blob: a2deef2cba54f7df31132c11ea7c5305c0449b20 [file] [log] [blame]
// Copyright 2017 Serde Developers
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! Deserialize JSON data to a Rust data structure.
use std::{i32, u64};
use std::io;
use std::marker::PhantomData;
use serde::de::{self, Unexpected};
use super::error::{Error, ErrorCode, Result};
use read::{self, Reference};
pub use read::{Read, IoRead, SliceRead, StrRead};
//////////////////////////////////////////////////////////////////////////////
/// A structure that deserializes JSON into Rust values.
pub struct Deserializer<R> {
read: R,
str_buf: Vec<u8>,
remaining_depth: u8,
}
impl<'de, R> Deserializer<R>
where
R: read::Read<'de>,
{
/// Create a JSON deserializer from one of the possible serde_json input
/// sources.
///
/// Typically it is more convenient to use one of these methods instead:
///
/// - Deserializer::from_str
/// - Deserializer::from_bytes
/// - Deserializer::from_reader
pub fn new(read: R) -> Self {
Deserializer {
read: read,
str_buf: Vec::with_capacity(128),
remaining_depth: 128,
}
}
}
impl<R> Deserializer<read::IoRead<R>>
where
R: io::Read,
{
/// Creates a JSON deserializer from an `io::Read`.
pub fn from_reader(reader: R) -> Self {
Deserializer::new(read::IoRead::new(reader))
}
}
impl<'a> Deserializer<read::SliceRead<'a>> {
/// Creates a JSON deserializer from a `&[u8]`.
pub fn from_slice(bytes: &'a [u8]) -> Self {
Deserializer::new(read::SliceRead::new(bytes))
}
}
impl<'a> Deserializer<read::StrRead<'a>> {
/// Creates a JSON deserializer from a `&str`.
pub fn from_str(s: &'a str) -> Self {
Deserializer::new(read::StrRead::new(s))
}
}
macro_rules! overflow {
($a:ident * 10 + $b:ident, $c:expr) => {
$a >= $c / 10 && ($a > $c / 10 || $b > $c % 10)
}
}
enum Number {
F64(f64),
U64(u64),
I64(i64),
}
impl Number {
fn visit<'de, V>(self, visitor: V) -> Result<V::Value>
where
V: de::Visitor<'de>,
{
match self {
Number::F64(x) => visitor.visit_f64(x),
Number::U64(x) => visitor.visit_u64(x),
Number::I64(x) => visitor.visit_i64(x),
}
}
}
impl<'de, R: Read<'de>> Deserializer<R> {
/// The `Deserializer::end` method should be called after a value has been fully deserialized.
/// This allows the `Deserializer` to validate that the input stream is at the end or that it
/// only has trailing whitespace.
pub fn end(&mut self) -> Result<()> {
match try!(self.parse_whitespace()) {
Some(_) => Err(self.peek_error(ErrorCode::TrailingCharacters)),
None => Ok(()),
}
}
/// Turn a JSON deserializer into an iterator over values of type T.
pub fn into_iter<T>(self) -> StreamDeserializer<'de, R, T>
where
T: de::Deserialize<'de>,
{
// This cannot be an implementation of std::iter::IntoIterator because
// we need the caller to choose what T is.
let offset = self.read.byte_offset();
StreamDeserializer {
de: self,
offset: offset,
output: PhantomData,
lifetime: PhantomData,
}
}
fn peek(&mut self) -> Result<Option<u8>> {
self.read.peek().map_err(Error::io)
}
fn peek_or_null(&mut self) -> Result<u8> {
Ok(try!(self.peek()).unwrap_or(b'\x00'))
}
fn eat_char(&mut self) {
self.read.discard();
}
fn next_char(&mut self) -> Result<Option<u8>> {
self.read.next().map_err(Error::io)
}
fn next_char_or_null(&mut self) -> Result<u8> {
Ok(try!(self.next_char()).unwrap_or(b'\x00'))
}
/// Error caused by a byte from next_char().
fn error(&mut self, reason: ErrorCode) -> Error {
let pos = self.read.position();
Error::syntax(reason, pos.line, pos.column)
}
/// Error caused by a byte from peek().
fn peek_error(&mut self, reason: ErrorCode) -> Error {
let pos = self.read.peek_position();
Error::syntax(reason, pos.line, pos.column)
}
/// Returns the first non-whitespace byte without consuming it, or `None` if
/// EOF is encountered.
