blob: c02f73fdf03648566b52bd7e698bc2d320cd0444 [file] [log] [blame]
//! Numeric traits and functions for the built-in numeric types.
#![stable(feature = "rust1", since = "1.0.0")]
use crate::ascii;
use crate::hint;
use crate::intrinsics;
use crate::mem;
use crate::str::FromStr;
// Used because the `?` operator is not allowed in a const context.
macro_rules! try_opt {
($e:expr) => {
match $e {
Some(x) => x,
None => return None,
}
};
}
#[allow_internal_unstable(const_likely)]
macro_rules! unlikely {
($e: expr) => {
intrinsics::unlikely($e)
};
}
// All these modules are technically private and only exposed for coretests:
#[cfg(not(no_fp_fmt_parse))]
pub mod bignum;
#[cfg(not(no_fp_fmt_parse))]
pub mod dec2flt;
#[cfg(not(no_fp_fmt_parse))]
pub mod diy_float;
#[cfg(not(no_fp_fmt_parse))]
pub mod flt2dec;
pub mod fmt;
#[macro_use]
mod int_macros; // import int_impl!
#[macro_use]
mod uint_macros; // import uint_impl!
mod error;
mod int_log10;
mod nonzero;
mod overflow_panic;
mod saturating;
mod wrapping;
#[stable(feature = "saturating_int_impl", since = "1.74.0")]
pub use saturating::Saturating;
#[stable(feature = "rust1", since = "1.0.0")]
pub use wrapping::Wrapping;
#[stable(feature = "rust1", since = "1.0.0")]
#[cfg(not(no_fp_fmt_parse))]
pub use dec2flt::ParseFloatError;
#[stable(feature = "rust1", since = "1.0.0")]
pub use error::ParseIntError;
#[unstable(
feature = "nonzero_internals",
reason = "implementation detail which may disappear or be replaced at any time",
issue = "none"
)]
pub use nonzero::ZeroablePrimitive;
#[stable(feature = "generic_nonzero", since = "1.79.0")]
pub use nonzero::NonZero;
#[stable(feature = "signed_nonzero", since = "1.34.0")]
pub use nonzero::{NonZeroI128, NonZeroI16, NonZeroI32, NonZeroI64, NonZeroI8, NonZeroIsize};
#[stable(feature = "nonzero", since = "1.28.0")]
pub use nonzero::{NonZeroU128, NonZeroU16, NonZeroU32, NonZeroU64, NonZeroU8, NonZeroUsize};
#[stable(feature = "try_from", since = "1.34.0")]
pub use error::TryFromIntError;
#[stable(feature = "int_error_matching", since = "1.55.0")]
pub use error::IntErrorKind;
macro_rules! usize_isize_to_xe_bytes_doc {
() => {
"
**Note**: This function returns an array of length 2, 4 or 8 bytes
depending on the target pointer size.
"
};
}
macro_rules! usize_isize_from_xe_bytes_doc {
() => {
"
**Note**: This function takes an array of length 2, 4 or 8 bytes
depending on the target pointer size.
"
};
}
macro_rules! midpoint_impl {
($SelfT:ty, unsigned) => {
/// Calculates the middle point of `self` and `rhs`.
///
/// `midpoint(a, b)` is `(a + b) >> 1` as if it were performed in a
/// sufficiently-large signed integral type. This implies that the result is
/// always rounded towards negative infinity and that no overflow will ever occur.
///
/// # Examples
///
/// ```
/// #![feature(num_midpoint)]
#[doc = concat!("assert_eq!(0", stringify!($SelfT), ".midpoint(4), 2);")]
#[doc = concat!("assert_eq!(1", stringify!($SelfT), ".midpoint(4), 2);")]
/// ```
#[unstable(feature = "num_midpoint", issue = "110840")]
#[rustc_const_unstable(feature = "const_num_midpoint", issue = "110840")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
pub const fn midpoint(self, rhs: $SelfT) -> $SelfT {
// Use the well known branchless algorithm from Hacker's Delight to compute
// `(a + b) / 2` without overflowing: `((a ^ b) >> 1) + (a & b)`.
((self ^ rhs) >> 1) + (self & rhs)
}
};
($SelfT:ty, $WideT:ty, unsigned) => {
/// Calculates the middle point of `self` and `rhs`.
///
/// `midpoint(a, b)` is `(a + b) >> 1` as if it were performed in a
/// sufficiently-large signed integral type. This implies that the result is
/// always rounded towards negative infinity and that no overflow will ever occur.
///
/// # Examples
///
/// ```
/// #![feature(num_midpoint)]
#[doc = concat!("assert_eq!(0", stringify!($SelfT), ".midpoint(4), 2);")]
#[doc = concat!("assert_eq!(1", stringify!($SelfT), ".midpoint(4), 2);")]
/// ```
#[unstable(feature = "num_midpoint", issue = "110840")]
#[rustc_const_unstable(feature = "const_num_midpoint", issue = "110840")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
pub const fn midpoint(self, rhs: $SelfT) -> $SelfT {
((self as $WideT + rhs as $WideT) / 2) as $SelfT
}
};
}
macro_rules! widening_impl {
($SelfT:ty, $WideT:ty, $BITS:literal, unsigned) => {
/// Calculates the complete product `self * rhs` without the possibility to overflow.
