use crate::error::{DeError as Error, DeResult as Result};
use serde::{
de::{self, DeserializeSeed, Visitor},
Deserialize,
};
pub struct Deserializer<'de> {
input: &'de [u8],
}
impl<'de> Deserializer<'de> {
pub fn from_bytes(input: &'de [u8]) -> Self {
Deserializer { input }
}
pub fn from_str(input: &'de str) -> Self {
Deserializer {
input: input.as_bytes(),
}
}
}
pub fn from_str<'a, T>(s: &'a str) -> Result<T>
where
T: Deserialize<'a>,
{
let mut deserializer = Deserializer::from_str(s);
let t = T::deserialize(&mut deserializer)?;
if deserializer.input.is_empty() {
Ok(t)
} else {
Err(Error::SyntaxError(deserializer.input[0], None))
}
}
pub fn from_bytes<'a, T>(b: &'a [u8]) -> Result<T>
where
T: Deserialize<'a>,
{
let mut deserializer = Deserializer::from_bytes(b);
let t = T::deserialize(&mut deserializer)?;
if deserializer.input.is_empty() {
Ok(t)
} else {
Err(Error::SyntaxError(deserializer.input[0], None))
}
}
impl<'de> Deserializer<'de> {
fn peek_next(&self) -> Result<u8> {
self.input.first().copied().ok_or(Error::UnexpectedEof)
}
fn peek_second(&self) -> Result<u8> {
let mut iter = self.input.iter();
iter.next().ok_or(Error::UnexpectedEof)?;
let val = iter.next().ok_or(Error::UnexpectedEof)?;
Ok(*val)
}
fn advance(&mut self) -> Result<u8> {
let ret = self.peek_next();
self.input = &self.input[1..];
ret
}
fn parse_byte_string(&mut self) -> Result<&'de [u8]> {
let num_bytes = self.advance_to(b':')?;
let num_bytes: usize = btoi::btoi(num_bytes).map_err(|e| Error::ParseIntegerError(e))?;
let bytes = self.advance_by(num_bytes)?;
Ok(bytes)
}
fn advance_by(&mut self, len: usize) -> Result<&'de [u8]> {
let ret = &self.input[0..len];
self.input = &self.input[(ret.len())..];
Ok(ret)
}
#[inline(always)]
fn advance_to_e(&mut self) -> Result<&'de [u8]> {
self.advance_to(b'e')
}
fn advance_to(&mut self, byte: u8) -> Result<&'de [u8]> {
let ret = slice_while(self.input, byte)?;
self.input = &self.input[(ret.len() + 1)..];
Ok(ret)
}
}
fn slice_while(bytes: &[u8], end_byte: u8) -> Result<&[u8]> {
let mut end = None;
for (i, v) in bytes.iter().enumerate() {
if *v == end_byte {
end = Some(i);
break;
}
}
match end {
Some(end_index) => {
let ret = &bytes[0..end_index];
Ok(ret)
}
None => Err(Error::UnexpectedEof),
}
}
impl<'de, 'a> de::Deserializer<'de> for &'a mut Deserializer<'de> {
type Error = Error;
fn deserialize_any<V>(self, visitor: V) -> Result<V::Value>
where
V: Visitor<'de>,
{
match self.peek_next()? {
b'i' if self.peek_second()? == b'-' => self.deserialize_i64(visitor),
b'i' => self.deserialize_u64(visitor),
b'l' => self.deserialize_seq(visitor),
b'd' => self.deserialize_map(visitor),
b'0'..=b'9' => self.deserialize_bytes(visitor),
other => Err(Error::SyntaxError(other, None)),
}
}
serde::forward_to_deserialize_any! {u8 u16 u32 i8 i16 i32 identifier ignored_any }
fn deserialize_bool<V>(self, visitor: V) -> Result<V::Value>
where
V: Visitor<'de>,
{
if self.advance()? == b'i' {
let b = self.advance_to_e()?;
if b.len() != 1 || ![b'0', b'1'].contains(&b[0]) {
return Err(Error::Message(
"expected integer between `0` to `1`".to_string(),
));
} else {
visitor.visit_bool(b[0] == b'1')
}
} else {
Err(Error::ExpectedInteger)
}
}
fn deserialize_i64<V>(self, visitor: V) -> Result<V::Value>
where
V: Visitor<'de>,
{
let marker = self.advance()?;
if marker != b'i' {
return Err(Error::SyntaxError(marker, Some(b'i')));
}
visitor
.visit_i64(btoi::btoi(self.advance_to_e()?).map_err(|x| Error::ParseIntegerError(x))?)