fn parse_whitespace(&mut self) -> Result<Option<u8>> {
loop {
match try!(self.peek()) {
Some(b' ') | Some(b'\n') | Some(b'\t') | Some(b'\r') => {
self.eat_char();
}
other => {
return Ok(other);
}
}
}
}
fn parse_value<V>(&mut self, visitor: V) -> Result<V::Value>
where
V: de::Visitor<'de>,
{
let peek = match try!(self.parse_whitespace()) {
Some(b) => b,
None => {
return Err(self.peek_error(ErrorCode::EofWhileParsingValue));
}
};
let value = match peek {
b'n' => {
self.eat_char();
try!(self.parse_ident(b"ull"));
visitor.visit_unit()
}
b't' => {
self.eat_char();
try!(self.parse_ident(b"rue"));
visitor.visit_bool(true)
}
b'f' => {
self.eat_char();
try!(self.parse_ident(b"alse"));
visitor.visit_bool(false)
}
b'-' => {
self.eat_char();
try!(self.parse_integer(false)).visit(visitor)
}
b'0'...b'9' => try!(self.parse_integer(true)).visit(visitor),
b'"' => {
self.eat_char();
self.str_buf.clear();
match try!(self.read.parse_str(&mut self.str_buf)) {
Reference::Borrowed(s) => visitor.visit_borrowed_str(s),
Reference::Copied(s) => visitor.visit_str(s),
}
}
b'[' => {
self.remaining_depth -= 1;
if self.remaining_depth == 0 {
return Err(self.peek_error(ErrorCode::RecursionLimitExceeded));
}
self.eat_char();
let ret = visitor.visit_seq(SeqAccess::new(self));
self.remaining_depth += 1;
match (ret, self.end_seq()) {
(Ok(ret), Ok(())) => Ok(ret),
(Err(err), _) | (_, Err(err)) => Err(err),
}
}
b'{' => {
self.remaining_depth -= 1;
if self.remaining_depth == 0 {
return Err(self.peek_error(ErrorCode::RecursionLimitExceeded));
}
self.eat_char();
let ret = visitor.visit_map(MapAccess::new(self));
self.remaining_depth += 1;
match (ret, self.end_map()) {
(Ok(ret), Ok(())) => Ok(ret),
(Err(err), _) | (_, Err(err)) => Err(err),
}
}
_ => Err(self.peek_error(ErrorCode::ExpectedSomeValue)),
};
match value {
Ok(value) => Ok(value),
// The de::Error and From<de::value::Error> impls both create errors
// with unknown line and column. Fill in the position here by
// looking at the current index in the input. There is no way to
// tell whether this should call `error` or `peek_error` so pick the
// one that seems correct more often. Worst case, the position is
// off by one character.
Err(err) => Err(err.fix_position(|code| self.error(code))),
}
}
fn parse_ident(&mut self, ident: &[u8]) -> Result<()> {
for c in ident {
if Some(*c) != try!(self.next_char()) {
return Err(self.error(ErrorCode::ExpectedSomeIdent));
}
}
Ok(())
}
fn parse_integer(&mut self, pos: bool) -> Result<Number> {
match try!(self.next_char_or_null()) {
b'0' => {
// There can be only one leading '0'.
match try!(self.peek_or_null()) {
b'0'...b'9' => Err(self.peek_error(ErrorCode::InvalidNumber)),
_ => self.parse_number(pos, 0),
}
}
c @ b'1'...b'9' => {
let mut res = (c - b'0') as u64;
loop {
match try!(self.peek_or_null()) {
c @ b'0'...b'9' => {
self.eat_char();
let digit = (c - b'0') as u64;
// We need to be careful with overflow. If we can, try to keep the
// number as a `u64` until we grow too large. At that point, switch to
// parsing the value as a `f64`.
if overflow!(res * 10 + digit, u64::MAX) {
return Ok(Number::F64(try!(self.parse_long_integer(
pos,
res,
1, // res * 10^1
))));
}
res = res * 10 + digit;
}
_ => {
return self.parse_number(pos, res);
}
}
}
}
_ => Err(self.error(ErrorCode::InvalidNumber)),
}
}
fn parse_long_integer(
&mut self,
pos: bool,
significand: u64,
mut exponent: i32,
) -> Result<f64> {
loop {
match try!(self.peek_or_null()) {
b'0'...b'9' => {
self.eat_char();
// This could overflow... if your integer is gigabytes long.
// Ignore that possibility.
exponent += 1;
}
b'.' => {
return self.parse_decimal(pos, significand, exponent);
}
b'e' | b'E' => {
return self.parse_exponent(pos, significand, exponent);
}
_ => {
return self.f64_from_parts(pos, significand, exponent);
}
}
}
}
fn parse_number(&mut self, pos: bool, significand: u64) -> Result<Number> {
Ok(match try!(self.peek_or_null()) {
b'.' => Number::F64(try!(self.parse_decimal(pos, significand, 0))),
b'e' | b'E' => Number::F64(try!(self.parse_exponent(pos, significand, 0))),
_ => {
if pos {
Number::U64(significand)
} else {
let neg = (significand as i64).wrapping_neg();
// Convert into a float if we underflow.
if neg > 0 {
Number::F64(-(significand as f64))
} else {
Number::I64(neg)
}
}
}
})
}
fn parse_decimal(
&mut self,
pos: bool,
mut significand: u64,
mut exponent: i32,
) -> Result<f64> {
self.eat_char();
let mut at_least_one_digit = false;
while let c @ b'0'...b'9' = try!(self.peek_or_null()) {
self.eat_char();
let digit = (c - b'0') as u64;
at_least_one_digit = true;
if overflow!(significand * 10 + digit, u64::MAX) {
// The next multiply/add would overflow, so just ignore all
// further digits.
while let b'0'...b'9' = try!(self.peek_or_null()) {
self.eat_char();
}
break;
}
significand = significand * 10 + digit;
exponent -= 1;
}
if !at_least_one_digit {
return Err(self.peek_error(ErrorCode::InvalidNumber));
}
match try!(self.peek_or_null()) {
b'e' | b'E' => self.parse_exponent(pos, significand, exponent),
_ => self.f64_from_parts(pos, significand, exponent),
}
}
fn parse_exponent(
&mut self,
pos: bool,
significand: u64,
starting_exp: i32,
) -> Result<f64> {
self.eat_char();
let pos_exp = match try!(self.peek_or_null()) {
b'+' => {
self.eat_char();
true
}
b'-' => {
self.eat_char();
false
}
_ => true,
};
// Make sure a digit follows the exponent place.