///
/// This returns the low-order (wrapping) bits and the high-order (overflow) bits
/// of the result as two separate values, in that order.
///
/// If you also need to add a carry to the wide result, then you want
/// [`Self::carrying_mul`] instead.
///
/// # Examples
///
/// Basic usage:
///
/// Please note that this example is shared between integer types.
/// Which explains why `u32` is used here.
///
/// ```
/// #![feature(bigint_helper_methods)]
/// assert_eq!(5u32.widening_mul(2), (10, 0));
/// assert_eq!(1_000_000_000u32.widening_mul(10), (1410065408, 2));
/// ```
#[unstable(feature = "bigint_helper_methods", issue = "85532")]
#[rustc_const_unstable(feature = "const_bigint_helper_methods", issue = "85532")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
pub const fn widening_mul(self, rhs: Self) -> (Self, Self) {
// note: longer-term this should be done via an intrinsic,
// but for now we can deal without an impl for u128/i128
// SAFETY: overflow will be contained within the wider types
let wide = unsafe { (self as $WideT).unchecked_mul(rhs as $WideT) };
(wide as $SelfT, (wide >> $BITS) as $SelfT)
}
/// Calculates the "full multiplication" `self * rhs + carry`
/// without the possibility to overflow.
///
/// This returns the low-order (wrapping) bits and the high-order (overflow) bits
/// of the result as two separate values, in that order.
///
/// Performs "long multiplication" which takes in an extra amount to add, and may return an
/// additional amount of overflow. This allows for chaining together multiple
/// multiplications to create "big integers" which represent larger values.
///
/// If you don't need the `carry`, then you can use [`Self::widening_mul`] instead.
///
/// # Examples
///
/// Basic usage:
///
/// Please note that this example is shared between integer types.
/// Which explains why `u32` is used here.
///
/// ```
/// #![feature(bigint_helper_methods)]
/// assert_eq!(5u32.carrying_mul(2, 0), (10, 0));
/// assert_eq!(5u32.carrying_mul(2, 10), (20, 0));
/// assert_eq!(1_000_000_000u32.carrying_mul(10, 0), (1410065408, 2));
/// assert_eq!(1_000_000_000u32.carrying_mul(10, 10), (1410065418, 2));
#[doc = concat!("assert_eq!(",
stringify!($SelfT), "::MAX.carrying_mul(", stringify!($SelfT), "::MAX, ", stringify!($SelfT), "::MAX), ",
"(0, ", stringify!($SelfT), "::MAX));"
)]
/// ```
///
/// This is the core operation needed for scalar multiplication when
/// implementing it for wider-than-native types.
///
/// ```
/// #![feature(bigint_helper_methods)]
/// fn scalar_mul_eq(little_endian_digits: &mut Vec<u16>, multiplicand: u16) {
/// let mut carry = 0;
/// for d in little_endian_digits.iter_mut() {
/// (*d, carry) = d.carrying_mul(multiplicand, carry);
/// }
/// if carry != 0 {
/// little_endian_digits.push(carry);
/// }
/// }
///
/// let mut v = vec![10, 20];
/// scalar_mul_eq(&mut v, 3);
/// assert_eq!(v, [30, 60]);
///
/// assert_eq!(0x87654321_u64 * 0xFEED, 0x86D3D159E38D);
/// let mut v = vec![0x4321, 0x8765];
/// scalar_mul_eq(&mut v, 0xFEED);
/// assert_eq!(v, [0xE38D, 0xD159, 0x86D3]);
/// ```
///
/// If `carry` is zero, this is similar to [`overflowing_mul`](Self::overflowing_mul),
/// except that it gives the value of the overflow instead of just whether one happened:
///
/// ```
/// #![feature(bigint_helper_methods)]
/// let r = u8::carrying_mul(7, 13, 0);
/// assert_eq!((r.0, r.1 != 0), u8::overflowing_mul(7, 13));
/// let r = u8::carrying_mul(13, 42, 0);
/// assert_eq!((r.0, r.1 != 0), u8::overflowing_mul(13, 42));
/// ```
///
/// The value of the first field in the returned tuple matches what you'd get
/// by combining the [`wrapping_mul`](Self::wrapping_mul) and
/// [`wrapping_add`](Self::wrapping_add) methods:
///
/// ```
/// #![feature(bigint_helper_methods)]
/// assert_eq!(
/// 789_u16.carrying_mul(456, 123).0,
/// 789_u16.wrapping_mul(456).wrapping_add(123),
/// );
/// ```
#[unstable(feature = "bigint_helper_methods", issue = "85532")]
#[rustc_const_unstable(feature = "bigint_helper_methods", issue = "85532")]
#[must_use = "this returns the result of the operation, \
without modifying the original"]
#[inline]
pub const fn carrying_mul(self, rhs: Self, carry: Self) -> (Self, Self) {
// note: longer-term this should be done via an intrinsic,
