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Add itertool.combinations.__reduce__ method #3931

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merged 1 commit into from
Nov 18, 2022
Merged

Add itertool.combinations.__reduce__ method #3931

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101 changes: 74 additions & 27 deletions vm/src/stdlib/itertools.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1308,6 +1308,7 @@ mod decl {
struct PyItertoolsCombinations {
pool: Vec<PyObjectRef>,
indices: PyRwLock<Vec<usize>>,
result: PyRwLock<Option<Vec<usize>>>,
r: AtomicCell<usize>,
exhausted: AtomicCell<bool>,
}
Expand Down Expand Up @@ -1341,6 +1342,7 @@ 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 +1352,39 @@ mod decl {
}

#[pyclass(with(IterNext, Constructor))]
impl PyItertoolsCombinations {}
impl PyItertoolsCombinations {
#[pymethod(magic)]
fn reduce(zelf: PyRef<Self>, vm: &VirtualMachine) -> PyTupleRef {
let result = zelf.result.read();
if let Some(result) = &*result {
if zelf.exhausted.load() {
vm.new_tuple((
zelf.class().to_owned(),
vm.new_tuple((vm.new_tuple(()), vm.ctx.new_int(zelf.r.load()))),
))
} else {
vm.new_tuple((
zelf.class().to_owned(),
vm.new_tuple((
vm.new_tuple(zelf.pool.clone()),
vm.ctx.new_int(zelf.r.load()),
)),
vm.ctx
.new_tuple(result.iter().map(|&i| zelf.pool[i].clone()).collect()),
))
}
} else {
vm.new_tuple((
zelf.class().to_owned(),
vm.new_tuple((
vm.new_tuple(zelf.pool.clone()),
vm.ctx.new_int(zelf.r.load()),
)),
))
}
}
}

impl IterNextIterable for PyItertoolsCombinations {}
impl IterNext for PyItertoolsCombinations {
fn next(zelf: &Py<Self>, vm: &VirtualMachine) -> PyResult<PyIterReturn> {
Expand All @@ -1367,38 +1401,51 @@ 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 = zelf.result.write();

let mut indices = zelf.indices.write();
if let Some(ref mut result) = *result {
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);
} 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);
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;
}
for j in 0..r {
result[j] = indices[j];
}
}
} else {
*result = Some((0..r).collect());
}

Ok(PyIterReturn::Return(res.into()))
Ok(PyIterReturn::Return(
vm.ctx
.new_tuple(
result
.as_ref()
.unwrap()
.iter()
.map(|&i| zelf.pool[i].clone())
.collect(),
)
.into(),
))
}
}

Expand Down