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// Copyright 2013-2014 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 for generic mathematics
#![doc(html_logo_url = "https://rust-num.github.io/num/rust-logo-128x128-blk-v2.png",
html_favicon_url = "https://rust-num.github.io/num/favicon.ico",
html_root_url = "https://rust-num.github.io/num/",
html_playground_url = "http://play.integer32.com/")]
use std::ops::{Add, Sub, Mul, Div, Rem};
use std::ops::{AddAssign, SubAssign, MulAssign, DivAssign, RemAssign};
use std::num::Wrapping;
pub use bounds::Bounded;
pub use float::{Float, FloatConst};
pub use identities::{Zero, One, zero, one};
pub use ops::checked::*;
pub use ops::wrapping::*;
pub use ops::saturating::Saturating;
pub use sign::{Signed, Unsigned, abs, abs_sub, signum};
pub use cast::*;
pub use int::PrimInt;
pub use pow::{pow, checked_pow};
pub mod identities;
pub mod sign;
pub mod ops;
pub mod bounds;
pub mod float;
pub mod cast;
pub mod int;
pub mod pow;
/// The base trait for numeric types, covering `0` and `1` values,
/// comparisons, basic numeric operations, and string conversion.
pub trait Num: PartialEq + Zero + One + NumOps
{
type FromStrRadixErr;
/// Convert from a string and radix <= 36.
///
/// # Examples
///
/// ```rust
/// use num_traits::Num;
///
/// let result = <i32 as Num>::from_str_radix("27", 10);
/// assert_eq!(result, Ok(27));
///
/// let result = <i32 as Num>::from_str_radix("foo", 10);
/// assert!(result.is_err());
/// ```
fn from_str_radix(str: &str, radix: u32) -> Result<Self, Self::FromStrRadixErr>;
}
/// The trait for types implementing basic numeric operations
///
/// This is automatically implemented for types which implement the operators.
pub trait NumOps<Rhs = Self, Output = Self>
: Add<Rhs, Output = Output>
+ Sub<Rhs, Output = Output>
+ Mul<Rhs, Output = Output>
+ Div<Rhs, Output = Output>
+ Rem<Rhs, Output = Output>
{}
impl<T, Rhs, Output> NumOps<Rhs, Output> for T
where T: Add<Rhs, Output = Output>
+ Sub<Rhs, Output = Output>
+ Mul<Rhs, Output = Output>
+ Div<Rhs, Output = Output>
+ Rem<Rhs, Output = Output>
{}
/// The trait for `Num` types which also implement numeric operations taking
/// the second operand by reference.
///
/// This is automatically implemented for types which implement the operators.
pub trait NumRef: Num + for<'r> NumOps<&'r Self> {}
impl<T> NumRef for T where T: Num + for<'r> NumOps<&'r T> {}
/// The trait for references which implement numeric operations, taking the
/// second operand either by value or by reference.
///
/// This is automatically implemented for types which implement the operators.
pub trait RefNum<Base>: NumOps<Base, Base> + for<'r> NumOps<&'r Base, Base> {}
impl<T, Base> RefNum<Base> for T where T: NumOps<Base, Base> + for<'r> NumOps<&'r Base, Base> {}
/// The trait for types implementing numeric assignment operators (like `+=`).
///
/// This is automatically implemented for types which implement the operators.
pub trait NumAssignOps<Rhs = Self>
: AddAssign<Rhs>
+ SubAssign<Rhs>
+ MulAssign<Rhs>
+ DivAssign<Rhs>
+ RemAssign<Rhs>
{}
impl<T, Rhs> NumAssignOps<Rhs> for T
where T: AddAssign<Rhs>
+ SubAssign<Rhs>
+ MulAssign<Rhs>
+ DivAssign<Rhs>
+ RemAssign<Rhs>
{}
/// The trait for `Num` types which also implement assignment operators.
///
/// This is automatically implemented for types which implement the operators.
pub trait NumAssign: Num + NumAssignOps {}
impl<T> NumAssign for T where T: Num + NumAssignOps {}
/// The trait for `NumAssign` types which also implement assignment operations
/// taking the second operand by reference.