// but for now we can deal without an impl for u128/i128
// SAFETY: overflow will be contained within the wider types
let wide = unsafe {
(self as $WideT).unchecked_mul(rhs as $WideT).unchecked_add(carry as $WideT)
};
(wide as $SelfT, (wide >> $BITS) as $SelfT)
}
};
}
impl i8 {
int_impl! {
Self = i8,
ActualT = i8,
UnsignedT = u8,
BITS = 8,
BITS_MINUS_ONE = 7,
Min = -128,
Max = 127,
rot = 2,
rot_op = "-0x7e",
rot_result = "0xa",
swap_op = "0x12",
swapped = "0x12",
reversed = "0x48",
le_bytes = "[0x12]",
be_bytes = "[0x12]",
to_xe_bytes_doc = "",
from_xe_bytes_doc = "",
bound_condition = "",
}
}
impl i16 {
int_impl! {
Self = i16,
ActualT = i16,
UnsignedT = u16,
BITS = 16,
BITS_MINUS_ONE = 15,
Min = -32768,
Max = 32767,
rot = 4,
rot_op = "-0x5ffd",
rot_result = "0x3a",
swap_op = "0x1234",
swapped = "0x3412",
reversed = "0x2c48",
le_bytes = "[0x34, 0x12]",
be_bytes = "[0x12, 0x34]",
to_xe_bytes_doc = "",
from_xe_bytes_doc = "",
bound_condition = "",
}
}
impl i32 {
int_impl! {
Self = i32,
ActualT = i32,
UnsignedT = u32,
BITS = 32,
BITS_MINUS_ONE = 31,
Min = -2147483648,
Max = 2147483647,
rot = 8,
rot_op = "0x10000b3",
rot_result = "0xb301",
swap_op = "0x12345678",
swapped = "0x78563412",
reversed = "0x1e6a2c48",
le_bytes = "[0x78, 0x56, 0x34, 0x12]",
be_bytes = "[0x12, 0x34, 0x56, 0x78]",
to_xe_bytes_doc = "",
from_xe_bytes_doc = "",
bound_condition = "",
}
}
impl i64 {
int_impl! {
Self = i64,
ActualT = i64,
UnsignedT = u64,
BITS = 64,
BITS_MINUS_ONE = 63,
Min = -9223372036854775808,
Max = 9223372036854775807,
rot = 12,
rot_op = "0xaa00000000006e1",
rot_result = "0x6e10aa",
swap_op = "0x1234567890123456",
swapped = "0x5634129078563412",
reversed = "0x6a2c48091e6a2c48",
le_bytes = "[0x56, 0x34, 0x12, 0x90, 0x78, 0x56, 0x34, 0x12]",
be_bytes = "[0x12, 0x34, 0x56, 0x78, 0x90, 0x12, 0x34, 0x56]",
to_xe_bytes_doc = "",
from_xe_bytes_doc = "",
bound_condition = "",
}
}
impl i128 {
int_impl! {
Self = i128,
ActualT = i128,
UnsignedT = u128,
BITS = 128,
BITS_MINUS_ONE = 127,
Min = -170141183460469231731687303715884105728,
Max = 170141183460469231731687303715884105727,
rot = 16,
rot_op = "0x13f40000000000000000000000004f76",
rot_result = "0x4f7613f4",
swap_op = "0x12345678901234567890123456789012",
swapped = "0x12907856341290785634129078563412",
reversed = "0x48091e6a2c48091e6a2c48091e6a2c48",
le_bytes = "[0x12, 0x90, 0x78, 0x56, 0x34, 0x12, 0x90, 0x78, \
0x56, 0x34, 0x12, 0x90, 0x78, 0x56, 0x34, 0x12]",
be_bytes = "[0x12, 0x34, 0x56, 0x78, 0x90, 0x12, 0x34, 0x56, \
0x78, 0x90, 0x12, 0x34, 0x56, 0x78, 0x90, 0x12]",
to_xe_bytes_doc = "",
from_xe_bytes_doc = "",
bound_condition = "",
}
}
#[cfg(target_pointer_width = "16")]
impl isize {
int_impl! {
Self = isize,
ActualT = i16,
UnsignedT = usize,
BITS = 16,
BITS_MINUS_ONE = 15,
Min = -32768,
Max = 32767,
rot = 4,
rot_op = "-0x5ffd",
rot_result = "0x3a",
swap_op = "0x1234",
swapped = "0x3412",
reversed = "0x2c48",
le_bytes = "[0x34, 0x12]",
be_bytes = "[0x12, 0x34]",
to_xe_bytes_doc = usize_isize_to_xe_bytes_doc!(),
from_xe_bytes_doc = usize_isize_from_xe_bytes_doc!(),
bound_condition = " on 16-bit targets",
}
}
#[cfg(target_pointer_width = "32")]
impl isize {
int_impl! {
Self = isize,
ActualT = i32,
UnsignedT = usize,
BITS = 32,
BITS_MINUS_ONE = 31,
Min = -2147483648,
Max = 2147483647,
rot = 8,
rot_op = "0x10000b3",
rot_result = "0xb301",
swap_op = "0x12345678",
swapped = "0x78563412",
reversed = "0x1e6a2c48",
le_bytes = "[0x78, 0x56, 0x34, 0x12]",
be_bytes = "[0x12, 0x34, 0x56, 0x78]",
to_xe_bytes_doc = usize_isize_to_xe_bytes_doc!(),
from_xe_bytes_doc = usize_isize_from_xe_bytes_doc!(),
bound_condition = " on 32-bit targets",
}
}
#[cfg(target_pointer_width = "64")]
impl isize {
int_impl! {
Self = isize,
ActualT = i64,
UnsignedT = usize,
BITS = 64,
BITS_MINUS_ONE = 63,
Min = -9223372036854775808,
Max = 9223372036854775807,
rot = 12,
rot_op = "0xaa00000000006e1",
rot_result = "0x6e10aa",
swap_op = "0x1234567890123456",
swapped = "0x5634129078563412",
reversed = "0x6a2c48091e6a2c48",
le_bytes = "[0x56, 0x34, 0x12, 0x90, 0x78, 0x56, 0x34, 0x12]",
be_bytes = "[0x12, 0x34, 0x56, 0x78, 0x90, 0x12, 0x34, 0x56]",
to_xe_bytes_doc = usize_isize_to_xe_bytes_doc!(),
from_xe_bytes_doc = usize_isize_from_xe_bytes_doc!(),
bound_condition = " on 64-bit targets",
}
}
/// If the 6th bit is set ascii is lower case.
