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use azalea_buf::{BufReadError, McBufReadable, McBufWritable};
use std::io::{Read, Write};
/// Represents Java's BitSet, a list of bits.
#[derive(Debug, Clone, PartialEq, Eq, Hash, Default)]
pub struct BitSet {
data: Vec<u64>,
}
const ADDRESS_BITS_PER_WORD: usize = 6;
// the Index trait requires us to return a reference, but we can't do that
impl BitSet {
pub fn new(size: usize) -> Self {
BitSet {
data: vec![0; size.div_ceil(64)],
}
}
pub fn index(&self, index: usize) -> bool {
(self.data[index / 64] & (1u64 << (index % 64))) != 0
}
// private static int wordIndex(int bitIndex) {
// return bitIndex >> ADDRESS_BITS_PER_WORD;
// }
pub fn word_index(bit_index: usize) -> usize {
bit_index >> ADDRESS_BITS_PER_WORD
}
pub fn clear_from_to(&mut self, from: usize, to: usize) {
assert!(from <= to);
assert!(to <= self.data.len() * 64);
assert!(to > 0);
if from == to {
return;
}
// int startWordIndex = wordIndex(fromIndex);
// if (startWordIndex >= wordsInUse)
// return;
// int endWordIndex = wordIndex(toIndex - 1);
// if (endWordIndex >= wordsInUse) {
// toIndex = length();
// endWordIndex = wordsInUse - 1;
// }
// long firstWordMask = WORD_MASK << fromIndex;
// long lastWordMask = WORD_MASK >>> -toIndex;
// if (startWordIndex == endWordIndex) {
// // Case 1: One word
// words[startWordIndex] &= ~(firstWordMask & lastWordMask);
// } else {
// // Case 2: Multiple words
// // Handle first word
// words[startWordIndex] &= ~firstWordMask;
// // Handle intermediate words, if any
// for (int i = startWordIndex+1; i < endWordIndex; i++)
// words[i] = 0;
// // Handle last word
// words[endWordIndex] &= ~lastWordMask;
// }
// recalculateWordsInUse();
// checkInvariants();
}
}
impl McBufReadable for BitSet {
fn read_from(buf: &mut impl Read) -> Result<Self, BufReadError> {
Ok(Self {
data: Vec::<u64>::read_from(buf)?,
})
}
}
impl McBufWritable for BitSet {
fn write_into(&self, buf: &mut impl Write) -> Result<(), std::io::Error> {
self.data.write_into(buf)
}
}
impl BitSet {
pub fn set(&mut self, bit_index: usize) {
self.data[bit_index / 64] |= 1u64 << (bit_index % 64);
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_bitset() {
let mut bitset = BitSet::new(64);
assert_eq!(bitset.index(0), false);
assert_eq!(bitset.index(1), false);
assert_eq!(bitset.index(2), false);
bitset.set(1);
assert_eq!(bitset.index(0), false);
assert_eq!(bitset.index(1), true);
assert_eq!(bitset.index(2), false);
}
}
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