use std::io::{Buffer, Reader, IoError};
use std::num::{cast, NumCast};
use std::error::{Error, FromError};
use rustc_serialize::Decoder;
use super::SizeLimit;
#[derive(PartialEq, Clone, Show)]
pub struct InvalidBytes {
desc: &'static str,
detail: Option<String>,
}
#[derive(PartialEq, Clone, Show)]
pub enum DecodingError {
IoError(IoError),
InvalidBytes(InvalidBytes),
SizeLimit
}
pub type DecodingResult<T> = Result<T, DecodingError>;
fn wrap_io(err: IoError) -> DecodingError {
DecodingError::IoError(err)
}
impl Error for DecodingError {
fn description(&self) -> &str {
match *self {
DecodingError::IoError(ref err) => err.description(),
DecodingError::InvalidBytes(ref ib) => ib.desc,
DecodingError::SizeLimit => "the size limit for decoding has been reached"
}
}
fn detail(&self) -> Option<String> {
match *self {
DecodingError::IoError(ref err) => err.detail(),
DecodingError::InvalidBytes(ref ib) => ib.detail.clone(),
DecodingError::SizeLimit => None
}
}
}
impl FromError<IoError> for DecodingError {
fn from_error(err: IoError) -> DecodingError {
DecodingError::IoError(err)
}
}
pub struct DecoderReader<'a, R: 'a> {
reader: &'a mut R,
size_limit: SizeLimit,
read: u64
}
impl<'a, R: Reader+Buffer> DecoderReader<'a, R> {
pub fn new(r: &'a mut R, size_limit: SizeLimit) -> DecoderReader<'a, R> {
DecoderReader {
reader: r,
size_limit: size_limit,
read: 0
}
}
}
impl <'a, A> DecoderReader<'a, A> {
fn read_bytes<I>(&mut self, count: I) -> Result<(), DecodingError>
where I: NumCast {
self.read += cast(count).unwrap();
match self.size_limit {
SizeLimit::Infinite => Ok(()),
SizeLimit::UpperBound(x) if self.read <= x => Ok(()),
SizeLimit::UpperBound(_) => Err(DecodingError::SizeLimit)
}
}
fn read_type<T>(&mut self) -> Result<(), DecodingError> {
use std::mem::size_of;
self.read_bytes(size_of::<T>())
}
}
impl<'a, R: Reader+Buffer> Decoder for DecoderReader<'a, R> {
type Error = DecodingError;
fn read_nil(&mut self) -> DecodingResult<()> {
Ok(())
}
fn read_usize(&mut self) -> DecodingResult<usize> {
Ok(try!(self.read_u64().map(|x| x as usize)))
}
fn read_u64(&mut self) -> DecodingResult<u64> {
try!(self.read_type::<u64>());
self.reader.read_be_u64().map_err(wrap_io)
}
fn read_u32(&mut self) -> DecodingResult<u32> {
try!(self.read_type::<u32>());
self.reader.read_be_u32().map_err(wrap_io)
}
fn read_u16(&mut self) -> DecodingResult<u16> {
try!(self.read_type::<u16>());
self.reader.read_be_u16().map_err(wrap_io)
}
fn read_u8(&mut self) -> DecodingResult<u8> {
try!(self.read_type::<u8>());
self.reader.read_u8().map_err(wrap_io)
}
fn read_isize(&mut self) -> DecodingResult<isize> {
self.read_i64().map(|x| x as isize)
}
fn read_i64(&mut self) -> DecodingResult<i64> {
try!(self.read_type::<i64>());
self.reader.read_be_i64().map_err(wrap_io)
}
fn read_i32(&mut self) -> DecodingResult<i32> {
try!(self.read_type::<i32>());
self.reader.read_be_i32().map_err(wrap_io)
}
fn read_i16(&mut self) -> DecodingResult<i16> {
try!(self.read_type::<i16>());
self.reader.read_be_i16().map_err(wrap_io)
}
fn read_i8(&mut self) -> DecodingResult<i8> {
try!(self.read_type::<i8>());
self.reader.read_i8().map_err(wrap_io)
}
fn read_bool(&mut self) -> DecodingResult<bool> {
let x = try!(self.read_i8());
match x {
1 => Ok(true),
0 => Ok(false),
_ => Err(DecodingError::InvalidBytes(InvalidBytes{
desc: "invalid u8 when decoding bool",
detail: Some(format!("Expected 0 or 1, got {}", x))
})),
}
}
fn read_f64(&mut self) -> DecodingResult<f64> {
try!(self.read_type::<f64>());
self.reader.read_be_f64().map_err(wrap_io)
}
fn read_f32(&mut self) -> DecodingResult<f32> {
try!(self.read_type::<f32>());
self.reader.read_be_f32().map_err(wrap_io)
}
fn read_char(&mut self) -> DecodingResult<char> {
let c = try!(self.reader.read_char().map_err(wrap_io));
try!(self.read_bytes(c.len_utf8()));
Ok(c)
