algorithm.rs - mozsearch

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// Adapted from https://github.com/Alexhuszagh/rust-lexical.

use crate::lexical::algorithm::*;

use crate::lexical::num::Float;

#[test]

fn float_fast_path_test() {

    // valid

    let mantissa = (1 << f32::MANTISSA_SIZE) - 1;

    let (min_exp, max_exp) = f32::exponent_limit();

    for exp in min_exp..=max_exp {

        let f = fast_path::<f32>(mantissa, exp);

        assert!(f.is_some(), "should be valid {:?}.", (mantissa, exp));

    // Check slightly above valid exponents

    let f = fast_path::<f32>(123, 15);

    assert_eq!(f, Some(1.23e+17));

    // Exponent is 1 too high, pushes over the mantissa.

    let f = fast_path::<f32>(123, 16);

    assert!(f.is_none());

    // Mantissa is too large, checked_mul should overflow.

    let f = fast_path::<f32>(mantissa, 11);

    assert!(f.is_none());

    // invalid exponents

    let (min_exp, max_exp) = f32::exponent_limit();

    let f = fast_path::<f32>(mantissa, min_exp - 1);

    assert!(f.is_none(), "exponent under min_exp");

    let f = fast_path::<f32>(mantissa, max_exp + 1);

    assert!(f.is_none(), "exponent above max_exp");

#[test]

fn double_fast_path_test() {

    // valid

    let mantissa = (1 << f64::MANTISSA_SIZE) - 1;

    let (min_exp, max_exp) = f64::exponent_limit();

    for exp in min_exp..=max_exp {

        let f = fast_path::<f64>(mantissa, exp);

        assert!(f.is_some(), "should be valid {:?}.", (mantissa, exp));

    // invalid exponents

    let (min_exp, max_exp) = f64::exponent_limit();

    let f = fast_path::<f64>(mantissa, min_exp - 1);

    assert!(f.is_none(), "exponent under min_exp");

    let f = fast_path::<f64>(mantissa, max_exp + 1);

    assert!(f.is_none(), "exponent above max_exp");

    assert_eq!(

        Some(0.04628372940652459),

        fast_path::<f64>(4628372940652459, -17)

);

    assert_eq!(None, fast_path::<f64>(26383446160308229, -272));

#[test]

fn moderate_path_test() {

    let (f, valid) = moderate_path::<f64>(1234567890, -1, false);

    assert!(valid, "should be valid");

    assert_eq!(f.into_float::<f64>(), 123456789.0);

    let (f, valid) = moderate_path::<f64>(1234567891, -1, false);

    assert!(valid, "should be valid");

    assert_eq!(f.into_float::<f64>(), 123456789.1);

    let (f, valid) = moderate_path::<f64>(12345678912, -2, false);

    assert!(valid, "should be valid");

    assert_eq!(f.into_float::<f64>(), 123456789.12);

    let (f, valid) = moderate_path::<f64>(123456789123, -3, false);

    assert!(valid, "should be valid");

    assert_eq!(f.into_float::<f64>(), 123456789.123);

    let (f, valid) = moderate_path::<f64>(1234567891234, -4, false);

    assert!(valid, "should be valid");

    assert_eq!(f.into_float::<f64>(), 123456789.1234);

    let (f, valid) = moderate_path::<f64>(12345678912345, -5, false);

    assert!(valid, "should be valid");

    assert_eq!(f.into_float::<f64>(), 123456789.12345);

    let (f, valid) = moderate_path::<f64>(123456789123456, -6, false);

    assert!(valid, "should be valid");

    assert_eq!(f.into_float::<f64>(), 123456789.123456);

    let (f, valid) = moderate_path::<f64>(1234567891234567, -7, false);

    assert!(valid, "should be valid");

    assert_eq!(f.into_float::<f64>(), 123456789.1234567);

    let (f, valid) = moderate_path::<f64>(12345678912345679, -8, false);

    assert!(valid, "should be valid");

    assert_eq!(f.into_float::<f64>(), 123456789.12345679);

    let (f, valid) = moderate_path::<f64>(4628372940652459, -17, false);

    assert!(valid, "should be valid");

    assert_eq!(f.into_float::<f64>(), 0.04628372940652459);

    let (f, valid) = moderate_path::<f64>(26383446160308229, -272, false);

    assert!(valid, "should be valid");

    assert_eq!(f.into_float::<f64>(), 2.6383446160308229e-256);

    let (_, valid) = moderate_path::<f64>(26383446160308230, -272, false);

    assert!(!valid, "should be invalid");