}
fn deserialize_u64<V>(self, visitor: V) -> Result<V::Value>
where
V: Visitor<'de>,
{
let marker = self.advance()?;
if marker != b'i' {
return Err(Error::SyntaxError(marker, Some(b'i')));
}
visitor
.visit_u64(btoi::btoi(self.advance_to_e()?).map_err(|x| Error::ParseIntegerError(x))?)
}
fn deserialize_f32<V>(self, _visitor: V) -> Result<V::Value>
where
V: Visitor<'de>,
{
Err(Error::Message("`f32` is not supported".to_string()))
}
fn deserialize_f64<V>(self, _visitor: V) -> Result<V::Value>
where
V: Visitor<'de>,
{
Err(Error::Message("`f64` is not supported".to_string()))
}
fn deserialize_char<V>(self, visitor: V) -> Result<V::Value>
where
V: Visitor<'de>,
{
let s = self.parse_byte_string()?;
if s.len() > 4 {
return Err(Error::ExpectedCharString);
}
let mut chars = std::str::from_utf8(s)?.chars();
if chars.clone().count() != 1 {
return Err(Error::ExpectedCharString);
}
let ch = chars.next().expect("this should not happen!!!");
visitor.visit_char(ch)
}
fn deserialize_str<V>(self, visitor: V) -> Result<V::Value>
where
V: Visitor<'de>,
{
let bytes = self.parse_byte_string()?;
let s = std::str::from_utf8(bytes)?;
visitor.visit_borrowed_str(s)
}
fn deserialize_string<V>(self, visitor: V) -> Result<V::Value>
where
V: Visitor<'de>,
{
self.deserialize_str(visitor)
}
fn deserialize_bytes<V>(self, visitor: V) -> Result<V::Value>
where
V: Visitor<'de>,
{
visitor.visit_borrowed_bytes(self.parse_byte_string()?)
}
fn deserialize_byte_buf<V>(self, visitor: V) -> Result<V::Value>
where
V: Visitor<'de>,
{
self.deserialize_bytes(visitor)
}
fn deserialize_option<V>(self, visitor: V) -> Result<V::Value>
where
V: Visitor<'de>,
{
if self.input.is_empty() {
visitor.visit_none()
} else {
visitor.visit_some(self)
}
}
fn deserialize_unit<V>(self, visitor: V) -> Result<V::Value>
where
V: Visitor<'de>,
{
self.advance_by(2)?;
visitor.visit_unit()
}
fn deserialize_unit_struct<V>(self, name: &'static str, visitor: V) -> Result<V::Value>
where
V: Visitor<'de>,
{
let decoded_name = self.parse_byte_string()?;
if name.as_bytes() != decoded_name {
Err(Error::ExpectedUnitStructName)
} else {
visitor.visit_unit()
}
}
fn deserialize_newtype_struct<V>(self, _name: &'static str, visitor: V) -> Result<V::Value>
where
V: Visitor<'de>,
{
visitor.visit_newtype_struct(self)
}
fn deserialize_seq<V>(self, visitor: V) -> Result<V::Value>
where
V: Visitor<'de>,
{
let peek = self.advance()?;
if peek == b'l' {
visitor.visit_seq(ListAccess { de: self })
} else {
Err(Error::SyntaxError(peek, Some(b'l')))
}
}
fn deserialize_tuple<V>(self, _len: usize, visitor: V) -> Result<V::Value>
where
V: Visitor<'de>,
{
let ret = self.deserialize_seq(visitor)?;
self.advance()?;
Ok(ret)
}
