use std::str;
use deser::de::{Deserialize, DeserializeDriver};
use deser::Atom;
use deser::Event;
use deser::{Error, ErrorKind};
enum Token<'a> {
Null,
Bool(bool),
Str(&'a str),
I64(i64),
U64(u64),
F64(f64),
SeqStart,
SeqEnd,
MapStart,
MapEnd,
Comma,
Colon,
}
macro_rules! overflow {
($a:ident * 10 + $b:ident, $c:expr) => {
$a >= $c / 10 && ($a > $c / 10 || $b > $c % 10)
};
}
pub struct Deserializer<'a> {
input: &'a [u8],
pos: usize,
buffer: Vec<u8>,
}
enum ContainerState {
Map { first: bool, key_pos: bool },
Seq { first: bool },
}
impl<'a> Deserializer<'a> {
pub fn new(input: &'a [u8]) -> Deserializer<'a> {
Deserializer {
input,
pos: 0,
buffer: Vec::new(),
}
}
pub fn deserialize<T: Deserialize>(&mut self) -> Result<T, Error> {
let mut out = None;
{
let mut driver = DeserializeDriver::new(&mut out);
self.deserialize_into(&mut driver)?;
}
out.take()
.ok_or_else(|| Error::new(ErrorKind::EndOfFile, "empty input"))
}
fn deserialize_into(&mut self, driver: &mut DeserializeDriver) -> Result<(), Error> {
let mut token = self.next_token()?;
let mut stack = vec![];
loop {
match token {
Token::MapEnd => {
if !matches!(stack.pop(), Some(ContainerState::Map { .. })) {
return Err(Error::new(ErrorKind::Unexpected, "unexpected end of map"));
}
driver.emit(Event::MapEnd)?;
}
Token::SeqEnd => {
if !matches!(stack.pop(), Some(ContainerState::Seq { .. })) {
return Err(Error::new(ErrorKind::Unexpected, "unexpected end of seq"));
}
driver.emit(Event::SeqEnd)?;
}
_ => {
if let Some(
ContainerState::Seq { first: false }
| ContainerState::Map {
first: false,
key_pos: true,
},
) = stack.last_mut()
{
if !matches!(token, Token::Comma) {
return Err(Error::new(ErrorKind::Unexpected, "expected a comma"));
}
token = self.next_token()?;
}
if let Some(ContainerState::Map {
first,
key_pos: key_pos @ true,
}) = stack.last_mut()
{
match token {
Token::Str(val) => driver.emit(Event::from(val))?,
_ => return Err(Error::new(ErrorKind::Unexpected, "expected map key")),
}
match self.next_token()? {
Token::Colon => {}
_ => return Err(Error::new(ErrorKind::Unexpected, "expected colon")),
}
token = self.next_token()?;
*first = false;
*key_pos = false;
continue;
}
match token {
Token::Null => driver.emit(Event::Atom(Atom::Null))?,
Token::Bool(val) => driver.emit(Event::from(val))?,
Token::Str(val) => driver.emit(Event::from(val))?,
Token::I64(val) => driver.emit(Event::from(val))?,
Token::U64(val) => driver.emit(Event::from(val))?,
Token::F64(val) => driver.emit(Event::from(val))?,
Token::MapStart => {
stack.push(ContainerState::Map {
first: true,
key_pos: true,
});
driver.emit(Event::MapStart)?;
token = self.next_token()?;
continue;
}
Token::SeqStart => {
stack.push(ContainerState::Seq { first: true });
driver.emit(Event::SeqStart)?;
token = self.next_token()?;
continue;
}
Token::Comma => {
return Err(Error::new(ErrorKind::Unexpected, "unexpected comma"));
}
Token::Colon => {
return Err(Error::new(ErrorKind::Unexpected, "unexpected colon"));