///
/// This is automatically implemented for types which implement the operators.
pub trait NumAssignRef: NumAssign + for<'r> NumAssignOps<&'r Self> {}
impl<T> NumAssignRef for T where T: NumAssign + for<'r> NumAssignOps<&'r T> {}
macro_rules! int_trait_impl {
($name:ident for $($t:ty)*) => ($(
impl $name for $t {
type FromStrRadixErr = ::std::num::ParseIntError;
#[inline]
fn from_str_radix(s: &str, radix: u32)
-> Result<Self, ::std::num::ParseIntError>
{
<$t>::from_str_radix(s, radix)
}
}
)*)
}
int_trait_impl!(Num for usize u8 u16 u32 u64 isize i8 i16 i32 i64);
impl<T: Num> Num for Wrapping<T>
where Wrapping<T>:
Add<Output = Wrapping<T>> + Sub<Output = Wrapping<T>>
+ Mul<Output = Wrapping<T>> + Div<Output = Wrapping<T>> + Rem<Output = Wrapping<T>>
{
type FromStrRadixErr = T::FromStrRadixErr;
fn from_str_radix(str: &str, radix: u32) -> Result<Self, Self::FromStrRadixErr> {
T::from_str_radix(str, radix).map(Wrapping)
}
}
#[derive(Debug)]
pub enum FloatErrorKind {
Empty,
Invalid,
}
// FIXME: std::num::ParseFloatError is stable in 1.0, but opaque to us,
// so there's not really any way for us to reuse it.
#[derive(Debug)]
pub struct ParseFloatError {
pub kind: FloatErrorKind,
}
// FIXME: The standard library from_str_radix on floats was deprecated, so we're stuck
// with this implementation ourselves until we want to make a breaking change.
// (would have to drop it from `Num` though)
macro_rules! float_trait_impl {
($name:ident for $($t:ty)*) => ($(
impl $name for $t {
type FromStrRadixErr = ParseFloatError;
fn from_str_radix(src: &str, radix: u32)
-> Result<Self, Self::FromStrRadixErr>
{
use self::FloatErrorKind::*;
use self::ParseFloatError as PFE;
// Special values
match src {
"inf" => return Ok(Float::infinity()),
"-inf" => return Ok(Float::neg_infinity()),
"NaN" => return Ok(Float::nan()),
_ => {},
}
fn slice_shift_char(src: &str) -> Option<(char, &str)> {
src.chars().nth(0).map(|ch| (ch, &src[1..]))
}
let (is_positive, src) = match slice_shift_char(src) {
None => return Err(PFE { kind: Empty }),
Some(('-', "")) => return Err(PFE { kind: Empty }),
Some(('-', src)) => (false, src),
Some((_, _)) => (true, src),
};
// The significand to accumulate
let mut sig = if is_positive { 0.0 } else { -0.0 };
// Necessary to detect overflow
let mut prev_sig = sig;
let mut cs = src.chars().enumerate();
// Exponent prefix and exponent index offset
let mut exp_info = None::<(char, usize)>;
// Parse the integer part of the significand
for (i, c) in cs.by_ref() {
match c.to_digit(radix) {
Some(digit) => {
// shift significand one digit left
sig = sig * (radix as $t);
// add/subtract current digit depending on sign
if is_positive {
sig = sig + ((digit as isize) as $t);
} else {
sig = sig - ((digit as isize) as $t);
}
// Detect overflow by comparing to last value, except
// if we've not seen any non-zero digits.
if prev_sig != 0.0 {
if is_positive && sig <= prev_sig
{ return Ok(Float::infinity()); }
if !is_positive && sig >= prev_sig
{ return Ok(Float::neg_infinity()); }
// Detect overflow by reversing the shift-and-add process
if is_positive && (prev_sig != (sig - digit as $t) / radix as $t)
{ return Ok(Float::infinity()); }
if !is_positive && (prev_sig != (sig + digit as $t) / radix as $t)
{ return Ok(Float::neg_infinity()); }
}
prev_sig = sig;
},
None => match c {
'e' | 'E' | 'p' | 'P' => {
exp_info = Some((c, i + 1));
break; // start of exponent
},
'.' => {
break; // start of fractional part
},
_ => {
return Err(PFE { kind: Invalid });
},
},
}
}
// If we are not yet at the exponent parse the fractional
// part of the significand
if exp_info.is_none() {
let mut power = 1.0;
for (i, c) in cs.by_ref() {
match c.to_digit(radix) {
Some(digit) => {
// Decrease power one order of magnitude
power = power / (radix as $t);
// add/subtract current digit depending on sign
sig = if is_positive {
sig + (digit as $t) * power
} else {
sig - (digit as $t) * power
};
// Detect overflow by comparing to last value
if is_positive && sig < prev_sig
{ return Ok(Float::infinity()); }
if !is_positive && sig > prev_sig
{ return Ok(Float::neg_infinity()); }
prev_sig = sig;
},
None => match c {
'e' | 'E' | 'p' | 'P' => {
exp_info = Some((c, i + 1));
break; // start of exponent
},
_ => {
return Err(PFE { kind: Invalid });
},
},
}
}
}
// Parse and calculate the exponent
let exp = match exp_info {
Some((c, offset)) => {
let base = match c {
'E' | 'e' if radix == 10 => 10.0,
'P' | 'p' if radix == 16 => 2.0,
_ => return Err(PFE { kind: Invalid }),
};
// Parse the exponent as decimal integer
let src = &src[offset..];
let (is_positive, exp) = match slice_shift_char(src) {
Some(('-', src)) => (false, src.parse::<usize>()),
Some(('+', src)) => (true, src.parse::<usize>()),
Some((_, _)) => (true, src.parse::<usize>()),
None => return Err(PFE { kind: Invalid }),
};
match (is_positive, exp) {
(true, Ok(exp)) => base.powi(exp as i32),
(false, Ok(exp)) => 1.0 / base.powi(exp as i32),
(_, Err(_)) => return Err(PFE { kind: Invalid }),
}
},
None => 1.0, // no exponent
};
Ok(sig * exp)
}
}
)*)
}
float_trait_impl!(Num for f32 f64);
/// A value bounded by a minimum and a maximum
///
/// If input is less than min then this returns min.