let mut exp = match try!(self.next_char_or_null()) {
c @ b'0'...b'9' => (c - b'0') as i32,
_ => {
return Err(self.error(ErrorCode::InvalidNumber));
}
};
while let c @ b'0'...b'9' = try!(self.peek_or_null()) {
self.eat_char();
let digit = (c - b'0') as i32;
if overflow!(exp * 10 + digit, i32::MAX) {
return self.parse_exponent_overflow(pos, significand, pos_exp);
}
exp = exp * 10 + digit;
}
let final_exp = if pos_exp {
starting_exp.saturating_add(exp)
} else {
starting_exp.saturating_sub(exp)
};
self.f64_from_parts(pos, significand, final_exp)
}
// This cold code should not be inlined into the middle of the hot
// exponent-parsing loop above.
#[cold]
#[inline(never)]
fn parse_exponent_overflow(
&mut self,
pos: bool,
significand: u64,
pos_exp: bool,
) -> Result<f64> {
// Error instead of +/- infinity.
if significand != 0 && pos_exp {
return Err(self.error(ErrorCode::NumberOutOfRange));
}
while let b'0'...b'9' = try!(self.peek_or_null()) {
self.eat_char();
}
Ok(if pos { 0.0 } else { -0.0 })
}
fn f64_from_parts(
&mut self,
pos: bool,
significand: u64,
mut exponent: i32,
) -> Result<f64> {
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(self.error(ErrorCode::NumberOutOfRange));
}
} else {
f /= pow;
}
break;
}
None => {
if f == 0.0 {
break;
}
if exponent >= 0 {
return Err(self.error(ErrorCode::NumberOutOfRange));
}
f /= 1e308;
exponent += 308;
}
}
}
Ok(if pos { f } else { -f })
}
fn parse_object_colon(&mut self) -> Result<()> {
match try!(self.parse_whitespace()) {
Some(b':') => {
self.eat_char();
Ok(())
}
Some(_) => Err(self.peek_error(ErrorCode::ExpectedColon)),
None => Err(self.peek_error(ErrorCode::EofWhileParsingObject)),
}
}
fn end_seq(&mut self) -> Result<()> {
match try!(self.parse_whitespace()) {
Some(b']') => {
self.eat_char();
Ok(())
}
Some(b',') => {
self.eat_char();
match self.parse_whitespace() {
Ok(Some(b']')) => Err(self.peek_error(ErrorCode::TrailingComma)),
_ => Err(self.peek_error(ErrorCode::TrailingCharacters)),
}
}
Some(_) => Err(self.peek_error(ErrorCode::TrailingCharacters)),
None => Err(self.peek_error(ErrorCode::EofWhileParsingList)),
}
}
fn end_map(&mut self) -> Result<()> {
match try!(self.parse_whitespace()) {
Some(b'}') => {
self.eat_char();
Ok(())
}
Some(b',') => Err(self.peek_error(ErrorCode::TrailingComma)),
Some(_) => Err(self.peek_error(ErrorCode::TrailingCharacters)),
None => Err(self.peek_error(ErrorCode::EofWhileParsingObject)),
}
}
fn ignore_value(&mut self) -> Result<()> {
let peek = match try!(self.parse_whitespace()) {
Some(b) => b,
None => {
return Err(self.peek_error(ErrorCode::EofWhileParsingValue));
}
};
match peek {
b'n' => {
self.eat_char();
self.parse_ident(b"ull")
}
b't' => {
self.eat_char();
self.parse_ident(b"rue")
}
b'f' => {
self.eat_char();
self.parse_ident(b"alse")
}
b'-' => {
self.eat_char();
self.ignore_integer()
}
b'0'...b'9' => {
self.ignore_integer()
}
b'"' => {
self.eat_char();
self.read.ignore_str()
}
b'[' => {
self.remaining_depth -= 1;
if self.remaining_depth == 0 {
return Err(self.peek_error(ErrorCode::RecursionLimitExceeded));
}
self.eat_char();
let res = self.ignore_seq();
self.remaining_depth += 1;
res
}
b'{' => {
self.remaining_depth -= 1;
if self.remaining_depth == 0 {
return Err(self.peek_error(ErrorCode::RecursionLimitExceeded));
}
self.eat_char();
let res = self.ignore_map();
self.remaining_depth += 1;
res
}
_ => {
Err(self.peek_error(ErrorCode::ExpectedSomeValue))
}
}
}
fn ignore_integer(&mut self) -> Result<()> {
match try!(self.next_char_or_null()) {
b'0' => {
// There can be only one leading '0'.
