// Copyright (c) 2018 The predicates-rs Project Developers. // // Licensed under the Apache License, Version 2.0 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. use std::fmt; use float_cmp::ApproxEq; use float_cmp::Ulps; use crate::reflection; use crate::Predicate; /// Predicate that ensures two numbers are "close" enough, understanding that rounding errors /// occur. /// /// This is created by the `predicate::float::is_close`. #[derive(Debug, Clone, Copy, PartialEq)] pub struct IsClosePredicate { target: f64, epsilon: f64, ulps: ::U, } impl IsClosePredicate { /// Set the amount of error allowed. /// /// Values `1`-`5` should work in most cases. Sometimes more control is needed and you will /// need to set `IsClosePredicate::epsilon` separately from `IsClosePredicate::ulps`. /// /// # Examples /// /// ``` /// use predicates::prelude::*; /// /// let a = 0.15_f64 + 0.15_f64 + 0.15_f64; /// let predicate_fn = predicate::float::is_close(a).distance(5); /// ``` pub fn distance(mut self, distance: ::U) -> Self { self.epsilon = (distance as f64) * ::std::f64::EPSILON; self.ulps = distance; self } /// Set the absolute deviation allowed. /// /// This is meant to handle problems near `0`. Values `1.`-`5.` epislons should work in most /// cases. /// /// # Examples /// /// ``` /// use predicates::prelude::*; /// /// let a = 0.15_f64 + 0.15_f64 + 0.15_f64; /// let predicate_fn = predicate::float::is_close(a).epsilon(5.0 * ::std::f64::EPSILON); /// ``` pub fn epsilon(mut self, epsilon: f64) -> Self { self.epsilon = epsilon; self } /// Set the relative deviation allowed. /// /// This is meant to handle large numbers. Values `1`-`5` should work in most cases. /// /// # Examples /// /// ``` /// use predicates::prelude::*; /// /// let a = 0.15_f64 + 0.15_f64 + 0.15_f64; /// let predicate_fn = predicate::float::is_close(a).ulps(5); /// ``` pub fn ulps(mut self, ulps: ::U) -> Self { self.ulps = ulps; self } } impl Predicate for IsClosePredicate { fn eval(&self, variable: &f64) -> bool { variable.approx_eq( self.target, float_cmp::F64Margin { epsilon: self.epsilon, ulps: self.ulps, }, ) } fn find_case<'a>(&'a self, expected: bool, variable: &f64) -> Option> { let actual = self.eval(variable); if expected == actual { Some( reflection::Case::new(Some(self), actual) .add_product(reflection::Product::new( "actual epsilon", (variable - self.target).abs(), )) .add_product(reflection::Product::new( "actual ulps", variable.ulps(&self.target).abs(), )), ) } else { None } } } impl reflection::PredicateReflection for IsClosePredicate { fn parameters<'a>(&'a self) -> Box> + 'a> { let params = vec![ reflection::Parameter::new("epsilon", &self.epsilon), reflection::Parameter::new("ulps", &self.ulps), ]; Box::new(params.into_iter()) } } impl fmt::Display for IsClosePredicate { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { let palette = crate::Palette::new(f.alternate()); write!( f, "{} {} {}", palette.var("var"), palette.description("!="), palette.expected(self.target), ) } } /// Create a new `Predicate` that ensures two numbers are "close" enough, understanding that /// rounding errors occur. /// /// # Examples /// /// ``` /// use predicates::prelude::*; /// /// let a = 0.15_f64 + 0.15_f64 + 0.15_f64; /// let b = 0.1_f64 + 0.1_f64 + 0.25_f64; /// let predicate_fn = predicate::float::is_close(a); /// assert_eq!(true, predicate_fn.eval(&b)); /// assert_eq!(false, predicate_fn.distance(0).eval(&b)); /// ``` pub fn is_close(target: f64) -> IsClosePredicate { IsClosePredicate { target, epsilon: 2.0 * ::std::f64::EPSILON, ulps: 2, } }