Added chumsky example

Author: zesterer

test_cases/Cargo.lock

@@ -8,3 +8,4 @@ edition = "2021"
 [dependencies]
 trybuild = "1"
 diesel = {version = "2.0.0-rc.0", default-features = false, features = ["sqlite", "postgres", "mysql"]}
+chumsky = "0.8.0"

test_cases/Cargo.toml

@@ -0,0 +1,108 @@
+use chumsky::prelude::*;
+use std::collections::HashMap;
+
+#[derive(Clone, Debug)]
+enum Json {
+    Invalid,
+    Null,
+    Bool(bool),
+    Str(String),
+    Num(f64),
+    Array(Vec<Json>),
+    Object(HashMap<String, Json>),
+}
+
+fn parser() -> impl Parser<char, Json, Error = Simple<char>> {
+    recursive(|value| {
+        let frac = just('.').chain(text::digits(10));
+
+        let exp = just('e')
+            .or(just('E'))
+            .chain(just('+').or(just('-')).or_not())
+            .chain(text::digits(10));
+
+        let number = just('-')
+            .or_not()
+            .chain(text::int(10))
+            .chain(frac.or_not().flatten())
+            .chain::<char, _, _>(exp.or_not().flatten())
+            .collect::<String>()
+            .from_str()
+            .unwrapped()
+            .labelled("number");
+
+        let escape = just('\\').ignore_then(
+            just('\\')
+                .or(just('/'))
+                .or(just('"'))
+                .or(just('b').to('\x08'))
+                .or(just('f').to('\x0C'))
+                .or(just('n').to('\n'))
+                .or(just('r').to('\r'))
+                .or(just('t').to('\t'))
+                .or(just('u').ignore_then(
+                    filter(|c: &char| c.is_digit(16))
+                        .repeated()
+                        .exactly(4)
+                        .collect::<String>()
+                        .validate(|digits, span, emit| {
+                            char::from_u32(u32::from_str_radix(&digits, 16).unwrap())
+                                .unwrap_or_else(|| {
+                                    emit(Simple::custom(span, "invalid unicode character"));
+                                    '\u{FFFD}' // unicode replacement character
+                                })
+                        }),
+                )),
+        );
+
+        let string = just('"')
+            .ignore_then(filter(|c| *c != '\\' && *c != '"').or(escape).repeated())
+            .then_ignore(just('"'))
+            .collect::<String>()
+            .labelled("string");
+
+        let array = value
+            .clone()
+            .chain(just(',').ignore_then(value.clone()).repeated())
+            .or_not()
+            .flatten()
+            .delimited_by(just('['), just(']'))
+            .map(Json::Array)
+            .labelled("array");
+
+        let member = string.clone().then_ignore(just(':').padded()).then(value);
+        let object = member
+            .clone()
+            .chain(just(',').padded().ignore_then(member).repeated())
+            .or_not()
+            .flatten()
+            .padded()
+            .delimited_by(just('{'), just('}'))
+            .collect::<HashMap<String, Json>>()
+            .map(Json::Object)
+            .labelled("object");
+
+        just("null")
+            .to(Json::Null)
+            .labelled("null")
+            .or(just("true").to(Json::Bool(true)).labelled("true"))
+            .or(just("false").to(Json::Bool(false)).labelled("false"))
+            .or(number.map(Json::Num))
+            // SWAP THESE LINES
+            .or(string)
+            //.or(string.map(Json::Str))
+            .or(array)
+            .or(object)
+            .recover_with(nested_delimiters('{', '}', [('[', ']')], |_| Json::Invalid))
+            .recover_with(nested_delimiters('[', ']', [('{', '}')], |_| Json::Invalid))
+            .recover_with(skip_then_retry_until(['}', ']']))
+            .padded()
+    })
+    .then_ignore(end().recover_with(skip_then_retry_until([])))
+}
+
+fn main() {
+    parser()
+        .parse("{ \"a\": 5, b: \"hello, world!\"}")
+        .unwrap();
+}

test_cases/tests/chumsky/json.rs

@@ -7,3 +7,8 @@ fn diesel() {
     t.compile_fail("tests/diesel/*.rs");
 }
 
+#[test]
+fn chumsky() {
+    let t = trybuild::TestCases::new();
+    t.compile_fail("tests/chumsky/*.rs");
+}