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use super::{Read, ReadError, Write, WriteError};
use alloc::vec::Vec;
use core::ops::Deref;
pub struct DataStream {
bytes: Vec<u8>,
pos: usize,
}
impl DataStream {
#[inline]
pub fn read<T: Read>(&mut self) -> Result<T, ReadError> {
T::read(&self.bytes, &mut self.pos)
}
#[allow(clippy::needless_pass_by_value)]
#[inline]
pub fn write<T: Write>(&mut self, thing: T) -> Result<(), WriteError> {
thing.write(&mut self.bytes, &mut self.pos)
}
#[inline]
#[must_use]
pub fn as_bytes(&self) -> &[u8] {
&self.bytes
}
#[inline]
#[must_use]
pub fn as_remaining_bytes(&self) -> Option<&[u8]> {
self.bytes.get(self.pos..)
}
#[inline]
pub fn reset(&mut self) {
self.pos = 0;
}
#[inline]
#[must_use]
pub const fn position(&self) -> usize {
self.pos
}
#[inline]
#[must_use]
pub fn remaining(&self) -> usize {
self.bytes.len() - self.pos
}
}
impl From<Vec<u8>> for DataStream {
#[must_use]
fn from(bytes: Vec<u8>) -> Self {
Self { bytes, pos: 0 }
}
}
impl From<&[u8]> for DataStream {
#[must_use]
fn from(bytes: &[u8]) -> Self {
Self {
bytes: bytes.to_vec(),
pos: 0,
}
}
}
impl Deref for DataStream {
type Target = [u8];
#[must_use]
fn deref(&self) -> &Self::Target {
self.as_bytes()
}
}
impl AsRef<[u8]> for DataStream {
fn as_ref(&self) -> &[u8] {
self.as_bytes()
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::{n, AccountName, Name};
#[test]
fn read_write() {
let account = AccountName::from(n!("eosio.token"));
let name = Name::from(n!("alice"));
let mut ds1 = DataStream::from(vec![0; 16]);
assert_eq!(ds1.position(), 0);
assert_eq!(ds1.remaining(), 16);
ds1.write(account).expect("failed to write account");
assert_eq!(ds1.position(), 8);
assert_eq!(ds1.remaining(), 8);
assert_eq!(
ds1.as_remaining_bytes()
.expect("failed to get remaining bytes")
.len(),
8
);
ds1.write(name).expect("failed to write name");
assert_eq!(ds1.position(), 16);
assert_eq!(ds1.remaining(), 0);
let bytes = ds1.as_bytes();
let mut ds2 = DataStream::from(bytes);
assert_eq!(ds2.position(), 0);
assert_eq!(ds2.remaining(), 16);
let account2 =
ds2.read::<AccountName>().expect("failed to read account");
assert_eq!(ds2.position(), 8);
assert_eq!(ds2.remaining(), 8);
let name2 = ds2.read::<Name>().expect("failed to read name");
assert_eq!(ds2.position(), 16);
assert_eq!(ds2.remaining(), 0);
assert_eq!(account, account2);
assert_eq!(name, name2);
}
}