const ASCII_CASE_MASK: u8 = 0b0010_0000;
impl u8 {
uint_impl! {
Self = u8,
ActualT = u8,
SignedT = i8,
NonZeroT = NonZero<u8>,
BITS = 8,
MAX = 255,
rot = 2,
rot_op = "0x82",
rot_result = "0xa",
swap_op = "0x12",
swapped = "0x12",
reversed = "0x48",
le_bytes = "[0x12]",
be_bytes = "[0x12]",
to_xe_bytes_doc = "",
from_xe_bytes_doc = "",
bound_condition = "",
}
widening_impl! { u8, u16, 8, unsigned }
midpoint_impl! { u8, u16, unsigned }
/// 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());
/// ```
#[must_use]
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
#[rustc_const_stable(feature = "const_u8_is_ascii", since = "1.43.0")]
#[inline]
pub const fn is_ascii(&self) -> bool {
*self <= 127
}
/// If the value of this byte is within the ASCII range, returns it as an
/// [ASCII character](ascii::Char). Otherwise, returns `None`.
#[must_use]
#[unstable(feature = "ascii_char", issue = "110998")]
#[inline]
pub const fn as_ascii(&self) -> Option<ascii::Char> {
ascii::Char::from_u8(*self)
}
/// 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`]: Self::make_ascii_uppercase
#[must_use = "to uppercase the value in-place, use `make_ascii_uppercase()`"]
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
#[rustc_const_stable(feature = "const_ascii_methods_on_intrinsics", since = "1.52.0")]
#[inline]
pub const fn to_ascii_uppercase(&self) -> u8 {
// Toggle the 6th bit if this is a lowercase letter
*self ^ ((self.is_ascii_lowercase() as u8) * ASCII_CASE_MASK)
}
/// 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`]: Self::make_ascii_lowercase
#[must_use = "to lowercase the value in-place, use `make_ascii_lowercase()`"]
#[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
#[rustc_const_stable(feature = "const_ascii_methods_on_intrinsics", since = "1.52.0")]
#[inline]
pub const fn to_ascii_lowercase(&self) -> u8 {
// Set the 6th bit if this is an uppercase letter
*self | (self.is_ascii_uppercase() as u8 * ASCII_CASE_MASK)
}
/// Assumes self is ascii
#[inline]
pub(crate) const fn ascii_change_case_unchecked(&self) -> u8 {
*self ^ ASCII_CASE_MASK
}
/// 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")]
#[rustc_const_stable(feature = "const_ascii_methods_on_intrinsics", since = "1.52.0")]
#[inline]
pub const 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`]: Self::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`]: Self::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
///
/// ```
/// 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 = b'\x1b';
///
/// 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());
/// ```
#[must_use]
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
#[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
#[inline]
pub const fn is_ascii_alphabetic(&self) -> bool {
matches!(*self, b'A'..=b'Z' | b'a'..=b'z')
}
/// Checks if the value is an ASCII uppercase character:
/// U+0041 'A' ..= U+005A 'Z'.
///
/// # Examples
///
/// ```
/// 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 = b'\x1b';
///
/// 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());
/// ```
#[must_use]
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
#[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
#[inline]
pub const fn is_ascii_uppercase(&self) -> bool {
matches!(*self, b'A'..=b'Z')
}
/// Checks if the value is an ASCII lowercase character:
/// U+0061 'a' ..= U+007A 'z'.
///
/// # Examples
///
/// ```
/// 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 = b'\x1b';
///
/// 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());
/// ```
#[must_use]
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
#[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
#[inline]
pub const fn is_ascii_lowercase(&self) -> bool {
matches!(*self, b'a'..=b'z')
}
/// 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
///
/// ```
/// 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 = b'\x1b';
///
/// 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());
/// ```
#[must_use]
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
#[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
#[inline]
pub const fn is_ascii_alphanumeric(&self) -> bool {
matches!(*self, b'0'..=b'9') | matches!(*self, b'A'..=b'Z') | matches!(*self, b'a'..=b'z')
}
/// Checks if the value is an ASCII decimal digit:
/// U+0030 '0' ..= U+0039 '9'.
///
/// # Examples
///
/// ```
/// 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 = b'\x1b';
///
/// 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());
/// ```
#[must_use]
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
#[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
#[inline]
pub const fn is_ascii_digit(&self) -> bool {
matches!(*self, b'0'..=b'9')
}
/// Checks if the value is an ASCII octal digit:
/// U+0030 '0' ..= U+0037 '7'.