if let b'0'...b'9' = try!(self.peek_or_null()) {
return Err(self.peek_error(ErrorCode::InvalidNumber));
}
}
b'1'...b'9' => {
while let b'0'...b'9' = try!(self.peek_or_null()) {
self.eat_char();
}
}
_ => {
return Err(self.error(ErrorCode::InvalidNumber));
}
}
match try!(self.peek_or_null()) {
b'.' => self.ignore_decimal(),
b'e' | b'E' => self.ignore_exponent(),
_ => Ok(()),
}
}
fn ignore_decimal(&mut self) -> Result<()> {
self.eat_char();
let mut at_least_one_digit = false;
while let b'0'...b'9' = try!(self.peek_or_null()) {
self.eat_char();
at_least_one_digit = true;
}
if !at_least_one_digit {
return Err(self.peek_error(ErrorCode::InvalidNumber));
}
match try!(self.peek_or_null()) {
b'e' | b'E' => self.ignore_exponent(),
_ => Ok(()),
}
}
fn ignore_exponent(&mut self) -> Result<()> {
self.eat_char();
match try!(self.peek_or_null()) {
b'+' | b'-' => self.eat_char(),
_ => {}
}
// Make sure a digit follows the exponent place.
match try!(self.next_char_or_null()) {
b'0'...b'9' => {}
_ => {
return Err(self.error(ErrorCode::InvalidNumber));
}
}
while let b'0'...b'9' = try!(self.peek_or_null()) {
self.eat_char();
}
Ok(())
}
fn ignore_seq(&mut self) -> Result<()> {
let mut first = true;
loop {
match try!(self.parse_whitespace()) {
Some(b']') => {
self.eat_char();
return Ok(());
}
Some(b',') if !first => {
self.eat_char();
}
Some(_) => {
if first {
first = false;
} else {
return Err(self.peek_error(ErrorCode::ExpectedListCommaOrEnd));
}
}
None => {
return Err(self.peek_error(ErrorCode::EofWhileParsingList));
}
}
try!(self.ignore_value());
}
}
fn ignore_map(&mut self) -> Result<()> {
let mut first = true;
loop {
let peek = match try!(self.parse_whitespace()) {
Some(b'}') => {
self.eat_char();
return Ok(());
}
Some(b',') if !first => {
self.eat_char();
try!(self.parse_whitespace())
}
Some(b) => {
if first {
first = false;
Some(b)
} else {
return Err(self.peek_error(ErrorCode::ExpectedObjectCommaOrEnd));
}
}
None => {
return Err(self.peek_error(ErrorCode::EofWhileParsingObject));
}
};
match peek {
Some(b'"') => {
self.eat_char();
try!(self.read.ignore_str());
}
Some(_) => {
return Err(self.peek_error(ErrorCode::KeyMustBeAString));
}
None => {
return Err(self.peek_error(ErrorCode::EofWhileParsingObject));
}
}
match try!(self.parse_whitespace()) {
Some(b':') => {
self.eat_char();
try!(self.ignore_value());
}
Some(_) => {
return Err(self.peek_error(ErrorCode::ExpectedColon));
}
None => {
return Err(self.peek_error(ErrorCode::EofWhileParsingObject));
}
}
}
}
}
#[cfg_attr(rustfmt, rustfmt_skip)]
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];
impl<'de, 'a, R: Read<'de>> de::Deserializer<'de> for &'a mut Deserializer<R> {
type Error = Error;
#[inline]
fn deserialize_any<V>(self, visitor: V) -> Result<V::Value>
where
V: de::Visitor<'de>,
{
self.parse_value(visitor)
}
/// Parses a `null` as a None, and any other values as a `Some(...)`.
#[inline]
fn deserialize_option<V>(self, visitor: V) -> Result<V::Value>
where
V: de::Visitor<'de>,
{
match try!(self.parse_whitespace()) {
Some(b'n') => {
self.eat_char();
try!(self.parse_ident(b"ull"));
visitor.visit_none()
}
_ => visitor.visit_some(self),
}
}
/// Parses a newtype struct as the underlying value.
#[inline]
fn deserialize_newtype_struct<V>(self, _name: &str, visitor: V) -> Result<V::Value>
where
V: de::Visitor<'de>,
{
visitor.visit_newtype_struct(self)
}
/// Parses an enum as an object like `{"$KEY":$VALUE}`, where $VALUE is either a straight
/// value, a `[..]`, or a `{..}`.
#[inline]
fn deserialize_enum<V>(
self,
_name: &str,
_variants: &'static [&'static str],
visitor: V,
) -> Result<V::Value>
where
V: de::Visitor<'de>,
{
match try!(self.parse_whitespace()) {
Some(b'{') => {
self.remaining_depth -= 1;
if self.remaining_depth == 0 {
return Err(self.peek_error(ErrorCode::RecursionLimitExceeded));
}
self.eat_char();
let value = try!(visitor.visit_enum(VariantAccess::new(self)));
self.remaining_depth += 1;
match try!(self.parse_whitespace()) {
Some(b'}') => {
self.eat_char();
Ok(value)
}
Some(_) => Err(self.error(ErrorCode::ExpectedSomeValue)),
None => Err(self.error(ErrorCode::EofWhileParsingObject)),
}
}
Some(b'"') => visitor.visit_enum(UnitVariantAccess::new(self)),
Some(_) => Err(self.peek_error(ErrorCode::ExpectedSomeValue)),
None => Err(self.peek_error(ErrorCode::EofWhileParsingValue)),
}
}
/// Parses a JSON string as bytes. Note that this function does not check
/// whether the bytes represent a valid UTF-8 string.