fn deserialize_tuple_struct<V>(
self,
_name: &'static str,
_len: usize,
visitor: V,
) -> Result<V::Value>
where
V: Visitor<'de>,
{
self.deserialize_seq(visitor)
}
fn deserialize_map<V>(self, visitor: V) -> Result<V::Value>
where
V: Visitor<'de>,
{
let next = self.advance()?;
if next == b'd' {
visitor.visit_map(self)
} else {
Err(Error::SyntaxError(next, Some(b'd')))
}
}
fn deserialize_struct<V>(
self,
_name: &'static str,
_fields: &'static [&'static str],
visitor: V,
) -> Result<V::Value>
where
V: Visitor<'de>,
{
self.deserialize_map(visitor)
}
fn deserialize_enum<V>(
self,
_name: &'static str,
_variants: &'static [&'static str],
visitor: V,
) -> Result<V::Value>
where
V: Visitor<'de>,
{
match self.peek_next()? {
b'd' => {
self.advance()?;
let res = visitor.visit_enum(&mut *self)?;
if self.advance()? != b'e' {
Err(Error::ExpectedEndOfDictionary)
} else {
Ok(res)
}
}
b'0'..=b'9' => {
use de::IntoDeserializer;
visitor
.visit_enum(std::str::from_utf8(self.parse_byte_string()?)?.into_deserializer())
}
_ => Err(Error::ExpectedDictionary),
}
}
}
struct ListAccess<'m, 'de: 'm> {
de: &'m mut Deserializer<'de>,
}
impl<'de, 'm> de::SeqAccess<'de> for ListAccess<'m, 'de> {
type Error = Error;
fn next_element_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>>
where
T: DeserializeSeed<'de>,
{
if self.de.peek_next()? == b'e' {
self.de.advance()?;
Ok(None)
} else {
Ok(Some(seed.deserialize(&mut *self.de)?))
}
}
}
impl<'de> de::MapAccess<'de> for Deserializer<'de> {
type Error = Error;
fn next_key_seed<K>(&mut self, seed: K) -> Result<Option<K::Value>>
where
K: DeserializeSeed<'de>,
{
if self.peek_next()? == b'e' {
self.advance()?;
Ok(None)
} else {
Ok(Some(seed.deserialize(&mut *self)?))
}
}
fn next_value_seed<V>(&mut self, seed: V) -> Result<V::Value>
where
V: DeserializeSeed<'de>,
{
Ok(seed.deserialize(&mut *self)?)
}
}
impl<'de> de::VariantAccess<'de> for &mut Deserializer<'de> {
type Error = Error;
fn unit_variant(self) -> Result<()> {
Err(Error::ExpectedString)
}
fn newtype_variant_seed<T>(self, seed: T) -> Result<T::Value>
where
T: DeserializeSeed<'de>,
{
seed.deserialize(&mut *self)
}
fn tuple_variant<V>(self, _len: usize, visitor: V) -> Result<V::Value>
where
V: Visitor<'de>,
{
de::Deserializer::deserialize_seq(self, visitor)
}
fn struct_variant<V>(self, _fields: &'static [&'static str], visitor: V) -> Result<V::Value>
where
V: Visitor<'de>,
{
de::Deserializer::deserialize_map(self, visitor)
}
}
impl<'de> de::EnumAccess<'de> for &mut Deserializer<'de> {
type Error = Error;
type Variant = Self;
fn variant_seed<V>(self, seed: V) -> Result<(V::Value, Self::Variant)>
where
V: DeserializeSeed<'de>,
{
let val = seed.deserialize(&mut *self)?;
Ok((val, self))