}
fn read_str(&mut self) -> DecodingResult<String> {
let len = try!(self.read_usize());
try!(self.read_bytes(len));
let vector = try!(self.reader.read_exact(len));
match String::from_utf8(vector) {
Ok(s) => Ok(s),
Err(err) => Err(DecodingError::InvalidBytes(InvalidBytes {
desc: "error while decoding utf8 string",
detail: Some(format!("Decoding error: {}", err))
})),
}
}
fn read_enum<T, F>(&mut self, _: &str, f: F) -> DecodingResult<T> where
F: FnOnce(&mut DecoderReader<'a, R>) -> DecodingResult<T> {
f(self)
}
fn read_enum_variant<T, F>(&mut self, names: &[&str], mut f: F) -> DecodingResult<T> where
F: FnMut(&mut DecoderReader<'a, R>, usize) -> DecodingResult<T> {
let id = try!(self.read_u32());
let id = id as usize;
if id >= names.len() {
Err(DecodingError::InvalidBytes(InvalidBytes {
desc: "out of bounds tag when reading enum variant",
detail: Some(format!("Expected tag < {}, got {}", names.len(), id))
}))
} else {
f(self, id)
}
}
fn read_enum_variant_arg<T, F>(&mut self, _: usize, f: F) -> DecodingResult<T> where
F: FnOnce(&mut DecoderReader<'a, R>) -> DecodingResult<T> {
f(self)
}
fn read_enum_struct_variant<T, F>(&mut self, names: &[&str], f: F) -> DecodingResult<T> where
F: FnMut(&mut DecoderReader<'a, R>, usize) -> DecodingResult<T> {
self.read_enum_variant(names, f)
}
fn read_enum_struct_variant_field<T, F>(&mut self,
_: &str,
f_idx: usize,
f: F)
-> DecodingResult<T> where
F: FnOnce(&mut DecoderReader<'a, R>) -> DecodingResult<T> {
self.read_enum_variant_arg(f_idx, f)
}
fn read_struct<T, F>(&mut self, _: &str, _: usize, f: F) -> DecodingResult<T> where
F: FnOnce(&mut DecoderReader<'a, R>) -> DecodingResult<T> {
f(self)
}
fn read_struct_field<T, F>(&mut self,
_: &str,
_: usize,
f: F)
-> DecodingResult<T> where
F: FnOnce(&mut DecoderReader<'a, R>) -> DecodingResult<T> {
f(self)
}
fn read_tuple<T, F>(&mut self, _: usize, f: F) -> DecodingResult<T> where
F: FnOnce(&mut DecoderReader<'a, R>) -> DecodingResult<T> {
f(self)
}
fn read_tuple_arg<T, F>(&mut self, _: usize, f: F) -> DecodingResult<T> where
F: FnOnce(&mut DecoderReader<'a, R>) -> DecodingResult<T> {
f(self)
}
fn read_tuple_struct<T, F>(&mut self, _: &str, len: usize, f: F) -> DecodingResult<T> where
F: FnOnce(&mut DecoderReader<'a, R>) -> DecodingResult<T> {
self.read_tuple(len, f)
}
fn read_tuple_struct_arg<T, F>(&mut self, a_idx: usize, f: F) -> DecodingResult<T> where
F: FnOnce(&mut DecoderReader<'a, R>) -> DecodingResult<T> {
self.read_tuple_arg(a_idx, f)
}
fn read_option<T, F>(&mut self, mut f: F) -> DecodingResult<T> where
F: FnMut(&mut DecoderReader<'a, R>, bool) -> DecodingResult<T> {
let x = try!(self.read_u8());
match x {
1 => f(self, true),
0 => f(self, false),
_ => Err(DecodingError::InvalidBytes(InvalidBytes {
desc: "invalid tag when decoding Option",
detail: Some(format!("Expected 0 or 1, got {}", x))
})),
}
}
fn read_seq<T, F>(&mut self, f: F) -> DecodingResult<T> where
F: FnOnce(&mut DecoderReader<'a, R>, usize) -> DecodingResult<T> {
let len = try!(self.read_usize());
f(self, len)
}
fn read_seq_elt<T, F>(&mut self, _: usize, f: F) -> DecodingResult<T> where
F: FnOnce(&mut DecoderReader<'a, R>) -> DecodingResult<T> {
f(self)
}
fn read_map<T, F>(&mut self, f: F) -> DecodingResult<T> where
F: FnOnce(&mut DecoderReader<'a, R>, usize) -> DecodingResult<T> {
let len = try!(self.read_usize());
f(self, len)
}
fn read_map_elt_key<T, F>(&mut self, _: usize, f: F) -> DecodingResult<T> where
F: FnOnce(&mut DecoderReader<'a, R>) -> DecodingResult<T> {
f(self)
}
fn read_map_elt_val<T, F>(&mut self, _: usize, f: F) -> DecodingResult<T> where
F: FnOnce(&mut DecoderReader<'a, R>) -> DecodingResult<T> {
f(self)
}
fn error(&mut self, err: &str) -> DecodingError {
DecodingError::InvalidBytes(InvalidBytes {
desc: "user-induced error",
detail: Some(err.to_string()),
})
}
}