by a specified amount, `n`,
        /// wrapping the truncated bits to the end of the resulting integer.
        ///
        /// Please note this isn't the same operation as `<<`!
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let n = 0x0123456789ABCDEFu64;
        /// let m = 0x3456789ABCDEF012u64;
        ///
        /// assert_eq!(n.rotate_left(12), m);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn rotate_left(self, n: u32) -> Self {
            // Protect against undefined behaviour for over-long bit shifts
            let n = n % $BITS;
            (self << n) | (self >> (($BITS - n) % $BITS))
        }

        /// Shifts the bits to the right by a specified amount, `n`,
        /// wrapping the truncated bits to the beginning of the resulting
        /// integer.
        ///
        /// Please note this isn't the same operation as `>>`!
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let n = 0x0123456789ABCDEFu64;
        /// let m = 0xDEF0123456789ABCu64;
        ///
        /// assert_eq!(n.rotate_right(12), m);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn rotate_right(self, n: u32) -> Self {
            // Protect against undefined behaviour for over-long bit shifts
            let n = n % $BITS;
            (self >> n) | (self << (($BITS - n) % $BITS))
        }

        /// Reverses the byte order of the integer.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let n: u16 = 0b0000000_01010101;
        /// assert_eq!(n, 85);
        ///
        /// let m = n.swap_bytes();
        ///
        /// assert_eq!(m, 0b01010101_00000000);
        /// assert_eq!(m, 21760);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn swap_bytes(self) -> Self {
            unsafe { intrinsics::bswap(self as $ActualT) as Self }
        }

        /// Converts an integer from big endian to the target's endianness.
        ///
        /// On big endian this is a no-op. On little endian the bytes are
        /// swapped.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let n = 0x0123456789ABCDEFu64;
        ///
        /// if cfg!(target_endian = "big") {
        ///     assert_eq!(u64::from_be(n), n)
        /// } else {
        ///     assert_eq!(u64::from_be(n), n.swap_bytes())
        /// }
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn from_be(x: Self) -> Self {
            if cfg!(target_endian = "big") { x } else { x.swap_bytes() }
        }

        /// Converts an integer from little endian to the target's endianness.
        ///
        /// On little endian this is a no-op. On big endian the bytes are
        /// swapped.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let n = 0x0123456789ABCDEFu64;
        ///
        /// if cfg!(target_endian = "little") {
        ///     assert_eq!(u64::from_le(n), n)
        /// } else {
        ///     assert_eq!(u64::from_le(n), n.swap_bytes())
        /// }
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn from_le(x: Self) -> Self {
            if cfg!(target_endian = "little") { x } else { x.swap_bytes() }
        }

        /// Converts `self` to big endian from the target's endianness.
        ///
        /// On big endian this is a no-op. On little endian the bytes are
        /// swapped.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let n = 0x0123456789ABCDEFu64;
        ///
        /// if cfg!(target_endian = "big") {
        ///     assert_eq!(n.to_be(), n)
        /// } else {
        ///     assert_eq!(n.to_be(), n.swap_bytes())
        /// }
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn to_be(self) -> Self { // or not to be?
            if cfg!(target_endian = "big") { self } else { self.swap_bytes() }
        }

        /// Converts `self` to little endian from the target's endianness.
        ///
        /// On little endian this is a no-op. On big endian the bytes are
        /// swapped.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// let n = 0x0123456789ABCDEFu64;
        ///
        /// if cfg!(target_endian = "little") {
        ///     assert_eq!(n.to_le(), n)
        /// } else {
        ///     assert_eq!(n.to_le(), n.swap_bytes())
        /// }
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn to_le(self) -> Self {
            if cfg!(target_endian = "little") { self } else { self.swap_bytes() }
        }

        /// Checked integer addition. Computes `self + rhs`, returning `None`
        /// if overflow occurred.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(5u16.checked_add(65530), Some(65535));
        /// assert_eq!(6u16.checked_add(65530), None);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn checked_add(self, rhs: Self) -> Option<Self> {
            let (a, b) = self.overflowing_add(rhs);
            if b {None} else {Some(a)}
        }

        /// Checked integer subtraction. Computes `self - rhs`, returning
        /// `None` if overflow occurred.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(1u8.checked_sub(1), Some(0));
        /// assert_eq!(0u8.checked_sub(1), None);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn checked_sub(self, rhs: Self) -> Option<Self> {
            let (a, b) = self.overflowing_sub(rhs);
            if b {None} else {Some(a)}
        }

        /// Checked integer multiplication. Computes `self * rhs`, returning
        /// `None` if overflow occurred.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(5u8.checked_mul(51), Some(255));
        /// assert_eq!(5u8.checked_mul(52), None);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn checked_mul(self, rhs: Self) -> Option<Self> {
            let (a, b) = self.overflowing_mul(rhs);
            if b {None} else {Some(a)}
        }

        /// Checked integer division. Computes `self / rhs`, returning `None`
        /// if `rhs == 0`.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(128u8.checked_div(2), Some(64));
        /// assert_eq!(1u8.checked_div(0), None);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn checked_div(self, rhs: Self) -> Option<Self> {
            match rhs {
                0 => None,
                rhs => Some(unsafe { intrinsics::unchecked_div(self, rhs) }),
            }
        }

        /// Checked integer remainder. Computes `self % rhs`, returning `None`
        /// if `rhs == 0`.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(5u32.checked_rem(2), Some(1));
        /// assert_eq!(5u32.checked_rem(0), None);
        /// ```
        #[stable(feature = "wrapping", since = "1.7.0")]
        #[inline]
        pub fn checked_rem(self, rhs: Self) -> Option<Self> {
            if rhs == 0 {
                None
            } else {
                Some(unsafe { intrinsics::unchecked_rem(self, rhs) })
            }
        }

        /// Checked negation. Computes `-self`, returning `None` unless `self ==
        /// 0`.
        ///
        /// Note that negating any positive integer will overflow.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(0u32.checked_neg(), Some(0));
        /// assert_eq!(1u32.checked_neg(), None);
        /// ```
        #[stable(feature = "wrapping", since = "1.7.0")]
        #[inline]
        pub fn checked_neg(self) -> Option<Self> {
            let (a, b) = self.overflowing_neg();
            if b {None} else {Some(a)}
        }

        /// Checked shift left. Computes `self << rhs`, returning `None`
        /// if `rhs` is larger than or equal to the number of bits in `self`.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(0x10u32.checked_shl(4), Some(0x100));
        /// assert_eq!(0x10u32.checked_shl(33), None);
        /// ```
        #[stable(feature = "wrapping", since = "1.7.0")]
        #[inline]
        pub fn checked_shl(self, rhs: u32) -> Option<Self> {
            let (a, b) = self.overflowing_shl(rhs);
            if b {None} else {Some(a)}
        }

        /// Checked shift right. Computes `self >> rhs`, returning `None`
        /// if `rhs` is larger than or equal to the number of bits in `self`.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(0x10u32.checked_shr(4), Some(0x1));
        /// assert_eq!(0x10u32.checked_shr(33), None);
        /// ```
        #[stable(feature = "wrapping", since = "1.7.0")]
        #[inline]
        pub fn checked_shr(self, rhs: u32) -> Option<Self> {
            let (a, b) = self.overflowing_shr(rhs);
            if b {None} else {Some(a)}
        }

        /// Saturating integer addition. Computes `self + rhs`, saturating at
        /// the numeric bounds instead of overflowing.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(100u8.saturating_add(1), 101);
        /// assert_eq!(200u8.saturating_add(127), 255);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn saturating_add(self, rhs: Self) -> Self {
            match self.checked_add(rhs) {
                Some(x) => x,
                None => Self::max_value(),
            }
        }

        /// Saturating integer subtraction. Computes `self - rhs`, saturating
        /// at the numeric bounds instead of overflowing.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(100u8.saturating_sub(27), 73);
        /// assert_eq!(13u8.saturating_sub(127), 0);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn saturating_sub(self, rhs: Self) -> Self {
            match self.checked_sub(rhs) {
                Some(x) => x,
                None => Self::min_value(),
            }
        }

        /// Saturating integer multiplication. Computes `self * rhs`,
        /// saturating at the numeric bounds instead of overflowing.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// use std::u32;
        ///
        /// assert_eq!(100u32.saturating_mul(127), 12700);
        /// assert_eq!((1u32 << 23).saturating_mul(1 << 23), u32::MAX);
        /// ```
        #[stable(feature = "wrapping", since = "1.7.0")]
        #[inline]
        pub fn saturating_mul(self, rhs: Self) -> Self {
            self.checked_mul(rhs).unwrap_or(Self::max_value())
        }

