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Implement round(number, digits) for digits != 0 #1521

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Merged
windelbouwman merged 4 commits into from
Oct 14, 2019
Merged

Implement round(number, digits) for digits != 0 #1521

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b858ae8
Implement round(number, digits) for digits != 0
janrg Oct 13, 2019
458fa3c
Fix formatting
janrg Oct 13, 2019
122aa96
Fix linter errors
janrg Oct 13, 2019
4fd38e6
Add test snippets, fix rounding for very small numbers
janrg Oct 14, 2019
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9 changes: 9 additions & 0 deletions tests/snippets/floats.py
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Original file line number Diff line number Diff line change
Expand Up @@ -165,6 +165,15 @@
assert isinstance(1.5.__round__(None), int)
assert 0.5.__round__(None) == 0
assert 1.5.__round__(None) == 2
assert 1.234.__round__(1) == 1.2
assert 1.23456.__round__(4) == 1.2346
assert 1.00000000001.__round__(10) == 1.0
assert 1234.5.__round__(-2) == 1200
assert 1.234.__round__(-1) == 0
assert 1.23456789.__round__(15) == 1.23456789
assert 1.2e300.__round__(-500) == 0
assert 1.234.__round__(500) == 1.234
assert 1.2e-300.__round__(299) == 0
assert_raises(TypeError, lambda: 0.5.__round__(0.0))
assert_raises(TypeError, lambda: 1.5.__round__(0.0))
assert_raises(OverflowError, float('inf').__round__)
Expand Down
27 changes: 24 additions & 3 deletions vm/src/obj/objfloat.rs
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
use hexf_parse;
use num_bigint::{BigInt, ToBigInt};
use num_rational::Ratio;
use num_traits::{float::Float, sign::Signed, ToPrimitive, Zero};
use num_traits::{float::Float, pow, sign::Signed, ToPrimitive, Zero};

use super::objbytes;
use super::objint;
Expand Down Expand Up @@ -477,7 +477,6 @@ impl PyFloat {
}
}
};

if let Some(ndigits) = ndigits {
if ndigits.is_zero() {
let fract = self.value.fract();
Expand All @@ -492,7 +491,29 @@ impl PyFloat {
};
Ok(vm.ctx.new_float(value))
} else {
Ok(vm.ctx.not_implemented())
let ndigits = match ndigits {
ndigits if *ndigits > i32::max_value().to_bigint().unwrap() => i32::max_value(),
ndigits if *ndigits < i32::min_value().to_bigint().unwrap() => i32::min_value(),
_ => ndigits.to_i32().unwrap(),
};
if (self.value > 1e+16_f64 && ndigits >= 0i32)
|| (ndigits + self.value.log10().floor() as i32 > 16i32)
{
return Ok(vm.ctx.new_float(self.value));
}
if ndigits >= 0i32 {
Ok(vm.ctx.new_float(
(self.value * pow(10.0, ndigits as usize)).round()
/ pow(10.0, ndigits as usize),
))
} else {
let result = (self.value / pow(10.0, (-ndigits) as usize)).round()
* pow(10.0, (-ndigits) as usize);
if result.is_nan() {
return Ok(vm.ctx.new_float(0.0));
}
Ok(vm.ctx.new_float(result))
}
}
} else {
let fract = self.value.fract();
Expand Down