///
/// The relevant part of the JSON specification is Section 8.2 of [RFC
/// 7159]:
///
/// > When all the strings represented in a JSON text are composed entirely
/// > of Unicode characters (however escaped), then that JSON text is
/// > interoperable in the sense that all software implementations that
/// > parse it will agree on the contents of names and of string values in
/// > objects and arrays.
/// >
/// > However, the ABNF in this specification allows member names and string
/// > values to contain bit sequences that cannot encode Unicode characters;
/// > for example, "\uDEAD" (a single unpaired UTF-16 surrogate). Instances
/// > of this have been observed, for example, when a library truncates a
/// > UTF-16 string without checking whether the truncation split a
/// > surrogate pair. The behavior of software that receives JSON texts
/// > containing such values is unpredictable; for example, implementations
/// > might return different values for the length of a string value or even
/// > suffer fatal runtime exceptions.
///
/// [RFC 7159]: https://tools.ietf.org/html/rfc7159
///
/// The behavior of serde_json is specified to fail on non-UTF-8 strings
/// when deserializing into Rust UTF-8 string types such as String, and
/// succeed with non-UTF-8 bytes when deserializing using this method.
///
/// Escape sequences are processed as usual, and for `\uXXXX` escapes it is
/// still checked if the hex number represents a valid Unicode code point.
///
/// # Examples
///
/// You can use this to parse JSON strings containing invalid UTF-8 bytes.
///
/// ```rust
/// extern crate serde_json;
/// extern crate serde_bytes;
///
/// use serde_bytes::ByteBuf;
///
/// fn look_at_bytes() -> Result<(), serde_json::Error> {
/// let json_data = b"\"some bytes: \xe5\x00\xe5\"";
/// let bytes: ByteBuf = serde_json::from_slice(json_data)?;
///
/// assert_eq!(b'\xe5', bytes[12]);
/// assert_eq!(b'\0', bytes[13]);
/// assert_eq!(b'\xe5', bytes[14]);
///
/// Ok(())
/// }
/// #
/// # fn main() {
/// # look_at_bytes().unwrap();
/// # }
/// ```
///
/// Backslash escape sequences like `\n` are still interpreted and required
/// to be valid, and `\u` escape sequences are required to represent valid
/// Unicode code points.
///
/// ```rust
/// extern crate serde_json;
/// extern crate serde_bytes;
///
/// use serde_bytes::ByteBuf;
///
/// fn look_at_bytes() {
/// let json_data = b"\"invalid unicode surrogate: \\uD801\"";
/// let parsed: Result<ByteBuf, _> = serde_json::from_slice(json_data);
///
/// assert!(parsed.is_err());
///
/// let expected_msg = "unexpected end of hex escape at line 1 column 35";
/// assert_eq!(expected_msg, parsed.unwrap_err().to_string());
/// }
/// #
/// # fn main() {
/// # look_at_bytes();
/// # }
/// ```
fn deserialize_bytes<V>(self, visitor: V) -> Result<V::Value>
where
V: de::Visitor<'de>,
{
match try!(self.parse_whitespace()) {
Some(b'"') => {
self.eat_char();
self.str_buf.clear();
match try!(self.read.parse_str_raw(&mut self.str_buf)) {
Reference::Borrowed(b) => visitor.visit_borrowed_bytes(b),
Reference::Copied(b) => visitor.visit_bytes(b),
}
}
_ => self.deserialize_any(visitor),
}
}
#[inline]
fn deserialize_byte_buf<V>(self, visitor: V) -> Result<V::Value>
where
V: de::Visitor<'de>,
{
self.deserialize_bytes(visitor)
}
fn deserialize_ignored_any<V>(self, visitor: V) -> Result<V::Value>
where
V: de::Visitor<'de>,
{
try!(self.ignore_value());
visitor.visit_unit()
}
forward_to_deserialize_any! {
bool i8 i16 i32 i64 u8 u16 u32 u64 f32 f64 char str string unit
unit_struct seq tuple tuple_struct map struct identifier
}
}
struct SeqAccess<'a, R: 'a> {
de: &'a mut Deserializer<R>,
first: bool,
}
impl<'a, R: 'a> SeqAccess<'a, R> {
fn new(de: &'a mut Deserializer<R>) -> Self {
SeqAccess {
de: de,
first: true,
}
}
}
impl<'de, 'a, R: Read<'de> + 'a> de::SeqAccess<'de> for SeqAccess<'a, R> {
type Error = Error;
fn next_element_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>>
where
T: de::DeserializeSeed<'de>,
{
let peek = match try!(self.de.parse_whitespace()) {
Some(b']') => {
return Ok(None);
}
Some(b',') if !self.first => {
self.de.eat_char();
