json_char/
json_char.rs

1use pom::parser::*;
2
3use std::char::{decode_utf16, REPLACEMENT_CHARACTER};
4use std::collections::HashMap;
5use std::iter::FromIterator;
6use std::str::FromStr;
7
8#[derive(Debug, PartialEq)]
9pub enum JsonValue {
10	Null,
11	Bool(bool),
12	Str(String),
13	Num(f64),
14	Array(Vec<JsonValue>),
15	Object(HashMap<String, JsonValue>),
16}
17
18fn space<'a>() -> Parser<'a, char, ()> {
19	one_of(" \t\r\n").repeat(0..).discard()
20}
21
22fn number<'a>() -> Parser<'a, char, f64> {
23	let integer = one_of("123456789") - one_of("0123456789").repeat(0..) | sym('0');
24	let frac = sym('.') + one_of("0123456789").repeat(1..);
25	let exp = one_of("eE") + one_of("+-").opt() + one_of("0123456789").repeat(1..);
26	let number = sym('-').opt() + integer + frac.opt() + exp.opt();
27	number
28		.collect()
29		.map(String::from_iter)
30		.convert(|s| f64::from_str(&s))
31}
32
33fn string<'a>() -> Parser<'a, char, String> {
34	let special_char = sym('\\')
35		| sym('/')
36		| sym('"')
37		| sym('b').map(|_| '\x08')
38		| sym('f').map(|_| '\x0C')
39		| sym('n').map(|_| '\n')
40		| sym('r').map(|_| '\r')
41		| sym('t').map(|_| '\t');
42	let escape_sequence = sym('\\') * special_char;
43	let char_string = (none_of("\\\"") | escape_sequence)
44		.repeat(1..)
45		.map(String::from_iter);
46	let utf16_char = tag("\\u") * is_a(|c: char| c.is_digit(16))
47		.repeat(4)
48		.map(String::from_iter)
49		.convert(|digits| u16::from_str_radix(&digits, 16));
50	let utf16_string = utf16_char.repeat(1..).map(|chars| {
51		decode_utf16(chars)
52			.map(|r| r.unwrap_or(REPLACEMENT_CHARACTER))
53			.collect::<String>()
54	});
55	let string = sym('"') * (char_string | utf16_string).repeat(0..) - sym('"');
56	string.map(|strings| strings.concat())
57}
58
59fn array<'a>() -> Parser<'a, char, Vec<JsonValue>> {
60	let elems = list(call(value), sym(',') * space());
61	sym('[') * space() * elems - sym(']')
62}
63
64fn object<'a>() -> Parser<'a, char, HashMap<String, JsonValue>> {
65	let member = string() - space() - sym(':') - space() + call(value);
66	let members = list(member, sym(',') * space());
67	let obj = sym('{') * space() * members - sym('}');
68	obj.map(|members| members.into_iter().collect::<HashMap<_, _>>())
69}
70
71fn value<'a>() -> Parser<'a, char, JsonValue> {
72	(tag("null").map(|_| JsonValue::Null)
73		| tag("true").map(|_| JsonValue::Bool(true))
74		| tag("false").map(|_| JsonValue::Bool(false))
75		| number().map(|num| JsonValue::Num(num))
76		| string().map(|text| JsonValue::Str(text))
77		| array().map(|arr| JsonValue::Array(arr))
78		| object().map(|obj| JsonValue::Object(obj)))
79		- space()
80}
81
82pub fn json<'a>() -> Parser<'a, char, JsonValue> {
83	space() * value() - end()
84}
85
86#[allow(dead_code)]
87fn main() {
88	let test = r#"
89	{
90        "Image": {
91            "Width":  800,
92            "Height": 600,
93            "Title":  "View from 15th Floor",
94            "Thumbnail": {
95                "Url":    "http://www.example.com/image/481989943",
96                "Height": 125,
97                "Width":  100
98            },
99            "Animated" : false,
100            "IDs": [116, 943, 234, 38793]
101        },
102        "escaped characters": "\u2192\uD83D\uDE00\"\t\uD834\uDD1E"
103    }"#;
104
105	let input: Vec<char> = test.chars().collect();
106	println!("{:?}", json().parse(&input));
107}
json_char/json_char.rs

json_char/
json_char.rs
