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// Copyright (C) 2019-2020 Aleo Systems Inc.
// This file is part of the snarkVM library.

// The snarkVM library is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// The snarkVM library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with the snarkVM library. If not, see <https://www.gnu.org/licenses/>.

#[derive(Debug)]
pub struct BitIterator<E> {
    t: E,
    n: usize,
}

#[allow(clippy::len_without_is_empty)]
impl<E: AsRef<[u64]>> BitIterator<E> {
    pub fn new(t: E) -> Self {
        let n = t.as_ref().len() * 64;

        BitIterator { t, n }
    }

    pub fn len(&self) -> usize {
        self.n
    }
}

impl<E: AsRef<[u64]>> Iterator for BitIterator<E> {
    type Item = bool;

    fn next(&mut self) -> Option<bool> {
        if self.n == 0 {
            None
        } else {
            self.n -= 1;
            let part = self.n / 64;
            let bit = self.n - (64 * part);

            Some(self.t.as_ref()[part] & (1 << bit) > 0)
        }
    }
}