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rust/compiler/rustc_serialize/src/json.rs
Joshua Nelson 0ad3dce83a Fix some clippy lints
2020-12-03 17:08:19 -05:00

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// Rust JSON serialization library.
// Copyright (c) 2011 Google Inc.
#![forbid(non_camel_case_types)]
#![allow(missing_docs)]
//! JSON parsing and serialization
//!
//! # What is JSON?
//!
//! JSON (JavaScript Object Notation) is a way to write data in Javascript.
//! Like XML, it allows to encode structured data in a text format that can be easily read by humans
//! Its simple syntax and native compatibility with JavaScript have made it a widely used format.
//!
//! Data types that can be encoded are JavaScript types (see the `Json` enum for more details):
//!
//! * `Boolean`: equivalent to rust's `bool`
//! * `Number`: equivalent to rust's `f64`
//! * `String`: equivalent to rust's `String`
//! * `Array`: equivalent to rust's `Vec<T>`, but also allowing objects of different types in the
//! same array
//! * `Object`: equivalent to rust's `BTreeMap<String, json::Json>`
//! * `Null`
//!
//! An object is a series of string keys mapping to values, in `"key": value` format.
//! Arrays are enclosed in square brackets ([ ... ]) and objects in curly brackets ({ ... }).
//! A simple JSON document encoding a person, their age, address and phone numbers could look like
//!
//! ```json
//! {
//! "FirstName": "John",
//! "LastName": "Doe",
//! "Age": 43,
//! "Address": {
//! "Street": "Downing Street 10",
//! "City": "London",
//! "Country": "Great Britain"
//! },
//! "PhoneNumbers": [
//! "+44 1234567",
//! "+44 2345678"
//! ]
//! }
//! ```
//!
//! # Rust Type-based Encoding and Decoding
//!
//! Rust provides a mechanism for low boilerplate encoding & decoding of values to and from JSON via
//! the serialization API.
//! To be able to encode a piece of data, it must implement the `serialize::Encodable` trait.
//! To be able to decode a piece of data, it must implement the `serialize::Decodable` trait.
//! The Rust compiler provides an annotation to automatically generate the code for these traits:
//! `#[derive(Decodable, Encodable)]`
//!
//! The JSON API provides an enum `json::Json` and a trait `ToJson` to encode objects.
//! The `ToJson` trait provides a `to_json` method to convert an object into a `json::Json` value.
//! A `json::Json` value can be encoded as a string or buffer using the functions described above.
//! You can also use the `json::Encoder` object, which implements the `Encoder` trait.
//!
//! When using `ToJson` the `Encodable` trait implementation is not mandatory.
//!
//! # Examples of use
//!
//! ## Using Autoserialization
//!
//! Create a struct called `TestStruct` and serialize and deserialize it to and from JSON using the
//! serialization API, using the derived serialization code.
//!
//! ```rust
//! # #![feature(rustc_private)]
//! use rustc_macros::{Decodable, Encodable};
//! use rustc_serialize::json;
//!
//! // Automatically generate `Decodable` and `Encodable` trait implementations
//! #[derive(Decodable, Encodable)]
//! pub struct TestStruct {
//! data_int: u8,
//! data_str: String,
//! data_vector: Vec<u8>,
//! }
//!
//! let object = TestStruct {
//! data_int: 1,
//! data_str: "homura".to_string(),
//! data_vector: vec![2,3,4,5],
//! };
//!
//! // Serialize using `json::encode`
//! let encoded = json::encode(&object).unwrap();
//!
//! // Deserialize using `json::decode`
//! let decoded: TestStruct = json::decode(&encoded[..]).unwrap();
//! ```
//!
//! ## Using the `ToJson` trait
//!
//! The examples above use the `ToJson` trait to generate the JSON string, which is required
//! for custom mappings.
//!
//! ### Simple example of `ToJson` usage
//!
//! ```rust
//! # #![feature(rustc_private)]
//! use rustc_macros::Encodable;
//! use rustc_serialize::json::{self, ToJson, Json};
//!
//! // A custom data structure
//! struct ComplexNum {
//! a: f64,
//! b: f64,
//! }
//!
//! // JSON value representation
//! impl ToJson for ComplexNum {
//! fn to_json(&self) -> Json {
//! Json::String(format!("{}+{}i", self.a, self.b))
//! }
//! }
//!
//! // Only generate `Encodable` trait implementation
//! #[derive(Encodable)]
//! pub struct ComplexNumRecord {
//! uid: u8,
//! dsc: String,
//! val: Json,
//! }
//!
//! let num = ComplexNum { a: 0.0001, b: 12.539 };
//! let data: String = json::encode(&ComplexNumRecord{
//! uid: 1,
//! dsc: "test".to_string(),
//! val: num.to_json(),
//! }).unwrap();
//! println!("data: {}", data);
//! // data: {"uid":1,"dsc":"test","val":"0.0001+12.539i"};
//! ```
//!
//! ### Verbose example of `ToJson` usage
//!
//! ```rust
//! # #![feature(rustc_private)]
//! use rustc_macros::Decodable;
//! use std::collections::BTreeMap;
//! use rustc_serialize::json::{self, Json, ToJson};
//!
//! // Only generate `Decodable` trait implementation
//! #[derive(Decodable)]
//! pub struct TestStruct {
//! data_int: u8,
//! data_str: String,
//! data_vector: Vec<u8>,
//! }
//!
//! // Specify encoding method manually
//! impl ToJson for TestStruct {
//! fn to_json(&self) -> Json {
//! let mut d = BTreeMap::new();
//! // All standard types implement `to_json()`, so use it
//! d.insert("data_int".to_string(), self.data_int.to_json());
//! d.insert("data_str".to_string(), self.data_str.to_json());
//! d.insert("data_vector".to_string(), self.data_vector.to_json());
//! Json::Object(d)
//! }
//! }
//!
//! // Serialize using `ToJson`
//! let input_data = TestStruct {
//! data_int: 1,
//! data_str: "madoka".to_string(),
//! data_vector: vec![2,3,4,5],
//! };
//! let json_obj: Json = input_data.to_json();
//! let json_str: String = json_obj.to_string();
//!
//! // Deserialize like before
//! let decoded: TestStruct = json::decode(&json_str).unwrap();
//! ```
use self::DecoderError::*;
use self::ErrorCode::*;
use self::InternalStackElement::*;
use self::JsonEvent::*;
use self::ParserError::*;
use self::ParserState::*;
use std::borrow::Cow;
use std::collections::{BTreeMap, HashMap};
use std::io;
use std::io::prelude::*;
use std::mem::swap;
use std::num::FpCategory as Fp;
use std::ops::Index;
use std::str::FromStr;
use std::string;
use std::{char, fmt, str};
use crate::Encodable;
/// Represents a json value
#[derive(Clone, PartialEq, PartialOrd, Debug)]
pub enum Json {
I64(i64),
U64(u64),
F64(f64),
String(string::String),
Boolean(bool),
Array(self::Array),
Object(self::Object),
Null,
}
pub type Array = Vec<Json>;
pub type Object = BTreeMap<string::String, Json>;
pub struct PrettyJson<'a> {
inner: &'a Json,
}
pub struct AsJson<'a, T> {
inner: &'a T,
}
pub struct AsPrettyJson<'a, T> {
inner: &'a T,
indent: Option<usize>,
}
/// The errors that can arise while parsing a JSON stream.
#[derive(Clone, Copy, PartialEq, Debug)]
pub enum ErrorCode {
InvalidSyntax,
InvalidNumber,
EOFWhileParsingObject,
EOFWhileParsingArray,
EOFWhileParsingValue,
EOFWhileParsingString,
KeyMustBeAString,
ExpectedColon,
TrailingCharacters,
TrailingComma,
InvalidEscape,
InvalidUnicodeCodePoint,
LoneLeadingSurrogateInHexEscape,
UnexpectedEndOfHexEscape,
UnrecognizedHex,
NotFourDigit,
NotUtf8,
}
#[derive(Clone, PartialEq, Debug)]
pub enum ParserError {
/// msg, line, col
SyntaxError(ErrorCode, usize, usize),
IoError(io::ErrorKind, String),
}
// Builder and Parser have the same errors.
pub type BuilderError = ParserError;
#[derive(Clone, PartialEq, Debug)]
pub enum DecoderError {
ParseError(ParserError),
ExpectedError(string::String, string::String),
MissingFieldError(string::String),
UnknownVariantError(string::String),
ApplicationError(string::String),
}
#[derive(Copy, Clone, Debug)]
pub enum EncoderError {
FmtError(fmt::Error),
BadHashmapKey,
}
/// Returns a readable error string for a given error code.
