Vendor dependencies for 0.3.0 release

vendor/winnow/examples/json/bench.rs

@@ -0,0 +1,78 @@
+use winnow::prelude::*;
+use winnow::Partial;
+
+mod json;
+mod parser_alt;
+mod parser_dispatch;
+mod parser_partial;
+
+fn json_bench(c: &mut criterion::Criterion) {
+    let data = [("small", SMALL), ("canada", CANADA)];
+    let mut group = c.benchmark_group("json");
+    for (name, sample) in data {
+        let len = sample.len();
+        group.throughput(criterion::Throughput::Bytes(len as u64));
+
+        group.bench_with_input(
+            criterion::BenchmarkId::new("dispatch", name),
+            &len,
+            |b, _| {
+                type Error = winnow::error::ErrMode<winnow::error::ContextError>;
+
+                b.iter(|| parser_dispatch::json::<Error>.parse_peek(sample).unwrap());
+            },
+        );
+        group.bench_with_input(
+            criterion::BenchmarkId::new("modeless", name),
+            &len,
+            |b, _| {
+                type Error = winnow::error::ContextError;
+
+                b.iter(|| parser_dispatch::json::<Error>.parse_peek(sample).unwrap());
+            },
+        );
+        group.bench_with_input(
+            criterion::BenchmarkId::new("empty-error", name),
+            &len,
+            |b, _| {
+                type Error<'i> = winnow::error::EmptyError;
+
+                b.iter(|| {
+                    parser_dispatch::json::<Error<'_>>
+                        .parse_peek(sample)
+                        .unwrap()
+                });
+            },
+        );
+        group.bench_with_input(criterion::BenchmarkId::new("alt", name), &len, |b, _| {
+            type Error = winnow::error::ContextError;
+
+            b.iter(|| parser_alt::json::<Error>.parse_peek(sample).unwrap());
+        });
+        group.bench_with_input(
+            criterion::BenchmarkId::new("streaming", name),
+            &len,
+            |b, _| {
+                type Error = winnow::error::ContextError;
+
+                b.iter(|| {
+                    parser_partial::json::<Error>
+                        .parse_peek(Partial::new(sample))
+                        .unwrap()
+                });
+            },
+        );
+    }
+    group.finish();
+}
+
+const SMALL: &str = "  { \"a\"\t: 42,
+  \"b\": [ \"x\", \"y\", 12 ,\"\\u2014\", \"\\uD83D\\uDE10\"] ,
+  \"c\": { \"hello\" : \"world\"
+  }
+  }  ";
+
+const CANADA: &str = include_str!("../../third_party/nativejson-benchmark/data/canada.json");
+
+criterion::criterion_group!(benches, json_bench,);
+criterion::criterion_main!(benches);

vendor/winnow/examples/json/json.rs

@@ -0,0 +1,11 @@
+use std::collections::HashMap;
+
+#[derive(Debug, PartialEq, Clone)]
+pub(crate) enum JsonValue {
+    Null,
+    Boolean(bool),
+    Str(String),
+    Num(f64),
+    Array(Vec<JsonValue>),
+    Object(HashMap<String, JsonValue>),
+}

