use rustc::lint::*;
use rustc_front::hir::*;
-use std::f64::consts as f64;
use utils::span_lint;
use syntax::ast::Lit_::*;
use syntax::ast::Lit;
is found; suggests to use the constant"
}
-const KNOWN_CONSTS : &'static [(f64, &'static str)] = &[(f64::E, "E"), (f64::FRAC_1_PI, "FRAC_1_PI"),
- (f64::FRAC_1_SQRT_2, "FRAC_1_SQRT_2"), (f64::FRAC_2_PI, "FRAC_2_PI"),
- (f64::FRAC_2_SQRT_PI, "FRAC_2_SQRT_PI"), (f64::FRAC_PI_2, "FRAC_PI_2"), (f64::FRAC_PI_3, "FRAC_PI_3"),
- (f64::FRAC_PI_4, "FRAC_PI_4"), (f64::FRAC_PI_6, "FRAC_PI_6"), (f64::FRAC_PI_8, "FRAC_PI_8"),
- (f64::LN_10, "LN_10"), (f64::LN_2, "LN_2"), (f64::LOG10_E, "LOG10_E"), (f64::LOG2_E, "LOG2_E"),
- (f64::PI, "PI"), (f64::SQRT_2, "SQRT_2")];
-
-const EPSILON_DIVISOR : f64 = 8192f64; //TODO: test to find a good value
+// Tuples are of the form (name, lower_bound, upper_bound)
+#[allow(approx_constant)]
+const KNOWN_CONSTS : &'static [(&'static str, f64, f64)] = &[
+ ("E", 2.7101, 2.7200),
+ ("FRAC_1_PI", 0.31829, 0.31840),
+ ("FRAC_1_SQRT_2", 0.7071, 0.7072),
+ ("FRAC_2_PI", 0.6366, 0.6370),
+ ("FRAC_2_SQRT_PI", 1.1283, 1.1284),
+ ("FRAC_PI_2", 1.5707, 1.5708),
+ ("FRAC_PI_3", 1.0471, 1.0472),
+ ("FRAC_PI_4", 0.7853, 0.7854),
+ ("FRAC_PI_6", 0.5235, 0.5236),
+ ("FRAC_PI_8", 0.3926, 0.3927),
+ ("LN_10", 2.302, 2.303),
+ ("LN_2", 0.6931, 0.6932),
+ ("LOG10_E", 0.4342, 0.4343),
+ ("LOG2_E", 1.4426, 1.4427),
+ ("PI", 3.140, 3.142),
+ ("SQRT_2", 1.4142, 1.4143),
+];
#[derive(Copy,Clone)]
pub struct ApproxConstant;
}
}
-fn check_known_consts(cx: &LateContext, e: &Expr, str: &str, module: &str) {
- if let Ok(value) = str.parse::<f64>() {
- for &(constant, name) in KNOWN_CONSTS {
- if !within_epsilon(constant, value) { continue; }
- span_lint(cx, APPROX_CONSTANT, e.span, &format!(
- "approximate value of `{}::{}` found. \
- Consider using it directly", module, &name));
+fn check_known_consts(cx: &LateContext, e: &Expr, s: &str, module: &str) {
+ if let Ok(value) = s.parse::<f64>() {
+ for &(name, lower_bound, upper_bound) in KNOWN_CONSTS {
+ if (value >= lower_bound) && (value < upper_bound) {
+ span_lint(cx, APPROX_CONSTANT, e.span, &format!(
+ "approximate value of `{}::{}` found. \
+ Consider using it directly", module, &name));
+ }
}
}
}
-
-fn within_epsilon(target: f64, value: f64) -> bool {
- f64::abs(value - target) < f64::abs(if target > value {
- target
- } else { value }) / EPSILON_DIVISOR
-}