///
/// # Examples
///
/// ```
/// #![feature(is_ascii_octdigit)]
///
/// let uppercase_a = b'A';
/// let a = b'a';
/// let zero = b'0';
/// let seven = b'7';
/// let nine = b'9';
/// let percent = b'%';
/// let lf = b'\n';
///
/// assert!(!uppercase_a.is_ascii_octdigit());
/// assert!(!a.is_ascii_octdigit());
/// assert!(zero.is_ascii_octdigit());
/// assert!(seven.is_ascii_octdigit());
/// assert!(!nine.is_ascii_octdigit());
/// assert!(!percent.is_ascii_octdigit());
/// assert!(!lf.is_ascii_octdigit());
/// ```
#[must_use]
#[unstable(feature = "is_ascii_octdigit", issue = "101288")]
#[rustc_const_unstable(feature = "is_ascii_octdigit", issue = "101288")]
#[inline]
pub const fn is_ascii_octdigit(&self) -> bool {
matches!(*self, b'0'..=b'7')
}
/// 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
///
/// ```
/// 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 = b'\x1b';
///
/// 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());
/// ```
#[must_use]
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
#[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
#[inline]
pub const fn is_ascii_hexdigit(&self) -> bool {
matches!(*self, b'0'..=b'9') | matches!(*self, b'A'..=b'F') | matches!(*self, b'a'..=b'f')
}
/// 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
///
/// ```
/// 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 = b'\x1b';
///
/// 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());
/// ```
#[must_use]
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
#[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
#[inline]
pub const fn is_ascii_punctuation(&self) -> bool {
matches!(*self, b'!'..=b'/')
| matches!(*self, b':'..=b'@')
| matches!(*self, b'['..=b'`')
| matches!(*self, b'{'..=b'~')
}
/// Checks if the value is an ASCII graphic character:
/// U+0021 '!' ..= U+007E '~'.
///
/// # Examples
///
/// ```
/// 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 = b'\x1b';
///
/// 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());
/// ```
#[must_use]
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
#[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
#[inline]
pub const fn is_ascii_graphic(&self) -> bool {
matches!(*self, b'!'..=b'~')
}
/// 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]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap07.html#tag_07_03_01
/// [bfs]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_05
///
/// # Examples
///
/// ```
/// 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 = b'\x1b';
///
/// 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());
/// ```
#[must_use]
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
#[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
#[inline]
pub const fn is_ascii_whitespace(&self) -> bool {
matches!(*self, b'\t' | b'\n' | b'\x0C' | b'\r' | b' ')
}
/// 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
///
/// ```
/// 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 = b'\x1b';
///
/// 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());
/// ```
#[must_use]
#[stable(feature = "ascii_ctype_on_intrinsics", since = "1.24.0")]
#[rustc_const_stable(feature = "const_ascii_ctype_on_intrinsics", since = "1.47.0")]
#[inline]
pub const fn is_ascii_control(&self) -> bool {
matches!(*self, b'\0'..=b'\x1F' | b'\x7F')
}
/// Returns an iterator that produces an escaped version of a `u8`,
/// treating it as an ASCII character.
///
/// The behavior is identical to [`ascii::escape_default`].
///
/// # Examples
///
/// ```
///
/// assert_eq!("0", b'0'.escape_ascii().to_string());
/// assert_eq!("\\t", b'\t'.escape_ascii().to_string());
/// assert_eq!("\\r", b'\r'.escape_ascii().to_string());
/// assert_eq!("\\n", b'\n'.escape_ascii().to_string());
/// assert_eq!("\\'", b'\''.escape_ascii().to_string());
/// assert_eq!("\\\"", b'"'.escape_ascii().to_string());
/// assert_eq!("\\\\", b'\\'.escape_ascii().to_string());
/// assert_eq!("\\x9d", b'\x9d'.escape_ascii().to_string());
/// ```
#[must_use = "this returns the escaped byte as an iterator, \
without modifying the original"]
#[stable(feature = "inherent_ascii_escape", since = "1.60.0")]
#[inline]
pub fn escape_ascii(self) -> ascii::EscapeDefault {
ascii::escape_default(self)
}
#[inline]
pub(crate) const fn is_utf8_char_boundary(self) -> bool {
// This is bit magic equivalent to: b < 128 || b >= 192
(self as i8) >= -0x40
}
}
impl u16 {
uint_impl! {
Self = u16,
ActualT = u16,
SignedT = i16,
NonZeroT = NonZero<u16>,
BITS = 16,
MAX = 65535,
rot = 4,
rot_op = "0xa003",
rot_result = "0x3a",
swap_op = "0x1234",
swapped = "0x3412",
reversed = "0x2c48",
le_bytes = "[0x34, 0x12]",
be_bytes = "[0x12, 0x34]",
to_xe_bytes_doc = "",
from_xe_bytes_doc = "",
bound_condition = "",
}
widening_impl! { u16, u32, 16, unsigned }
midpoint_impl! { u16, u32, unsigned }
/// Checks if the value is a Unicode surrogate code point, which are disallowed values for [`char`].