        /// Wrapping (modular) addition. Computes `self + rhs`,
        /// wrapping around at the boundary of the type.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(200u8.wrapping_add(55), 255);
        /// assert_eq!(200u8.wrapping_add(155), 99);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn wrapping_add(self, rhs: Self) -> Self {
            unsafe {
                intrinsics::overflowing_add(self, rhs)
            }
        }

        /// Wrapping (modular) subtraction. Computes `self - rhs`,
        /// wrapping around at the boundary of the type.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(100u8.wrapping_sub(100), 0);
        /// assert_eq!(100u8.wrapping_sub(155), 201);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn wrapping_sub(self, rhs: Self) -> Self {
            unsafe {
                intrinsics::overflowing_sub(self, rhs)
            }
        }

        /// Wrapping (modular) multiplication. Computes `self *
        /// rhs`, wrapping around at the boundary of the type.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(10u8.wrapping_mul(12), 120);
        /// assert_eq!(25u8.wrapping_mul(12), 44);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn wrapping_mul(self, rhs: Self) -> Self {
            unsafe {
                intrinsics::overflowing_mul(self, rhs)
            }
        }

        /// Wrapping (modular) division. Computes `self / rhs`.
        /// Wrapped division on unsigned types is just normal division.
        /// There's no way wrapping could ever happen.
        /// This function exists, so that all operations
        /// are accounted for in the wrapping operations.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(100u8.wrapping_div(10), 10);
        /// ```
        #[stable(feature = "num_wrapping", since = "1.2.0")]
        #[inline]
        pub fn wrapping_div(self, rhs: Self) -> Self {
            self / rhs
        }

        /// Wrapping (modular) remainder. Computes `self % rhs`.
        /// Wrapped remainder calculation on unsigned types is
        /// just the regular remainder calculation.
        /// There's no way wrapping could ever happen.
        /// This function exists, so that all operations
        /// are accounted for in the wrapping operations.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(100u8.wrapping_rem(10), 0);
        /// ```
        #[stable(feature = "num_wrapping", since = "1.2.0")]
        #[inline]
        pub fn wrapping_rem(self, rhs: Self) -> Self {
            self % rhs
        }

        /// Wrapping (modular) negation. Computes `-self`,
        /// wrapping around at the boundary of the type.
        ///
        /// Since unsigned types do not have negative equivalents
        /// all applications of this function will wrap (except for `-0`).
        /// For values smaller than the corresponding signed type's maximum
        /// the result is the same as casting the corresponding signed value.
        /// Any larger values are equivalent to `MAX + 1 - (val - MAX - 1)` where
        /// `MAX` is the corresponding signed type's maximum.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(100u8.wrapping_neg(), 156);
        /// assert_eq!(0u8.wrapping_neg(), 0);
        /// assert_eq!(180u8.wrapping_neg(), 76);
        /// assert_eq!(180u8.wrapping_neg(), (127 + 1) - (180u8 - (127 + 1)));
        /// ```
        #[stable(feature = "num_wrapping", since = "1.2.0")]
        #[inline]
        pub fn wrapping_neg(self) -> Self {
            self.overflowing_neg().0
        }

        /// Panic-free bitwise shift-left; yields `self << mask(rhs)`,
        /// where `mask` removes any high-order bits of `rhs` that
        /// would cause the shift to exceed the bitwidth of the type.
        ///
        /// Note that this is *not* the same as a rotate-left; the
        /// RHS of a wrapping shift-left is restricted to the range
        /// of the type, rather than the bits shifted out of the LHS
        /// being returned to the other end. The primitive integer
        /// types all implement a `rotate_left` function, which may
        /// be what you want instead.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(1u8.wrapping_shl(7), 128);
        /// assert_eq!(1u8.wrapping_shl(8), 1);
        /// ```
        #[stable(feature = "num_wrapping", since = "1.2.0")]
        #[inline]
        pub fn wrapping_shl(self, rhs: u32) -> Self {
            unsafe {
                intrinsics::unchecked_shl(self, (rhs & ($BITS - 1)) as $SelfT)
            }
        }

        /// Panic-free bitwise shift-right; yields `self >> mask(rhs)`,
        /// where `mask` removes any high-order bits of `rhs` that
        /// would cause the shift to exceed the bitwidth of the type.
        ///
        /// Note that this is *not* the same as a rotate-right; the
        /// RHS of a wrapping shift-right is restricted to the range
        /// of the type, rather than the bits shifted out of the LHS
        /// being returned to the other end. The primitive integer
        /// types all implement a `rotate_right` function, which may
        /// be what you want instead.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(128u8.wrapping_shr(7), 1);
        /// assert_eq!(128u8.wrapping_shr(8), 128);
        /// ```
        #[stable(feature = "num_wrapping", since = "1.2.0")]
        #[inline]
        pub fn wrapping_shr(self, rhs: u32) -> Self {
            unsafe {
                intrinsics::unchecked_shr(self, (rhs & ($BITS - 1)) as $SelfT)
            }
        }

        /// Calculates `self` + `rhs`
        ///
        /// Returns a tuple of the addition along with a boolean indicating
        /// whether an arithmetic overflow would occur. If an overflow would
        /// have occurred then the wrapped value is returned.
        ///
        /// # Examples
        ///
        /// Basic usage
        ///
        /// ```
        /// use std::u32;
        ///
        /// assert_eq!(5u32.overflowing_add(2), (7, false));
        /// assert_eq!(u32::MAX.overflowing_add(1), (0, true));
        /// ```
        #[inline]
        #[stable(feature = "wrapping", since = "1.7.0")]
        pub fn overflowing_add(self, rhs: Self) -> (Self, bool) {
            let (a, b) = unsafe {
                intrinsics::add_with_overflow(self as $ActualT,
                                              rhs as $ActualT)
            };
            (a as Self, b)
        }

        /// Calculates `self` - `rhs`
        ///
        /// Returns a tuple of the subtraction along with a boolean indicating
        /// whether an arithmetic overflow would occur. If an overflow would
        /// have occurred then the wrapped value is returned.
        ///
        /// # Examples
        ///
        /// Basic usage
        ///
        /// ```
        /// use std::u32;
        ///
        /// assert_eq!(5u32.overflowing_sub(2), (3, false));
        /// assert_eq!(0u32.overflowing_sub(1), (u32::MAX, true));
        /// ```
        #[inline]
        #[stable(feature = "wrapping", since = "1.7.0")]
        pub fn overflowing_sub(self, rhs: Self) -> (Self, bool) {
            let (a, b) = unsafe {
                intrinsics::sub_with_overflow(self as $ActualT,
                                              rhs as $ActualT)
            };
            (a as Self, b)
        }

        /// Calculates the multiplication of `self` and `rhs`.
        ///
        /// Returns a tuple of the multiplication along with a boolean
        /// indicating whether an arithmetic overflow would occur. If an
        /// overflow would have occurred then the wrapped value is returned.
        ///
        /// # Examples
        ///
        /// Basic usage
        ///
        /// ```
        /// assert_eq!(5u32.overflowing_mul(2), (10, false));
        /// assert_eq!(1_000_000_000u32.overflowing_mul(10), (1410065408, true));
        /// ```
        #[inline]
        #[stable(feature = "wrapping", since = "1.7.0")]
        pub fn overflowing_mul(self, rhs: Self) -> (Self, bool) {
            let (a, b) = unsafe {
                intrinsics::mul_with_overflow(self as $ActualT,
                                              rhs as $ActualT)
            };
            (a as Self, b)
        }

        /// Calculates the divisor when `self` is divided by `rhs`.
        ///
        /// Returns a tuple of the divisor along with a boolean indicating
        /// whether an arithmetic overflow would occur. Note that for unsigned
        /// integers overflow never occurs, so the second value is always
        /// `false`.
        ///
        /// # Panics
        ///
        /// This function will panic if `rhs` is 0.
        ///
        /// # Examples
        ///
        /// Basic usage
        ///
        /// ```
        /// assert_eq!(5u32.overflowing_div(2), (2, false));
        /// ```
        #[inline]
        #[stable(feature = "wrapping", since = "1.7.0")]
        pub fn overflowing_div(self, rhs: Self) -> (Self, bool) {
            (self / rhs, false)
        }