vendor/winnow/examples/json/main.rs

@@ -0,0 +1,98 @@
+mod json;
+mod parser_alt;
+mod parser_dispatch;
+#[allow(dead_code)]
+mod parser_partial;
+
+use winnow::error::EmptyError;
+use winnow::prelude::*;
+
+fn main() -> Result<(), lexopt::Error> {
+    let args = Args::parse()?;
+
+    let data = args.input.as_deref().unwrap_or(if args.invalid {
+        "  { \"a\"\t: 42,
+  \"b\": [ \"x\", \"y\", 12 ] ,
+  \"c\": { 1\"hello\" : \"world\"
+  }
+  } "
+    } else {
+        "  { \"a\"\t: 42,
+  \"b\": [ \"x\", \"y\", 12 ] ,
+  \"c\": { \"hello\" : \"world\"
+  }
+  } "
+    });
+
+    let result = match args.implementation {
+        Impl::Naive => parser_alt::json::<EmptyError>.parse(data),
+        Impl::Dispatch => parser_dispatch::json::<EmptyError>.parse(data),
+    };
+    match result {
+        Ok(json) => {
+            println!("{json:#?}");
+        }
+        Err(err) => {
+            if args.pretty {
+                println!("{err}");
+            } else {
+                println!("{err:#?}");
+            }
+        }
+    }
+
+    Ok(())
+}
+
+#[derive(Default)]
+struct Args {
+    input: Option<String>,
+    invalid: bool,
+    pretty: bool,
+    implementation: Impl,
+}
+
+enum Impl {
+    Naive,
+    Dispatch,
+}
+
+impl Default for Impl {
+    fn default() -> Self {
+        Self::Naive
+    }
+}
+
+impl Args {
+    fn parse() -> Result<Self, lexopt::Error> {
+        use lexopt::prelude::*;
+
+        let mut res = Args::default();
+
+        let mut args = lexopt::Parser::from_env();
+        while let Some(arg) = args.next()? {
+            match arg {
+                Long("invalid") => {
+                    res.invalid = true;
+                }
+                Long("pretty") => {
+                    // Only case where pretty matters
+                    res.pretty = true;
+                    res.invalid = true;
+                }
+                Long("impl") => {
+                    res.implementation = args.value()?.parse_with(|s| match s {
+                        "naive" => Ok(Impl::Naive),
+                        "dispatch" => Ok(Impl::Dispatch),
+                        _ => Err("expected `naive`, `dispatch`"),
+                    })?;
+                }
+                Value(input) => {
+                    res.input = Some(input.string()?);
+                }
+                _ => return Err(arg.unexpected()),
+            }
+        }
+        Ok(res)
+    }
+}

