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use crate::{resp::Value, Error, RedisError, Result};
use bytes::{Buf, BytesMut};
use log::trace;
use std::str::{self, FromStr};
use tokio_util::codec::Decoder;
pub(crate) struct ValueDecoder;
impl Decoder for ValueDecoder {
type Item = Value;
type Error = Error;
fn decode(&mut self, src: &mut BytesMut) -> Result<Option<Value>> {
Ok(decode(src, 0)?.map(|(item, pos)| {
trace!(
"decode: {}",
String::from_utf8_lossy(&src.as_ref()[..pos]).replace("\r\n", "\\r\\n")
);
src.advance(pos);
item
}))
}
}
fn decode(buf: &mut BytesMut, idx: usize) -> Result<Option<(Value, usize)>> {
if buf.len() <= idx {
return Ok(None);
}
let first_byte = buf[idx];
let idx = idx + 1;
match first_byte {
b'$' => Ok(decode_bulk_string(buf, idx)?.map(|(bs, pos)| match bs {
Some(bs) => (Value::BulkString(bs), pos),
None => (Value::Nil, pos),
})),
b'*' => Ok(decode_array(buf, idx)?.map(|(v, pos)| match v {
Some(v) => (Value::Array(v), pos),
None => (Value::Nil, pos),
})),
b'%' => Ok(decode_map(buf, idx)?.map(|(v, pos)| match v {
Some(v) => (Value::Array(v), pos),
None => (Value::Nil, pos),
})),
b'~' => Ok(decode_array(buf, idx)?.map(|(v, pos)| match v {
Some(v) => (Value::Array(v), pos),
None => (Value::Nil, pos),
})),
b':' => Ok(decode_number::<i64>(buf, idx)?.map(|(i, pos)| (Value::Integer(i), pos))),
b',' => Ok(decode_number::<f64>(buf, idx)?.map(|(d, pos)| (Value::Double(d), pos))),
b'+' => {
Ok(decode_string(buf, idx)?.map(|(s, pos)| (Value::SimpleString(s.to_owned()), pos)))
}
b'-' => decode_string(buf, idx)?
.map(|(s, pos)| RedisError::from_str(s).map(|e| (Value::Error(e), pos)))
.transpose(),
b'_' => Ok(decode_null(buf, idx)?.map(|pos| (Value::Nil, pos))),
b'#' => Ok(decode_boolean(buf, idx)?.map(|(i, pos)| (Value::Integer(i), pos))),
b'=' => Ok(decode_bulk_string(buf, idx)?.map(|(bs, pos)| match bs {
Some(bs) => (Value::BulkString(bs), pos),
None => (Value::Nil, pos),
})),
b'>' => Ok(decode_array(buf, idx)?.map(|(v, pos)| match v {
Some(v) => (Value::Push(v), pos),
None => (Value::Nil, pos),
})),
_ => Err(Error::Client(format!(
"Unknown data type '{}' (0x{:02x})",
first_byte as char, first_byte
))),
}
}
fn decode_line(buf: &mut BytesMut, idx: usize) -> Result<Option<(&[u8], usize)>> {
match buf[idx..].iter().position(|b| *b == b'\r') {
Some(pos) if buf.len() > idx + pos + 1 && buf[idx + pos + 1] == b'\n' => {
let slice = &buf[idx..idx + pos];
Ok(Some((slice, pos + idx + 2)))
}
_ => Ok(None),
}
}
fn decode_bulk_string(buf: &mut BytesMut, idx: usize) -> Result<Option<(Option<Vec<u8>>, usize)>> {
match decode_number::<isize>(buf, idx)? {
None => Ok(None),
Some((-1, pos)) => Ok(Some((None, pos))),
Some((len, pos)) if len >= 0 => {
let len = len as usize;
if buf.len() - pos < len + 2 {
if buf.len() - pos == len + 1 && buf[pos + len] != b'\r' {
Err(Error::Client("Cannot parse bulk string".to_owned()))
} else {
Ok(None) }
} else if buf[pos + len] != b'\r' || buf[pos + len + 1] != b'\n' {
Err(Error::Client("Cannot parse bulk string".to_owned()))
} else {
Ok(Some((Some(buf[pos..(pos + len)].to_vec()), pos + len + 2)))
}
}
_ => Err(Error::Client("Cannot parse bulk string".to_owned())),
}
}
fn decode_array(buf: &mut BytesMut, idx: usize) -> Result<Option<(Option<Vec<Value>>, usize)>> {
match decode_number::<isize>(buf, idx)? {
None => Ok(None),
Some((-1, pos)) => Ok(Some((None, pos))),
Some((len, mut pos)) => {
let mut values = Vec::with_capacity(len as usize);
for _ in 0..len {
match decode(buf, pos)? {
None => return Ok(None),
Some((value, new_pos)) => {
values.push(value);
pos = new_pos;
}
}
}
Ok(Some((Some(values), pos)))
}
}
}
fn decode_map(buf: &mut BytesMut, idx: usize) -> Result<Option<(Option<Vec<Value>>, usize)>> {
match decode_number::<isize>(buf, idx)? {
None => Ok(None),
Some((-1, pos)) => Ok(Some((None, pos))),
Some((len, mut pos)) => {
let len = len * 2;
let mut values = Vec::with_capacity(len as usize);
for _ in 0..len {
match decode(buf, pos)? {
None => return Ok(None),
Some((value, new_pos)) => {
values.push(value);
pos = new_pos;
}
}
}
Ok(Some((Some(values), pos)))
}
}
}
fn decode_string(buf: &mut BytesMut, idx: usize) -> Result<Option<(&str, usize)>> {
match decode_line(buf, idx)? {
Some((slice, pos)) => Ok(Some((str::from_utf8(slice)?, pos))),
None => Ok(None),
}
}
fn decode_number<T>(buf: &mut BytesMut, idx: usize) -> Result<Option<(T, usize)>>
where
T: FromStr,
{
match decode_line(buf, idx)? {
Some((slice, pos)) => {
let str = str::from_utf8(slice)?;
match str.parse::<T>() {
Ok(d) => Ok(Some((d, pos))),
Err(_) => Err(Error::Client("Cannot parse number".to_owned())),
}
}
None => Ok(None),
}
}
fn decode_null(buf: &mut BytesMut, idx: usize) -> Result<Option<usize>> {
match decode_line(buf, idx)? {
Some((slice, pos)) if slice.is_empty() => Ok(Some(pos)),
None => Ok(None),
_ => Err(Error::Client("Cannot parse null".to_owned())),
}
}
fn decode_boolean(buf: &mut BytesMut, idx: usize) -> Result<Option<(i64, usize)>> {
match decode_line(buf, idx)? {
Some((slice, pos)) if slice.len() == 1 => match slice[0] {
b't' => Ok(Some((1, pos))),
b'f' => Ok(Some((0, pos))),
_ => Err(Error::Client("Cannot parse boolean".to_owned())),
},
None => Ok(None),
_ => Err(Error::Client("Cannot parse boolean".to_owned())),
}
}