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use std::cell::Cell;
use crate::pyobject::{
PyClassImpl, PyContext, PyObjectRef, PyRef, PyResult, PyValue, TypeProtocol,
};
use crate::vm::VirtualMachine;
use super::objtype;
use super::objtype::PyClassRef;
pub fn get_iter(vm: &VirtualMachine, iter_target: &PyObjectRef) -> PyResult {
if let Some(method_or_err) = vm.get_method(iter_target.clone(), "__iter__") {
let method = method_or_err?;
vm.invoke(&method, vec![])
} else {
vm.get_method_or_type_error(iter_target.clone(), "__getitem__", || {
format!("Cannot iterate over {}", iter_target.class().name)
})?;
let obj_iterator = PySequenceIterator {
position: Cell::new(0),
obj: iter_target.clone(),
reversed: false,
};
Ok(obj_iterator.into_ref(vm).into_object())
}
}
pub fn call_next(vm: &VirtualMachine, iter_obj: &PyObjectRef) -> PyResult {
vm.call_method(iter_obj, "__next__", vec![])
}
pub fn get_next_object(
vm: &VirtualMachine,
iter_obj: &PyObjectRef,
) -> PyResult<Option<PyObjectRef>> {
let next_obj: PyResult = call_next(vm, iter_obj);
match next_obj {
Ok(value) => Ok(Some(value)),
Err(next_error) => {
if objtype::isinstance(&next_error, &vm.ctx.exceptions.stop_iteration) {
Ok(None)
} else {
Err(next_error)
}
}
}
}
pub fn get_all(vm: &VirtualMachine, iter_obj: &PyObjectRef) -> PyResult<Vec<PyObjectRef>> {
let mut elements = vec![];
loop {
let element = get_next_object(vm, iter_obj)?;
match element {
Some(v) => elements.push(v),
None => break,
}
}
Ok(elements)
}
pub fn new_stop_iteration(vm: &VirtualMachine) -> PyObjectRef {
let stop_iteration_type = vm.ctx.exceptions.stop_iteration.clone();
vm.new_exception(stop_iteration_type, "End of iterator".to_string())
}
#[pyclass]
#[derive(Debug)]
pub struct PySequenceIterator {
pub position: Cell<isize>,
pub obj: PyObjectRef,
pub reversed: bool,
}
impl PyValue for PySequenceIterator {
fn class(vm: &VirtualMachine) -> PyClassRef {
vm.ctx.iter_type()
}
}
#[pyimpl]
impl PySequenceIterator {
#[pymethod(name = "__next__")]
fn next(&self, vm: &VirtualMachine) -> PyResult {
if self.position.get() >= 0 {
let step: isize = if self.reversed { -1 } else { 1 };
let number = vm.ctx.new_int(self.position.get());
match vm.call_method(&self.obj, "__getitem__", vec![number]) {
Ok(val) => {
self.position.set(self.position.get() + step);
Ok(val)
}
Err(ref e) if objtype::isinstance(&e, &vm.ctx.exceptions.index_error) => {
Err(new_stop_iteration(vm))
}
Err(e) => Err(e),
}
} else {
Err(new_stop_iteration(vm))
}
}
#[pymethod(name = "__iter__")]
fn iter(zelf: PyRef<Self>, _vm: &VirtualMachine) -> PyRef<Self> {
zelf
}
}
pub fn init(context: &PyContext) {
PySequenceIterator::extend_class(context, &context.types.iter_type);
}