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pub fn string_to_adjacency_matrix(graph_str: &str) -> (Vec<f32>, usize) {
let bytes = graph_str.as_bytes();
let size = size_from_bytes(bytes).unwrap_or_else(|err| {
panic!("{}", err);
});
let mut bit_vec: Vec<u8> = Vec::new();
bytes.iter().skip(1).map(|byte| byte - 63).for_each(|byte| {
for shift in (0..6).rev() {
if (byte & 1 << shift) > 0 {
bit_vec.push(1);
} else {
bit_vec.push(0);
}
}
});
let adjusted_bit_vec_len = bit_vec.len() - (bit_vec.len() - (size * (size - 1)) / 2);
let mut bit_vec_iter = bit_vec[0..adjusted_bit_vec_len].iter();
let mut adjacency_matrix = vec![0.0; size * size];
for i in 1..size {
for j in 0..i {
if *(bit_vec_iter.next().unwrap()) == 1 {
adjacency_matrix[i * size + j] = 1.0;
adjacency_matrix[j * size + i] = 1.0;
}
}
}
(adjacency_matrix, size)
}
pub fn adjacency_matrix_to_string(adjacency_matrix: &[f32], size: usize) -> String {
let mut size_bytes = size_to_bytes(size).unwrap_or_else(|err| {
panic!("{}", err);
});
let mut bit_vec = Vec::new();
for i in 1..size {
for j in 0..i {
if adjacency_matrix[i * size + j] == 1.0 {
bit_vec.push(1);
} else {
bit_vec.push(0);
}
}
}
let mut bytes = bit_vec_to_bytes(bit_vec);
size_bytes.append(&mut bytes);
unsafe { String::from_utf8_unchecked(size_bytes) }
}
fn int_to_bit_vec(mut x: usize) -> Vec<u8> {
let mut bit_vec = Vec::new();
while x != 0 {
if x & 1 == 1 {
bit_vec.push(1);
} else {
bit_vec.push(0);
}
x >>= 1;
}
bit_vec.reverse();
bit_vec
}
fn bit_vec_to_bytes(mut bit_vec: Vec<u8>) -> Vec<u8> {
let next_multiple_of_six = bit_vec.len() - 1 - (bit_vec.len() - 1) % 6 + 6;
for _ in 0..(next_multiple_of_six - bit_vec.len()) {
bit_vec.push(0);
}
let mut bytes = Vec::new();
let mut bit_vec_iter = bit_vec.iter();
for _ in 0..(bit_vec.len() / 6) {
let mut byte: u8 = 0;
for shift in (0..6).rev() {
byte |= bit_vec_iter.next().unwrap() << shift;
}
bytes.push(byte);
}
bytes.iter().map(|byte| byte + 63).collect()
}
fn size_from_bytes(bytes: &[u8]) -> Result<usize, &'static str> {
if bytes[0] == 126 {
return Err("size is greater than 62");
}
Ok((bytes[0] - 63) as usize)
}
fn size_to_bytes(size: usize) -> Result<Vec<u8>, &'static str> {
match size {
s if s <= 62 => Ok(vec![size as u8 + 63]),
s if s <= 258047 => {
let mut size_bytes = vec![126];
size_bytes.append(&mut bit_vec_to_bytes(int_to_bit_vec(size)));
Ok(size_bytes)
}
_ => Err("size is greater than 258,047"),
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn size_four_graph_to_adjacency_matrix() {
let graph_str = String::from("C]");
let (adjacency_matrix, size) = string_to_adjacency_matrix(&graph_str);
assert_eq!(
adjacency_matrix,
vec![0.0, 0.0, 1.0, 1.0, 0.0, 0.0, 1.0, 1.0, 1.0, 1.0, 0.0, 0.0, 1.0, 1.0, 0.0, 0.0]
);
assert_eq!(size, 4);
}
#[test]
fn size_120000_to_bytes() {
let size = 120000;
let bytes = vec![126, 121, 101, 63];
assert_eq!(size_to_bytes(size).unwrap(), bytes);
}
}