Files
mini-redis/src/parse.rs
2020-03-28 14:00:47 -07:00

99 lines
2.6 KiB
Rust

use crate::Frame;
use bytes::Bytes;
use std::{error, fmt, io, str, vec};
/// Utility for parsing a command
#[derive(Debug)]
pub(crate) struct Parse {
parts: vec::IntoIter<Box<Frame>>,
}
#[derive(Debug)]
pub(crate) enum ParseError {
EndOfStream,
Invalid,
UnknownCommand(String),
}
impl Parse {
pub(crate) fn new(frame: Frame) -> Result<Parse, ParseError> {
let array = match frame {
Frame::Array(array) => array,
_ => return Err(ParseError::Invalid),
};
Ok(Parse {
parts: array.into_iter(),
})
}
fn next(&mut self) -> Result<Frame, ParseError> {
self.parts
.next()
.map(|frame| *frame)
.ok_or(ParseError::EndOfStream)
}
pub(crate) fn next_string(&mut self) -> Result<String, ParseError> {
match self.next()? {
Frame::Simple(s) => Ok(s),
Frame::Bulk(data) => str::from_utf8(&data[..])
.map(|s| s.to_string())
.map_err(|_| ParseError::Invalid),
_ => Err(ParseError::Invalid),
}
}
pub(crate) fn next_bytes(&mut self) -> Result<Bytes, ParseError> {
match self.next()? {
Frame::Simple(s) => Ok(Bytes::from(s.into_bytes())),
Frame::Bulk(data) => Ok(data),
_ => Err(ParseError::Invalid),
}
}
pub(crate) fn next_int(&mut self) -> Result<u64, ParseError> {
use atoi::atoi;
match self.next()? {
Frame::Integer(v) => Ok(v),
Frame::Simple(data) => atoi::<u64>(data.as_bytes()).ok_or(ParseError::Invalid),
Frame::Bulk(data) => atoi::<u64>(&data).ok_or(ParseError::Invalid),
_ => Err(ParseError::Invalid),
}
}
/// Ensure there are no more entries in the array
pub(crate) fn finish(&mut self) -> Result<(), ParseError> {
if self.parts.next().is_none() {
Ok(())
} else {
Err(ParseError::Invalid)
}
}
}
impl From<ParseError> for io::Error {
fn from(src: ParseError) -> io::Error {
io::Error::new(io::ErrorKind::Other, format!("{}", src))
}
}
impl fmt::Display for ParseError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let msg = match self {
ParseError::EndOfStream => "end of stream".to_string(),
ParseError::Invalid => "invalid".to_string(),
ParseError::UnknownCommand(cmd) => format!("unknown command `{}`", cmd),
};
write!(f, "{}", &msg)
}
}
impl std::error::Error for ParseError {
fn source(&self) -> Option<&(dyn error::Error + 'static)> {
None
}
}