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Merged
merged 2 commits into from
Nov 18, 2022
Merged

Add combinations.__reduce__ #4272

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5608808
Add itertool.combinations.__reduce__ method
seryoungshim17 Jul 19, 2022
dd93ec3
Add combinations.__reduce__
yonmilk Nov 11, 2022
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102 changes: 73 additions & 29 deletions vm/src/stdlib/itertools.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,10 @@ pub(crate) use decl::make_module;
#[pymodule(name = "itertools")]
mod decl {
use crate::{
builtins::{int, PyGenericAlias, PyInt, PyIntRef, PyList, PyTuple, PyTupleRef, PyTypeRef},
builtins::{
int, tuple::IntoPyTuple, PyGenericAlias, PyInt, PyIntRef, PyList, PyTuple, PyTupleRef,
PyTypeRef,
},
common::{
lock::{PyMutex, PyRwLock, PyRwLockWriteGuard},
rc::PyRc,
Expand Down Expand Up @@ -1308,6 +1311,7 @@ mod decl {
struct PyItertoolsCombinations {
pool: Vec<PyObjectRef>,
indices: PyRwLock<Vec<usize>>,
result: PyRwLock<Option<Vec<PyObjectRef>>>,
r: AtomicCell<usize>,
exhausted: AtomicCell<bool>,
}
Expand Down Expand Up @@ -1341,6 +1345,7 @@ mod decl {
PyItertoolsCombinations {
pool,
indices: PyRwLock::new((0..r).collect()),
result: PyRwLock::new(None),
r: AtomicCell::new(r),
exhausted: AtomicCell::new(r > n),
}
Expand All @@ -1350,7 +1355,36 @@ mod decl {
}

#[pyclass(with(IterNext, Constructor))]
impl PyItertoolsCombinations {}
impl PyItertoolsCombinations {
#[pymethod(magic)]
fn reduce(zelf: PyRef<Self>, vm: &VirtualMachine) -> PyTupleRef {
let r = zelf.r.load();

let class = zelf.class().to_owned();

if zelf.exhausted.load() {
return vm.new_tuple((
class,
vm.new_tuple((vm.ctx.empty_tuple.clone(), vm.ctx.new_int(r))),
));
}

let tup = vm.new_tuple((zelf.pool.clone().into_pytuple(vm), vm.ctx.new_int(r)));

if zelf.result.read().is_none() {
vm.new_tuple((class, tup))
} else {
let mut indices: Vec<PyObjectRef> = Vec::new();

for item in &zelf.indices.read()[..r] {
indices.push(vm.new_pyobj(*item));
}

vm.new_tuple((class, tup, indices.into_pytuple(vm)))
}
}
}

impl IterNextIterable for PyItertoolsCombinations {}
impl IterNext for PyItertoolsCombinations {
fn next(zelf: &Py<Self>, vm: &VirtualMachine) -> PyResult<PyIterReturn> {
Expand All @@ -1367,38 +1401,48 @@ mod decl {
return Ok(PyIterReturn::Return(vm.new_tuple(()).into()));
}

let res = vm.ctx.new_tuple(
zelf.indices
.read()
.iter()
.map(|&i| zelf.pool[i].clone())
.collect(),
);
let mut result_lock = zelf.result.write();
let result = if let Some(ref mut result) = *result_lock {
let mut indices = zelf.indices.write();

let mut indices = zelf.indices.write();
// Scan indices right-to-left until finding one that is not at its maximum (i + n - r).
let mut idx = r as isize - 1;
while idx >= 0 && indices[idx as usize] == idx as usize + n - r {
idx -= 1;
}

// Scan indices right-to-left until finding one that is not at its maximum (i + n - r).
let mut idx = r as isize - 1;
while idx >= 0 && indices[idx as usize] == idx as usize + n - r {
idx -= 1;
}
// If no suitable index is found, then the indices are all at
// their maximum value and we're done.
if idx < 0 {
zelf.exhausted.store(true);
return Ok(PyIterReturn::StopIteration(None));
} else {
// Increment the current index which we know is not at its
// maximum. Then move back to the right setting each index
// to its lowest possible value (one higher than the index
// to its left -- this maintains the sort order invariant).
indices[idx as usize] += 1;
for j in idx as usize + 1..r {
indices[j] = indices[j - 1] + 1;
}

// If no suitable index is found, then the indices are all at
// their maximum value and we're done.
if idx < 0 {
zelf.exhausted.store(true);
} else {
// Increment the current index which we know is not at its
// maximum. Then move back to the right setting each index
// to its lowest possible value (one higher than the index
// to its left -- this maintains the sort order invariant).
indices[idx as usize] += 1;
for j in idx as usize + 1..r {
indices[j] = indices[j - 1] + 1;
// Update the result tuple for the new indices
// starting with i, the leftmost index that changed
for i in idx as usize..r {
let index = indices[i];
let elem = &zelf.pool[index];
result[i] = elem.to_owned();
}

result.to_vec()
}
}
} else {
let res = zelf.pool[0..r].to_vec();
*result_lock = Some(res.clone());
res
};

Ok(PyIterReturn::Return(res.into()))
Ok(PyIterReturn::Return(vm.ctx.new_tuple(result).into()))
}
}

Expand Down