1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145

use super::{
    IterStatus, PositionIterInternal, PyGenericAlias, PyIntRef, PyTupleRef, PyType, PyTypeRef,
};
use crate::common::lock::{PyMutex, PyRwLock};
use crate::{
    class::PyClassImpl,
    convert::ToPyObject,
    function::OptionalArg,
    protocol::{PyIter, PyIterReturn},
    types::{Constructor, IterNext, Iterable, SelfIter},
    AsObject, Context, Py, PyObjectRef, PyPayload, PyResult, VirtualMachine,
};
use malachite_bigint::BigInt;
use num_traits::Zero;

#[pyclass(module = false, name = "enumerate", traverse)]
#[derive(Debug)]
pub struct PyEnumerate {
    #[pytraverse(skip)]
    counter: PyRwLock<BigInt>,
    iterator: PyIter,
}

impl PyPayload for PyEnumerate {
    fn class(ctx: &Context) -> &'static Py<PyType> {
        ctx.types.enumerate_type
    }
}

#[derive(FromArgs)]
pub struct EnumerateArgs {
    iterator: PyIter,
    #[pyarg(any, optional)]
    start: OptionalArg<PyIntRef>,
}

impl Constructor for PyEnumerate {
    type Args = EnumerateArgs;

    fn py_new(
        cls: PyTypeRef,
        Self::Args { iterator, start }: Self::Args,
        vm: &VirtualMachine,
    ) -> PyResult {
        let counter = start.map_or_else(BigInt::zero, |start| start.as_bigint().clone());
        PyEnumerate {
            counter: PyRwLock::new(counter),
            iterator,
        }
        .into_ref_with_type(vm, cls)
        .map(Into::into)
    }
}

#[pyclass(with(Py, IterNext, Iterable, Constructor), flags(BASETYPE))]
impl PyEnumerate {
    #[pyclassmethod(magic)]
    fn class_getitem(cls: PyTypeRef, args: PyObjectRef, vm: &VirtualMachine) -> PyGenericAlias {
        PyGenericAlias::new(cls, args, vm)
    }
}

#[pyclass]
impl Py<PyEnumerate> {
    #[pymethod(magic)]
    fn reduce(&self) -> (PyTypeRef, (PyIter, BigInt)) {
        (
            self.class().to_owned(),
            (self.iterator.clone(), self.counter.read().clone()),
        )
    }
}

impl SelfIter for PyEnumerate {}
impl IterNext for PyEnumerate {
    fn next(zelf: &Py<Self>, vm: &VirtualMachine) -> PyResult<PyIterReturn> {
        let next_obj = match zelf.iterator.next(vm)? {
            PyIterReturn::StopIteration(v) => return Ok(PyIterReturn::StopIteration(v)),
            PyIterReturn::Return(obj) => obj,
        };
        let mut counter = zelf.counter.write();
        let position = counter.clone();
        *counter += 1;
        Ok(PyIterReturn::Return((position, next_obj).to_pyobject(vm)))
    }
}

#[pyclass(module = false, name = "reversed", traverse)]
#[derive(Debug)]
pub struct PyReverseSequenceIterator {
    internal: PyMutex<PositionIterInternal<PyObjectRef>>,
}

impl PyPayload for PyReverseSequenceIterator {
    fn class(ctx: &Context) -> &'static Py<PyType> {
        ctx.types.reverse_iter_type
    }
}

#[pyclass(with(IterNext, Iterable))]
impl PyReverseSequenceIterator {
    pub fn new(obj: PyObjectRef, len: usize) -> Self {
        let position = len.saturating_sub(1);
        Self {
            internal: PyMutex::new(PositionIterInternal::new(obj, position)),
        }
    }

    #[pymethod(magic)]
    fn length_hint(&self, vm: &VirtualMachine) -> PyResult<usize> {
        let internal = self.internal.lock();
        if let IterStatus::Active(obj) = &internal.status {
            if internal.position <= obj.length(vm)? {
                return Ok(internal.position + 1);
            }
        }
        Ok(0)
    }

    #[pymethod(magic)]
    fn setstate(&self, state: PyObjectRef, vm: &VirtualMachine) -> PyResult<()> {
        self.internal.lock().set_state(state, |_, pos| pos, vm)
    }

    #[pymethod(magic)]
    fn reduce(&self, vm: &VirtualMachine) -> PyTupleRef {
        self.internal
            .lock()
            .builtins_reversed_reduce(|x| x.clone(), vm)
    }
}

impl SelfIter for PyReverseSequenceIterator {}
impl IterNext for PyReverseSequenceIterator {
    fn next(zelf: &Py<Self>, vm: &VirtualMachine) -> PyResult<PyIterReturn> {
        zelf.internal
            .lock()
            .rev_next(|obj, pos| PyIterReturn::from_getitem_result(obj.get_item(&pos, vm), vm))
    }
}

pub fn init(context: &Context) {
    PyEnumerate::extend_class(context, context.types.enumerate_type);
    PyReverseSequenceIterator::extend_class(context, context.types.reverse_iter_type);
}