From 9604957c72ca31d722da8ec5f0fb22ea59cae00d Mon Sep 17 00:00:00 2001 From: David Hewitt <1939362+davidhewitt@users.noreply.github.com> Date: Thu, 17 Aug 2023 09:14:12 +0100 Subject: [PATCH] further refactor num-bigint conversion --- src/conversions/num_bigint.rs | 332 +++++++++++++++++----------------- 1 file changed, 163 insertions(+), 169 deletions(-) diff --git a/src/conversions/num_bigint.rs b/src/conversions/num_bigint.rs index d9428fea932..5cc2157d446 100644 --- a/src/conversions/num_bigint.rs +++ b/src/conversions/num_bigint.rs @@ -51,54 +51,10 @@ use crate::{ ffi, types::*, FromPyObject, IntoPy, Py, PyAny, PyObject, PyResult, Python, ToPyObject, }; -use num_bigint::{BigInt, BigUint, Sign}; -use std::os::raw::c_int; +use num_bigint::{BigInt, BigUint}; #[cfg(not(Py_LIMITED_API))] -use std::os::raw::c_uchar; - -#[cfg(Py_LIMITED_API)] -use std::slice; - -#[cfg(not(Py_LIMITED_API))] -#[inline] -unsafe fn extract(ob: &PyLong, length: usize, is_signed: c_int) -> PyResult> { - let mut buffer = Vec::::with_capacity(length); - crate::err::error_on_minusone( - ob.py(), - ffi::_PyLong_AsByteArray( - ob.as_ptr() as *mut ffi::PyLongObject, - buffer.as_mut_ptr() as *mut u8, - length * 4, - 1, - is_signed, - ), - )?; - buffer.set_len(length); - - Ok(buffer) -} - -#[cfg(Py_LIMITED_API)] -#[inline] -unsafe fn extract(ob: &PyLong, length: usize, is_signed: c_int) -> PyResult> { - use crate::intern; - let py = ob.py(); - let kwargs = if is_signed != 0 { - let kwargs = PyDict::new(py); - kwargs.set_item(intern!(py, "signed"), true)?; - Some(kwargs) - } else { - None - }; - let bytes_obj = ob - .getattr(intern!(py, "to_bytes"))? - .call((length * 4, intern!(py, "little")), kwargs)?; - let bytes: &PyBytes = bytes_obj.downcast_unchecked(); - let bytes_u32 = slice::from_raw_parts(bytes.as_bytes().as_ptr().cast(), length); - - Ok(bytes_u32.to_vec()) -} +use num_bigint::Sign; // for identical functionality between BigInt and BigUint macro_rules! bigint_conversion { @@ -110,7 +66,7 @@ macro_rules! bigint_conversion { let bytes = $to_bytes(self); unsafe { let obj = ffi::_PyLong_FromByteArray( - bytes.as_ptr() as *const c_uchar, + bytes.as_ptr().cast(), bytes.len(), 1, $is_signed, @@ -153,41 +109,46 @@ bigint_conversion!(BigInt, 1, BigInt::to_signed_bytes_le); impl<'source> FromPyObject<'source> for BigInt { fn extract(ob: &'source PyAny) -> PyResult { let py = ob.py(); - unsafe { - let num: Py = Py::from_owned_ptr_or_err(py, ffi::PyNumber_Index(ob.as_ptr()))?; - let n_bits = { - cfg_if::cfg_if! { - if #[cfg(not(Py_LIMITED_API))] { - // fast path - let n_bits = ffi::_PyLong_NumBits(num.as_ptr()); - if n_bits == (-1isize as usize) { - return Err(crate::PyErr::fetch(py)); - } - n_bits - } else { - // slow path - let n_bits_obj = num.getattr(py, crate::intern!(py, "bit_length"))?.call0(py)?; - let n_bits_int: &PyLong = n_bits_obj.downcast_unchecked(py); - n_bits_int.extract::()? + // fast path - checking for subclass of `int` just checks a bit in the type object + let num_owned: Py; + let num = if let Ok(long) = ob.downcast::() { + long + } else { + num_owned = unsafe { Py::from_owned_ptr_or_err(py, ffi::PyNumber_Index(ob.as_ptr()))? }; + num_owned.as_ref(py) + }; + let n_bits = int_n_bits(num)?; + if n_bits == 0 { + return Ok(BigInt::from(0isize)); + } + #[cfg(not(Py_LIMITED_API))] + { + let mut buffer = int_to_u32_vec(num, (n_bits + 32) / 32, true)?; + let sign = if buffer.last().copied().map_or(false, |last| last >> 31 != 0) { + // BigInt::new takes an unsigned array, so need to convert from two's complement + // flip all bits, 'subtract' 1 (by adding one to the unsigned array) + let mut elements = buffer.iter_mut(); + for element in elements.by_ref() { + *element = (!