[−][src]Enum kserd::Number

pub enum Number {
    Uint(u128),
    Int(i128),
    Float(f64),
}

A numerical value.

Number captures Rust numerical primitives: unsigned integers, signed integers, and floating point decimal numbers. The data is stored inside an enum housing the maximum size of each numerical type (128 bits for integers, 64 bits for floats). The numbers are also canonicalized, that is Eq and Ord are implemented and comparisons can be made between integers and floats.

TODO: Operations (add, subtract, etc) are to be added in the future.

The number line extends from negative infinity, through zero, to positive infinity. Nan is above positive infinity. All zeroes are treated equally (-0 == +0), as well as all Nans.

[ -∞, .., 0, .., +∞, NaN ]

Examples

Number can be constructed straight from any of the Rust numbers using the From trait.

let n: Number = 123456u32.into();
assert_eq!(n, Number::Uint(123456));

Comparisons can be made between different number types.

let n = Number::from(100u8);
assert_eq!(n, Number::from(100.0f32));
assert_eq!(n, Number::from(100i32));
assert_ne!(n, Number::from(99.99f64));

PartialEq is also implemented for each Rust number.

let n = Number::from(100u8);
assert_eq!(n, 100.0f32);
assert_eq!(n, 100i32);
assert_ne!(n, 99.99);

Ordering is likewise implemented.

let n = Number::from(100u8);
assert!(n < Number::from(101));
assert!(n > Number::from(-100));
assert!(n > Number::from(99.99));
// Likewise with literal numbers
assert!(n < 101);
assert!(n > -100);
assert!(n > 99.99);

An exmaple of the canonicalized ordering.

use std::f64::{INFINITY, NEG_INFINITY, NAN};

// use an ordered set
let mut set = std::collections::BTreeSet::new();

set.insert(Number::from(0));
set.insert((-0.0).into());
set.insert((-1.0).into());
set.insert(0.5.into());
set.insert(INFINITY.into());
set.insert((-100).into());
set.insert(NAN.into());
set.insert(NAN.into());
set.insert((-0.0).into());
set.insert(NEG_INFINITY.into());
set.insert(100.0.into());

let expected: Vec<Number> = vec![
     NEG_INFINITY,
     -100.0,
     -1.0,
     0.0,
     0.5,
     100.0,
     INFINITY,
     NAN,
].into_iter().map(Number::from).collect();

assert_eq!(set.into_iter().collect::<Vec<_>>(), expected);

Variants

Uint(u128)Int(i128)Float(f64)

Methods

`impl Number`[src]

`pub fn as_u128(&self) -> Result<u128, IntoIntError>`[src]

Represent Number as an unsigned integer.

Example

use kserd::ds::IntoIntError;
use std::f64::{INFINITY, NEG_INFINITY, NAN};

// generally the conversion will work
assert_eq!(Number::from(100i32).as_u128(), Ok(100));
assert_eq!(Number::from(100.0).as_u128(), Ok(100));
// can also work if fractional part of float is smaller than valid amount
assert_eq!(Number::from(3.0 + 5e-11).as_u128(), Ok(3));
// can fail if outside
assert_eq!(Number::from(-100i32).as_u128(), Err(IntoIntError));
assert_eq!(Number::from(0.5).as_u128(), Err(IntoIntError));
assert_eq!(Number::from(INFINITY).as_u128(), Err(IntoIntError));
assert_eq!(Number::from(NEG_INFINITY).as_u128(), Err(IntoIntError));
assert_eq!(Number::from(NAN).as_u128(), Err(IntoIntError));

`pub fn as_i128(&self) -> Result<i128, IntoIntError>`[src]

Represent Number as a signed integer.

Example

use kserd::ds::IntoIntError;
use std::f64::{INFINITY, NEG_INFINITY, NAN};

// generally the conversion will work
assert_eq!(Number::from(100u32).as_i128(), Ok(100));
assert_eq!(Number::from(100.0).as_i128(), Ok(100));
// can also work if fractional part of float is smaller than valid amount
assert_eq!(Number::from(3.0 + 5e-11).as_i128(), Ok(3));
// can fail if outside
assert_eq!(Number::from(0.5).as_i128(), Err(IntoIntError));
assert_eq!(Number::from(INFINITY).as_i128(), Err(IntoIntError));
assert_eq!(Number::from(NEG_INFINITY).as_i128(), Err(IntoIntError));
assert_eq!(Number::from(NAN).as_i128(), Err(IntoIntError));

`pub fn as_f64(&self) -> f64`[src]

Represent Number as a floating point decimal. Does not fail, but is a lossy conversion if an integer.

Examples

assert_eq!(Number::from(100u8).as_f64(), 100.0);
assert_eq!(Number::from(-100).as_f64(), -100.0);
// lossy conversion if integers get large.
assert_eq!(Number::from(u128::max_value()).as_f64(), 3402823669209385e23);
assert_eq!(Number::from(i128::max_value()).as_f64(), 17014118346046923e22);
assert_eq!(Number::from(i128::min_value()).as_f64(), -17014118346046923e22);