pub fn error_str(error: ErrorCode) -> &'static str {
match error {
InvalidSyntax => "invalid syntax",
InvalidNumber => "invalid number",
EOFWhileParsingObject => "EOF While parsing object",
EOFWhileParsingArray => "EOF While parsing array",
EOFWhileParsingValue => "EOF While parsing value",
EOFWhileParsingString => "EOF While parsing string",
KeyMustBeAString => "key must be a string",
ExpectedColon => "expected `:`",
TrailingCharacters => "trailing characters",
TrailingComma => "trailing comma",
InvalidEscape => "invalid escape",
UnrecognizedHex => "invalid \\u{ esc}ape (unrecognized hex)",
NotFourDigit => "invalid \\u{ esc}ape (not four digits)",
NotUtf8 => "contents not utf-8",
InvalidUnicodeCodePoint => "invalid Unicode code point",
LoneLeadingSurrogateInHexEscape => "lone leading surrogate in hex escape",
UnexpectedEndOfHexEscape => "unexpected end of hex escape",
}
}
/// Shortcut function to decode a JSON `&str` into an object
pub fn decode<T: crate::Decodable<Decoder>>(s: &str) -> DecodeResult<T> {
let json = match from_str(s) {
Ok(x) => x,
Err(e) => return Err(ParseError(e)),
};
let mut decoder = Decoder::new(json);
crate::Decodable::decode(&mut decoder)
}
/// Shortcut function to encode a `T` into a JSON `String`
pub fn encode<T: for<'r> crate::Encodable<Encoder<'r>>>(
object: &T,
) -> Result<string::String, EncoderError> {
let mut s = String::new();
{
let mut encoder = Encoder::new(&mut s);
object.encode(&mut encoder)?;
}
Ok(s)
}
impl fmt::Display for ErrorCode {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
error_str(*self).fmt(f)
}
}
fn io_error_to_error(io: io::Error) -> ParserError {
IoError(io.kind(), io.to_string())
}
impl fmt::Display for ParserError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// FIXME this should be a nicer error
fmt::Debug::fmt(self, f)
}
}
impl fmt::Display for DecoderError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// FIXME this should be a nicer error
fmt::Debug::fmt(self, f)
}
}
impl std::error::Error for DecoderError {}
impl fmt::Display for EncoderError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
// FIXME this should be a nicer error
fmt::Debug::fmt(self, f)
}
}
impl std::error::Error for EncoderError {}
impl From<fmt::Error> for EncoderError {
/// Converts a [`fmt::Error`] into `EncoderError`
///
/// This conversion does not allocate memory.
fn from(err: fmt::Error) -> EncoderError {
EncoderError::FmtError(err)
}
}
pub type EncodeResult = Result<(), EncoderError>;
pub type DecodeResult<T> = Result<T, DecoderError>;
fn escape_str(wr: &mut dyn fmt::Write, v: &str) -> EncodeResult {
wr.write_str("\"")?;
let mut start = 0;
for (i, byte) in v.bytes().enumerate() {
let escaped = match byte {
b'"' => "\\\"",
b'\\' => "\\\\",
b'\x00' => "\\u0000",
b'\x01' => "\\u0001",
b'\x02' => "\\u0002",
b'\x03' => "\\u0003",
b'\x04' => "\\u0004",
b'\x05' => "\\u0005",
b'\x06' => "\\u0006",
b'\x07' => "\\u0007",
b'\x08' => "\\b",
b'\t' => "\\t",
b'\n' => "\\n",
b'\x0b' => "\\u000b",
b'\x0c' => "\\f",
b'\r' => "\\r",
b'\x0e' => "\\u000e",
b'\x0f' => "\\u000f",
b'\x10' => "\\u0010",
b'\x11' => "\\u0011",
b'\x12' => "\\u0012",
b'\x13' => "\\u0013",
b'\x14' => "\\u0014",
b'\x15' => "\\u0015",
b'\x16' => "\\u0016",
b'\x17' => "\\u0017",
b'\x18' => "\\u0018",
b'\x19' => "\\u0019",
b'\x1a' => "\\u001a",
b'\x1b' => "\\u001b",
b'\x1c' => "\\u001c",
b'\x1d' => "\\u001d",
b'\x1e' => "\\u001e",
b'\x1f' => "\\u001f",
b'\x7f' => "\\u007f",
_ => {
continue;
}
};
if start < i {
wr.write_str(&v[start..i])?;
}
wr.write_str(escaped)?;
start = i + 1;
}
if start != v.len() {
wr.write_str(&v[start..])?;
}
wr.write_str("\"")?;
Ok(())
}
fn escape_char(writer: &mut dyn fmt::Write, v: char) -> EncodeResult {
escape_str(writer, v.encode_utf8(&mut [0; 4]))
}
fn spaces(wr: &mut dyn fmt::Write, mut n: usize) -> EncodeResult {
const BUF: &str = " ";
while n >= BUF.len() {
wr.write_str(BUF)?;
n -= BUF.len();
}
if n > 0 {
wr.write_str(&BUF[..n])?;
}
Ok(())
}
fn fmt_number_or_null(v: f64) -> string::String {
match v.classify() {
Fp::Nan | Fp::Infinite => string::String::from("null"),
_ if v.fract() != 0f64 => v.to_string(),
_ => v.to_string() + ".0",
}
}
/// A structure for implementing serialization to JSON.
pub struct Encoder<'a> {
writer: &'a mut (dyn fmt::Write + 'a),
is_emitting_map_key: bool,
}
impl<'a> Encoder<'a> {
/// Creates a new JSON encoder whose output will be written to the writer
/// specified.
pub fn new(writer: &'a mut dyn fmt::Write) -> Encoder<'a> {
Encoder { writer, is_emitting_map_key: false }
}
}
macro_rules! emit_enquoted_if_mapkey {
($enc:ident,$e:expr) => {{
if $enc.is_emitting_map_key {
write!($enc.writer, "\"{}\"", $e)?;
} else {
write!($enc.writer, "{}", $e)?;
}
Ok(())
}};
}
impl<'a> crate::Encoder for Encoder<'a> {
type Error = EncoderError;
fn emit_unit(&mut self) -> EncodeResult {
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
write!(self.writer, "null")?;
Ok(())
}
fn emit_usize(&mut self, v: usize) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_u128(&mut self, v: u128) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_u64(&mut self, v: u64) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_u32(&mut self, v: u32) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_u16(&mut self, v: u16) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_u8(&mut self, v: u8) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_isize(&mut self, v: isize) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_i128(&mut self, v: i128) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_i64(&mut self, v: i64) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_i32(&mut self, v: i32) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_i16(&mut self, v: i16) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_i8(&mut self, v: i8) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_bool(&mut self, v: bool) -> EncodeResult {
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
if v {
write!(self.writer, "true")?;
} else {
write!(self.writer, "false")?;
}
Ok(())
}
fn emit_f64(&mut self, v: f64) -> EncodeResult {
emit_enquoted_if_mapkey!(self, fmt_number_or_null(v))
}
fn emit_f32(&mut self, v: f32) -> EncodeResult {
self.emit_f64(f64::from(v))
}
fn emit_char(&mut self, v: char) -> EncodeResult {
escape_char(self.writer, v)
}
fn emit_str(&mut self, v: &str) -> EncodeResult {
escape_str(self.writer, v)
}
fn emit_enum<F>(&mut self, _name: &str, f: F) -> EncodeResult
where
F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
{
f(self)
}
fn emit_enum_variant<F>(&mut self, name: &str, _id: usize, cnt: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
{
// enums are encoded as strings or objects
// Bunny => "Bunny"
// Kangaroo(34,"William") => {"variant": "Kangaroo", "fields": [34,"William"]}
if cnt == 0 {
escape_str(self.writer, name)
} else {
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
write!(self.writer, "{{\"variant\":")?;
escape_str(self.writer, name)?;
write!(self.writer, ",\"fields\":[")?;
f(self)?;
write!(self.writer, "]}}")?;
Ok(())
}
}
fn emit_enum_variant_arg<F>(&mut self, idx: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
if idx != 0 {
write!(self.writer, ",")?;
}
f(self)
}
fn emit_enum_struct_variant<F>(
&mut self,
name: &str,
id: usize,
cnt: usize,
f: F,
) -> EncodeResult
where
F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
self.emit_enum_variant(name, id, cnt, f)
}
fn emit_enum_struct_variant_field<F>(&mut self, _: &str, idx: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
self.emit_enum_variant_arg(idx, f)
}
fn emit_struct<F>(&mut self, _: &str, _: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
write!(self.writer, "{{")?;
f(self)?;
write!(self.writer, "}}")?;
Ok(())
}
fn emit_struct_field<F>(&mut self, name: &str, idx: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
if idx != 0 {
write!(self.writer, ",")?;
}
escape_str(self.writer, name)?;
write!(self.writer, ":")?;
f(self)
}
fn emit_tuple<F>(&mut self, len: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
self.emit_seq(len, f)
}
fn emit_tuple_arg<F>(&mut self, idx: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
self.emit_seq_elt(idx, f)
}
fn emit_tuple_struct<F>(&mut self, _name: &str, len: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
self.emit_seq(len, f)
}
fn emit_tuple_struct_arg<F>(&mut self, idx: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
self.emit_seq_elt(idx, f)
}
fn emit_option<F>(&mut self, f: F) -> EncodeResult
where
F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
f(self)
}
fn emit_option_none(&mut self) -> EncodeResult {
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
self.emit_unit()
}
fn emit_option_some<F>(&mut self, f: F) -> EncodeResult
where
F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
f(self)
}
fn emit_seq<F>(&mut self, _len: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
write!(self.writer, "[")?;
f(self)?;
write!(self.writer, "]")?;
Ok(())
}
fn emit_seq_elt<F>(&mut self, idx: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
if idx != 0 {
write!(self.writer, ",")?;
}
f(self)
}
fn emit_map<F>(&mut self, _len: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
write!(self.writer, "{{")?;
f(self)?;
write!(self.writer, "}}")?;
Ok(())
}
fn emit_map_elt_key<F>(&mut self, idx: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
if idx != 0 {
write!(self.writer, ",")?