/// If input is greater than max then this returns max.
/// Otherwise this returns input.
#[inline]
pub fn clamp<T: PartialOrd>(input: T, min: T, max: T) -> T {
debug_assert!(min <= max, "min must be less than or equal to max");
if input < min {
min
} else if input > max {
max
} else {
input
}
}
#[test]
fn clamp_test() {
// Int test
assert_eq!(1, clamp(1, -1, 2));
assert_eq!(-1, clamp(-2, -1, 2));
assert_eq!(2, clamp(3, -1, 2));
// Float test
assert_eq!(1.0, clamp(1.0, -1.0, 2.0));
assert_eq!(-1.0, clamp(-2.0, -1.0, 2.0));
assert_eq!(2.0, clamp(3.0, -1.0, 2.0));
}
#[test]
fn from_str_radix_unwrap() {
// The Result error must impl Debug to allow unwrap()
let i: i32 = Num::from_str_radix("0", 10).unwrap();
assert_eq!(i, 0);
let f: f32 = Num::from_str_radix("0.0", 10).unwrap();
assert_eq!(f, 0.0);
}
macro_rules! test_wrapping_from_str_radix {
($($t:ty)+) => {
$(
for &(s, r) in &[("42", 10), ("42", 2), ("-13.0", 10), ("foo", 10)] {
let w = Wrapping::<$t>::from_str_radix(s, r).map(|w| w.0);
assert_eq!(w, <$t as Num>::from_str_radix(s, r));
}
)+
};
}
#[test]
fn wrapping_is_num() {
fn require_num<T: Num>(_: &T) {}
require_num(&Wrapping(42_u32));
require_num(&Wrapping(-42));
}
#[test]
fn wrapping_from_str_radix() {
test_wrapping_from_str_radix!(usize u8 u16 u32 u64 isize i8 i16 i32 i64);
}
#[test]
fn check_num_ops() {
fn compute<T: Num + Copy>(x: T, y: T) -> T {
x * y / y % y + y - y
}
assert_eq!(compute(1, 2), 1)
}
#[test]
fn check_numref_ops() {
fn compute<T: NumRef>(x: T, y: &T) -> T {
x * y / y % y + y - y
}
assert_eq!(compute(1, &2), 1)
}
#[test]
fn check_refnum_ops() {
fn compute<T: Copy>(x: &T, y: T) -> T
where for<'a> &'a T: RefNum<T>
{
&(&(&(&(x * y) / y) % y) + y) - y
}
assert_eq!(compute(&1, 2), 1)
}
#[test]
fn check_refref_ops() {
fn compute<T>(x: &T, y: &T) -> T
where for<'a> &'a T: RefNum<T>
{
&(&(&(&(x * y) / y) % y) + y) - y
}
assert_eq!(compute(&1, &2), 1)
}
#[test]
fn check_numassign_ops() {
fn compute<T: NumAssign + Copy>(mut x: T, y: T) -> T {
x *= y;
x /= y;
x %= y;
x += y;
x -= y;
x
}
assert_eq!(compute(1, 2), 1)
}
// TODO test `NumAssignRef`, but even the standard numeric types don't
// implement this yet. (see rust pr41336)