        /// Calculates the remainder when `self` is divided by `rhs`.
        ///
        /// Returns a tuple of the remainder after dividing along with a boolean
        /// indicating whether an arithmetic overflow would occur. Note that for
        /// unsigned integers overflow never occurs, so the second value is
        /// always `false`.
        ///
        /// # Panics
        ///
        /// This function will panic if `rhs` is 0.
        ///
        /// # Examples
        ///
        /// Basic usage
        ///
        /// ```
        /// assert_eq!(5u32.overflowing_rem(2), (1, false));
        /// ```
        #[inline]
        #[stable(feature = "wrapping", since = "1.7.0")]
        pub fn overflowing_rem(self, rhs: Self) -> (Self, bool) {
            (self % rhs, false)
        }

        /// Negates self in an overflowing fashion.
        ///
        /// Returns `!self + 1` using wrapping operations to return the value
        /// that represents the negation of this unsigned value. Note that for
        /// positive unsigned values overflow always occurs, but negating 0 does
        /// not overflow.
        ///
        /// # Examples
        ///
        /// Basic usage
        ///
        /// ```
        /// assert_eq!(0u32.overflowing_neg(), (0, false));
        /// assert_eq!(2u32.overflowing_neg(), (-2i32 as u32, true));
        /// ```
        #[inline]
        #[stable(feature = "wrapping", since = "1.7.0")]
        pub fn overflowing_neg(self) -> (Self, bool) {
            ((!self).wrapping_add(1), self != 0)
        }

        /// Shifts self left by `rhs` bits.
        ///
        /// Returns a tuple of the shifted version of self along with a boolean
        /// indicating whether the shift value was larger than or equal to the
        /// number of bits. If the shift value is too large, then value is
        /// masked (N-1) where N is the number of bits, and this value is then
        /// used to perform the shift.
        ///
        /// # Examples
        ///
        /// Basic usage
        ///
        /// ```
        /// assert_eq!(0x10u32.overflowing_shl(4), (0x100, false));
        /// assert_eq!(0x10u32.overflowing_shl(36), (0x100, true));
        /// ```
        #[inline]
        #[stable(feature = "wrapping", since = "1.7.0")]
        pub fn overflowing_shl(self, rhs: u32) -> (Self, bool) {
            (self.wrapping_shl(rhs), (rhs > ($BITS - 1)))
        }

        /// Shifts self right by `rhs` bits.
        ///
        /// Returns a tuple of the shifted version of self along with a boolean
        /// indicating whether the shift value was larger than or equal to the
        /// number of bits. If the shift value is too large, then value is
        /// masked (N-1) where N is the number of bits, and this value is then
        /// used to perform the shift.
        ///
        /// # Examples
        ///
        /// Basic usage
        ///
        /// ```
        /// assert_eq!(0x10u32.overflowing_shr(4), (0x1, false));
        /// assert_eq!(0x10u32.overflowing_shr(36), (0x1, true));
        /// ```
        #[inline]
        #[stable(feature = "wrapping", since = "1.7.0")]
        pub fn overflowing_shr(self, rhs: u32) -> (Self, bool) {
            (self.wrapping_shr(rhs), (rhs > ($BITS - 1)))

        }

        /// Raises self to the power of `exp`, using exponentiation by squaring.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(2u32.pow(4), 16);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        #[rustc_inherit_overflow_checks]
        pub fn pow(self, mut exp: u32) -> Self {
            let mut base = self;
            let mut acc = 1;

            while exp > 1 {
                if (exp & 1) == 1 {
                    acc = acc * base;
                }
                exp /= 2;
                base = base * base;
            }

            // Deal with the final bit of the exponent separately, since
            // squaring the base afterwards is not necessary and may cause a
            // needless overflow.
            if exp == 1 {
                acc = acc * base;
            }

            acc
        }

        /// Returns `true` if and only if `self == 2^k` for some `k`.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert!(16u8.is_power_of_two());
        /// assert!(!10u8.is_power_of_two());
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn is_power_of_two(self) -> bool {
            (self.wrapping_sub(1)) & self == 0 && !(self == 0)
        }

        // Returns one less than next power of two.
        // (For 8u8 next power of two is 8u8 and for 6u8 it is 8u8)
        //
        // 8u8.one_less_than_next_power_of_two() == 7
        // 6u8.one_less_than_next_power_of_two() == 7
        //
        // This method cannot overflow, as in the `next_power_of_two`
        // overflow cases it instead ends up returning the maximum value
        // of the type, and can return 0 for 0.
        #[inline]
        fn one_less_than_next_power_of_two(self) -> Self {
            if self <= 1 { return 0; }

            // Because `p > 0`, it cannot consist entirely of leading zeros.
            // That means the shift is always in-bounds, and some processors
            // (such as intel pre-haswell) have more efficient ctlz
            // intrinsics when the argument is non-zero.
            let p = self - 1;
            let z = unsafe { intrinsics::ctlz_nonzero(p) };
            <$SelfT>::max_value() >> z
        }

        /// Returns the smallest power of two greater than or equal to `self`.
        ///
        /// When return value overflows (i.e. `self > (1 << (N-1))` for type
        /// `uN`), it panics in debug mode and return value is wrapped to 0 in
        /// release mode (the only situation in which method can return 0).
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(2u8.next_power_of_two(), 2);
        /// assert_eq!(3u8.next_power_of_two(), 4);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        #[inline]
        pub fn next_power_of_two(self) -> Self {
            // Call the trait to get overflow checks
            ops::Add::add(self.one_less_than_next_power_of_two(), 1)
        }

        /// Returns the smallest power of two greater than or equal to `n`. If
        /// the next power of two is greater than the type's maximum value,
        /// `None` is returned, otherwise the power of two is wrapped in `Some`.
        ///
        /// # Examples
        ///
        /// Basic usage:
        ///
        /// ```
        /// assert_eq!(2u8.checked_next_power_of_two(), Some(2));
        /// assert_eq!(3u8.checked_next_power_of_two(), Some(4));
        /// assert_eq!(200u8.checked_next_power_of_two(), None);
        /// ```
        #[stable(feature = "rust1", since = "1.0.0")]
        pub fn checked_next_power_of_two(self) -> Option<Self> {
            self.one_less_than_next_power_of_two().checked_add(1)
        }
    }
}

#[lang = "u8"]
impl u8 {
    uint_impl! { u8, u8, 8 }


    /// Checks if the value is within the ASCII range.
    ///
    /// # Examples
    ///
    /// ```
    /// let ascii = 97u8;
    /// let non_ascii = 150u8;
    ///
    /// assert!(ascii.is_ascii());
    /// assert!(!non_ascii.is_ascii());
    /// ```
    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
    #[inline]
    pub fn is_ascii(&self) -> bool {
        *self & 128 == 0
    }

    /// Makes a copy of the value in its ASCII upper case equivalent.
    ///
    /// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z',
    /// but non-ASCII letters are unchanged.
    ///
    /// To uppercase the value in-place, use [`make_ascii_uppercase`].
    ///
    /// # Examples
    ///
    /// ```
    /// let lowercase_a = 97u8;
    ///
    /// assert_eq!(65, lowercase_a.to_ascii_uppercase());
    /// ```
    ///
    /// [`make_ascii_uppercase`]: #method.make_ascii_uppercase
    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
    #[inline]
    pub fn to_ascii_uppercase(&self) -> u8 {
        ASCII_UPPERCASE_MAP[*self as usize]
    }

    /// Makes a copy of the value in its ASCII lower case equivalent.
    ///
    /// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z',
    /// but non-ASCII letters are unchanged.
    ///
    /// To lowercase the value in-place, use [`make_ascii_lowercase`].
    ///
    /// # Examples
    ///
    /// ```
    /// let uppercase_a = 65u8;
    ///
    /// assert_eq!(97, uppercase_a.to_ascii_lowercase());
    /// ```
    ///
    /// [`make_ascii_lowercase`]: #method.make_ascii_lowercase
    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
    #[inline]
    pub fn to_ascii_lowercase(&self) -> u8 {
        ASCII_LOWERCASE_MAP[*self as usize]
    }