}
self.is_emitting_map_key = true;
f(self)?;
self.is_emitting_map_key = false;
Ok(())
}
fn emit_map_elt_val<F>(&mut self, _idx: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut Encoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
write!(self.writer, ":")?;
f(self)
}
}
/// Another encoder for JSON, but prints out human-readable JSON instead of
/// compact data
pub struct PrettyEncoder<'a> {
writer: &'a mut (dyn fmt::Write + 'a),
curr_indent: usize,
indent: usize,
is_emitting_map_key: bool,
}
impl<'a> PrettyEncoder<'a> {
/// Creates a new encoder whose output will be written to the specified writer
pub fn new(writer: &'a mut dyn fmt::Write) -> PrettyEncoder<'a> {
PrettyEncoder { writer, curr_indent: 0, indent: 2, is_emitting_map_key: false }
}
/// Sets the number of spaces to indent for each level.
/// This is safe to set during encoding.
pub fn set_indent(&mut self, indent: usize) {
// self.indent very well could be 0 so we need to use checked division.
let level = self.curr_indent.checked_div(self.indent).unwrap_or(0);
self.indent = indent;
self.curr_indent = level * self.indent;
}
}
impl<'a> crate::Encoder for PrettyEncoder<'a> {
type Error = EncoderError;
fn emit_unit(&mut self) -> EncodeResult {
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
write!(self.writer, "null")?;
Ok(())
}
fn emit_usize(&mut self, v: usize) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_u128(&mut self, v: u128) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_u64(&mut self, v: u64) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_u32(&mut self, v: u32) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_u16(&mut self, v: u16) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_u8(&mut self, v: u8) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_isize(&mut self, v: isize) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_i128(&mut self, v: i128) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_i64(&mut self, v: i64) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_i32(&mut self, v: i32) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_i16(&mut self, v: i16) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_i8(&mut self, v: i8) -> EncodeResult {
emit_enquoted_if_mapkey!(self, v)
}
fn emit_bool(&mut self, v: bool) -> EncodeResult {
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
if v {
write!(self.writer, "true")?;
} else {
write!(self.writer, "false")?;
}
Ok(())
}
fn emit_f64(&mut self, v: f64) -> EncodeResult {
emit_enquoted_if_mapkey!(self, fmt_number_or_null(v))
}
fn emit_f32(&mut self, v: f32) -> EncodeResult {
self.emit_f64(f64::from(v))
}
fn emit_char(&mut self, v: char) -> EncodeResult {
escape_char(self.writer, v)
}
fn emit_str(&mut self, v: &str) -> EncodeResult {
escape_str(self.writer, v)
}
fn emit_enum<F>(&mut self, _name: &str, f: F) -> EncodeResult
where
F: FnOnce(&mut PrettyEncoder<'a>) -> EncodeResult,
{
f(self)
}
fn emit_enum_variant<F>(&mut self, name: &str, _id: usize, cnt: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut PrettyEncoder<'a>) -> EncodeResult,
{
if cnt == 0 {
escape_str(self.writer, name)
} else {
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
writeln!(self.writer, "{{")?;
self.curr_indent += self.indent;
spaces(self.writer, self.curr_indent)?;
write!(self.writer, "\"variant\": ")?;
escape_str(self.writer, name)?;
writeln!(self.writer, ",")?;
spaces(self.writer, self.curr_indent)?;
writeln!(self.writer, "\"fields\": [")?;
self.curr_indent += self.indent;
f(self)?;
self.curr_indent -= self.indent;
writeln!(self.writer)?;
spaces(self.writer, self.curr_indent)?;
self.curr_indent -= self.indent;
writeln!(self.writer, "]")?;
spaces(self.writer, self.curr_indent)?;
write!(self.writer, "}}")?;
Ok(())
}
}
fn emit_enum_variant_arg<F>(&mut self, idx: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut PrettyEncoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
if idx != 0 {
writeln!(self.writer, ",")?;
}
spaces(self.writer, self.curr_indent)?;
f(self)
}
fn emit_enum_struct_variant<F>(
&mut self,
name: &str,
id: usize,
cnt: usize,
f: F,
) -> EncodeResult
where
F: FnOnce(&mut PrettyEncoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
self.emit_enum_variant(name, id, cnt, f)
}
fn emit_enum_struct_variant_field<F>(&mut self, _: &str, idx: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut PrettyEncoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
self.emit_enum_variant_arg(idx, f)
}
fn emit_struct<F>(&mut self, _: &str, len: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut PrettyEncoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
if len == 0 {
write!(self.writer, "{{}}")?;
} else {
write!(self.writer, "{{")?;
self.curr_indent += self.indent;
f(self)?;
self.curr_indent -= self.indent;
writeln!(self.writer)?;
spaces(self.writer, self.curr_indent)?;
write!(self.writer, "}}")?;
}
Ok(())
}
fn emit_struct_field<F>(&mut self, name: &str, idx: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut PrettyEncoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
if idx == 0 {
writeln!(self.writer)?;
} else {
writeln!(self.writer, ",")?;
}
spaces(self.writer, self.curr_indent)?;
escape_str(self.writer, name)?;
write!(self.writer, ": ")?;
f(self)
}
fn emit_tuple<F>(&mut self, len: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut PrettyEncoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
self.emit_seq(len, f)
}
fn emit_tuple_arg<F>(&mut self, idx: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut PrettyEncoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
self.emit_seq_elt(idx, f)
}
fn emit_tuple_struct<F>(&mut self, _: &str, len: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut PrettyEncoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
self.emit_seq(len, f)
}
fn emit_tuple_struct_arg<F>(&mut self, idx: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut PrettyEncoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
self.emit_seq_elt(idx, f)
}
fn emit_option<F>(&mut self, f: F) -> EncodeResult
where
F: FnOnce(&mut PrettyEncoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
f(self)
}
fn emit_option_none(&mut self) -> EncodeResult {
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
self.emit_unit()
}
fn emit_option_some<F>(&mut self, f: F) -> EncodeResult
where
F: FnOnce(&mut PrettyEncoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
f(self)
}
fn emit_seq<F>(&mut self, len: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut PrettyEncoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
if len == 0 {
write!(self.writer, "[]")?;
} else {
write!(self.writer, "[")?;
self.curr_indent += self.indent;
f(self)?;
self.curr_indent -= self.indent;
writeln!(self.writer)?;
spaces(self.writer, self.curr_indent)?;
write!(self.writer, "]")?;
}
Ok(())
}
fn emit_seq_elt<F>(&mut self, idx: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut PrettyEncoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
if idx == 0 {
writeln!(self.writer)?;
} else {
writeln!(self.writer, ",")?;
}
spaces(self.writer, self.curr_indent)?;
f(self)
}
fn emit_map<F>(&mut self, len: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut PrettyEncoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
if len == 0 {
write!(self.writer, "{{}}")?;
} else {
write!(self.writer, "{{")?;
self.curr_indent += self.indent;
f(self)?;
self.curr_indent -= self.indent;
writeln!(self.writer)?;
spaces(self.writer, self.curr_indent)?;
write!(self.writer, "}}")?;
}
Ok(())
}
fn emit_map_elt_key<F>(&mut self, idx: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut PrettyEncoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
if idx == 0 {
writeln!(self.writer)?;
} else {
writeln!(self.writer, ",")?;
}
spaces(self.writer, self.curr_indent)?;
self.is_emitting_map_key = true;
f(self)?;
self.is_emitting_map_key = false;
Ok(())
}
fn emit_map_elt_val<F>(&mut self, _idx: usize, f: F) -> EncodeResult
where
F: FnOnce(&mut PrettyEncoder<'a>) -> EncodeResult,
{
if self.is_emitting_map_key {
return Err(EncoderError::BadHashmapKey);
}
write!(self.writer, ": ")?;
f(self)
}
}
impl<E: crate::Encoder> Encodable<E> for Json {
fn encode(&self, e: &mut E) -> Result<(), E::Error> {
match *self {
Json::I64(v) => v.encode(e),
Json::U64(v) => v.encode(e),
Json::F64(v) => v.encode(e),
Json::String(ref v) => v.encode(e),
Json::Boolean(v) => v.encode(e),
Json::Array(ref v) => v.encode(e),
Json::Object(ref v) => v.encode(e),
Json::Null => e.emit_unit(),
}
}
}
/// Creates an `AsJson` wrapper which can be used to print a value as JSON
/// on-the-fly via `write!`
pub fn as_json<T>(t: &T) -> AsJson<'_, T> {
AsJson { inner: t }
}
/// Creates an `AsPrettyJson` wrapper which can be used to print a value as JSON
/// on-the-fly via `write!`
pub fn as_pretty_json<T>(t: &T) -> AsPrettyJson<'_, T> {
AsPrettyJson { inner: t, indent: None }
}
impl Json {
/// Borrow this json object as a pretty object to generate a pretty
/// representation for it via `Display`.