*element).wrapping_add(1); + if *element != 0 { + // if the element didn't wrap over, no need to keep adding further ... + break; } } - }; - - if n_bits == 0 { - return Ok(BigInt::from(0isize)); - } - let n_digits = (n_bits + 32) / 32; - let mut buffer = extract(num.as_ref(py), n_digits, 1)?; - buffer - .iter_mut() - .for_each(|chunk| *chunk = u32::from_le(*chunk)); - - Ok(if buffer.last().unwrap() >> 31 != 0 { - buffer.iter_mut().for_each(|element| *element = !*element); - BigInt::new(Sign::Minus, buffer) - 1 + // ... so just two's complement the rest + for element in elements { + *element = !*element; + } + Sign::Minus } else { - BigInt::new(Sign::Plus, buffer) - }) + Sign::Plus + }; + Ok(BigInt::new(sign, buffer)) + } + #[cfg(Py_LIMITED_API)] + { + let bytes = int_to_py_bytes(num, (n_bits + 8) / 8, true)?; + Ok(BigInt::from_signed_bytes_le(bytes.as_bytes())) } } } @@ -196,37 +157,92 @@ impl<'source> FromPyObject<'source> for BigInt { impl<'source> FromPyObject<'source> for BigUint { fn extract(ob: &'source PyAny) -> PyResult { let py = ob.py(); - unsafe { - let num: Py = Py::from_owned_ptr_or_err(py, ffi::PyNumber_Index(ob.as_ptr()))?; - let n_bits = { - cfg_if::cfg_if! { - if #[cfg(not(Py_LIMITED_API))] { - // fast path - let n_bits = ffi::_PyLong_NumBits(num.as_ptr()); - if n_bits == (-1isize as usize) { - return Err(crate::PyErr::fetch(py)); - } - n_bits - } else { - // slow path - let n_bits_obj = num.getattr(py, crate::intern!(py, "bit_length"))?.call0(py)?; - let n_bits_int: &PyLong = n_bits_obj.downcast_unchecked(py); - n_bits_int.extract::()? - } - } - }; + // fast path - checking for subclass of `int` just checks a bit in the type object + let num_owned: Py; + let num = if let Ok(long) = ob.downcast::() { + long + } else { + num_owned = unsafe { Py::from_owned_ptr_or_err(py, ffi::PyNumber_Index(ob.as_ptr()))? }; + num_owned.as_ref(py) + }; + let n_bits = int_n_bits(num)?; + if n_bits == 0 { + return Ok(BigUint::from(0usize)); + } + #[cfg(not(Py_LIMITED_API))] + { + let buffer = int_to_u32_vec(num, (n_bits + 31) / 32, false)?; + Ok(BigUint::new(buffer)) + } + #[cfg(Py_LIMITED_API)] + { + let bytes = int_to_py_bytes(num, (n_bits + 7) / 8, false)?; + Ok(BigUint::from_bytes_le(bytes.as_bytes())) + } + } +} - if n_bits == 0 { - return Ok(BigUint::from(0usize)); - } - let n_digits = (n_bits + 31) / 32; - let mut buffer = extract(num.as_ref(py), n_digits, 0)?; - buffer - .iter_mut() - .for_each(|chunk| *chunk = u32::from_le(*chunk)); +#[cfg(not(Py_LIMITED_API))] +#[inline] +fn int_to_u32_vec(long: &PyLong, n_digits: usize, is_signed: bool) -> PyResult> { + let mut buffer = Vec::with_capacity(n_digits); + unsafe { + crate::err::error_on_minusone( + long.py(), + ffi::_PyLong_AsByteArray( + long.as_ptr().cast(), + buffer.as_mut_ptr() as *mut u8, + n_digits * 4, + 1, + is_signed.into(), + ), + )?; + buffer.set_len(n_digits) + }; + buffer + .iter_mut() + .for_each(|chunk| *chunk = u32::from_le(*chunk)); - Ok(BigUint::new(buffer)) + Ok(buffer) +} + +#[cfg(Py_LIMITED_API)] +fn int_to_py_bytes(long: &PyLong, n_bytes: usize, is_signed: bool) -> PyResult<&PyBytes> { + use crate::intern; + let py = long.py(); + let kwargs = if is_signed { + let kwargs = PyDict::new(py); + kwargs.set_item(intern!(py, "signed"), true)?; + Some(kwargs) + } else { + None + }; + let bytes = long.call_method( + intern!(py, "to_bytes"), + (n_bytes, intern!(py, "little")), + kwargs, + )?; + Ok(bytes.downcast()?) +} + +#[inline] +fn int_n_bits(long: &PyLong) -> PyResult { + let py = long.py(); + #[cfg(not(Py_LIMITED_API))] + { + // fast path + let n_bits = unsafe { ffi::_PyLong_NumBits(long.as_ptr()) }; + if n_bits == (-1isize as usize) { + return Err(crate::PyErr::fetch(py)); } + Ok(n_bits) + } + + #[cfg(Py_LIMITED_API)] + { + // slow path + long.call_method0(crate::intern!(py, "bit_length")) + .and_then(PyAny::extract) } } @@ -236,82 +252,62 @@ mod tests { use crate::types::{PyDict, PyModule}; use indoc::indoc; - fn python_fib(py: Python<'_>) -> &PyModule { - let fib_code = indoc!