    /// Checks that two values are an ASCII case-insensitive match.
    ///
    /// This is equivalent to `to_ascii_lowercase(a) == to_ascii_lowercase(b)`.
    ///
    /// # Examples
    ///
    /// ```
    /// let lowercase_a = 97u8;
    /// let uppercase_a = 65u8;
    ///
    /// assert!(lowercase_a.eq_ignore_ascii_case(&uppercase_a));
    /// ```
    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
    #[inline]
    pub fn eq_ignore_ascii_case(&self, other: &u8) -> bool {
        self.to_ascii_lowercase() == other.to_ascii_lowercase()
    }

    /// Converts this value to its ASCII upper case equivalent in-place.
    ///
    /// ASCII letters 'a' to 'z' are mapped to 'A' to 'Z',
    /// but non-ASCII letters are unchanged.
    ///
    /// To return a new uppercased value without modifying the existing one, use
    /// [`to_ascii_uppercase`].
    ///
    /// # Examples
    ///
    /// ```
    /// let mut byte = b'a';
    ///
    /// byte.make_ascii_uppercase();
    ///
    /// assert_eq!(b'A', byte);
    /// ```
    ///
    /// [`to_ascii_uppercase`]: #method.to_ascii_uppercase
    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
    #[inline]
    pub fn make_ascii_uppercase(&mut self) {
        *self = self.to_ascii_uppercase();
    }

    /// Converts this value to its ASCII lower case equivalent in-place.
    ///
    /// ASCII letters 'A' to 'Z' are mapped to 'a' to 'z',
    /// but non-ASCII letters are unchanged.
    ///
    /// To return a new lowercased value without modifying the existing one, use
    /// [`to_ascii_lowercase`].
    ///
    /// # Examples
    ///
    /// ```
    /// let mut byte = b'A';
    ///
    /// byte.make_ascii_lowercase();
    ///
    /// assert_eq!(b'a', byte);
    /// ```
    ///
    /// [`to_ascii_lowercase`]: #method.to_ascii_lowercase
    #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
    #[inline]
    pub fn make_ascii_lowercase(&mut self) {
        *self = self.to_ascii_lowercase();
    }

    /// Checks if the value is an ASCII alphabetic character:
    ///
    /// - U+0041 'A' ... U+005A 'Z', or
    /// - U+0061 'a' ... U+007A 'z'.
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ascii_ctype)]
    ///
    /// let uppercase_a = b'A';
    /// let uppercase_g = b'G';
    /// let a = b'a';
    /// let g = b'g';
    /// let zero = b'0';
    /// let percent = b'%';
    /// let space = b' ';
    /// let lf = b'\n';
    /// let esc = 0x1b_u8;
    ///
    /// assert!(uppercase_a.is_ascii_alphabetic());
    /// assert!(uppercase_g.is_ascii_alphabetic());
    /// assert!(a.is_ascii_alphabetic());
    /// assert!(g.is_ascii_alphabetic());
    /// assert!(!zero.is_ascii_alphabetic());
    /// assert!(!percent.is_ascii_alphabetic());
    /// assert!(!space.is_ascii_alphabetic());
    /// assert!(!lf.is_ascii_alphabetic());
    /// assert!(!esc.is_ascii_alphabetic());
    /// ```
    #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
    #[inline]
    pub fn is_ascii_alphabetic(&self) -> bool {
        if *self >= 0x80 { return false; }
        match ASCII_CHARACTER_CLASS[*self as usize] {
            L | Lx | U | Ux => true,
            _ => false
        }
    }

    /// Checks if the value is an ASCII uppercase character:
    /// U+0041 'A' ... U+005A 'Z'.
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ascii_ctype)]
    ///
    /// let uppercase_a = b'A';
    /// let uppercase_g = b'G';
    /// let a = b'a';
    /// let g = b'g';
    /// let zero = b'0';
    /// let percent = b'%';
    /// let space = b' ';
    /// let lf = b'\n';
    /// let esc = 0x1b_u8;
    ///
    /// assert!(uppercase_a.is_ascii_uppercase());
    /// assert!(uppercase_g.is_ascii_uppercase());
    /// assert!(!a.is_ascii_uppercase());
    /// assert!(!g.is_ascii_uppercase());
    /// assert!(!zero.is_ascii_uppercase());
    /// assert!(!percent.is_ascii_uppercase());
    /// assert!(!space.is_ascii_uppercase());
    /// assert!(!lf.is_ascii_uppercase());
    /// assert!(!esc.is_ascii_uppercase());
    /// ```
    #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
    #[inline]
    pub fn is_ascii_uppercase(&self) -> bool {
        if *self >= 0x80 { return false }
        match ASCII_CHARACTER_CLASS[*self as usize] {
            U | Ux => true,
            _ => false
        }
    }

    /// Checks if the value is an ASCII lowercase character:
    /// U+0061 'a' ... U+007A 'z'.
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ascii_ctype)]
    ///
    /// let uppercase_a = b'A';
    /// let uppercase_g = b'G';
    /// let a = b'a';
    /// let g = b'g';
    /// let zero = b'0';
    /// let percent = b'%';
    /// let space = b' ';
    /// let lf = b'\n';
    /// let esc = 0x1b_u8;
    ///
    /// assert!(!uppercase_a.is_ascii_lowercase());
    /// assert!(!uppercase_g.is_ascii_lowercase());
    /// assert!(a.is_ascii_lowercase());
    /// assert!(g.is_ascii_lowercase());
    /// assert!(!zero.is_ascii_lowercase());
    /// assert!(!percent.is_ascii_lowercase());
    /// assert!(!space.is_ascii_lowercase());
    /// assert!(!lf.is_ascii_lowercase());
    /// assert!(!esc.is_ascii_lowercase());
    /// ```
    #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
    #[inline]
    pub fn is_ascii_lowercase(&self) -> bool {
        if *self >= 0x80 { return false }
        match ASCII_CHARACTER_CLASS[*self as usize] {
            L | Lx => true,
            _ => false
        }
    }

    /// Checks if the value is an ASCII alphanumeric character:
    ///
    /// - U+0041 'A' ... U+005A 'Z', or
    /// - U+0061 'a' ... U+007A 'z', or
    /// - U+0030 '0' ... U+0039 '9'.
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ascii_ctype)]
    ///
    /// let uppercase_a = b'A';
    /// let uppercase_g = b'G';
    /// let a = b'a';
    /// let g = b'g';
    /// let zero = b'0';
    /// let percent = b'%';
    /// let space = b' ';
    /// let lf = b'\n';
    /// let esc = 0x1b_u8;
    ///
    /// assert!(uppercase_a.is_ascii_alphanumeric());
    /// assert!(uppercase_g.is_ascii_alphanumeric());
    /// assert!(a.is_ascii_alphanumeric());
    /// assert!(g.is_ascii_alphanumeric());
    /// assert!(zero.is_ascii_alphanumeric());
    /// assert!(!percent.is_ascii_alphanumeric());
    /// assert!(!space.is_ascii_alphanumeric());
    /// assert!(!lf.is_ascii_alphanumeric());
    /// assert!(!esc.is_ascii_alphanumeric());
    /// ```
    #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
    #[inline]
    pub fn is_ascii_alphanumeric(&self) -> bool {
        if *self >= 0x80 { return false }
        match ASCII_CHARACTER_CLASS[*self as usize] {
            D | L | Lx | U | Ux => true,
            _ => false
        }
    }

    /// Checks if the value is an ASCII decimal digit:
    /// U+0030 '0' ... U+0039 '9'.
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ascii_ctype)]
    ///
    /// let uppercase_a = b'A';
    /// let uppercase_g = b'G';
    /// let a = b'a';
    /// let g = b'g';
    /// let zero = b'0';
    /// let percent = b'%';
    /// let space = b' ';
    /// let lf = b'\n';
    /// let esc = 0x1b_u8;
    ///
    /// assert!(!uppercase_a.is_ascii_digit());
    /// assert!(!uppercase_g.is_ascii_digit());
    /// assert!(!a.is_ascii_digit());
    /// assert!(!g.is_ascii_digit());
    /// assert!(zero.is_ascii_digit());
    /// assert!(!percent.is_ascii_digit());
    /// assert!(!space.is_ascii_digit());
    /// assert!(!lf.is_ascii_digit());
    /// assert!(!esc.is_ascii_digit());
    /// ```
    #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
    #[inline]
    pub fn is_ascii_digit(&self) -> bool {
        if *self >= 0x80 { return false }
        match ASCII_CHARACTER_CLASS[*self as usize] {
            D => true,
            _ => false
        }
    }