///
/// # Examples
///
/// ```
/// #![feature(utf16_extra)]
///
/// let low_non_surrogate = 0xA000u16;
/// let low_surrogate = 0xD800u16;
/// let high_surrogate = 0xDC00u16;
/// let high_non_surrogate = 0xE000u16;
///
/// assert!(!low_non_surrogate.is_utf16_surrogate());
/// assert!(low_surrogate.is_utf16_surrogate());
/// assert!(high_surrogate.is_utf16_surrogate());
/// assert!(!high_non_surrogate.is_utf16_surrogate());
/// ```
#[must_use]
#[unstable(feature = "utf16_extra", issue = "94919")]
#[rustc_const_unstable(feature = "utf16_extra_const", issue = "94919")]
#[inline]
pub const fn is_utf16_surrogate(self) -> bool {
matches!(self, 0xD800..=0xDFFF)
}
}
impl u32 {
uint_impl! {
Self = u32,
ActualT = u32,
SignedT = i32,
NonZeroT = NonZero<u32>,
BITS = 32,
MAX = 4294967295,
rot = 8,
rot_op = "0x10000b3",
rot_result = "0xb301",
swap_op = "0x12345678",
swapped = "0x78563412",
reversed = "0x1e6a2c48",
le_bytes = "[0x78, 0x56, 0x34, 0x12]",
be_bytes = "[0x12, 0x34, 0x56, 0x78]",
to_xe_bytes_doc = "",
from_xe_bytes_doc = "",
bound_condition = "",
}
widening_impl! { u32, u64, 32, unsigned }
midpoint_impl! { u32, u64, unsigned }
}
impl u64 {
uint_impl! {
Self = u64,
ActualT = u64,
SignedT = i64,
NonZeroT = NonZero<u64>,
BITS = 64,
MAX = 18446744073709551615,
rot = 12,
rot_op = "0xaa00000000006e1",
rot_result = "0x6e10aa",
swap_op = "0x1234567890123456",
swapped = "0x5634129078563412",
reversed = "0x6a2c48091e6a2c48",
le_bytes = "[0x56, 0x34, 0x12, 0x90, 0x78, 0x56, 0x34, 0x12]",
be_bytes = "[0x12, 0x34, 0x56, 0x78, 0x90, 0x12, 0x34, 0x56]",
to_xe_bytes_doc = "",
from_xe_bytes_doc = "",
bound_condition = "",
}
widening_impl! { u64, u128, 64, unsigned }
midpoint_impl! { u64, u128, unsigned }
}
impl u128 {
uint_impl! {
Self = u128,
ActualT = u128,
SignedT = i128,
NonZeroT = NonZero<u128>,
BITS = 128,
MAX = 340282366920938463463374607431768211455,
rot = 16,
rot_op = "0x13f40000000000000000000000004f76",
rot_result = "0x4f7613f4",
swap_op = "0x12345678901234567890123456789012",
swapped = "0x12907856341290785634129078563412",
reversed = "0x48091e6a2c48091e6a2c48091e6a2c48",
le_bytes = "[0x12, 0x90, 0x78, 0x56, 0x34, 0x12, 0x90, 0x78, \
0x56, 0x34, 0x12, 0x90, 0x78, 0x56, 0x34, 0x12]",
be_bytes = "[0x12, 0x34, 0x56, 0x78, 0x90, 0x12, 0x34, 0x56, \
0x78, 0x90, 0x12, 0x34, 0x56, 0x78, 0x90, 0x12]",
to_xe_bytes_doc = "",
from_xe_bytes_doc = "",
bound_condition = "",
}
midpoint_impl! { u128, unsigned }
}
#[cfg(target_pointer_width = "16")]
impl usize {
uint_impl! {
Self = usize,
ActualT = u16,
SignedT = isize,
NonZeroT = NonZero<usize>,
BITS = 16,
MAX = 65535,
rot = 4,
rot_op = "0xa003",
rot_result = "0x3a",
swap_op = "0x1234",
swapped = "0x3412",
reversed = "0x2c48",
le_bytes = "[0x34, 0x12]",
be_bytes = "[0x12, 0x34]",
to_xe_bytes_doc = usize_isize_to_xe_bytes_doc!(),
from_xe_bytes_doc = usize_isize_from_xe_bytes_doc!(),
bound_condition = " on 16-bit targets",
}
widening_impl! { usize, u32, 16, unsigned }
midpoint_impl! { usize, u32, unsigned }
}
#[cfg(target_pointer_width = "32")]
impl usize {
uint_impl! {
Self = usize,
ActualT = u32,
SignedT = isize,
NonZeroT = NonZero<usize>,
BITS = 32,
MAX = 4294967295,
rot = 8,
rot_op = "0x10000b3",
rot_result = "0xb301",
swap_op = "0x12345678",
swapped = "0x78563412",
reversed = "0x1e6a2c48",
le_bytes = "[0x78, 0x56, 0x34, 0x12]",
be_bytes = "[0x12, 0x34, 0x56, 0x78]",
to_xe_bytes_doc = usize_isize_to_xe_bytes_doc!(),
from_xe_bytes_doc = usize_isize_from_xe_bytes_doc!(),
bound_condition = " on 32-bit targets",
}
widening_impl! { usize, u64, 32, unsigned }
midpoint_impl! { usize, u64, unsigned }
}
#[cfg(target_pointer_width = "64")]
impl usize {
uint_impl! {
Self = usize,
ActualT = u64,
SignedT = isize,
NonZeroT = NonZero<usize>,
BITS = 64,
MAX = 18446744073709551615,
rot = 12,
rot_op = "0xaa00000000006e1",
rot_result = "0x6e10aa",
swap_op = "0x1234567890123456",
swapped = "0x5634129078563412",
reversed = "0x6a2c48091e6a2c48",
le_bytes = "[0x56, 0x34, 0x12, 0x90, 0x78, 0x56, 0x34, 0x12]",
be_bytes = "[0x12, 0x34, 0x56, 0x78, 0x90, 0x12, 0x34, 0x56]",
to_xe_bytes_doc = usize_isize_to_xe_bytes_doc!(),
from_xe_bytes_doc = usize_isize_from_xe_bytes_doc!(),
bound_condition = " on 64-bit targets",
}
widening_impl! { usize, u128, 64, unsigned }
midpoint_impl! { usize, u128, unsigned }
}
impl usize {
/// Returns an `usize` where every byte is equal to `x`.