try!(self.de.parse_whitespace())
}
Some(b) => {
if self.first {
self.first = false;
Some(b)
} else {
return Err(self.de.peek_error(ErrorCode::ExpectedListCommaOrEnd));
}
}
None => {
return Err(self.de.peek_error(ErrorCode::EofWhileParsingList));
}
};
match peek {
Some(b']') => Err(self.de.peek_error(ErrorCode::TrailingComma)),
Some(_) => Ok(Some(try!(seed.deserialize(&mut *self.de)))),
None => Err(self.de.peek_error(ErrorCode::EofWhileParsingValue)),
}
}
}
struct MapAccess<'a, R: 'a> {
de: &'a mut Deserializer<R>,
first: bool,
}
impl<'a, R: 'a> MapAccess<'a, R> {
fn new(de: &'a mut Deserializer<R>) -> Self {
MapAccess {
de: de,
first: true,
}
}
}
impl<'de, 'a, R: Read<'de> + 'a> de::MapAccess<'de> for MapAccess<'a, R> {
type Error = Error;
fn next_key_seed<K>(&mut self, seed: K) -> Result<Option<K::Value>>
where
K: de::DeserializeSeed<'de>,
{
let peek = match try!(self.de.parse_whitespace()) {
Some(b'}') => {
return Ok(None);
}
Some(b',') if !self.first => {
self.de.eat_char();
try!(self.de.parse_whitespace())
}
Some(b) => {
if self.first {
self.first = false;
Some(b)
} else {
return Err(self.de.peek_error(ErrorCode::ExpectedObjectCommaOrEnd));
}
}
None => {
return Err(self.de.peek_error(ErrorCode::EofWhileParsingObject));
}
};
match peek {
Some(b'"') => seed.deserialize(MapKey { de: &mut *self.de }).map(Some),
Some(b'}') => Err(self.de.peek_error(ErrorCode::TrailingComma)),
Some(_) => Err(self.de.peek_error(ErrorCode::KeyMustBeAString)),
None => Err(self.de.peek_error(ErrorCode::EofWhileParsingValue)),
}
}
fn next_value_seed<V>(&mut self, seed: V) -> Result<V::Value>
where
V: de::DeserializeSeed<'de>,
{
try!(self.de.parse_object_colon());
seed.deserialize(&mut *self.de)
}
}
struct VariantAccess<'a, R: 'a> {
de: &'a mut Deserializer<R>,
}
impl<'a, R: 'a> VariantAccess<'a, R> {
fn new(de: &'a mut Deserializer<R>) -> Self {
VariantAccess { de: de }
}
}
impl<'de, 'a, R: Read<'de> + 'a> de::EnumAccess<'de> for VariantAccess<'a, R> {
type Error = Error;
type Variant = Self;
fn variant_seed<V>(self, seed: V) -> Result<(V::Value, Self)>
where
V: de::DeserializeSeed<'de>,
{
let val = try!(seed.deserialize(&mut *self.de));
try!(self.de.parse_object_colon());
Ok((val, self))
}
}
impl<'de, 'a, R: Read<'de> + 'a> de::VariantAccess<'de> for VariantAccess<'a, R> {
type Error = Error;
fn unit_variant(self) -> Result<()> {
de::Deserialize::deserialize(self.de)
}
fn newtype_variant_seed<T>(self, seed: T) -> Result<T::Value>
where
T: de::DeserializeSeed<'de>,
{
seed.deserialize(self.de)
}
fn tuple_variant<V>(self, _len: usize, visitor: V) -> Result<V::Value>
where
V: de::Visitor<'de>,
{
de::Deserializer::deserialize_any(self.de, visitor)
}
fn struct_variant<V>(self, _fields: &'static [&'static str], visitor: V) -> Result<V::Value>
where
V: de::Visitor<'de>,
{
de::Deserializer::deserialize_any(self.de, visitor)
}
}
struct UnitVariantAccess<'a, R: 'a> {
de: &'a mut Deserializer<R>,
}
impl<'a, R: 'a> UnitVariantAccess<'a, R> {
fn new(de: &'a mut Deserializer<R>) -> Self {
UnitVariantAccess { de: de }
}
}
impl<'de, 'a, R: Read<'de> + 'a> de::EnumAccess<'de> for UnitVariantAccess<'a, R> {
type Error = Error;
type Variant = Self;
fn variant_seed<V>(self, seed: V) -> Result<(V::Value, Self)>
where
V: de::DeserializeSeed<'de>,
{
let variant = try!(seed.deserialize(&mut *self.de));
Ok((variant, self))
}
}
impl<'de, 'a, R: Read<'de> + 'a> de::VariantAccess<'de> for UnitVariantAccess<'a, R> {
type Error = Error;
fn unit_variant(self) -> Result<()> {
Ok(())
}
fn newtype_variant_seed<T>(self, _seed: T) -> Result<T::Value>
where
T: de::DeserializeSeed<'de>,
{
Err(de::Error::invalid_type(Unexpected::UnitVariant, &"newtype variant"),)
}
fn tuple_variant<V>(self, _len: usize, _visitor: V) -> Result<V::Value>
where
V: de::Visitor<'de>,
{
Err(de::Error::invalid_type(Unexpected::UnitVariant, &"tuple variant"),)
}
fn struct_variant<V>(self, _fields: &'static [&'static str], _visitor: V) -> Result<V::Value>
where
V: de::Visitor<'de>,
{
Err(de::Error::invalid_type(Unexpected::UnitVariant, &"struct variant"),)
}
}
/// Only deserialize from this after peeking a '"' byte! Otherwise it may
/// deserialize invalid JSON successfully.