    /// Checks if the value is an ASCII hexadecimal digit:
    ///
    /// - U+0030 '0' ... U+0039 '9', or
    /// - U+0041 'A' ... U+0046 'F', or
    /// - U+0061 'a' ... U+0066 'f'.
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ascii_ctype)]
    ///
    /// let uppercase_a = b'A';
    /// let uppercase_g = b'G';
    /// let a = b'a';
    /// let g = b'g';
    /// let zero = b'0';
    /// let percent = b'%';
    /// let space = b' ';
    /// let lf = b'\n';
    /// let esc = 0x1b_u8;
    ///
    /// assert!(uppercase_a.is_ascii_hexdigit());
    /// assert!(!uppercase_g.is_ascii_hexdigit());
    /// assert!(a.is_ascii_hexdigit());
    /// assert!(!g.is_ascii_hexdigit());
    /// assert!(zero.is_ascii_hexdigit());
    /// assert!(!percent.is_ascii_hexdigit());
    /// assert!(!space.is_ascii_hexdigit());
    /// assert!(!lf.is_ascii_hexdigit());
    /// assert!(!esc.is_ascii_hexdigit());
    /// ```
    #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
    #[inline]
    pub fn is_ascii_hexdigit(&self) -> bool {
        if *self >= 0x80 { return false }
        match ASCII_CHARACTER_CLASS[*self as usize] {
            D | Lx | Ux => true,
            _ => false
        }
    }

    /// Checks if the value is an ASCII punctuation character:
    ///
    /// - U+0021 ... U+002F `! " # $ % & ' ( ) * + , - . /`, or
    /// - U+003A ... U+0040 `: ; < = > ? @`, or
    /// - U+005B ... U+0060 ``[ \ ] ^ _ ` ``, or
    /// - U+007B ... U+007E `{ | } ~`
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ascii_ctype)]
    ///
    /// let uppercase_a = b'A';
    /// let uppercase_g = b'G';
    /// let a = b'a';
    /// let g = b'g';
    /// let zero = b'0';
    /// let percent = b'%';
    /// let space = b' ';
    /// let lf = b'\n';
    /// let esc = 0x1b_u8;
    ///
    /// assert!(!uppercase_a.is_ascii_punctuation());
    /// assert!(!uppercase_g.is_ascii_punctuation());
    /// assert!(!a.is_ascii_punctuation());
    /// assert!(!g.is_ascii_punctuation());
    /// assert!(!zero.is_ascii_punctuation());
    /// assert!(percent.is_ascii_punctuation());
    /// assert!(!space.is_ascii_punctuation());
    /// assert!(!lf.is_ascii_punctuation());
    /// assert!(!esc.is_ascii_punctuation());
    /// ```
    #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
    #[inline]
    pub fn is_ascii_punctuation(&self) -> bool {
        if *self >= 0x80 { return false }
        match ASCII_CHARACTER_CLASS[*self as usize] {
            P => true,
            _ => false
        }
    }

    /// Checks if the value is an ASCII graphic character:
    /// U+0021 '@' ... U+007E '~'.
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ascii_ctype)]
    ///
    /// let uppercase_a = b'A';
    /// let uppercase_g = b'G';
    /// let a = b'a';
    /// let g = b'g';
    /// let zero = b'0';
    /// let percent = b'%';
    /// let space = b' ';
    /// let lf = b'\n';
    /// let esc = 0x1b_u8;
    ///
    /// assert!(uppercase_a.is_ascii_graphic());
    /// assert!(uppercase_g.is_ascii_graphic());
    /// assert!(a.is_ascii_graphic());
    /// assert!(g.is_ascii_graphic());
    /// assert!(zero.is_ascii_graphic());
    /// assert!(percent.is_ascii_graphic());
    /// assert!(!space.is_ascii_graphic());
    /// assert!(!lf.is_ascii_graphic());
    /// assert!(!esc.is_ascii_graphic());
    /// ```
    #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
    #[inline]
    pub fn is_ascii_graphic(&self) -> bool {
        if *self >= 0x80 { return false; }
        match ASCII_CHARACTER_CLASS[*self as usize] {
            Ux | U | Lx | L | D | P => true,
            _ => false
        }
    }

    /// Checks if the value is an ASCII whitespace character:
    /// U+0020 SPACE, U+0009 HORIZONTAL TAB, U+000A LINE FEED,
    /// U+000C FORM FEED, or U+000D CARRIAGE RETURN.
    ///
    /// Rust uses the WhatWG Infra Standard's [definition of ASCII
    /// whitespace][infra-aw]. There are several other definitions in
    /// wide use. For instance, [the POSIX locale][pct] includes
    /// U+000B VERTICAL TAB as well as all the above characters,
    /// but—from the very same specification—[the default rule for
    /// "field splitting" in the Bourne shell][bfs] considers *only*
    /// SPACE, HORIZONTAL TAB, and LINE FEED as whitespace.
    ///
    /// If you are writing a program that will process an existing
    /// file format, check what that format's definition of whitespace is
    /// before using this function.
    ///
    /// [infra-aw]: https://infra.spec.whatwg.org/#ascii-whitespace
    /// [pct]: http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap07.html#tag_07_03_01
    /// [bfs]: http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_05
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ascii_ctype)]
    ///
    /// let uppercase_a = b'A';
    /// let uppercase_g = b'G';
    /// let a = b'a';
    /// let g = b'g';
    /// let zero = b'0';
    /// let percent = b'%';
    /// let space = b' ';
    /// let lf = b'\n';
    /// let esc = 0x1b_u8;
    ///
    /// assert!(!uppercase_a.is_ascii_whitespace());
    /// assert!(!uppercase_g.is_ascii_whitespace());
    /// assert!(!a.is_ascii_whitespace());
    /// assert!(!g.is_ascii_whitespace());
    /// assert!(!zero.is_ascii_whitespace());
    /// assert!(!percent.is_ascii_whitespace());
    /// assert!(space.is_ascii_whitespace());
    /// assert!(lf.is_ascii_whitespace());
    /// assert!(!esc.is_ascii_whitespace());
    /// ```
    #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
    #[inline]
    pub fn is_ascii_whitespace(&self) -> bool {
        if *self >= 0x80 { return false; }
        match ASCII_CHARACTER_CLASS[*self as usize] {
            Cw | W => true,
            _ => false
        }
    }

    /// Checks if the value is an ASCII control character:
    /// U+0000 NUL ... U+001F UNIT SEPARATOR, or U+007F DELETE.
    /// Note that most ASCII whitespace characters are control
    /// characters, but SPACE is not.
    ///
    /// # Examples
    ///
    /// ```
    /// #![feature(ascii_ctype)]
    ///
    /// let uppercase_a = b'A';
    /// let uppercase_g = b'G';
    /// let a = b'a';
    /// let g = b'g';
    /// let zero = b'0';
    /// let percent = b'%';
    /// let space = b' ';
    /// let lf = b'\n';
    /// let esc = 0x1b_u8;
    ///
    /// assert!(!uppercase_a.is_ascii_control());
    /// assert!(!uppercase_g.is_ascii_control());
    /// assert!(!a.is_ascii_control());
    /// assert!(!g.is_ascii_control());
    /// assert!(!zero.is_ascii_control());
    /// assert!(!percent.is_ascii_control());
    /// assert!(!space.is_ascii_control());
    /// assert!(lf.is_ascii_control());
    /// assert!(esc.is_ascii_control());
    /// ```
    #[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
    #[inline]
    pub fn is_ascii_control(&self) -> bool {
        if *self >= 0x80 { return false; }
        match ASCII_CHARACTER_CLASS[*self as usize] {
            C | Cw => true,
            _ => false
        }
    }
}

#[lang = "u16"]
impl u16 {
    uint_impl! { u16, u16, 16 }
}

#[lang = "u32"]
impl u32 {
    uint_impl! { u32, u32, 32 }
}

#[lang = "u64"]
impl u64 {
    uint_impl! { u64, u64, 64 }
}

#[lang = "u128"]
impl u128 {
    uint_impl! { u128, u128, 128 }
}

#[cfg(target_pointer_width = "16")]
#[lang = "usize"]
impl usize {
    uint_impl! { usize, u16, 16 }
}
#[cfg(target_pointer_width = "32")]
#[lang = "usize"]
impl usize {
    uint_impl! { usize, u32, 32 }
}

