Merge pull request RustPython#600 from adrian17/as_ratio

windelbouwman · web-flow · commit 458ead0cbc81 · 2019-03-05T07:22:38.000+01:00
Add float.as_integer_ratio()
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/tests/snippets/floats.py b/tests/snippets/floats.py
@@ -87,3 +87,22 @@
 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)
+
diff --git a/vm/Cargo.toml b/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"}
diff --git a/vm/src/obj/objfloat.rs b/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),
+    );
 }