#[inline]
pub(crate) const fn repeat_u8(x: u8) -> usize {
usize::from_ne_bytes([x; mem::size_of::<usize>()])
}
/// Returns an `usize` where every byte pair is equal to `x`.
#[inline]
pub(crate) const fn repeat_u16(x: u16) -> usize {
let mut r = 0usize;
let mut i = 0;
while i < mem::size_of::<usize>() {
// Use `wrapping_shl` to make it work on targets with 16-bit `usize`
r = r.wrapping_shl(16) | (x as usize);
i += 2;
}
r
}
}
/// 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.
///
/// # Examples
///
/// ```
/// use std::num::FpCategory;
///
/// 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!(sub.classify(), FpCategory::Subnormal);
/// assert_eq!(nan.classify(), FpCategory::Nan);
/// ```
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
#[stable(feature = "rust1", since = "1.0.0")]
pub enum FpCategory {
/// NaN (not a number): this value results from calculations like `(-1.0).sqrt()`.
///
/// See [the documentation for `f32`](f32) for more information on the unusual properties
/// of NaN.
#[stable(feature = "rust1", since = "1.0.0")]
Nan,
/// Positive or negative infinity, which often results from dividing a nonzero number
/// by zero.
#[stable(feature = "rust1", since = "1.0.0")]
Infinite,
/// Positive or negative zero.
///
/// See [the documentation for `f32`](f32) for more information on the signedness of zeroes.
#[stable(feature = "rust1", since = "1.0.0")]
Zero,
/// “Subnormal” or “denormal” floating point representation (less precise, relative to
/// their magnitude, than [`Normal`]).
///
/// Subnormal numbers are larger in magnitude than [`Zero`] but smaller in magnitude than all
/// [`Normal`] numbers.
///
/// [`Normal`]: Self::Normal
/// [`Zero`]: Self::Zero
#[stable(feature = "rust1", since = "1.0.0")]
Subnormal,
/// A regular floating point number, not any of the exceptional categories.
///
/// The smallest positive normal numbers are [`f32::MIN_POSITIVE`] and [`f64::MIN_POSITIVE`],
/// and the largest positive normal numbers are [`f32::MAX`] and [`f64::MAX`]. (Unlike signed
/// integers, floating point numbers are symmetric in their range, so negating any of these
/// constants will produce their negative counterpart.)
#[stable(feature = "rust1", since = "1.0.0")]
Normal,
}
macro_rules! from_str_radix_int_impl {
($($t:ty)*) => {$(
#[stable(feature = "rust1", since = "1.0.0")]
impl FromStr for $t {
type Err = ParseIntError;
fn from_str(src: &str) -> Result<Self, ParseIntError> {
<$t>::from_str_radix(src, 10)
}
}
)*}
}
from_str_radix_int_impl! { isize i8 i16 i32 i64 i128 usize u8 u16 u32 u64 u128 }
/// Determines if a string of text of that length of that radix could be guaranteed to be
/// stored in the given type T.
/// Note that if the radix is known to the compiler, it is just the check of digits.len that
/// is done at runtime.
#[doc(hidden)]
#[inline(always)]
#[unstable(issue = "none", feature = "std_internals")]
pub const fn can_not_overflow<T>(radix: u32, is_signed_ty: bool, digits: &[u8]) -> bool {
radix <= 16 && digits.len() <= mem::size_of::<T>() * 2 - is_signed_ty as usize
}
#[track_caller]
const fn from_str_radix_panic_ct(_radix: u32) -> ! {
panic!("from_str_radix_int: must lie in the range `[2, 36]`");
}
#[track_caller]
fn from_str_radix_panic_rt(radix: u32) -> ! {
panic!("from_str_radix_int: must lie in the range `[2, 36]` - found {}", radix);
}
#[cfg_attr(not(feature = "panic_immediate_abort"), inline(never))]
#[cfg_attr(feature = "panic_immediate_abort", inline)]
#[cold]
#[track_caller]
const fn from_str_radix_assert(radix: u32) {
if 2 > radix || radix > 36 {
// The only difference between these two functions is their panic message.
intrinsics::const_eval_select((radix,), from_str_radix_panic_ct, from_str_radix_panic_rt);
}
}
macro_rules! from_str_radix {
($($int_ty:ty)+) => {$(
impl $int_ty {
/// Converts a string slice in a given base to an integer.