#[cfg(target_pointer_width = "64")]
#[lang = "usize"]
impl usize {
    uint_impl! { usize, u64, 64 }
}

/// A classification of floating point numbers.
///
/// This `enum` is used as the return type for [`f32::classify`] and [`f64::classify`]. See
/// their documentation for more.
///
/// [`f32::classify`]: ../../std/primitive.f32.html#method.classify
/// [`f64::classify`]: ../../std/primitive.f64.html#method.classify
///
/// # Examples
///
/// ```
/// use std::num::FpCategory;
/// use std::f32;
///
/// let num = 12.4_f32;
/// let inf = f32::INFINITY;
/// let zero = 0f32;
/// let sub: f32 = 1.1754942e-38;
/// let nan = f32::NAN;
///
/// assert_eq!(num.classify(), FpCategory::Normal);
/// assert_eq!(inf.classify(), FpCategory::Infinite);
/// assert_eq!(zero.classify(), FpCategory::Zero);
/// assert_eq!(nan.classify(), FpCategory::Nan);
/// assert_eq!(sub.classify(), FpCategory::Subnormal);
/// ```
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
#[stable(feature = "rust1", since = "1.0.0")]
pub enum FpCategory {
    /// "Not a Number", often obtained by dividing by zero.
    #[stable(feature = "rust1", since = "1.0.0")]
    Nan,

    /// Positive or negative infinity.
    #[stable(feature = "rust1", since = "1.0.0")]
    Infinite,

    /// Positive or negative zero.
    #[stable(feature = "rust1", since = "1.0.0")]
    Zero,

    /// De-normalized floating point representation (less precise than `Normal`).
    #[stable(feature = "rust1", since = "1.0.0")]
    Subnormal,

    /// A regular floating point number.
    #[stable(feature = "rust1", since = "1.0.0")]
    Normal,
}

/// A built-in floating point number.
#[doc(hidden)]
#[unstable(feature = "core_float",
           reason = "stable interface is via `impl f{32,64}` in later crates",
           issue = "32110")]
pub trait Float: Sized {
    /// Type used by `to_bits` and `from_bits`.
    #[stable(feature = "core_float_bits", since = "1.24.0")]
    type Bits;

    /// Returns `true` if this value is NaN and false otherwise.
    #[stable(feature = "core", since = "1.6.0")]
    fn is_nan(self) -> bool;
    /// Returns `true` if this value is positive infinity or negative infinity and
    /// false otherwise.
    #[stable(feature = "core", since = "1.6.0")]
    fn is_infinite(self) -> bool;
    /// Returns `true` if this number is neither infinite nor NaN.
    #[stable(feature = "core", since = "1.6.0")]
    fn is_finite(self) -> bool;
    /// Returns `true` if this number is neither zero, infinite, denormal, or NaN.
    #[stable(feature = "core", since = "1.6.0")]
    fn is_normal(self) -> bool;
    /// Returns the category that this number falls into.
    #[stable(feature = "core", since = "1.6.0")]
    fn classify(self) -> FpCategory;

    /// Computes the absolute value of `self`. Returns `Float::nan()` if the
    /// number is `Float::nan()`.
    #[stable(feature = "core", since = "1.6.0")]
    fn abs(self) -> Self;
    /// Returns a number that represents the sign of `self`.
    ///
    /// - `1.0` if the number is positive, `+0.0` or `Float::infinity()`
    /// - `-1.0` if the number is negative, `-0.0` or `Float::neg_infinity()`
    /// - `Float::nan()` if the number is `Float::nan()`
    #[stable(feature = "core", since = "1.6.0")]
    fn signum(self) -> Self;

    /// Returns `true` if `self` is positive, including `+0.0` and
    /// `Float::infinity()`.
    #[stable(feature = "core", since = "1.6.0")]
    fn is_sign_positive(self) -> bool;
    /// Returns `true` if `self` is negative, including `-0.0` and
    /// `Float::neg_infinity()`.
    #[stable(feature = "core", since = "1.6.0")]
    fn is_sign_negative(self) -> bool;

    /// Take the reciprocal (inverse) of a number, `1/x`.
    #[stable(feature = "core", since = "1.6.0")]
    fn recip(self) -> Self;

    /// Raise a number to an integer power.
    ///
    /// Using this function is generally faster than using `powf`
    #[stable(feature = "core", since = "1.6.0")]
    fn powi(self, n: i32) -> Self;

    /// Convert radians to degrees.
    #[stable(feature = "deg_rad_conversions", since="1.7.0")]
    fn to_degrees(self) -> Self;
    /// Convert degrees to radians.
    #[stable(feature = "deg_rad_conversions", since="1.7.0")]
    fn to_radians(self) -> Self;

    /// Returns the maximum of the two numbers.
    #[stable(feature = "core_float_min_max", since="1.20.0")]
    fn max(self, other: Self) -> Self;
    /// Returns the minimum of the two numbers.
    #[stable(feature = "core_float_min_max", since="1.20.0")]
    fn min(self, other: Self) -> Self;

    /// Raw transmutation to integer.
    #[stable(feature = "core_float_bits", since="1.24.0")]
    fn to_bits(self) -> Self::Bits;
    /// Raw transmutation from integer.
    #[stable(feature = "core_float_bits", since="1.24.0")]
    fn from_bits(v: Self::Bits) -> Self;
}

macro_rules! from_str_radix_int_impl {
    ($($t:ty)*) => {$(
        #[stable(feature = "rust1", since = "1.0.0")]
        impl FromStr for $t {
            type Err = ParseIntError;
            fn from_str(src: &str) -> Result<Self, ParseIntError> {
                from_str_radix(src, 10)
            }
        }
    )*}
}
from_str_radix_int_impl! { isize i8 i16 i32 i64 i128 usize u8 u16 u32 u64 u128 }

/// The error type returned when a checked integral type conversion fails.
#[unstable(feature = "try_from", issue = "33417")]
#[derive(Debug, Copy, Clone)]
pub struct TryFromIntError(());

impl TryFromIntError {
    #[unstable(feature = "int_error_internals",
               reason = "available through Error trait and this method should \
                         not be exposed publicly",
               issue = "0")]
    #[doc(hidden)]
    pub fn __description(&self) -> &str {
        "out of range integral type conversion attempted"
    }
}

#[unstable(feature = "try_from", issue = "33417")]
impl fmt::Display for TryFromIntError {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        self.__description().fmt(fmt)
    }
}

#[unstable(feature = "try_from", issue = "33417")]
impl From<Infallible> for TryFromIntError {
    fn from(infallible: Infallible) -> TryFromIntError {
        match infallible {
        }
    }
}

// no possible bounds violation
macro_rules! try_from_unbounded {
    ($source:ty, $($target:ty),*) => {$(
        #[unstable(feature = "try_from", issue = "33417")]
        impl TryFrom<$source> for $target {
            type Error = Infallible;

            #[inline]
            fn try_from(value: $source) -> Result<Self, Self::Error> {
                Ok(value as $target)
            }
        }
    )*}
}

// only negative bounds
macro_rules! try_from_lower_bounded {
    ($source:ty, $($target:ty),*) => {$(
        #[unstable(feature = "try_from", issue = "33417")]
        impl TryFrom<$source> for $target {
            type Error = TryFromIntError;

            #[inline]
            fn try_from(u: $source) -> Result<$target, TryFromIntError> {
                if u >= 0 {
                    Ok(u as $target)
                } else {
                    Err(TryFromIntError(()))
                }
            }
        }
    )*}
}

// unsigned to signed (only positive bound)
macro_rules! try_from_upper_bounded {
    ($source:ty, $($target:ty),*) => {$(
        #[unstable(feature = "try_from", issue = "33417")]
        impl TryFrom<$source> for $target {
            type Error = TryFromIntError;

            #[inline]
            fn try_from(u: $source) -> Result<$target, TryFromIntError> {
                if u > (<$target>::max_value() as $source) {
                    Err(TryFromIntError(()))
                } else {
                    Ok(u as $target)
                }
            }
        }
    )*}
}

// all other cases
macro_rules! try_from_both_bounded {
    ($source:ty, $($target:ty),*) => {$(
        #[unstable(feature = "try_from", issue = "33417")]
        impl TryFrom<$source> for $target {
            type Error = TryFromIntError;