pub fn pretty(&self) -> PrettyJson<'_> {
PrettyJson { inner: self }
}
/// If the Json value is an Object, returns the value associated with the provided key.
/// Otherwise, returns None.
pub fn find(&self, key: &str) -> Option<&Json> {
match *self {
Json::Object(ref map) => map.get(key),
_ => None,
}
}
/// Attempts to get a nested Json Object for each key in `keys`.
/// If any key is found not to exist, `find_path` will return `None`.
/// Otherwise, it will return the Json value associated with the final key.
pub fn find_path<'a>(&'a self, keys: &[&str]) -> Option<&'a Json> {
let mut target = self;
for key in keys {
target = target.find(*key)?;
}
Some(target)
}
/// If the Json value is an Object, performs a depth-first search until
/// a value associated with the provided key is found. If no value is found
/// or the Json value is not an Object, returns `None`.
pub fn search(&self, key: &str) -> Option<&Json> {
match *self {
Json::Object(ref map) => match map.get(key) {
Some(json_value) => Some(json_value),
None => {
for v in map.values() {
match v.search(key) {
x if x.is_some() => return x,
_ => (),
}
}
None
}
},
_ => None,
}
}
/// Returns `true` if the Json value is an `Object`.
pub fn is_object(&self) -> bool {
self.as_object().is_some()
}
/// If the Json value is an `Object`, returns the associated `BTreeMap`;
/// returns `None` otherwise.
pub fn as_object(&self) -> Option<&Object> {
match *self {
Json::Object(ref map) => Some(map),
_ => None,
}
}
/// Returns `true` if the Json value is an `Array`.
pub fn is_array(&self) -> bool {
self.as_array().is_some()
}
/// If the Json value is an `Array`, returns the associated vector;
/// returns `None` otherwise.
pub fn as_array(&self) -> Option<&Array> {
match *self {
Json::Array(ref array) => Some(&*array),
_ => None,
}
}
/// Returns `true` if the Json value is a `String`.
pub fn is_string(&self) -> bool {
self.as_string().is_some()
}
/// If the Json value is a `String`, returns the associated `str`;
/// returns `None` otherwise.
pub fn as_string(&self) -> Option<&str> {
match *self {
Json::String(ref s) => Some(&s[..]),
_ => None,
}
}
/// Returns `true` if the Json value is a `Number`.
pub fn is_number(&self) -> bool {
matches!(*self, Json::I64(_) | Json::U64(_) | Json::F64(_))
}
/// Returns `true` if the Json value is a `i64`.
pub fn is_i64(&self) -> bool {
matches!(*self, Json::I64(_))
}
/// Returns `true` if the Json value is a `u64`.
pub fn is_u64(&self) -> bool {
matches!(*self, Json::U64(_))
}
/// Returns `true` if the Json value is a `f64`.
pub fn is_f64(&self) -> bool {
matches!(*self, Json::F64(_))
}
/// If the Json value is a number, returns or cast it to a `i64`;
/// returns `None` otherwise.
pub fn as_i64(&self) -> Option<i64> {
match *self {
Json::I64(n) => Some(n),
Json::U64(n) => Some(n as i64),
_ => None,
}
}
/// If the Json value is a number, returns or cast it to a `u64`;
/// returns `None` otherwise.
pub fn as_u64(&self) -> Option<u64> {
match *self {
Json::I64(n) => Some(n as u64),
Json::U64(n) => Some(n),
_ => None,
}
}
/// If the Json value is a number, returns or cast it to a `f64`;
/// returns `None` otherwise.
pub fn as_f64(&self) -> Option<f64> {
match *self {
Json::I64(n) => Some(n as f64),
Json::U64(n) => Some(n as f64),
Json::F64(n) => Some(n),
_ => None,
}
}
/// Returns `true` if the Json value is a `Boolean`.
pub fn is_boolean(&self) -> bool {
self.as_boolean().is_some()
}
/// If the Json value is a `Boolean`, returns the associated `bool`;
/// returns `None` otherwise.
pub fn as_boolean(&self) -> Option<bool> {
match *self {
Json::Boolean(b) => Some(b),
_ => None,
}
}
/// Returns `true` if the Json value is a `Null`.
pub fn is_null(&self) -> bool {
self.as_null().is_some()
}
/// If the Json value is a `Null`, returns `()`;
/// returns `None` otherwise.
pub fn as_null(&self) -> Option<()> {
match *self {
Json::Null => Some(()),
_ => None,
}
}
}
impl<'a> Index<&'a str> for Json {
type Output = Json;
fn index(&self, idx: &'a str) -> &Json {
self.find(idx).unwrap()
}
}
impl Index<usize> for Json {
type Output = Json;
fn index(&self, idx: usize) -> &Json {
match *self {
Json::Array(ref v) => &v[idx],
_ => panic!("can only index Json with usize if it is an array"),
}
}
}
/// The output of the streaming parser.
#[derive(PartialEq, Clone, Debug)]
pub enum JsonEvent {
ObjectStart,
ObjectEnd,
ArrayStart,
ArrayEnd,
BooleanValue(bool),
I64Value(i64),
U64Value(u64),
F64Value(f64),
StringValue(string::String),
NullValue,
Error(ParserError),
}
#[derive(PartialEq, Debug)]
enum ParserState {
// Parse a value in an array, true means first element.
ParseArray(bool),
// Parse ',' or ']' after an element in an array.
ParseArrayComma,
// Parse a key:value in an object, true means first element.
ParseObject(bool),
// Parse ',' or ']' after an element in an object.
ParseObjectComma,
// Initial state.
ParseStart,
// Expecting the stream to end.
ParseBeforeFinish,
// Parsing can't continue.
ParseFinished,
}
/// A Stack represents the current position of the parser in the logical
/// structure of the JSON stream.
///
/// An example is `foo.bar[3].x`.
#[derive(Default)]
pub struct Stack {
stack: Vec<InternalStackElement>,
str_buffer: Vec<u8>,
}
/// StackElements compose a Stack.
///
/// As an example, `StackElement::Key("foo")`, `StackElement::Key("bar")`,
/// `StackElement::Index(3)`, and `StackElement::Key("x")` are the
/// StackElements composing the stack that represents `foo.bar[3].x`.
#[derive(PartialEq, Clone, Debug)]
pub enum StackElement<'l> {
Index(u32),
Key(&'l str),
}
// Internally, Key elements are stored as indices in a buffer to avoid
// allocating a string for every member of an object.
#[derive(PartialEq, Clone, Debug)]
enum InternalStackElement {
InternalIndex(u32),
InternalKey(u16, u16), // start, size
}
impl Stack {
pub fn new() -> Stack {
Self::default()
}
/// Returns The number of elements in the Stack.
pub fn len(&self) -> usize {
self.stack.len()
}
/// Returns `true` if the stack is empty.
pub fn is_empty(&self) -> bool {
self.stack.is_empty()
}
/// Provides access to the StackElement at a given index.