///
/// The string is expected to be an optional `+` sign
/// followed by digits.
/// Leading and trailing whitespace represent an error.
/// Digits are a subset of these characters, depending on `radix`:
///
/// * `0-9`
/// * `a-z`
/// * `A-Z`
///
/// # Panics
///
/// This function panics if `radix` is not in the range from 2 to 36.
///
/// # Examples
///
/// Basic usage:
///
/// ```
#[doc = concat!("assert_eq!(", stringify!($int_ty), "::from_str_radix(\"A\", 16), Ok(10));")]
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_int_from_str", issue = "59133")]
pub const fn from_str_radix(src: &str, radix: u32) -> Result<$int_ty, ParseIntError> {
use self::IntErrorKind::*;
use self::ParseIntError as PIE;
from_str_radix_assert(radix);
if src.is_empty() {
return Err(PIE { kind: Empty });
}
#[allow(unused_comparisons)]
let is_signed_ty = 0 > <$int_ty>::MIN;
// 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, mut digits) = match src {
[b'+' | b'-'] => {
return Err(PIE { kind: InvalidDigit });
}
[b'+', rest @ ..] => (true, rest),
[b'-', rest @ ..] if is_signed_ty => (false, rest),
_ => (true, src),
};
let mut result = 0;
macro_rules! unwrap_or_PIE {
($option:expr, $kind:ident) => {
match $option {
Some(value) => value,
None => return Err(PIE { kind: $kind }),
}
};
}
if can_not_overflow::<$int_ty>(radix, is_signed_ty, digits) {
// If the len of the str is short compared to the range of the type
// we are parsing into, then we can be certain that an overflow will not occur.
// This bound is when `radix.pow(digits.len()) - 1 <= T::MAX` but the condition
// above is a faster (conservative) approximation of this.
//
// Consider radix 16 as it has the highest information density per digit and will thus overflow the earliest:
// `u8::MAX` is `ff` - any str of len 2 is guaranteed to not overflow.
// `i8::MAX` is `7f` - only a str of len 1 is guaranteed to not overflow.
macro_rules! run_unchecked_loop {
($unchecked_additive_op:tt) => {{
while let [c, rest @ ..] = digits {
result = result * (radix as $int_ty);
let x = unwrap_or_PIE!((*c as char).to_digit(radix), InvalidDigit);
result = result $unchecked_additive_op (x as $int_ty);
digits = rest;
}
}};
}
if is_positive {
run_unchecked_loop!(+)
} else {
run_unchecked_loop!(-)
};
} else {
macro_rules! run_checked_loop {
($checked_additive_op:ident, $overflow_err:ident) => {{
while let [c, rest @ ..] = digits {
// When `radix` is passed in as a literal, rather than doing a slow `imul`
// the compiler can use shifts if `radix` can be expressed as a
// sum of powers of 2 (x*10 can be written as x*8 + x*2).
// When the compiler can't use these optimisations,
// the latency of the multiplication can be hidden by issuing it
// before the result is needed to improve performance on
// modern out-of-order CPU as multiplication here is slower
// than the other instructions, we can get the end result faster
// doing multiplication first and let the CPU spends other cycles
// doing other computation and get multiplication result later.
let mul = result.checked_mul(radix as $int_ty);
let x = unwrap_or_PIE!((*c as char).to_digit(radix), InvalidDigit) as $int_ty;
result = unwrap_or_PIE!(mul, $overflow_err);
result = unwrap_or_PIE!(<$int_ty>::$checked_additive_op(result, x), $overflow_err);
digits = rest;
}
}};
}
if is_positive {
run_checked_loop!(checked_add, PosOverflow)
} else {
run_checked_loop!(checked_sub, NegOverflow)
};
}
Ok(result)
}
}
)+}
}
from_str_radix! { i8 u8 i16 u16 i32 u32 i64 u64 i128 u128 }
// Re-use the relevant implementation of from_str_radix for isize and usize to avoid outputting two
// identical functions.
macro_rules! from_str_radix_size_impl {
($($t:ident $size:ty),*) => {$(
impl $size {
/// Converts a string slice in a given base to an integer.
///
/// The string is expected to be an optional `+` sign
/// followed by digits.
/// Leading and trailing whitespace represent an error.
/// Digits are a subset of these characters, depending on `radix`:
///
/// * `0-9`
/// * `a-z`
/// * `A-Z`
///
/// # Panics
///
/// This function panics if `radix` is not in the range from 2 to 36.
///
/// # Examples
///
/// Basic usage:
///
/// ```
#[doc = concat!("assert_eq!(", stringify!($size), "::from_str_radix(\"A\", 16), Ok(10));")]
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_int_from_str", issue = "59133")]
pub const fn from_str_radix(src: &str, radix: u32) -> Result<$size, ParseIntError> {
match <$t>::from_str_radix(src, radix) {
Ok(x) => Ok(x as $size),
Err(e) => Err(e),
}
}
})*}
}
#[cfg(target_pointer_width = "16")]
from_str_radix_size_impl! { i16 isize, u16 usize }
#[cfg(target_pointer_width = "32")]
from_str_radix_size_impl! { i32 isize, u32 usize }
#[cfg(target_pointer_width = "64")]
from_str_radix_size_impl! { i64 isize, u64 usize }