            #[inline]
            fn try_from(u: $source) -> Result<$target, TryFromIntError> {
                let min = <$target>::min_value() as $source;
                let max = <$target>::max_value() as $source;
                if u < min || u > max {
                    Err(TryFromIntError(()))
                } else {
                    Ok(u as $target)
                }
            }
        }
    )*}
}

macro_rules! rev {
    ($mac:ident, $source:ty, $($target:ty),*) => {$(
        $mac!($target, $source);
    )*}
}

/// intra-sign conversions
try_from_upper_bounded!(u16, u8);
try_from_upper_bounded!(u32, u16, u8);
try_from_upper_bounded!(u64, u32, u16, u8);
try_from_upper_bounded!(u128, u64, u32, u16, u8);

try_from_both_bounded!(i16, i8);
try_from_both_bounded!(i32, i16, i8);
try_from_both_bounded!(i64, i32, i16, i8);
try_from_both_bounded!(i128, i64, i32, i16, i8);

// unsigned-to-signed
try_from_upper_bounded!(u8, i8);
try_from_upper_bounded!(u16, i8, i16);
try_from_upper_bounded!(u32, i8, i16, i32);
try_from_upper_bounded!(u64, i8, i16, i32, i64);
try_from_upper_bounded!(u128, i8, i16, i32, i64, i128);

// signed-to-unsigned
try_from_lower_bounded!(i8, u8, u16, u32, u64, u128);
try_from_lower_bounded!(i16, u16, u32, u64, u128);
try_from_lower_bounded!(i32, u32, u64, u128);
try_from_lower_bounded!(i64, u64, u128);
try_from_lower_bounded!(i128, u128);
try_from_both_bounded!(i16, u8);
try_from_both_bounded!(i32, u16, u8);
try_from_both_bounded!(i64, u32, u16, u8);
try_from_both_bounded!(i128, u64, u32, u16, u8);

// usize/isize
try_from_upper_bounded!(usize, isize);
try_from_lower_bounded!(isize, usize);

#[cfg(target_pointer_width = "16")]
mod ptr_try_from_impls {
    use super::TryFromIntError;
    use convert::{Infallible, TryFrom};

    try_from_upper_bounded!(usize, u8);
    try_from_unbounded!(usize, u16, u32, u64, u128);
    try_from_upper_bounded!(usize, i8, i16);
    try_from_unbounded!(usize, i32, i64, i128);

    try_from_both_bounded!(isize, u8);
    try_from_lower_bounded!(isize, u16, u32, u64, u128);
    try_from_both_bounded!(isize, i8);
    try_from_unbounded!(isize, i16, i32, i64, i128);

    rev!(try_from_unbounded, usize, u16);
    rev!(try_from_upper_bounded, usize, u32, u64, u128);
    rev!(try_from_lower_bounded, usize, i8, i16);
    rev!(try_from_both_bounded, usize, i32, i64, i128);

    rev!(try_from_unbounded, isize, u8);
    rev!(try_from_upper_bounded, isize, u16, u32, u64, u128);
    rev!(try_from_unbounded, isize, i16);
    rev!(try_from_both_bounded, isize, i32, i64, i128);
}

#[cfg(target_pointer_width = "32")]
mod ptr_try_from_impls {
    use super::TryFromIntError;
    use convert::{Infallible, TryFrom};

    try_from_upper_bounded!(usize, u8, u16);
    try_from_unbounded!(usize, u32, u64, u128);
    try_from_upper_bounded!(usize, i8, i16, i32);
    try_from_unbounded!(usize, i64, i128);

    try_from_both_bounded!(isize, u8, u16);
    try_from_lower_bounded!(isize, u32, u64, u128);
    try_from_both_bounded!(isize, i8, i16);
    try_from_unbounded!(isize, i32, i64, i128);

    rev!(try_from_unbounded, usize, u16, u32);
    rev!(try_from_upper_bounded, usize, u64, u128);
    rev!(try_from_lower_bounded, usize, i8, i16, i32);
    rev!(try_from_both_bounded, usize, i64, i128);

    rev!(try_from_unbounded, isize, u8, u16);
    rev!(try_from_upper_bounded, isize, u32, u64, u128);
    rev!(try_from_unbounded, isize, i16, i32);
    rev!(try_from_both_bounded, isize, i64, i128);
}

#[cfg(target_pointer_width = "64")]
mod ptr_try_from_impls {
    use super::TryFromIntError;
    use convert::{Infallible, TryFrom};

    try_from_upper_bounded!(usize, u8, u16, u32);
    try_from_unbounded!(usize, u64, u128);
    try_from_upper_bounded!(usize, i8, i16, i32, i64);
    try_from_unbounded!(usize, i128);

    try_from_both_bounded!(isize, u8, u16, u32);
    try_from_lower_bounded!(isize, u64, u128);
    try_from_both_bounded!(isize, i8, i16, i32);
    try_from_unbounded!(isize, i64, i128);

    rev!(try_from_unbounded, usize, u16, u32, u64);
    rev!(try_from_upper_bounded, usize, u128);
    rev!(try_from_lower_bounded, usize, i8, i16, i32, i64);
    rev!(try_from_both_bounded, usize, i128);

    rev!(try_from_unbounded, isize, u8, u16, u32);
    rev!(try_from_upper_bounded, isize, u64, u128);
    rev!(try_from_unbounded, isize, i16, i32, i64);
    rev!(try_from_both_bounded, isize, i128);
}

#[doc(hidden)]
trait FromStrRadixHelper: PartialOrd + Copy {
    fn min_value() -> Self;
    fn max_value() -> Self;
    fn from_u32(u: u32) -> Self;
    fn checked_mul(&self, other: u32) -> Option<Self>;
    fn checked_sub(&self, other: u32) -> Option<Self>;
    fn checked_add(&self, other: u32) -> Option<Self>;
}

macro_rules! doit {
    ($($t:ty)*) => ($(impl FromStrRadixHelper for $t {
        #[inline]
        fn min_value() -> Self { Self::min_value() }
        #[inline]
        fn max_value() -> Self { Self::max_value() }
        #[inline]
        fn from_u32(u: u32) -> Self { u as Self }
        #[inline]
        fn checked_mul(&self, other: u32) -> Option<Self> {
            Self::checked_mul(*self, other as Self)
        }
        #[inline]
        fn checked_sub(&self, other: u32) -> Option<Self> {
            Self::checked_sub(*self, other as Self)
        }
        #[inline]
        fn checked_add(&self, other: u32) -> Option<Self> {
            Self::checked_add(*self, other as Self)
        }
    })*)
}
doit! { i8 i16 i32 i64 i128 isize u8 u16 u32 u64 u128 usize }

fn from_str_radix<T: FromStrRadixHelper>(src: &str, radix: u32) -> Result<T, ParseIntError> {
    use self::IntErrorKind::*;
    use self::ParseIntError as PIE;

    assert!(radix >= 2 && radix <= 36,
           "from_str_radix_int: must lie in the range `[2, 36]` - found {}",
           radix);

    if src.is_empty() {
        return Err(PIE { kind: Empty });
    }

    let is_signed_ty = T::from_u32(0) > T::min_value();

    // all valid digits are ascii, so we will just iterate over the utf8 bytes
    // and cast them to chars. .to_digit() will safely return None for anything
    // other than a valid ascii digit for the given radix, including the first-byte
    // of multi-byte sequences
    let src = src.as_bytes();

    let (is_positive, digits) = match src[0] {
        b'+' => (true, &src[1..]),
        b'-' if is_signed_ty => (false, &src[1..]),
        _ => (true, src),
    };

    if digits.is_empty() {
        return Err(PIE { kind: Empty });
    }

    let mut result = T::from_u32(0);
    if is_positive {
        // The number is positive
        for &c in digits {
            let x = match (c as char).to_digit(radix) {
                Some(x) => x,
                None => return Err(PIE { kind: InvalidDigit }),
            };
            result = match result.checked_mul(radix) {
                Some(result) => result,
                None => return Err(PIE { kind: Overflow }),
            };
            result = match result.checked_add(x) {
                Some(result) => result,
                None => return Err(PIE { kind: Overflow }),
            };
        }
    } else {
        // The number is negative
        for &c in digits {
            let x = match (c as char).to_digit(radix) {
                Some(x) => x,
                None => return Err(PIE { kind: InvalidDigit }),
            };
            result = match result.checked_mul(radix) {
                Some(result) => result,
                None => return Err(PIE { kind: Underflow }),
            };
            result = match result.checked_sub(x) {
                Some(result) => result,
                None => return Err(PIE { kind: Underflow }),
            };
        }
    }
    Ok(result)
}