}
Token::SeqEnd | Token::MapEnd => unreachable!(),
}
}
}
match stack.last_mut() {
None => {
return if self.parse_whitespace().is_some() {
Err(Error::new(ErrorKind::Unexpected, "garbage after input"))
} else {
Ok(())
}
}
Some(ContainerState::Map { first, key_pos }) => {
token = self.next_token()?;
*key_pos = true;
*first = false;
}
Some(ContainerState::Seq { first }) => {
token = self.next_token()?;
*first = false;
}
}
}
}
fn next(&mut self) -> Option<u8> {
if self.pos < self.input.len() {
let ch = self.input[self.pos];
self.pos += 1;
Some(ch)
} else {
None
}
}
fn next_or_nul(&mut self) -> u8 {
self.next().unwrap_or(b'\0')
}
fn peek(&mut self) -> Option<u8> {
if self.pos < self.input.len() {
Some(self.input[self.pos])
} else {
None
}
}
fn peek_or_nul(&mut self) -> u8 {
self.peek().unwrap_or(b'\0')
}
fn bump(&mut self) {
self.pos += 1;
}
fn parse_str(&mut self) -> Result<&str, Error> {
fn result(bytes: &[u8]) -> &str {
unsafe { str::from_utf8_unchecked(bytes) }
}
let mut start = self.pos;
self.buffer.clear();
loop {
while self.pos < self.input.len() && !ESCAPE[usize::from(self.input[self.pos])] {
self.pos += 1;
}
if self.pos == self.input.len() {
return Err(Error::new(
ErrorKind::Unexpected,
"unexpected end of string",
));
}
match self.input[self.pos] {
b'"' => {
if self.buffer.is_empty() {
let borrowed = &self.input[start..self.pos];
self.pos += 1;
return Ok(result(borrowed));
} else {
self.buffer.extend_from_slice(&self.input[start..self.pos]);
self.pos += 1;
return Ok(result(&self.buffer));
}
}
b'\\' => {
self.buffer.extend_from_slice(&self.input[start..self.pos]);
self.pos += 1;
self.parse_escape()?;
start = self.pos;
}
_ => {
return Err(Error::new(
ErrorKind::Unexpected,
"unexpected character in string",
));
}
}
}
}
fn next_or_eof(&mut self) -> Result<u8, Error> {
self.next()
.ok_or_else(|| Error::new(ErrorKind::EndOfFile, "unexpected end of file"))
}
fn parse_escape(&mut self) -> Result<(), Error> {
let ch = self.next_or_eof()?;
match ch {
b'"' => self.buffer.push(b'"'),
b'\\' => self.buffer.push(b'\\'),
b'/' => self.buffer.push(b'/'),
b'b' => self.buffer.push(b'\x08'),
b'f' => self.buffer.push(b'\x0c'),
b'n' => self.buffer.push(b'\n'),
b'r' => self.buffer.push(b'\r'),
b't' => self.buffer.push(b'\t'),
b'u' => {
let c = match self.decode_hex_escape()? {
0xDC00..=0xDFFF => {
return Err(Error::new(ErrorKind::Unexpected, "invalid string"));
}
n1 @ 0xD800..=0xDBFF => {
if self.next_or_eof()? != b'\\' {
return Err(Error::new(ErrorKind::Unexpected, "invalid string"));
}
if self.next_or_eof()? != b'u' {
return Err(Error::new(ErrorKind::Unexpected, "invalid string"));
}
let n2 = self.decode_hex_escape()?;
if n2 < 0xDC00 || n2 > 0xDFFF {
return Err(Error::new(ErrorKind::Unexpected, "invalid string"));
}
let n = (u32::from(n1 - 0xD800) << 10 | u32::from(n2 - 0xDC00)) + 0x1_0000;
match char::from_u32(n) {
Some(c) => c,
None => {
return Err(Error::new(ErrorKind::Unexpected, "invalid string"));
}
}
}
