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Fix itertools chain #3788

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Merged
youknowone merged 6 commits into from
Jun 15, 2022
Merged

Fix itertools chain #3788

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a9d16e2
test: itertools.chain evaluate lazliy
rng-dynamics Jun 10, 2022
4c11720
feat: itertools.chain evaluate lazily
rng-dynamics Jun 12, 2022
33bcc89
test: itertools.chain stop iteration on error
rng-dynamics Jun 14, 2022
ec18a12
refactor
rng-dynamics Jun 14, 2022
76ef074
Release source when PyIterReturn::StopIteration
rng-dynamics Jun 14, 2022
480f5f1
fix tests
rng-dynamics Jun 14, 2022
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12 changes: 12 additions & 0 deletions extra_tests/snippets/stdlib_itertools.py
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Original file line number Diff line number Diff line change
Expand Up @@ -50,6 +50,18 @@
with assert_raises(TypeError):
next(x)

# iterables are lazily evaluted
x = chain.from_iterable(itertools.repeat(range(2)))
assert next(x) == 0
assert next(x) == 1
assert next(x) == 0
assert next(x) == 1

x = chain(1, [2])
with assert_raises(TypeError):
next(x)
with assert_raises(StopIteration):
next(x)

# itertools.count tests

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90 changes: 51 additions & 39 deletions vm/src/stdlib/itertools.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,7 @@ mod decl {
rc::PyRc,
};
use crate::{
builtins::{int, PyGenericAlias, PyInt, PyIntRef, PyTuple, PyTupleRef, PyTypeRef},
builtins::{int, PyGenericAlias, PyInt, PyIntRef, PyList, PyTuple, PyTupleRef, PyTypeRef},
convert::ToPyObject,
function::{ArgCallable, FuncArgs, OptionalArg, OptionalOption, PosArgs},
identifier,
Expand All @@ -25,19 +25,18 @@ mod decl {
#[pyclass(name = "chain")]
#[derive(Debug, PyPayload)]
struct PyItertoolsChain {
iterables: Vec<PyObjectRef>,
cur_idx: AtomicCell<usize>,
cached_iter: PyRwLock<Option<PyIter>>,
source: PyRwLock<Option<PyIter>>,
active: PyRwLock<Option<PyIter>>,
}

#[pyimpl(with(IterNext))]
impl PyItertoolsChain {
#[pyslot]
fn slot_new(cls: PyTypeRef, args: FuncArgs, vm: &VirtualMachine) -> PyResult {
let args_list = PyList::from(args.args);
PyItertoolsChain {
iterables: args.args,
cur_idx: AtomicCell::new(0),
cached_iter: PyRwLock::new(None),
source: PyRwLock::new(Some(args_list.to_pyobject(vm).get_iter(vm)?)),
active: PyRwLock::new(None),
}
.into_ref_with_type(vm, cls)
.map(Into::into)
Expand All @@ -46,13 +45,12 @@ mod decl {
#[pyclassmethod]
fn from_iterable(
cls: PyTypeRef,
iterable: PyObjectRef,
source: PyObjectRef,
vm: &VirtualMachine,
) -> PyResult<PyRef<Self>> {
PyItertoolsChain {
iterables: iterable.try_to_value(vm)?,
cur_idx: AtomicCell::new(0),
cached_iter: PyRwLock::new(None),
source: PyRwLock::new(Some(source.get_iter(vm)?)),
active: PyRwLock::new(None),
}
.into_ref_with_type(vm, cls)
}
Expand All @@ -65,37 +63,51 @@ mod decl {
impl IterNextIterable for PyItertoolsChain {}
impl IterNext for PyItertoolsChain {
fn next(zelf: &Py<Self>, vm: &VirtualMachine) -> PyResult<PyIterReturn> {
loop {
let pos = zelf.cur_idx.load();
if pos >= zelf.iterables.len() {
break;
}
let cur_iter = if zelf.cached_iter.read().is_none() {
// We need to call "get_iter" outside of the lock.
let iter = zelf.iterables[pos].clone().get_iter(vm)?;
*zelf.cached_iter.write() = Some(iter.clone());
iter
} else if let Some(cached_iter) = (*zelf.cached_iter.read()).clone() {
cached_iter
} else {
// Someone changed cached iter to None since we checked.
continue;
};

// We need to call "next" outside of the lock.
match cur_iter.next(vm) {
Ok(PyIterReturn::Return(ok)) => return Ok(PyIterReturn::Return(ok)),
Ok(PyIterReturn::StopIteration(_)) => {
zelf.cur_idx.fetch_add(1);
*zelf.cached_iter.write() = None;
let source = if let Some(source) = zelf.source.read().clone() {
source
} else {
return Ok(PyIterReturn::StopIteration(None));
};
let next = loop {
let maybe_active = zelf.active.read().clone();
if let Some(active) = maybe_active {
match active.next(vm) {
Ok(PyIterReturn::Return(ok)) => {
break Ok(PyIterReturn::Return(ok));
}
Ok(PyIterReturn::StopIteration(_)) => {
*zelf.active.write() = None;
}
Err(err) => {
break Err(err);
}
}
Err(err) => {
return Err(err);
} else {
match source.next(vm) {
Ok(PyIterReturn::Return(ok)) => match ok.get_iter(vm) {
Ok(iter) => {
*zelf.active.write() = Some(iter);
}
Err(err) => {
break Err(err);
}
},
Ok(PyIterReturn::StopIteration(_)) => {
break Ok(PyIterReturn::StopIteration(None));
}
Err(err) => {
break Err(err);
}
}
}
}

Ok(PyIterReturn::StopIteration(None))
};
match next {
Err(_) | Ok(PyIterReturn::StopIteration(_)) => {
*zelf.source.write() = None;
}
_ => {}
};
next
}
}

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