schala/subtrees/parser-combinator/tests/json_parser.rs

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use parser_combinator::choice::choice;
use parser_combinator::combinators::repeated;
use parser_combinator::primitives::{any_char, literal, literal_char, one_of, pred};
use parser_combinator::sequence::seq;
use parser_combinator::Parser;
use parser_combinator::Representation;
use proptest::prelude::*;
use rstest::*;
proptest! {
#[test]
fn doesnt_crash(s in "\\PC*") {
let _output = json_object().parse(&s);
}
#[test]
fn parse_string(s in r#"[^"]+"#) {
let input = format!("\"{}\"", s);
let output = json_string().parse(&input).unwrap();
match output {
(JsonValue::Str(output_s), "") if output_s == s => (),
_ => panic!(),
}
}
}
#[test]
fn test_parsing() {
let output = literal("a").parse("a yolo");
assert_eq!(output.unwrap(), ("a", " yolo"));
}
/*
* JSON BNF
* <JSON> ::= <value>
<value> ::= <object> | <array> | <boolean> | <string> | <number> | <null>
<array> ::= "[" [<value>] {"," <value>}* "]"
<object> ::= "{" [<property>] {"," <property>}* "}"
<property> ::= <string> ":" <value>
*/
#[derive(Debug, Clone, PartialEq)]
enum JsonValue {
Null,
Bool(bool),
Str(String),
Num(f64),
Array(Vec<JsonValue>),
Object(Vec<(String, JsonValue)>),
}
trait JsonParser<'a, T>: Parser<&'a str, T, &'a str> {}
impl<'a, T, P> JsonParser<'a, T> for P where P: Parser<&'a str, T, &'a str> {}
fn json_null<'a>() -> impl JsonParser<'a, JsonValue> {
literal("null").to(JsonValue::Null)
}
fn json_bool<'a>() -> impl JsonParser<'a, JsonValue> {
choice((
literal("true").to(JsonValue::Bool(true)),
literal("false").to(JsonValue::Bool(false)),
))
}
fn json_number<'a>() -> impl JsonParser<'a, JsonValue> {
fn digit<'a>() -> impl JsonParser<'a, &'a str> {
one_of("1234567890")
}
fn digits<'a>() -> impl JsonParser<'a, Vec<&'a str>> {
repeated(digit()).at_least(1)
}
let json_number_inner = choice((
seq((digits(), literal(".").ignore_then(digits()).optional())).map(
|(mut digits, maybe_decimal)| {
if let Some(decimal_digits) = maybe_decimal {
digits.push(".");
digits.extend(decimal_digits.into_iter());
}
digits.into_iter().collect::<String>()
},
),
literal(".").ignore_then(digits()).map(|decimal_digits| {
let mut d = vec!["."];
d.extend(decimal_digits.into_iter());
d.into_iter().collect::<String>()
}),
))
.map(|digits| digits.parse::<f64>().unwrap());
literal("-")
.optional()
.then(json_number_inner)
.map(|(maybe_sign, mut val)| {
if maybe_sign.is_some() {
val *= -1.0;
}
JsonValue::Num(val)
})
}
fn json_string_raw<'a>() -> impl JsonParser<'a, String> {
seq((
literal_char('"'),
repeated(pred(any_char, |ch| *ch != '"')),
literal_char('"'),
))
.map(|(_, s, _)| s.iter().cloned().collect::<String>())
}
fn json_string<'a>() -> impl JsonParser<'a, JsonValue> {
json_string_raw().map(JsonValue::Str)
}
fn whitespace<'a>() -> impl JsonParser<'a, ()> {
repeated(choice((
literal_char('\t'),
literal_char('\n'),
literal_char(' '),
)))
.to(())
}
fn json_array<'a>() -> impl JsonParser<'a, JsonValue> {
move |input| {
let val = json_value().surrounded_by(whitespace());
repeated(val)
.separated_by(literal(","), false)
.delimited(literal_char('['), literal_char(']'))
.map(JsonValue::Array)
.parse(input)
}
}
fn json_object<'a>() -> impl JsonParser<'a, JsonValue> {
move |input| {
let kv = json_string_raw()
.surrounded_by(whitespace())
.then_ignore(literal_char(':'))
.then(json_value().surrounded_by(whitespace()));
repeated(kv)
.separated_by(literal_char(','), false)
.delimited(literal_char('{'), literal_char('}'))
.map(JsonValue::Object)
.parse(input)
}
}
fn json_value<'a>() -> impl JsonParser<'a, JsonValue> {
choice((
json_null(),
json_bool(),
json_number(),
json_string(),
json_array(),
json_object(),
))
}
#[test]
fn parse_json_primitives() {
assert_eq!(
json_string().parse(r#""yolo swagg""#).unwrap(),
(JsonValue::Str("yolo swagg".into()), "")
);
assert_eq!(
json_number().parse("-383").unwrap().0,
JsonValue::Num(-383f64)
);
assert_eq!(
json_number().parse("-.383").unwrap().0,
JsonValue::Num(-0.383)
);
assert_eq!(
json_number().parse(".383").unwrap().0,
JsonValue::Num(0.383)
);
assert_eq!(
json_number().parse("-1.383").unwrap().0,
JsonValue::Num(-1.383)
);
}
#[rstest]
#[case(r#"[ 4, 9, "ara",]"#)]
fn parse_json_array_err(#[case] input: &str) {
assert!(json_array().parse(input).is_err());
}
#[rstest]
#[case("[[],[]]", (JsonValue::Array(vec![JsonValue::Array(vec![]), JsonValue::Array(vec![])]), ""))]
#[case(r#"[ 4, 9, "foo" ]"#, (
JsonValue::Array(vec![
JsonValue::Num(4.),
JsonValue::Num(9.0),
JsonValue::Str("foo".to_string())
]),
""
))]
#[case(r#"[8,null,[],5],{}"#,
(
JsonValue::Array(vec![
JsonValue::Num(8.),
JsonValue::Null,
JsonValue::Array(vec![]),
JsonValue::Num(5.),
]),
",{}"
))]
fn parse_json_array(#[case] input: &str, #[case] expected: (JsonValue, &str)) {
assert_eq!(json_array().parse(input).unwrap(), expected);
}
#[test]
fn parse_json_object() {
assert_eq!(
json_object().parse(r#"{ "a": 23}"#).unwrap().0,
JsonValue::Object(vec![("a".into(), JsonValue::Num(23.))])
);
assert_eq!(
json_object().parse(r#"{}"#).unwrap().0,
JsonValue::Object(vec![])
);
}
#[test]
fn parse_json_document() {
let test_json = include_str!("joplin-cfg.json");
let parsed_json = json_object().parse(test_json);
assert!(parsed_json.is_ok());
}
#[rstest]
#[case(json_null().representation(), Representation::new("null"))]
#[case(json_bool().representation(), Representation::new("true | false"))]
#[case(json_number().representation(), Representation::new("- | ε (1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | )+ . (1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | )+ | ε | . (1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | )+"))]
fn representations_test(
#[case] parser_representation: Representation,
#[case] expected: Representation,
) {
assert_eq!(parser_representation, expected);
}