n => match char::from_u32(u32::from(n)) {
Some(c) => c,
None => {
return Err(Error::new(ErrorKind::Unexpected, "invalid string"));
}
},
};
self.buffer
.extend_from_slice(c.encode_utf8(&mut [0_u8; 4]).as_bytes());
}
_ => {
return Err(Error::new(ErrorKind::Unexpected, "invalid string"));
}
}
Ok(())
}
fn decode_hex_escape(&mut self) -> Result<u16, Error> {
let mut n = 0;
for _ in 0..4 {
n = match self.next_or_eof()? {
c @ b'0'..=b'9' => n * 16_u16 + u16::from(c - b'0'),
b'a' | b'A' => n * 16_u16 + 10_u16,
b'b' | b'B' => n * 16_u16 + 11_u16,
b'c' | b'C' => n * 16_u16 + 12_u16,
b'd' | b'D' => n * 16_u16 + 13_u16,
b'e' | b'E' => n * 16_u16 + 14_u16,
b'f' | b'F' => n * 16_u16 + 15_u16,
_ => {
return Err(Error::new(ErrorKind::Unexpected, "invalid hex escape"));
}
};
}
Ok(n)
}
fn parse_whitespace(&mut self) -> Option<u8> {
loop {
match self.peek() {
Some(b' ') | Some(b'\n') | Some(b'\t') | Some(b'\r') => {
self.bump();
}
other => {
return other;
}
}
}
}
fn parse_ident(&mut self, ident: &[u8]) -> Result<(), Error> {
for expected in ident {
match self.next() {
None => {
return Err(Error::new(ErrorKind::EndOfFile, "unexpected end of file"));
}
Some(next) => {
if next != *expected {
return Err(Error::new(ErrorKind::Unexpected, "unexpected character"));
}
}
}
}
Ok(())
}
fn parse_integer(&mut self, nonnegative: bool, first_digit: u8) -> Result<Token, Error> {
match first_digit {
b'0' => match self.peek_or_nul() {
b'0'..=b'9' => Err(Error::new(
ErrorKind::Unexpected,
"only a single leading 0 is allowed",
)),
_ => self.parse_number(nonnegative, 0),
},
c @ b'1'..=b'9' => {
let mut res = u64::from(c - b'0');
loop {
match self.peek_or_nul() {
c @ b'0'..=b'9' => {
self.bump();
let digit = u64::from(c - b'0');
if overflow!(res * 10 + digit, u64::max_value()) {
return self
.parse_long_integer(
nonnegative,
res,
1, )
.map(Token::F64);
}
res = res * 10 + digit;
}
_ => {
return self.parse_number(nonnegative, res);
}
}
}
}
_ => Err(Error::new(ErrorKind::Unexpected, "invalid integer")),
}
}
fn parse_long_integer(
&mut self,
nonnegative: bool,
significand: u64,
mut exponent: i32,
) -> Result<f64, Error> {
loop {
match self.peek_or_nul() {
b'0'..=b'9' => {
self.bump();
exponent += 1;
}
b'.' => {
return self.parse_decimal(nonnegative, significand, exponent);
}
b'e' | b'E' => {
return self.parse_exponent(nonnegative, significand, exponent);
}
_ => {
return f64_from_parts(nonnegative, significand, exponent);
}
}
}
}
fn parse_number(&mut self, nonnegative: bool, significand: u64) -> Result<Token, Error> {
match self.peek_or_nul() {
b'.' => self
.parse_decimal(nonnegative, significand, 0)
.map(Token::F64),
b'e' | b'E' => self
.parse_exponent(nonnegative, significand, 0)
.map(Token::F64),
_ => {
Ok(if nonnegative {
Token::U64(significand)
} else {
let neg = (significand as i64).wrapping_neg();
if neg > 0 {
Token::F64(-(significand as f64))
} else {
Token::I64(neg)
}
})
}
}
}
fn parse_decimal(
&mut self,
nonnegative: bool,
mut significand: u64,
