91 lines
2 KiB
Rust
91 lines
2 KiB
Rust
|
use std::io;
|
||
|
|
||
|
pub struct StackVec<'a, T: 'a> {
|
||
|
data: &'a mut [T],
|
||
|
length: usize,
|
||
|
}
|
||
|
|
||
|
impl<'a, T> StackVec<'a, T> {
|
||
|
pub fn from(data: &mut [T]) -> StackVec<T> {
|
||
|
StackVec{
|
||
|
data,
|
||
|
length: 0,
|
||
|
}
|
||
|
}
|
||
|
}
|
||
|
|
||
|
impl<'a, T> StackVec<'a, T> {
|
||
|
pub fn len(&self) -> usize {
|
||
|
self.length
|
||
|
}
|
||
|
}
|
||
|
|
||
|
impl<'a> io::Write for StackVec<'a, u8> {
|
||
|
fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
|
||
|
if buf.len() > (self.data.len() - self.length) {
|
||
|
// not enough space on buffer.
|
||
|
return Err(io::Error::from(io::ErrorKind::WriteZero));
|
||
|
}
|
||
|
let mut writable = &mut self.data[self.length..][0..buf.len()];
|
||
|
writable.copy_from_slice(buf);
|
||
|
self.length += buf.len();
|
||
|
Ok(buf.len())
|
||
|
}
|
||
|
|
||
|
fn flush(&mut self) -> io::Result<()> {
|
||
|
Ok(())
|
||
|
}
|
||
|
}
|
||
|
|
||
|
#[cfg(test)]
|
||
|
mod tests {
|
||
|
use super::*;
|
||
|
|
||
|
#[test]
|
||
|
fn vec_write() {
|
||
|
use std::io::Write;
|
||
|
|
||
|
let mut buf = [0u8; 200];
|
||
|
{
|
||
|
let mut vec = StackVec::from(&mut buf);
|
||
|
assert!(vec.write("Hello World!".as_bytes()).is_ok());
|
||
|
}
|
||
|
assert_eq!(buf[1] as char, 'e');
|
||
|
}
|
||
|
|
||
|
fn add_values<T: io::Write>(vec: &mut T) {
|
||
|
for i in 0..BUF_LEN {
|
||
|
assert!(vec.write(&[((i % 256) & 0xff) as u8]).is_ok());
|
||
|
}
|
||
|
}
|
||
|
|
||
|
use test::Bencher;
|
||
|
|
||
|
const BUF_LEN : usize = 1024 * 1024 * 1; // 10MB
|
||
|
|
||
|
#[bench]
|
||
|
fn vec_stack(bencher: &mut Bencher) {
|
||
|
bencher.iter(|| {
|
||
|
let mut buff = [0u8; BUF_LEN];
|
||
|
let mut v = StackVec::from(&mut buff);
|
||
|
add_values(&mut v);
|
||
|
});
|
||
|
}
|
||
|
|
||
|
#[bench]
|
||
|
fn vec_heap(bencher: &mut Bencher) {
|
||
|
bencher.iter(|| {
|
||
|
let mut v = Vec::new();
|
||
|
|
||
|
add_values(&mut v);
|
||
|
});
|
||
|
}
|
||
|
|
||
|
#[bench]
|
||
|
fn vec_heap_cap(bencher: &mut Bencher) {
|
||
|
bencher.iter(|| {
|
||
|
let mut v = Vec::with_capacity(BUF_LEN);
|
||
|
add_values(&mut v);
|
||
|
});
|
||
|
}
|
||
|
}
|