/// lower indices are at the bottom of the stack while higher indices are
/// at the top.
pub fn get(&self, idx: usize) -> StackElement<'_> {
match self.stack[idx] {
InternalIndex(i) => StackElement::Index(i),
InternalKey(start, size) => StackElement::Key(
str::from_utf8(&self.str_buffer[start as usize..start as usize + size as usize])
.unwrap(),
),
}
}
/// Compares this stack with an array of StackElement<'_>s.
pub fn is_equal_to(&self, rhs: &[StackElement<'_>]) -> bool {
if self.stack.len() != rhs.len() {
return false;
}
for (i, r) in rhs.iter().enumerate() {
if self.get(i) != *r {
return false;
}
}
true
}
/// Returns `true` if the bottom-most elements of this stack are the same as
/// the ones passed as parameter.
pub fn starts_with(&self, rhs: &[StackElement<'_>]) -> bool {
if self.stack.len() < rhs.len() {
return false;
}
for (i, r) in rhs.iter().enumerate() {
if self.get(i) != *r {
return false;
}
}
true
}
/// Returns `true` if the top-most elements of this stack are the same as
/// the ones passed as parameter.
pub fn ends_with(&self, rhs: &[StackElement<'_>]) -> bool {
if self.stack.len() < rhs.len() {
return false;
}
let offset = self.stack.len() - rhs.len();
for (i, r) in rhs.iter().enumerate() {
if self.get(i + offset) != *r {
return false;
}
}
true
}
/// Returns the top-most element (if any).
pub fn top(&self) -> Option<StackElement<'_>> {
match self.stack.last() {
None => None,
Some(&InternalIndex(i)) => Some(StackElement::Index(i)),
Some(&InternalKey(start, size)) => Some(StackElement::Key(
str::from_utf8(&self.str_buffer[start as usize..(start + size) as usize]).unwrap(),
)),
}
}
// Used by Parser to insert StackElement::Key elements at the top of the stack.
fn push_key(&mut self, key: string::String) {
self.stack.push(InternalKey(self.str_buffer.len() as u16, key.len() as u16));
self.str_buffer.extend(key.as_bytes());
}
// Used by Parser to insert StackElement::Index elements at the top of the stack.
fn push_index(&mut self, index: u32) {
self.stack.push(InternalIndex(index));
}
// Used by Parser to remove the top-most element of the stack.
fn pop(&mut self) {
assert!(!self.is_empty());
match *self.stack.last().unwrap() {
InternalKey(_, sz) => {
let new_size = self.str_buffer.len() - sz as usize;
self.str_buffer.truncate(new_size);
}
InternalIndex(_) => {}
}
self.stack.pop();
}
// Used by Parser to test whether the top-most element is an index.
fn last_is_index(&self) -> bool {
matches!(self.stack.last(), Some(InternalIndex(_)))
}
// Used by Parser to increment the index of the top-most element.
fn bump_index(&mut self) {
let len = self.stack.len();
let idx = match *self.stack.last().unwrap() {
InternalIndex(i) => i + 1,
_ => {
panic!();
}
};
self.stack[len - 1] = InternalIndex(idx);
}
}
/// A streaming JSON parser implemented as an iterator of JsonEvent, consuming
/// an iterator of char.
pub struct Parser<T> {
rdr: T,
ch: Option<char>,
line: usize,
col: usize,
// We maintain a stack representing where we are in the logical structure
// of the JSON stream.
stack: Stack,
// A state machine is kept to make it possible to interrupt and resume parsing.
state: ParserState,
}
impl<T: Iterator<Item = char>> Iterator for Parser<T> {
type Item = JsonEvent;
fn next(&mut self) -> Option<JsonEvent> {
if self.state == ParseFinished {
return None;
}
if self.state == ParseBeforeFinish {
self.parse_whitespace();
// Make sure there is no trailing characters.
if self.eof() {
self.state = ParseFinished;
return None;
} else {
return Some(self.error_event(TrailingCharacters));
}
}
Some(self.parse())
}
}
impl<T: Iterator<Item = char>> Parser<T> {
/// Creates the JSON parser.
pub fn new(rdr: T) -> Parser<T> {
let mut p = Parser {
rdr,
ch: Some('\x00'),
line: 1,
col: 0,
stack: Stack::new(),
state: ParseStart,
};
p.bump();
p
}
/// Provides access to the current position in the logical structure of the
/// JSON stream.
pub fn stack(&self) -> &Stack {
&self.stack
}
fn eof(&self) -> bool {
self.ch.is_none()
}
fn ch_or_null(&self) -> char {
self.ch.unwrap_or('\x00')
}
fn bump(&mut self) {
self.ch = self.rdr.next();
if self.ch_is('\n') {
self.line += 1;
self.col = 1;
} else {
self.col += 1;
}
}
fn next_char(&mut self) -> Option<char> {
self.bump();
self.ch
}
fn ch_is(&self, c: char) -> bool {
self.ch == Some(c)
}
fn error<U>(&self, reason: ErrorCode) -> Result<U, ParserError> {
Err(SyntaxError(reason, self.line, self.col))
}
fn parse_whitespace(&mut self) {
while self.ch_is(' ') || self.ch_is('\n') || self.ch_is('\t') || self.ch_is('\r') {
self.bump();
}
}
fn parse_number(&mut self) -> JsonEvent {
let neg = if self.ch_is('-') {
self.bump();
true
} else {
false
};
let res = match self.parse_u64() {
Ok(res) => res,
Err(e) => {
return Error(e);
}
};
if self.ch_is('.') || self.ch_is('e') || self.ch_is('E') {
let mut res = res as f64;
if self.ch_is('.') {
res = match self.parse_decimal(res) {
Ok(res) => res,
Err(e) => {
return Error(e);
}
};
}
if self.ch_is('e') || self.ch_is('E') {
res = match self.parse_exponent(res) {
Ok(res) => res,
Err(e) => {
return Error(e);
}
};
}
if neg {
res *= -1.0;
}
F64Value(res)
} else if neg {
let res = (res as i64).wrapping_neg();
// Make sure we didn't underflow.
if res > 0 {
Error(SyntaxError(InvalidNumber, self.line, self.col))
} else {
I64Value(res)
}
} else {
U64Value(res)
}
}
fn parse_u64(&mut self) -> Result<u64, ParserError> {
let mut accum = 0u64;
let last_accum = 0; // necessary to detect overflow.
match self.ch_or_null() {
'0' => {
self.bump();
// A leading '0' must be the only digit before the decimal point.
if let '0'..='9' = self.ch_or_null() {
return self.error(InvalidNumber);
}
}
'1'..='9' => {
while !self.eof() {
match self.ch_or_null() {
c @ '0'..='9' => {
accum = accum.wrapping_mul(10);
accum = accum.wrapping_add((c as u64) - ('0' as u64));
// Detect overflow by comparing to the last value.
if accum <= last_accum {
return self.error(InvalidNumber);
}
self.bump();
}
_ => break,
}
}
}
_ => return self.error(InvalidNumber),
}
Ok(accum)
}
fn parse_decimal(&mut self, mut res: f64) -> Result<f64, ParserError> {
self.bump();
// Make sure a digit follows the decimal place.
match self.ch_or_null() {
'0'..='9' => (),
_ => return self.error(InvalidNumber),
}
let mut dec = 1.0;
while !self.eof() {
match self.ch_or_null() {
c @ '0'..='9' => {
dec /= 10.0;
res += (((c as isize) - ('0' as isize)) as f64) * dec;
self.bump();
}
_ => break,
}
}
Ok(res)
}
fn parse_exponent(&mut self, mut res: f64) -> Result<f64, ParserError> {
self.bump();
let mut exp = 0;
let mut neg_exp = false;
if self.ch_is('+') {
self.bump();
} else if self.ch_is('-') {
self.bump();
neg_exp = true;
}
// Make sure a digit follows the exponent place.
match self.ch_or_null() {
'0'..='9' => (),
_ => return self.error(InvalidNumber),
}
while !self.eof() {
match self.ch_or_null() {
c @ '0'..='9' => {
exp *= 10;
exp += (c as usize) - ('0' as usize);
self.bump();
}
_ => break,
}
}
let exp = 10_f64.powi(exp as i32);
if neg_exp {
res /= exp;
} else {
res *= exp;
}
Ok(res)
}
fn decode_hex_escape(&mut self) -> Result<u16, ParserError> {
let mut i = 0;
let mut n = 0;
while i < 4 && !self.eof() {
self.bump();
n = match self.ch_or_null() {
c @ '0'..='9' => n * 16 + ((c as u16) - ('0' as u16)),
'a' | 'A' => n * 16 + 10,
'b' | 'B' => n * 16 + 11,
'c' | 'C' => n * 16 + 12,
'd' | 'D' => n * 16 + 13,
'e' | 'E' => n * 16 + 14,
'f' | 'F' => n * 16 + 15,
_ => return self.error(InvalidEscape),
};
i += 1;
}
// Error out if we didn't parse 4 digits.