struct MapKey<'a, R: 'a> {
de: &'a mut Deserializer<R>,
}
macro_rules! deserialize_integer_key {
($deserialize:ident => $visit:ident) => {
fn $deserialize<V>(self, visitor: V) -> Result<V::Value>
where
V: de::Visitor<'de>,
{
self.de.eat_char();
self.de.str_buf.clear();
let string = try!(self.de.read.parse_str(&mut self.de.str_buf));
match (string.parse(), string) {
(Ok(integer), _) => visitor.$visit(integer),
(Err(_), Reference::Borrowed(s)) => visitor.visit_borrowed_str(s),
(Err(_), Reference::Copied(s)) => visitor.visit_str(s),
}
}
}
}
impl<'de, 'a, R> de::Deserializer<'de> for MapKey<'a, R>
where
R: Read<'de>,
{
type Error = Error;
#[inline]
fn deserialize_any<V>(self, visitor: V) -> Result<V::Value>
where
V: de::Visitor<'de>,
{
self.de.parse_value(visitor)
}
deserialize_integer_key!(deserialize_i8 => visit_i8);
deserialize_integer_key!(deserialize_i16 => visit_i16);
deserialize_integer_key!(deserialize_i32 => visit_i32);
deserialize_integer_key!(deserialize_i64 => visit_i64);
deserialize_integer_key!(deserialize_u8 => visit_u8);
deserialize_integer_key!(deserialize_u16 => visit_u16);
deserialize_integer_key!(deserialize_u32 => visit_u32);
deserialize_integer_key!(deserialize_u64 => visit_u64);
#[inline]
fn deserialize_option<V>(self, visitor: V) -> Result<V::Value>
where
V: de::Visitor<'de>,
{
// Map keys cannot be null.
visitor.visit_some(self)
}
#[inline]
fn deserialize_newtype_struct<V>(self, _name: &'static str, visitor: V) -> Result<V::Value>
where
V: de::Visitor<'de>,
{
visitor.visit_newtype_struct(self)
}
#[inline]
fn deserialize_enum<V>(
self,
name: &'static str,
variants: &'static [&'static str],
visitor: V,
) -> Result<V::Value>
where
V: de::Visitor<'de>,
{
self.de.deserialize_enum(name, variants, visitor)
}
#[inline]
fn deserialize_bytes<V>(self, visitor: V) -> Result<V::Value>
where
V: de::Visitor<'de>,
{
self.de.deserialize_bytes(visitor)
}
#[inline]
fn deserialize_byte_buf<V>(self, visitor: V) -> Result<V::Value>
where
V: de::Visitor<'de>,
{
self.de.deserialize_bytes(visitor)
}
forward_to_deserialize_any! {
bool f32 f64 char str string unit unit_struct seq tuple tuple_struct map
struct identifier ignored_any
}
}
//////////////////////////////////////////////////////////////////////////////
/// Iterator that deserializes a stream into multiple JSON values.
///
/// A stream deserializer can be created from any JSON deserializer using the
/// `Deserializer::into_iter` method.
///
/// The data must consist of JSON arrays and JSON objects optionally separated
/// by whitespace. A null, boolean, number, or string at the top level are all
/// errors.
///
/// ```rust
/// extern crate serde_json;
///
/// use serde_json::{Deserializer, Value};
///
/// fn main() {
/// let data = "{\"k\": 3} {} [0, 1, 2]";
///
/// let stream = Deserializer::from_str(data).into_iter::<Value>();
///
/// for value in stream {
/// println!("{}", value.unwrap());
/// }
/// }
/// ```
pub struct StreamDeserializer<'de, R, T> {
de: Deserializer<R>,
offset: usize,
output: PhantomData<T>,
lifetime: PhantomData<&'de ()>,
}
impl<'de, R, T> StreamDeserializer<'de, R, T>
where
R: read::Read<'de>,
T: de::Deserialize<'de>,
{
/// Create a JSON stream deserializer from one of the possible serde_json
/// input sources.
///
/// Typically it is more convenient to use one of these methods instead:
///
/// - Deserializer::from_str(...).into_iter()
/// - Deserializer::from_bytes(...).into_iter()
/// - Deserializer::from_reader(...).into_iter()
pub fn new(read: R) -> Self {
let offset = read.byte_offset();
StreamDeserializer {
de: Deserializer::new(read),
offset: offset,
output: PhantomData,
lifetime: PhantomData,
}
}
/// Returns the number of bytes so far deserialized into a successful `T`.
///
/// If a stream deserializer returns an EOF error, new data can be joined to
/// `old_data[stream.byte_offset()..]` to try again.
///
/// ```rust
/// let data = b"[0] [1] [";
///
/// let de = serde_json::Deserializer::from_slice(data);
/// let mut stream = de.into_iter::<Vec<i32>>();
/// assert_eq!(0, stream.byte_offset());
///
/// println!("{:?}", stream.next()); // [0]
/// assert_eq!(3, stream.byte_offset());
///
/// println!("{:?}", stream.next()); // [1]
/// assert_eq!(7, stream.byte_offset());
///
/// println!("{:?}", stream.next()); // error
/// assert_eq!(8, stream.byte_offset());
///
/// // If err.is_eof(), can join the remaining data to new data and continue.
/// let remaining = &data[stream.byte_offset()..];
/// ```
///
/// *Note:* In the future this method may be changed to return the number of
/// bytes so far deserialized into a successful T *or* syntactically valid
/// JSON skipped over due to a type error. See [serde-rs/json#70] for an
/// example illustrating this.