( - r#" - def fib(n): - f0, f1 = 0, 1 - for _ in range(n): - f0, f1 = f1, f0 + f1 - return f0 - - def fib_neg(n): - return -fib(n) - "# - ); - PyModule::from_code(py, fib_code, "fib.py", "fib").unwrap() - } - - fn rust_fib(n: usize) -> T + fn rust_fib() -> impl Iterator where T: From, for<'a> &'a T: std::ops::Add, { - let mut f0: T = T::from(0); + let mut f0: T = T::from(1); let mut f1: T = T::from(1); - for _ in 0..n { + std::iter::from_fn(move || { let f2 = &f0 + &f1; - f0 = std::mem::replace(&mut f1, f2); - } - f0 + Some(std::mem::replace(&mut f0, std::mem::replace(&mut f1, f2))) + }) + } + + fn python_fib(py: Python<'_>) -> impl Iterator + '_ { + let mut f0 = 1.to_object(py); + let mut f1 = 1.to_object(py); + std::iter::from_fn(move || { + let f2 = f0.call_method1(py, "__add__", (f1.as_ref(py),)).unwrap(); + Some(std::mem::replace(&mut f0, std::mem::replace(&mut f1, f2))) + }) } #[test] fn convert_biguint() { Python::with_gil(|py| { - let rs_result: BigUint = rust_fib(400); - let fib = python_fib(py); - let locals = PyDict::new(py); - locals.set_item("rs_result", &rs_result).unwrap(); - locals.set_item("fib", fib).unwrap(); - // Checks if Rust BigUint -> Python Long conversion is correct - py.run("assert fib.fib(400) == rs_result", None, Some(locals)) - .unwrap(); - // Checks if Python Long -> Rust BigUint conversion is correct if N is small - let py_result: BigUint = - FromPyObject::extract(fib.getattr("fib").unwrap().call1((400,)).unwrap()).unwrap(); - assert_eq!(rs_result, py_result); - // Checks if Python Long -> Rust BigUint conversion is correct if N is large - let rs_result: BigUint = rust_fib(2000); - let py_result: BigUint = - FromPyObject::extract(fib.getattr("fib").unwrap().call1((2000,)).unwrap()).unwrap(); - assert_eq!(rs_result, py_result); + // check the first 2000 numbers in the fibonacci sequence + for (py_result, rs_result) in python_fib(py).zip(rust_fib::()).take(2000) { + // Python -> Rust + assert_eq!(py_result.extract::(py).unwrap(), rs_result); + // Rust -> Python + assert!(py_result.as_ref(py).eq(rs_result).unwrap()); + } }); } #[test] fn convert_bigint() { Python::with_gil(|py| { - let rs_result = rust_fib::(400) * -1; - let fib = python_fib(py); - let locals = PyDict::new(py); - locals.set_item("rs_result", &rs_result).unwrap(); - locals.set_item("fib", fib).unwrap(); - // Checks if Rust BigInt -> Python Long conversion is correct - py.run("assert fib.fib_neg(400) == rs_result", None, Some(locals)) - .unwrap(); - // Checks if Python Long -> Rust BigInt conversion is correct if N is small - let py_result: BigInt = - FromPyObject::extract(fib.getattr("fib_neg").unwrap().call1((400,)).unwrap()) - .unwrap(); - assert_eq!(rs_result, py_result); - // Checks if Python Long -> Rust BigInt conversion is correct if N is large - let rs_result = rust_fib::(2000) * -1; - let py_result: BigInt = - FromPyObject::extract(fib.getattr("fib_neg").unwrap().call1((2000,)).unwrap()) - .unwrap(); - assert_eq!(rs_result, py_result); - }) + // check the first 2000 numbers in the fibonacci sequence + for (py_result, rs_result) in python_fib(py).zip(rust_fib::()).take(2000) { + // Python -> Rust + assert_eq!(py_result.extract::(py).unwrap(), rs_result); + // Rust -> Python + assert!(py_result.as_ref(py).eq(&rs_result).unwrap()); + + // negate + + let rs_result = rs_result * -1; + let py_result = py_result.call_method0(py, "__neg__").unwrap(); + + // Python -> Rust + assert_eq!(py_result.extract::(py).unwrap(), rs_result); + // Rust -> Python + assert!(py_result.as_ref(py).eq(rs_result).unwrap()); + } + }); } fn python_index_class(py: Python<'_>) -> &PyModule { @@ -341,9 +337,7 @@ mod tests { #[test] fn handle_zero() { Python::with_gil(|py| { - let fib = python_fib(py); - let zero: BigInt = - FromPyObject::extract(fib.getattr("fib").unwrap().call1((0,)).unwrap()).unwrap(); + let zero: BigInt = 0.to_object(py).extract(py).unwrap(); assert_eq!(zero, BigInt::from(0)); }) }