if i != 4 {
return self.error(InvalidEscape);
}
Ok(n)
}
fn parse_str(&mut self) -> Result<string::String, ParserError> {
let mut escape = false;
let mut res = string::String::new();
loop {
self.bump();
if self.eof() {
return self.error(EOFWhileParsingString);
}
if escape {
match self.ch_or_null() {
'"' => res.push('"'),
'\\' => res.push('\\'),
'/' => res.push('/'),
'b' => res.push('\x08'),
'f' => res.push('\x0c'),
'n' => res.push('\n'),
'r' => res.push('\r'),
't' => res.push('\t'),
'u' => match self.decode_hex_escape()? {
0xDC00..=0xDFFF => return self.error(LoneLeadingSurrogateInHexEscape),
// Non-BMP characters are encoded as a sequence of
// two hex escapes, representing UTF-16 surrogates.
n1 @ 0xD800..=0xDBFF => {
match (self.next_char(), self.next_char()) {
(Some('\\'), Some('u')) => (),
_ => return self.error(UnexpectedEndOfHexEscape),
}
let n2 = self.decode_hex_escape()?;
if !(0xDC00..=0xDFFF).contains(&n2) {
return self.error(LoneLeadingSurrogateInHexEscape);
}
let c =
(u32::from(n1 - 0xD800) << 10 | u32::from(n2 - 0xDC00)) + 0x1_0000;
res.push(char::from_u32(c).unwrap());
}
n => match char::from_u32(u32::from(n)) {
Some(c) => res.push(c),
None => return self.error(InvalidUnicodeCodePoint),
},
},
_ => return self.error(InvalidEscape),
}
escape = false;
} else if self.ch_is('\\') {
escape = true;
} else {
match self.ch {
Some('"') => {
self.bump();
return Ok(res);
}
Some(c) => res.push(c),
None => unreachable!(),
}
}
}
}
// Invoked at each iteration, consumes the stream until it has enough
// information to return a JsonEvent.
// Manages an internal state so that parsing can be interrupted and resumed.
// Also keeps track of the position in the logical structure of the json
// stream isize the form of a stack that can be queried by the user using the
// stack() method.
fn parse(&mut self) -> JsonEvent {
loop {
// The only paths where the loop can spin a new iteration
// are in the cases ParseArrayComma and ParseObjectComma if ','
// is parsed. In these cases the state is set to (respectively)
// ParseArray(false) and ParseObject(false), which always return,
// so there is no risk of getting stuck in an infinite loop.
// All other paths return before the end of the loop's iteration.
self.parse_whitespace();
match self.state {
ParseStart => {
return self.parse_start();
}
ParseArray(first) => {
return self.parse_array(first);
}
ParseArrayComma => {
if let Some(evt) = self.parse_array_comma_or_end() {
return evt;
}
}
ParseObject(first) => {
return self.parse_object(first);
}
ParseObjectComma => {
self.stack.pop();
if self.ch_is(',') {
self.state = ParseObject(false);
self.bump();
} else {
return self.parse_object_end();
}
}
_ => {
return self.error_event(InvalidSyntax);
}
}
}
}
fn parse_start(&mut self) -> JsonEvent {
let val = self.parse_value();
self.state = match val {
Error(_) => ParseFinished,
ArrayStart => ParseArray(true),
ObjectStart => ParseObject(true),
_ => ParseBeforeFinish,
};
val
}
fn parse_array(&mut self, first: bool) -> JsonEvent {
if self.ch_is(']') {
if !first {
self.error_event(InvalidSyntax)
} else {
self.state = if self.stack.is_empty() {
ParseBeforeFinish
} else if self.stack.last_is_index() {
ParseArrayComma
} else {
ParseObjectComma
};
self.bump();
ArrayEnd
}
} else {
if first {
self.stack.push_index(0);
}
let val = self.parse_value();
self.state = match val {
Error(_) => ParseFinished,
ArrayStart => ParseArray(true),
ObjectStart => ParseObject(true),
_ => ParseArrayComma,
};
val
}
}
fn parse_array_comma_or_end(&mut self) -> Option<JsonEvent> {
if self.ch_is(',') {
self.stack.bump_index();
self.state = ParseArray(false);
self.bump();
None
} else if self.ch_is(']') {
self.stack.pop();
self.state = if self.stack.is_empty() {
ParseBeforeFinish
} else if self.stack.last_is_index() {
ParseArrayComma
} else {
ParseObjectComma
};
self.bump();
Some(ArrayEnd)
} else if self.eof() {
Some(self.error_event(EOFWhileParsingArray))
} else {
Some(self.error_event(InvalidSyntax))
}
}
fn parse_object(&mut self, first: bool) -> JsonEvent {
if self.ch_is('}') {
if !first {
if self.stack.is_empty() {
return self.error_event(TrailingComma);
} else {
self.stack.pop();
}
}
self.state = if self.stack.is_empty() {
ParseBeforeFinish
} else if self.stack.last_is_index() {
ParseArrayComma
} else {
ParseObjectComma
};
self.bump();
return ObjectEnd;
}
if self.eof() {
return self.error_event(EOFWhileParsingObject);
}
if !self.ch_is('"') {
return self.error_event(KeyMustBeAString);
}
let s = match self.parse_str() {
Ok(s) => s,
Err(e) => {
self.state = ParseFinished;
return Error(e);
}
};
self.parse_whitespace();
if self.eof() {
return self.error_event(EOFWhileParsingObject);
} else if self.ch_or_null() != ':' {
return self.error_event(ExpectedColon);
}
self.stack.push_key(s);
self.bump();
self.parse_whitespace();
let val = self.parse_value();
self.state = match val {
Error(_) => ParseFinished,
ArrayStart => ParseArray(true),
ObjectStart => ParseObject(true),
_ => ParseObjectComma,
};
val
}
fn parse_object_end(&mut self) -> JsonEvent {
if self.ch_is('}') {
self.state = if self.stack.is_empty() {
ParseBeforeFinish
} else if self.stack.last_is_index() {
ParseArrayComma
} else {
ParseObjectComma
};
self.bump();
ObjectEnd
} else if self.eof() {
self.error_event(EOFWhileParsingObject)
} else {
self.error_event(InvalidSyntax)
}
}
fn parse_value(&mut self) -> JsonEvent {
if self.eof() {
return self.error_event(EOFWhileParsingValue);
}
match self.ch_or_null() {
'n' => self.parse_ident("ull", NullValue),
't' => self.parse_ident("rue", BooleanValue(true)),
'f' => self.parse_ident("alse", BooleanValue(false)),
'0'..='9' | '-' => self.parse_number(),
'"' => match self.parse_str() {
Ok(s) => StringValue(s),
Err(e) => Error(e),
},
'[' => {
self.bump();
ArrayStart
}
'{' => {
self.bump();
ObjectStart
}
_ => self.error_event(InvalidSyntax),
}
}
fn parse_ident(&mut self, ident: &str, value: JsonEvent) -> JsonEvent {
if ident.chars().all(|c| Some(c) == self.next_char()) {
self.bump();
value
} else {
Error(SyntaxError(InvalidSyntax, self.line, self.col))
}
}
fn error_event(&mut self, reason: ErrorCode) -> JsonEvent {
self.state = ParseFinished;
Error(SyntaxError(reason, self.line, self.col))
}
}
/// A Builder consumes a json::Parser to create a generic Json structure.
pub struct Builder<T> {
parser: Parser<T>,
token: Option<JsonEvent>,
}
impl<T: Iterator<Item = char>> Builder<T> {
/// Creates a JSON Builder.
pub fn new(src: T) -> Builder<T> {
Builder { parser: Parser::new(src), token: None }
}
// Decode a Json value from a Parser.