mut exponent: i32,
) -> Result<f64, Error> {
self.bump();
let mut at_least_one_digit = false;
while let c @ b'0'..=b'9' = self.peek_or_nul() {
self.bump();
let digit = u64::from(c - b'0');
at_least_one_digit = true;
if overflow!(significand * 10 + digit, u64::max_value()) {
while let b'0'..=b'9' = self.peek_or_nul() {
self.bump();
}
break;
}
significand = significand * 10 + digit;
exponent -= 1;
}
if !at_least_one_digit {
return Err(Error::new(ErrorKind::Unexpected, "expected a digit"));
}
match self.peek_or_nul() {
b'e' | b'E' => self.parse_exponent(nonnegative, significand, exponent),
_ => f64_from_parts(nonnegative, significand, exponent),
}
}
fn parse_exponent(
&mut self,
nonnegative: bool,
significand: u64,
starting_exp: i32,
) -> Result<f64, Error> {
self.bump();
let positive_exp = match self.peek_or_nul() {
b'+' => {
self.bump();
true
}
b'-' => {
self.bump();
false
}
_ => true,
};
let mut exp = match self.next_or_nul() {
c @ b'0'..=b'9' => i32::from(c - b'0'),
_ => {
return Err(Error::new(
ErrorKind::Unexpected,
"expected digit after exponent",
));
}
};
while let c @ b'0'..=b'9' = self.peek_or_nul() {
self.bump();
let digit = i32::from(c - b'0');
if overflow!(exp * 10 + digit, i32::max_value()) {
return self.parse_exponent_overflow(nonnegative, significand, positive_exp);
}
exp = exp * 10 + digit;
}
let final_exp = if positive_exp {
starting_exp.saturating_add(exp)
} else {
starting_exp.saturating_sub(exp)
};
f64_from_parts(nonnegative, significand, final_exp)
}
#[cold]
#[inline(never)]
fn parse_exponent_overflow(
&mut self,
nonnegative: bool,
significand: u64,
positive_exp: bool,
) -> Result<f64, Error> {
if significand != 0 && positive_exp {
return Err(Error::new(ErrorKind::Unexpected, "infinity takes no sign"));
}
while let b'0'..=b'9' = self.peek_or_nul() {
self.bump();
}
Ok(if nonnegative { 0.0 } else { -0.0 })
}
fn next_token(&mut self) -> Result<Token, Error> {
let peek = match self.parse_whitespace() {
Some(b) => b,
None => return Err(Error::new(ErrorKind::EndOfFile, "unexpected end of file")),
};
self.bump();
match peek {
b'"' => self.parse_str().map(Token::Str),
digit @ b'0'..=b'9' => self.parse_integer(true, digit),
b'-' => {
let first_digit = self.next_or_nul();
self.parse_integer(false, first_digit)
}
b'{' => Ok(Token::MapStart),
b'[' => Ok(Token::SeqStart),
b'}' => Ok(Token::MapEnd),
b']' => Ok(Token::SeqEnd),
b',' => Ok(Token::Comma),
b':' => Ok(Token::Colon),
b'n' => {
self.parse_ident(b"ull")?;
Ok(Token::Null)
}
b't' => {
self.parse_ident(b"rue")?;
Ok(Token::Bool(true))
}
b'f' => {
self.parse_ident(b"alse")?;
Ok(Token::Bool(false))
}
_ => Err(Error::new(ErrorKind::Unexpected, "unexpected character")),
}
}
}
fn f64_from_parts(nonnegative: bool, significand: u64, mut exponent: i32) -> Result<f64, Error> {
let mut f = significand as f64;
loop {
match POW10.get(exponent.abs() as usize) {
Some(&pow) => {
if exponent >= 0 {
f *= pow;
if f.is_infinite() {