/// An error which can be returned when parsing an integer.
///
/// This error is used as the error type for the `from_str_radix()` functions
/// on the primitive integer types, such as [`i8::from_str_radix`].
///
/// [`i8::from_str_radix`]: ../../std/primitive.i8.html#method.from_str_radix
#[derive(Debug, Clone, PartialEq, Eq)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct ParseIntError {
    kind: IntErrorKind,
}

#[derive(Debug, Clone, PartialEq, Eq)]
enum IntErrorKind {
    Empty,
    InvalidDigit,
    Overflow,
    Underflow,
}

impl ParseIntError {
    #[unstable(feature = "int_error_internals",
               reason = "available through Error trait and this method should \
                         not be exposed publicly",
               issue = "0")]
    #[doc(hidden)]
    pub fn __description(&self) -> &str {
        match self.kind {
            IntErrorKind::Empty => "cannot parse integer from empty string",
            IntErrorKind::InvalidDigit => "invalid digit found in string",
            IntErrorKind::Overflow => "number too large to fit in target type",
            IntErrorKind::Underflow => "number too small to fit in target type",
        }
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
impl fmt::Display for ParseIntError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        self.__description().fmt(f)
    }
}

#[stable(feature = "rust1", since = "1.0.0")]
pub use num::dec2flt::ParseFloatError;

// Conversion traits for primitive integer and float types
// Conversions T -> T are covered by a blanket impl and therefore excluded
// Some conversions from and to usize/isize are not implemented due to portability concerns
macro_rules! impl_from {
    ($Small: ty, $Large: ty, #[$attr:meta]) => {
        #[$attr]
        impl From<$Small> for $Large {
            #[inline]
            fn from(small: $Small) -> $Large {
                small as $Large
            }
        }
    }
}

// Unsigned -> Unsigned
impl_from! { u8, u16, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
impl_from! { u8, u32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
impl_from! { u8, u64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
impl_from! { u8, u128, #[unstable(feature = "i128", issue = "35118")] }
impl_from! { u8, usize, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
impl_from! { u16, u32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
impl_from! { u16, u64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
impl_from! { u16, u128, #[unstable(feature = "i128", issue = "35118")] }
impl_from! { u32, u64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
impl_from! { u32, u128, #[unstable(feature = "i128", issue = "35118")] }
impl_from! { u64, u128, #[unstable(feature = "i128", issue = "35118")] }

// Signed -> Signed
impl_from! { i8, i16, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
impl_from! { i8, i32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
impl_from! { i8, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
impl_from! { i8, i128, #[unstable(feature = "i128", issue = "35118")] }
impl_from! { i8, isize, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
impl_from! { i16, i32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
impl_from! { i16, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
impl_from! { i16, i128, #[unstable(feature = "i128", issue = "35118")] }
impl_from! { i32, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
impl_from! { i32, i128, #[unstable(feature = "i128", issue = "35118")] }
impl_from! { i64, i128, #[unstable(feature = "i128", issue = "35118")] }

// Unsigned -> Signed
impl_from! { u8, i16, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
impl_from! { u8, i32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
impl_from! { u8, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
impl_from! { u8, i128, #[unstable(feature = "i128", issue = "35118")] }
impl_from! { u16, i32, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
impl_from! { u16, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
impl_from! { u16, i128, #[unstable(feature = "i128", issue = "35118")] }
impl_from! { u32, i64, #[stable(feature = "lossless_int_conv", since = "1.5.0")] }
impl_from! { u32, i128, #[unstable(feature = "i128", issue = "35118")] }
impl_from! { u64, i128, #[unstable(feature = "i128", issue = "35118")] }

// Note: integers can only be represented with full precision in a float if
// they fit in the significand, which is 24 bits in f32 and 53 bits in f64.
// Lossy float conversions are not implemented at this time.

// Signed -> Float
impl_from! { i8, f32, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
impl_from! { i8, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
impl_from! { i16, f32, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
impl_from! { i16, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
impl_from! { i32, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }

// Unsigned -> Float
impl_from! { u8, f32, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
impl_from! { u8, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
impl_from! { u16, f32, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
impl_from! { u16, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }
impl_from! { u32, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }

// Float -> Float
impl_from! { f32, f64, #[stable(feature = "lossless_float_conv", since = "1.6.0")] }

static ASCII_LOWERCASE_MAP: [u8; 256] = [
    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
    0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
    0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
    0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
    b' ', b'!', b'"', b'#', b'$', b'%', b'&', b'\'',
    b'(', b')', b'*', b'+', b',', b'-', b'.', b'/',
    b'0', b'1', b'2', b'3', b'4', b'5', b'6', b'7',
    b'8', b'9', b':', b';', b'<', b'=', b'>', b'?',
    b'@',

          b'a', b'b', b'c', b'd', b'e', b'f', b'g',
    b'h', b'i', b'j', b'k', b'l', b'm', b'n', b'o',
    b'p', b'q', b'r', b's', b't', b'u', b'v', b'w',
    b'x', b'y', b'z',

                      b'[', b'\\', b']', b'^', b'_',
    b'`', b'a', b'b', b'c', b'd', b'e', b'f', b'g',
    b'h', b'i', b'j', b'k', b'l', b'm', b'n', b'o',
    b'p', b'q', b'r', b's', b't', b'u', b'v', b'w',
    b'x', b'y', b'z', b'{', b'|', b'}', b'~', 0x7f,
    0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
    0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
    0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
    0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
    0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
    0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
    0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7,
    0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
    0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
    0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
    0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,
    0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
    0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7,
    0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
    0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
    0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff,
];

static ASCII_UPPERCASE_MAP: [u8; 256] = [
    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
    0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
    0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
    0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
    b' ', b'!', b'"', b'#', b'$', b'%', b'&', b'\'',
    b'(', b')', b'*', b'+', b',', b'-', b'.', b'/',
    b'0', b'1', b'2', b'3', b'4', b'5', b'6', b'7',
    b'8', b'9', b':', b';', b'<', b'=', b'>', b'?',
    b'@', b'A', b'B', b'C', b'D', b'E', b'F', b'G',
    b'H', b'I', b'J', b'K', b'L', b'M', b'N', b'O',
    b'P', b'Q', b'R', b'S', b'T', b'U', b'V', b'W',
    b'X', b'Y', b'Z', b'[', b'\\', b']', b'^', b'_',
    b'`',

          b'A', b'B', b'C', b'D', b'E', b'F', b'G',
    b'H', b'I', b'J', b'K', b'L', b'M', b'N', b'O',
    b'P', b'Q', b'R', b'S', b'T', b'U', b'V', b'W',
    b'X', b'Y', b'Z',

                      b'{', b'|', b'}', b'~', 0x7f,
    0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
    0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
    0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
    0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
    0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
    0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
    0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7,
    0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
    0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
    0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
    0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,
    0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
    0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7,
    0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
    0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
    0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff,
];

enum AsciiCharacterClass {
    C,  // control
    Cw, // control whitespace
    W,  // whitespace
    D,  // digit
    L,  // lowercase
    Lx, // lowercase hex digit
    U,  // uppercase
    Ux, // uppercase hex digit
    P,  // punctuation
}
use self::AsciiCharacterClass::*;

static ASCII_CHARACTER_CLASS: [AsciiCharacterClass; 128] = [
//  _0 _1 _2 _3 _4 _5 _6 _7 _8 _9 _a _b _c _d _e _f
    C, C, C, C, C, C, C, C, C, Cw,Cw,C, Cw,Cw,C, C, // 0_
    C, C, C, C, C, C, C, C, C, C, C, C, C, C, C, C, // 1_
    W, P, P, P, P, P, P, P, P, P, P, P, P, P, P, P, // 2_
    D, D, D, D, D, D, D, D, D, D, P, P, P, P, P, P, // 3_
    P, Ux,Ux,Ux,Ux,Ux,Ux,U, U, U, U, U, U, U, U, U, // 4_
    U, U, U, U, U, U, U, U, U, U, U, P, P, P, P, P, // 5_
    P, Lx,Lx,Lx,Lx,Lx,Lx,L, L, L, L, L, L, L, L, L, // 6_
    L, L, L, L, L, L, L, L, L, L, L, P, P, P, P, C, // 7_
];