}
}
#[cfg(test)]
mod tests {
use super::*;
type Ret = std::result::Result<(), Box<dyn std::error::Error>>;
#[test]
fn primitives() -> Ret {
assert_eq!(from_str::<i32>("i1e")?, 1);
assert_eq!(from_str::<i32>("i-1e")?, -1);
assert_eq!(from_str::<u32>("i0e")?, 0);
assert_eq!(from_str::<u32>("i1e")?, 1);
assert_eq!(from_str::<u64>(&format!("i{}e", u64::MAX))?, u64::MAX);
assert_eq!(from_str::<i64>(&format!("i{}e", i64::MAX))?, i64::MAX);
assert_eq!(from_str::<i64>(&format!("i{}e", i64::MIN))?, i64::MIN);
assert_eq!(from_str::<bool>("i1e")?, true);
assert_eq!(from_str::<bool>("i0e")?, false);
assert_eq!(from_str::<bool>("i2e").ok(), None);
assert_eq!(from_str::<bool>("i-1e").ok(), None);
assert_eq!(from_str::<char>("1:a")?, 'a');
assert_eq!(from_str::<char>("2:ab").ok(), None);
Ok(())
}
#[test]
fn byte_string() -> Ret {
assert_eq!(from_str::<&[u8]>("5:hello")?, b"hello");
assert_eq!(
from_str::<serde_bytes::ByteBuf>("5:hello")?.as_slice(),
b"hello"
);
assert_eq!(from_str::<&str>("5:hello")?, "hello");
assert_eq!(from_str::<String>("5:hello")?, "hello".to_string());
Ok(())
}
#[test]
fn seq() -> Ret {
assert_eq!(from_str::<Vec<u8>>("li1ei2ei3ee")?, vec![1, 2, 3]);
assert_eq!(from_str::<Vec<&str>>("l1:a1:b1:ce")?, vec!["a", "b", "c"]);
assert_eq!(
from_str::<(&str, &str, &str)>("l1:a1:b1:ce")?,
("a", "b", "c")
);
assert_eq!(from_str::<[&str; 3]>("l1:a1:b1:ce")?, ["a", "b", "c"]);
Ok(())
}
#[test]
fn dictionary() -> Ret {
use std::collections::HashMap;
let hm = from_str::<HashMap<&str, i64>>("d1:ai1e1:bi2e1:ci3ee")?;
let mut test_hm = HashMap::new();
test_hm.insert("a", 1);
test_hm.insert("b", 2);
test_hm.insert("c", 3);
assert_eq!(hm, test_hm);
Ok(())
}
#[test]
fn options() -> Ret {
assert_eq!(from_str::<Option<i32>>("")?, None);
assert_eq!(from_str::<Option<i32>>("i55e")?, Some(55));
Ok(())
}
#[test]
fn unit() -> Ret {
assert_eq!(from_str::<()>(":0")?, ());
Ok(())
}
#[test]
fn unit_struct() -> Ret {
#[derive(Debug, Deserialize, Eq, PartialEq)]
struct EmptyInside;
assert_eq!(from_str::<EmptyInside>("11:EmptyInside")?, EmptyInside);
Ok(())
}
#[test]
fn unit_variant() -> Ret {
use serde::Serialize;
#[derive(Debug, Serialize, Deserialize, Eq, PartialEq)]
enum E {
A,
B,
};
assert_eq!(from_str::<E>("1:A")?, E::A);
assert_eq!(from_str::<E>("1:B")?, E::B);
Ok(())
}
#[test]
fn newtype_struct() -> Ret {
#[derive(Debug, Deserialize, Eq, PartialEq)]
struct Kg(u32);
assert_eq!(from_str::<Kg>("i100e")?, Kg(100));
Ok(())
}
#[test]
fn newtype_variant() -> Ret {
#[derive(Debug, Deserialize, Eq, PartialEq)]
enum E {
N(u8),
S(&'static str),
}
assert_eq!(from_str::<E>("d1:Ni1ee")?, E::N(1));
assert_eq!(from_str::<E>("d1:S3:bufe")?, E::S("buf"));
Ok(())
}
}