return Err(Error::new(ErrorKind::OutOfRange, "infinite float"));
}
} else {
f /= pow;
}
break;
}
None => {
if f == 0.0 {
break;
}
if exponent >= 0 {
return Err(Error::new(ErrorKind::Unexpected, "unexpected float"));
}
f /= 1e308;
exponent += 308;
}
}
}
Ok(if nonnegative { f } else { -f })
}
#[allow(clippy::excessive_precision)]
static POW10: [f64; 309] = [
1e000, 1e001, 1e002, 1e003, 1e004, 1e005, 1e006, 1e007, 1e008, 1e009, 1e010, 1e011, 1e012, 1e013, 1e014, 1e015, 1e016, 1e017, 1e018, 1e019, 1e020, 1e021, 1e022, 1e023, 1e024, 1e025, 1e026, 1e027, 1e028, 1e029, 1e030, 1e031, 1e032, 1e033, 1e034, 1e035, 1e036, 1e037, 1e038, 1e039, 1e040, 1e041, 1e042, 1e043, 1e044, 1e045, 1e046, 1e047, 1e048, 1e049, 1e050, 1e051, 1e052, 1e053, 1e054, 1e055, 1e056, 1e057, 1e058, 1e059, 1e060, 1e061, 1e062, 1e063, 1e064, 1e065, 1e066, 1e067, 1e068, 1e069, 1e070, 1e071, 1e072, 1e073, 1e074, 1e075, 1e076, 1e077, 1e078, 1e079, 1e080, 1e081, 1e082, 1e083, 1e084, 1e085, 1e086, 1e087, 1e088, 1e089, 1e090, 1e091, 1e092, 1e093, 1e094, 1e095, 1e096, 1e097, 1e098, 1e099, 1e100, 1e101, 1e102, 1e103, 1e104, 1e105, 1e106, 1e107, 1e108, 1e109, 1e110, 1e111, 1e112, 1e113, 1e114, 1e115, 1e116, 1e117, 1e118, 1e119, 1e120, 1e121, 1e122, 1e123, 1e124, 1e125, 1e126, 1e127, 1e128, 1e129, 1e130, 1e131, 1e132, 1e133, 1e134, 1e135, 1e136, 1e137, 1e138, 1e139, 1e140, 1e141, 1e142, 1e143, 1e144, 1e145, 1e146, 1e147, 1e148, 1e149, 1e150, 1e151, 1e152, 1e153, 1e154, 1e155, 1e156, 1e157, 1e158, 1e159, 1e160, 1e161, 1e162, 1e163, 1e164, 1e165, 1e166, 1e167, 1e168, 1e169, 1e170, 1e171, 1e172, 1e173, 1e174, 1e175, 1e176, 1e177, 1e178, 1e179, 1e180, 1e181, 1e182, 1e183, 1e184, 1e185, 1e186, 1e187, 1e188, 1e189, 1e190, 1e191, 1e192, 1e193, 1e194, 1e195, 1e196, 1e197, 1e198, 1e199, 1e200, 1e201, 1e202, 1e203, 1e204, 1e205, 1e206, 1e207, 1e208, 1e209, 1e210, 1e211, 1e212, 1e213, 1e214, 1e215, 1e216, 1e217, 1e218, 1e219, 1e220, 1e221, 1e222, 1e223, 1e224, 1e225, 1e226, 1e227, 1e228, 1e229, 1e230, 1e231, 1e232, 1e233, 1e234, 1e235, 1e236, 1e237, 1e238, 1e239, 1e240, 1e241, 1e242, 1e243, 1e244, 1e245, 1e246, 1e247, 1e248, 1e249, 1e250, 1e251, 1e252, 1e253, 1e254, 1e255, 1e256, 1e257, 1e258, 1e259, 1e260, 1e261, 1e262, 1e263, 1e264, 1e265, 1e266, 1e267, 1e268, 1e269, 1e270, 1e271, 1e272, 1e273, 1e274, 1e275, 1e276, 1e277, 1e278, 1e279, 1e280, 1e281, 1e282, 1e283, 1e284, 1e285, 1e286, 1e287, 1e288, 1e289, 1e290, 1e291, 1e292, 1e293, 1e294, 1e295, 1e296, 1e297, 1e298, 1e299, 1e300, 1e301, 1e302, 1e303, 1e304, 1e305, 1e306, 1e307, 1e308,
];
const CT: bool = true; const QU: bool = true; const BS: bool = true; const O: bool = false;
#[rustfmt::skip]
static ESCAPE: [bool; 256] = [
CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, CT, O, O, QU, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, BS, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, O, ];
pub fn from_str<T: Deserialize>(s: &str) -> Result<T, Error> {
Deserializer::new(s.as_bytes()).deserialize()
}