pub fn build(&mut self) -> Result<Json, BuilderError> {
self.bump();
let result = self.build_value();
self.bump();
match self.token {
None => {}
Some(Error(ref e)) => {
return Err(e.clone());
}
ref tok => {
panic!("unexpected token {:?}", tok.clone());
}
}
result
}
fn bump(&mut self) {
self.token = self.parser.next();
}
fn build_value(&mut self) -> Result<Json, BuilderError> {
match self.token {
Some(NullValue) => Ok(Json::Null),
Some(I64Value(n)) => Ok(Json::I64(n)),
Some(U64Value(n)) => Ok(Json::U64(n)),
Some(F64Value(n)) => Ok(Json::F64(n)),
Some(BooleanValue(b)) => Ok(Json::Boolean(b)),
Some(StringValue(ref mut s)) => {
let mut temp = string::String::new();
swap(s, &mut temp);
Ok(Json::String(temp))
}
Some(Error(ref e)) => Err(e.clone()),
Some(ArrayStart) => self.build_array(),
Some(ObjectStart) => self.build_object(),
Some(ObjectEnd) => self.parser.error(InvalidSyntax),
Some(ArrayEnd) => self.parser.error(InvalidSyntax),
None => self.parser.error(EOFWhileParsingValue),
}
}
fn build_array(&mut self) -> Result<Json, BuilderError> {
self.bump();
let mut values = Vec::new();
loop {
if self.token == Some(ArrayEnd) {
return Ok(Json::Array(values.into_iter().collect()));
}
match self.build_value() {
Ok(v) => values.push(v),
Err(e) => return Err(e),
}
self.bump();
}
}
fn build_object(&mut self) -> Result<Json, BuilderError> {
self.bump();
let mut values = BTreeMap::new();
loop {
match self.token {
Some(ObjectEnd) => {
return Ok(Json::Object(values));
}
Some(Error(ref e)) => {
return Err(e.clone());
}
None => {
break;
}
_ => {}
}
let key = match self.parser.stack().top() {
Some(StackElement::Key(k)) => k.to_owned(),
_ => {
panic!("invalid state");
}
};
match self.build_value() {
Ok(value) => {
values.insert(key, value);
}
Err(e) => {
return Err(e);
}
}
self.bump();
}
self.parser.error(EOFWhileParsingObject)
}
}
/// Decodes a json value from an `&mut io::Read`
pub fn from_reader(rdr: &mut dyn Read) -> Result<Json, BuilderError> {
let mut contents = Vec::new();
match rdr.read_to_end(&mut contents) {
Ok(c) => c,
Err(e) => return Err(io_error_to_error(e)),
};
let s = match str::from_utf8(&contents).ok() {
Some(s) => s,
_ => return Err(SyntaxError(NotUtf8, 0, 0)),
};
let mut builder = Builder::new(s.chars());
builder.build()
}
/// Decodes a json value from a string
pub fn from_str(s: &str) -> Result<Json, BuilderError> {
let mut builder = Builder::new(s.chars());
builder.build()
}
/// A structure to decode JSON to values in rust.
pub struct Decoder {
stack: Vec<Json>,
}
impl Decoder {
/// Creates a new decoder instance for decoding the specified JSON value.
pub fn new(json: Json) -> Decoder {
Decoder { stack: vec![json] }
}
fn pop(&mut self) -> Json {
self.stack.pop().unwrap()
}
}
macro_rules! expect {
($e:expr, Null) => {{
match $e {
Json::Null => Ok(()),
other => Err(ExpectedError("Null".to_owned(), other.to_string())),
}
}};
($e:expr, $t:ident) => {{
match $e {
Json::$t(v) => Ok(v),
other => Err(ExpectedError(stringify!($t).to_owned(), other.to_string())),
}
}};
}
macro_rules! read_primitive {
($name:ident, $ty:ty) => {
fn $name(&mut self) -> DecodeResult<$ty> {
match self.pop() {
Json::I64(f) => Ok(f as $ty),
Json::U64(f) => Ok(f as $ty),
Json::F64(f) => Err(ExpectedError("Integer".to_owned(), f.to_string())),
// re: #12967.. a type w/ numeric keys (ie HashMap<usize, V> etc)
// is going to have a string here, as per JSON spec.
Json::String(s) => match s.parse().ok() {
Some(f) => Ok(f),
None => Err(ExpectedError("Number".to_owned(), s)),
},
value => Err(ExpectedError("Number".to_owned(), value.to_string())),
}
}
};
}
impl crate::Decoder for Decoder {
type Error = DecoderError;
fn read_nil(&mut self) -> DecodeResult<()> {
expect!(self.pop(), Null)
}
read_primitive! { read_usize, usize }
read_primitive! { read_u8, u8 }
read_primitive! { read_u16, u16 }
read_primitive! { read_u32, u32 }
read_primitive! { read_u64, u64 }
read_primitive! { read_u128, u128 }
read_primitive! { read_isize, isize }
read_primitive! { read_i8, i8 }
read_primitive! { read_i16, i16 }
read_primitive! { read_i32, i32 }
read_primitive! { read_i64, i64 }
read_primitive! { read_i128, i128 }
fn read_f32(&mut self) -> DecodeResult<f32> {
self.read_f64().map(|x| x as f32)
}
fn read_f64(&mut self) -> DecodeResult<f64> {
match self.pop() {
Json::I64(f) => Ok(f as f64),
Json::U64(f) => Ok(f as f64),
Json::F64(f) => Ok(f),
Json::String(s) => {
// re: #12967.. a type w/ numeric keys (ie HashMap<usize, V> etc)
// is going to have a string here, as per JSON spec.
match s.parse().ok() {
Some(f) => Ok(f),
None => Err(ExpectedError("Number".to_owned(), s)),
}
}
Json::Null => Ok(f64::NAN),
value => Err(ExpectedError("Number".to_owned(), value.to_string())),
}
}
fn read_bool(&mut self) -> DecodeResult<bool> {
expect!(self.pop(), Boolean)
}
fn read_char(&mut self) -> DecodeResult<char> {
let s = self.read_str()?;
{
let mut it = s.chars();
if let (Some(c), None) = (it.next(), it.next()) {
// exactly one character
return Ok(c);
}
}
Err(ExpectedError("single character string".to_owned(), s.to_string()))
}
fn read_str(&mut self) -> DecodeResult<Cow<'_, str>> {
expect!(self.pop(), String).map(Cow::Owned)
}
fn read_enum<T, F>(&mut self, _name: &str, f: F) -> DecodeResult<T>
where
F: FnOnce(&mut Decoder) -> DecodeResult<T>,
{
f(self)
}
fn read_enum_variant<T, F>(&mut self, names: &[&str], mut f: F) -> DecodeResult<T>
where
F: FnMut(&mut Decoder, usize) -> DecodeResult<T>,
{
let name = match self.pop() {
Json::String(s) => s,
Json::Object(mut o) => {
let n = match o.remove(&"variant".to_owned()) {
Some(Json::String(s)) => s,
Some(val) => return Err(ExpectedError("String".to_owned(), val.to_string())),
None => return Err(MissingFieldError("variant".to_owned())),
};
match o.remove(&"fields".to_string()) {
Some(Json::Array(l)) => {
self.stack.extend(l.into_iter().rev());
}
Some(val) => return Err(ExpectedError("Array".to_owned(), val.to_string())),
None => return Err(MissingFieldError("fields".to_owned())),
}
n
}
json => return Err(ExpectedError("String or Object".to_owned(), json.to_string())),
};
let idx = match names.iter().position(|n| *n == &name[..]) {
Some(idx) => idx,
None => return Err(UnknownVariantError(name)),
};
f(self, idx)
}
fn read_enum_variant_arg<T, F>(&mut self, _idx: usize, f: F) -> DecodeResult<T>
where
F: FnOnce(&mut Decoder) -> DecodeResult<T>,
{
f(self)
}
fn read_enum_struct_variant<T, F>(&mut self, names: &[&str], f: F) -> DecodeResult<T>
where
F: FnMut(&mut Decoder, usize) -> DecodeResult<T>,
{
self.read_enum_variant(names, f)
}
fn read_enum_struct_variant_field<T, F>(
&mut self,
_name: &str,
idx: usize,
f: F,
) -> DecodeResult<T>
where
F: FnOnce(&mut Decoder) -> DecodeResult<T>,
{
self.read_enum_variant_arg(idx, f)
}
fn read_struct<T, F>(&mut self, _name: &str, _len: usize, f: F) -> DecodeResult<T>
where
F: FnOnce(&mut Decoder) -> DecodeResult<T>,
{
let value = f(self)?;
self.pop();
Ok(value)
}
fn read_struct_field<T, F>(&mut self, name: &str, _idx: usize, f: F) -> DecodeResult<T>
where
F: FnOnce(&mut Decoder) -> DecodeResult<T>,
{
let mut obj = expect!(self.pop(), Object)?;
let value = match obj.remove(&name.to_string()) {
None => {
// Add a Null and try to parse it as an Option<_>
// to get None as a default value.
self.stack.push(Json::Null);
match f(self) {
Ok(x) => x,
Err(_) => return Err(MissingFieldError(name.to_string())),
}
}
Some(json) => {
self.stack.push(json);
f(self)?
