Add float.as_integer_ratio()

Cargo.lock

@@ -514,6 +514,16 @@ dependencies = [
  "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "num-rational"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "num-bigint 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-integer 0.1.39 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "num-traits"
 version = "0.2.6"
@@ -756,6 +766,7 @@ dependencies = [
  "num-bigint 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-complex 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-integer 0.1.39 (registry+https://github.com/rust-lang/crates.io-index)",
+ "num-rational 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand 0.5.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 1.0.3 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1285,6 +1296,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum num-bigint 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "10b8423ea72ec64751198856a853e07b37087cfc9b53a87ecb19bff67b6d1320"
 "checksum num-complex 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "107b9be86cd2481930688277b675b0114578227f034674726605b8a482d8baf8"
 "checksum num-integer 0.1.39 (registry+https://github.com/rust-lang/crates.io-index)" = "e83d528d2677f0518c570baf2b7abdcf0cd2d248860b68507bdcb3e91d4c0cea"
+"checksum num-rational 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "4e96f040177bb3da242b5b1ecf3f54b5d5af3efbbfb18608977a5d2767b22f10"
 "checksum num-traits 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)" = "0b3a5d7cc97d6d30d8b9bc8fa19bf45349ffe46241e8816f50f62f6d6aaabee1"
 "checksum ordermap 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)" = "a86ed3f5f244b372d6b1a00b72ef7f8876d0bc6a78a4c9985c53614041512063"
 "checksum petgraph 0.4.13 (registry+https://github.com/rust-lang/crates.io-index)" = "9c3659d1ee90221741f65dd128d9998311b0e40c5d3c23a62445938214abce4f"

tests/snippets/floats.py

@@ -87,3 +87,22 @@ assert 2.0.__rsub__(1) == -1.0
 assert (1.7).real == 1.7
 assert (1.3).is_integer() == False
 assert (1.0).is_integer()    == True
+
+assert (0.875).as_integer_ratio() == (7, 8)
+assert (-0.875).as_integer_ratio() == (-7, 8)
+assert (0.0).as_integer_ratio() == (0, 1)
+assert (11.5).as_integer_ratio() == (23, 2)
+assert (0.0).as_integer_ratio() == (0, 1)
+assert (2.5).as_integer_ratio() == (5, 2)
+assert (0.5).as_integer_ratio() == (1, 2)
+assert (2.1).as_integer_ratio() == (4728779608739021, 2251799813685248)
+assert (-2.1).as_integer_ratio() == (-4728779608739021, 2251799813685248)
+assert (-2100.0).as_integer_ratio() == (-2100, 1)
+assert (2.220446049250313e-16).as_integer_ratio() == (1, 4503599627370496)
+assert (1.7976931348623157e+308).as_integer_ratio() == (179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368, 1)
+assert (2.2250738585072014e-308).as_integer_ratio() == (1, 44942328371557897693232629769725618340449424473557664318357520289433168951375240783177119330601884005280028469967848339414697442203604155623211857659868531094441973356216371319075554900311523529863270738021251442209537670585615720368478277635206809290837627671146574559986811484619929076208839082406056034304)
+
+assert_raises(OverflowError, float('inf').as_integer_ratio)
+assert_raises(OverflowError, float('-inf').as_integer_ratio)
+assert_raises(ValueError, float('nan').as_integer_ratio)
+

vm/Cargo.toml

@@ -10,6 +10,7 @@ num-complex = "0.2"
 num-bigint = "0.2.1"
 num-traits = "0.2"
 num-integer = "0.1.39"
+num-rational = "0.2.1"
 rand = "0.5"
 log = "0.3"
 rustpython_parser = {path = "../parser"}

vm/src/obj/objfloat.rs

@@ -2,12 +2,14 @@ use super::objbytes;
 use super::objint;
 use super::objstr;
 use super::objtype;
+use crate::function::PyRef;
 use crate::pyobject::{
     PyContext, PyFuncArgs, PyObject, PyObjectPayload, PyObjectPayload2, PyObjectRef, PyResult,
     TypeProtocol,
 };
 use crate::vm::VirtualMachine;
 use num_bigint::ToBigInt;
+use num_rational::Ratio;
 use num_traits::ToPrimitive;
 
 #[derive(Debug, Copy, Clone, PartialEq)]
@@ -27,6 +29,25 @@ impl From<f64> for PyFloat {
     }
 }
 
+impl PyFloat {
+    fn as_integer_ratio(zelf: PyRef<Self>, vm: &mut VirtualMachine) -> PyResult {
+        let value = zelf.value;
+        if value.is_infinite() {
+            return Err(
+                vm.new_overflow_error("cannot convert Infinity to integer ratio".to_string())
+            );
+        }
+        if value.is_nan() {
+            return Err(vm.new_value_error("cannot convert NaN to integer ratio".to_string()));
+        }
+
+        let ratio = Ratio::from_float(value).unwrap();
+        let numer = vm.ctx.new_int(ratio.numer().clone());
+        let denom = vm.ctx.new_int(ratio.denom().clone());
+        Ok(vm.ctx.new_tuple(vec![numer, denom]))
+    }
+}
+
 fn float_repr(vm: &mut VirtualMachine, args: PyFuncArgs) -> PyResult {
     arg_check!(vm, args, required = [(float, Some(vm.ctx.float_type()))]);
     let v = get_value(float);
@@ -494,4 +515,9 @@ pub fn init(context: &PyContext) {
         "is_integer",
         context.new_rustfunc(float_is_integer),
     );
+    context.set_attr(
+        &float_type,
+        "as_integer_ratio",
+        context.new_rustfunc(PyFloat::as_integer_ratio),
+    );
 }