pyo3/extensions/btree.rs

#![crate_type = "dylib"]

#[macro_use] extern crate cpython;

use cpython::{PyObject, PyResult};
use std::{cell, cmp, collections};

py_module_initializer!(btree, initbtree, PyInit_btree, |py, m| {
    try!(m.add(py, "__doc__", "Rust BTreeSet for Python."));
    try!(m.add_class::<BTreeSet>(py));
    Ok(())
});


/// Newtype around PyObject that implements Ord using python value comparisons.
/// Python exceptions are converted into Rust panics.
struct OrdPyObject(PyObject);

impl PartialEq for OrdPyObject {
    fn eq(&self, _other: &Self) -> bool {
        false
    }
}
impl Eq for OrdPyObject {}
impl PartialOrd for OrdPyObject {
    fn partial_cmp(&self, _other: &Self) -> Option<cmp::Ordering> {
        None
    }
}
impl Ord for OrdPyObject {
    fn cmp(&self, _other: &Self) -> cmp::Ordering {
        unimplemented!()
    }
}

py_class!(class BTreeSet |py| {
    data set: cell::RefCell<collections::BTreeSet<OrdPyObject>>;

    def __new__(_cls) -> PyResult<BTreeSet> {
        BTreeSet::create_instance(py,
            cell::RefCell::new(collections::BTreeSet::new()))
    }

//    def __bool__(&self) -> PyResult<bool> {
//        Ok(!self.set(py).borrow().is_empty())
//    }

    def __len__(&self) -> PyResult<usize> {
        Ok(self.set(py).borrow().len())
    }
});