}
};
self.stack.push(Json::Object(obj));
Ok(value)
}
fn read_tuple<T, F>(&mut self, tuple_len: usize, f: F) -> DecodeResult<T>
where
F: FnOnce(&mut Decoder) -> DecodeResult<T>,
{
self.read_seq(move |d, len| {
if len == tuple_len {
f(d)
} else {
Err(ExpectedError(format!("Tuple{}", tuple_len), format!("Tuple{}", len)))
}
})
}
fn read_tuple_arg<T, F>(&mut self, idx: usize, f: F) -> DecodeResult<T>
where
F: FnOnce(&mut Decoder) -> DecodeResult<T>,
{
self.read_seq_elt(idx, f)
}
fn read_tuple_struct<T, F>(&mut self, _name: &str, len: usize, f: F) -> DecodeResult<T>
where
F: FnOnce(&mut Decoder) -> DecodeResult<T>,
{
self.read_tuple(len, f)
}
fn read_tuple_struct_arg<T, F>(&mut self, idx: usize, f: F) -> DecodeResult<T>
where
F: FnOnce(&mut Decoder) -> DecodeResult<T>,
{
self.read_tuple_arg(idx, f)
}
fn read_option<T, F>(&mut self, mut f: F) -> DecodeResult<T>
where
F: FnMut(&mut Decoder, bool) -> DecodeResult<T>,
{
match self.pop() {
Json::Null => f(self, false),
value => {
self.stack.push(value);
f(self, true)
}
}
}
fn read_seq<T, F>(&mut self, f: F) -> DecodeResult<T>
where
F: FnOnce(&mut Decoder, usize) -> DecodeResult<T>,
{
let array = expect!(self.pop(), Array)?;
let len = array.len();
self.stack.extend(array.into_iter().rev());
f(self, len)
}
fn read_seq_elt<T, F>(&mut self, _idx: usize, f: F) -> DecodeResult<T>
where
F: FnOnce(&mut Decoder) -> DecodeResult<T>,
{
f(self)
}
fn read_map<T, F>(&mut self, f: F) -> DecodeResult<T>
where
F: FnOnce(&mut Decoder, usize) -> DecodeResult<T>,
{
let obj = expect!(self.pop(), Object)?;
let len = obj.len();
for (key, value) in obj {
self.stack.push(value);
self.stack.push(Json::String(key));
}
f(self, len)
}
fn read_map_elt_key<T, F>(&mut self, _idx: usize, f: F) -> DecodeResult<T>
where
F: FnOnce(&mut Decoder) -> DecodeResult<T>,
{
f(self)
}
fn read_map_elt_val<T, F>(&mut self, _idx: usize, f: F) -> DecodeResult<T>
where
F: FnOnce(&mut Decoder) -> DecodeResult<T>,
{
f(self)
}
fn error(&mut self, err: &str) -> DecoderError {
ApplicationError(err.to_string())
}
}
/// A trait for converting values to JSON
pub trait ToJson {
/// Converts the value of `self` to an instance of JSON
fn to_json(&self) -> Json;
}
macro_rules! to_json_impl_i64 {
($($t:ty), +) => (
$(impl ToJson for $t {
fn to_json(&self) -> Json {
Json::I64(*self as i64)
}
})+
)
}
to_json_impl_i64! { isize, i8, i16, i32, i64 }
macro_rules! to_json_impl_u64 {
($($t:ty), +) => (
$(impl ToJson for $t {
fn to_json(&self) -> Json {
Json::U64(*self as u64)
}
})+
)
}
to_json_impl_u64! { usize, u8, u16, u32, u64 }
impl ToJson for Json {
fn to_json(&self) -> Json {
self.clone()
}
}
impl ToJson for f32 {
fn to_json(&self) -> Json {
f64::from(*self).to_json()
}
}
impl ToJson for f64 {
fn to_json(&self) -> Json {
match self.classify() {
Fp::Nan | Fp::Infinite => Json::Null,
_ => Json::F64(*self),
}
}
}
impl ToJson for () {
fn to_json(&self) -> Json {
Json::Null
}
}
impl ToJson for bool {
fn to_json(&self) -> Json {
Json::Boolean(*self)
}
}
impl ToJson for str {
fn to_json(&self) -> Json {
Json::String(self.to_string())
}
}
impl ToJson for string::String {
fn to_json(&self) -> Json {
Json::String((*self).clone())
}
}
macro_rules! tuple_impl {
// use variables to indicate the arity of the tuple
($($tyvar:ident),* ) => {
// the trailing commas are for the 1 tuple
impl<
$( $tyvar : ToJson ),*
> ToJson for ( $( $tyvar ),* , ) {
#[inline]
#[allow(non_snake_case)]
fn to_json(&self) -> Json {
match *self {
($(ref $tyvar),*,) => Json::Array(vec![$($tyvar.to_json()),*])
}
}
}
}
}
tuple_impl! {A}
tuple_impl! {A, B}
tuple_impl! {A, B, C}
tuple_impl! {A, B, C, D}
tuple_impl! {A, B, C, D, E}
tuple_impl! {A, B, C, D, E, F}
tuple_impl! {A, B, C, D, E, F, G}
tuple_impl! {A, B, C, D, E, F, G, H}
tuple_impl! {A, B, C, D, E, F, G, H, I}
tuple_impl! {A, B, C, D, E, F, G, H, I, J}
tuple_impl! {A, B, C, D, E, F, G, H, I, J, K}
tuple_impl! {A, B, C, D, E, F, G, H, I, J, K, L}
impl<A: ToJson> ToJson for [A] {
fn to_json(&self) -> Json {
Json::Array(self.iter().map(|elt| elt.to_json()).collect())
}
}
impl<A: ToJson> ToJson for Vec<A> {
fn to_json(&self) -> Json {
Json::Array(self.iter().map(|elt| elt.to_json()).collect())
}
}
impl<T: ToString, A: ToJson> ToJson for BTreeMap<T, A> {
fn to_json(&self) -> Json {
let mut d = BTreeMap::new();
for (key, value) in self {
d.insert(key.to_string(), value.to_json());
}
Json::Object(d)
}
}
impl<A: ToJson> ToJson for HashMap<string::String, A> {
fn to_json(&self) -> Json {
let mut d = BTreeMap::new();
for (key, value) in self {
d.insert((*key).clone(), value.to_json());
}
Json::Object(d)
}
}
impl<A: ToJson> ToJson for Option<A> {
fn to_json(&self) -> Json {
match *self {
None => Json::Null,
Some(ref value) => value.to_json(),
}
}
}
struct FormatShim<'a, 'b> {
inner: &'a mut fmt::Formatter<'b>,
}
impl<'a, 'b> fmt::Write for FormatShim<'a, 'b> {
fn write_str(&mut self, s: &str) -> fmt::Result {
match self.inner.write_str(s) {
Ok(_) => Ok(()),
Err(_) => Err(fmt::Error),
}
}
}
impl fmt::Display for Json {
/// Encodes a json value into a string
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let mut shim = FormatShim { inner: f };
let mut encoder = Encoder::new(&mut shim);
match self.encode(&mut encoder) {
Ok(_) => Ok(()),
Err(_) => Err(fmt::Error),
}
}
}
impl<'a> fmt::Display for PrettyJson<'a> {
/// Encodes a json value into a string
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let mut shim = FormatShim { inner: f };
let mut encoder = PrettyEncoder::new(&mut shim);
match self.inner.encode(&mut encoder) {
Ok(_) => Ok(()),
Err(_) => Err(fmt::Error),
}
}
}
impl<'a, T: for<'r> Encodable<Encoder<'r>>> fmt::Display for AsJson<'a, T> {
/// Encodes a json value into a string
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let mut shim = FormatShim { inner: f };
let mut encoder = Encoder::new(&mut shim);
match self.inner.encode(&mut encoder) {
Ok(_) => Ok(()),
Err(_) => Err(fmt::Error),
}
}
}
impl<'a, T> AsPrettyJson<'a, T> {
/// Sets the indentation level for the emitted JSON
pub fn indent(mut self, indent: usize) -> AsPrettyJson<'a, T> {
self.indent = Some(indent);
self
}
}
impl<'a, T: for<'x> Encodable<PrettyEncoder<'x>>> fmt::Display for AsPrettyJson<'a, T> {
/// Encodes a json value into a string
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let mut shim = FormatShim { inner: f };
let mut encoder = PrettyEncoder::new(&mut shim);
if let Some(n) = self.indent {
encoder.set_indent(n);
}
match self.inner.encode(&mut encoder) {
Ok(_) => Ok(()),
Err(_) => Err(fmt::Error),
}
}
}
impl FromStr for Json {
type Err = BuilderError;
fn from_str(s: &str) -> Result<Json, BuilderError> {
from_str(s)
}
}
#[cfg(test)]
mod tests;
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