///
/// [serde-rs/json#70]: https://github.com/serde-rs/json/issues/70
pub fn byte_offset(&self) -> usize {
self.offset
}
}
impl<'de, R, T> Iterator for StreamDeserializer<'de, R, T>
where
R: Read<'de>,
T: de::Deserialize<'de>,
{
type Item = Result<T>;
fn next(&mut self) -> Option<Result<T>> {
// skip whitespaces, if any
// this helps with trailing whitespaces, since whitespaces between
// values are handled for us.
match self.de.parse_whitespace() {
Ok(None) => {
self.offset = self.de.read.byte_offset();
None
}
Ok(Some(b'{')) | Ok(Some(b'[')) => {
self.offset = self.de.read.byte_offset();
let result = de::Deserialize::deserialize(&mut self.de);
if result.is_ok() {
self.offset = self.de.read.byte_offset();
}
Some(result)
}
Ok(Some(_)) => Some(Err(self.de.peek_error(ErrorCode::ExpectedObjectOrArray))),
Err(e) => Some(Err(e)),
}
}
}
//////////////////////////////////////////////////////////////////////////////
fn from_trait<'de, R, T>(read: R) -> Result<T>
where
R: Read<'de>,
T: de::Deserialize<'de>,
{
let mut de = Deserializer::new(read);
let value = try!(de::Deserialize::deserialize(&mut de));
// Make sure the whole stream has been consumed.
try!(de.end());
Ok(value)
}
/// Deserialize an instance of type `T` from an IO stream of JSON.
///
/// # Errors
///
/// This conversion can fail if the structure of the input does not match the
/// structure expected by `T`, for example if `T` is a struct type but the input
/// contains something other than a JSON map. It can also fail if the structure
/// is correct but `T`'s implementation of `Deserialize` decides that something
/// is wrong with the data, for example required struct fields are missing from
/// the JSON map or some number is too big to fit in the expected primitive
/// type.
///
/// ```rust
/// #[macro_use]
/// extern crate serde_derive;
///
/// extern crate serde;
/// extern crate serde_json;
///
/// use std::error::Error;
/// use std::fs::File;
/// use std::path::Path;
///
/// #[derive(Deserialize, Debug)]
/// struct User {
/// fingerprint: String,
/// location: String,
/// }
///
/// fn read_user_from_file<P: AsRef<Path>>(path: P) -> Result<User, Box<Error>> {
/// // Open the file in read-only mode.
/// let file = File::open(path)?;
///
/// // Read the JSON contents of the file as an instance of `User`.
/// let u = serde_json::from_reader(file)?;
///
/// // Return the `User`.
/// Ok(u)
/// }
///
/// fn main() {
/// # }
/// # fn fake_main() {
/// let u = read_user_from_file("test.json").unwrap();
/// println!("{:#?}", u);
/// }
/// ```
pub fn from_reader<R, T>(rdr: R) -> Result<T>
where
R: io::Read,
T: de::DeserializeOwned,
{
from_trait(read::IoRead::new(rdr))
}
/// Deserialize an instance of type `T` from bytes of JSON text.
///
/// # Errors
///
/// This conversion can fail if the structure of the input does not match the
/// structure expected by `T`, for example if `T` is a struct type but the input
/// contains something other than a JSON map. It can also fail if the structure
/// is correct but `T`'s implementation of `Deserialize` decides that something
/// is wrong with the data, for example required struct fields are missing from
/// the JSON map or some number is too big to fit in the expected primitive
/// type.
///
/// ```rust
/// #[macro_use]
/// extern crate serde_derive;
///
/// extern crate serde;
/// extern crate serde_json;
///
/// #[derive(Deserialize, Debug)]
/// struct User {
/// fingerprint: String,
/// location: String,
/// }
///
/// fn main() {
/// // The type of `j` is `&[u8]`
/// let j = b"{
/// \"fingerprint\": \"0xF9BA143B95FF6D82\",
/// \"location\": \"Menlo Park, CA\"
/// }";
///
/// let u: User = serde_json::from_slice(j).unwrap();
/// println!("{:#?}", u);
/// }
/// ```
pub fn from_slice<'a, T>(v: &'a [u8]) -> Result<T>
where
T: de::Deserialize<'a>,
{
from_trait(read::SliceRead::new(v))
}
/// Deserialize an instance of type `T` from a string of JSON text.
///
/// # Errors
///
/// This conversion can fail if the structure of the input does not match the
/// structure expected by `T`, for example if `T` is a struct type but the input
/// contains something other than a JSON map. It can also fail if the structure
/// is correct but `T`'s implementation of `Deserialize` decides that something
/// is wrong with the data, for example required struct fields are missing from
/// the JSON map or some number is too big to fit in the expected primitive
/// type.
///
/// ```rust
/// #[macro_use]
/// extern crate serde_derive;
///
/// extern crate serde;
/// extern crate serde_json;
///
/// #[derive(Deserialize, Debug)]
/// struct User {
/// fingerprint: String,
/// location: String,
/// }
///
/// fn main() {
/// // The type of `j` is `&str`
/// let j = "{
/// \"fingerprint\": \"0xF9BA143B95FF6D82\",
/// \"location\": \"Menlo Park, CA\"
/// }";
///
/// let u: User = serde_json::from_str(j).unwrap();
/// println!("{:#?}", u);
/// }
/// ```
pub fn from_str<'a, T>(s: &'a str) -> Result<T>
where
T: de::Deserialize<'a>,
{
from_trait(read::StrRead::new(s))
}