vendor/winnow/examples/json/parser_alt.rs

@@ -0,0 +1,323 @@
+use std::collections::HashMap;
+use std::str;
+
+use winnow::prelude::*;
+use winnow::{
+    ascii::float,
+    combinator::alt,
+    combinator::cut_err,
+    combinator::{delimited, preceded, separated_pair, terminated},
+    combinator::{repeat, separated},
+    error::{AddContext, ParserError, StrContext},
+    token::{any, none_of, take, take_while},
+};
+
+use crate::json::JsonValue;
+
+pub(crate) type Stream<'i> = &'i str;
+
+/// The root element of a JSON parser is any value
+///
+/// A parser has the following signature:
+/// `&mut Stream -> ModalResult<Output, ContextError>`, with `ModalResult` defined as:
+/// `type ModalResult<O, E = (I, ErrorKind)> = Result<O, Err<E>>;`
+///
+/// most of the times you can ignore the error type and use the default (but this
+/// examples shows custom error types later on!)
+///
+/// Here we use `&str` as input type, but parsers can be generic over
+/// the input type, work directly with `&[u8]`, or any other type that
+/// implements the required traits.
+pub(crate) fn json<'i, E: ParserError<Stream<'i>> + AddContext<Stream<'i>, StrContext>>(
+    input: &mut Stream<'i>,
+) -> ModalResult<JsonValue, E> {
+    delimited(ws, json_value, ws).parse_next(input)
+}
+
+/// `alt` is a combinator that tries multiple parsers one by one, until
+/// one of them succeeds
+fn json_value<'i, E: ParserError<Stream<'i>> + AddContext<Stream<'i>, StrContext>>(
+    input: &mut Stream<'i>,
+) -> ModalResult<JsonValue, E> {
+    // `alt` combines the each value parser. It returns the result of the first
+    // successful parser, or an error
+    alt((
+        null.value(JsonValue::Null),
+        boolean.map(JsonValue::Boolean),
+        string.map(JsonValue::Str),
+        float.map(JsonValue::Num),
+        array.map(JsonValue::Array),
+        object.map(JsonValue::Object),
+    ))
+    .parse_next(input)
+}
+
+/// `literal(string)` generates a parser that takes the argument string.
+///
+/// This also shows returning a sub-slice of the original input
+fn null<'i, E: ParserError<Stream<'i>>>(input: &mut Stream<'i>) -> ModalResult<&'i str, E> {
+    // This is a parser that returns `"null"` if it sees the string "null", and
+    // an error otherwise
+    "null".parse_next(input)
+}
+
+/// We can combine `tag` with other functions, like `value` which returns a given constant value on
+/// success.
+fn boolean<'i, E: ParserError<Stream<'i>>>(input: &mut Stream<'i>) -> ModalResult<bool, E> {
+    // This is a parser that returns `true` if it sees the string "true", and
+    // an error otherwise
+    let parse_true = "true".value(true);
+
+    // This is a parser that returns `false` if it sees the string "false", and
+    // an error otherwise
+    let parse_false = "false".value(false);
+
+    alt((parse_true, parse_false)).parse_next(input)
+}
+
+/// This parser gathers all `char`s up into a `String`with a parse to take the double quote
+/// character, before the string (using `preceded`) and after the string (using `terminated`).
+fn string<'i, E: ParserError<Stream<'i>> + AddContext<Stream<'i>, StrContext>>(
+    input: &mut Stream<'i>,
+) -> ModalResult<String, E> {
+    preceded(
+        '\"',
+        // `cut_err` transforms an `ErrMode::Backtrack(e)` to `ErrMode::Cut(e)`, signaling to
+        // combinators like  `alt` that they should not try other parsers. We were in the
+        // right branch (since we found the `"` character) but encountered an error when
+        // parsing the string
+        cut_err(terminated(
+            repeat(0.., character).fold(String::new, |mut string, c| {
+                string.push(c);
+                string
+            }),
+            '\"',
+        )),
+    )
+    // `context` lets you add a static string to errors to provide more information in the
+    // error chain (to indicate which parser had an error)
+    .context(StrContext::Expected("string".into()))
+    .parse_next(input)
+}
+
+/// You can mix the above declarative parsing with an imperative style to handle more unique cases,
+/// like escaping
+fn character<'i, E: ParserError<Stream<'i>>>(input: &mut Stream<'i>) -> ModalResult<char, E> {
+    let c = none_of('\"').parse_next(input)?;
+    if c == '\\' {
+        alt((
+            any.verify_map(|c| {
+                Some(match c {
+                    '"' | '\\' | '/' => c,
+                    'b' => '\x08',
+                    'f' => '\x0C',
+                    'n' => '\n',
+                    'r' => '\r',
+                    't' => '\t',
+                    _ => return None,
+                })
+            }),
+            preceded('u', unicode_escape),
+        ))
+        .parse_next(input)
+    } else {
+        Ok(c)
+    }
+}
+
+fn unicode_escape<'i, E: ParserError<Stream<'i>>>(input: &mut Stream<'i>) -> ModalResult<char, E> {
+    alt((
+        // Not a surrogate
+        u16_hex
+            .verify(|cp| !(0xD800..0xE000).contains(cp))
+            .map(|cp| cp as u32),
+        // See https://en.wikipedia.org/wiki/UTF-16#Code_points_from_U+010000_to_U+10FFFF for details
+        separated_pair(u16_hex, "\\u", u16_hex)
+            .verify(|(high, low)| (0xD800..0xDC00).contains(high) && (0xDC00..0xE000).contains(low))
+            .map(|(high, low)| {
+                let high_ten = (high as u32) - 0xD800;
+                let low_ten = (low as u32) - 0xDC00;
+                (high_ten << 10) + low_ten + 0x10000
+            }),
+    ))
+    .verify_map(
+        // Could be probably replaced with .unwrap() or _unchecked due to the verify checks
+        std::char::from_u32,
+    )
+    .parse_next(input)
+}
+
+fn u16_hex<'i, E: ParserError<Stream<'i>>>(input: &mut Stream<'i>) -> ModalResult<u16, E> {
+    take(4usize)
+        .verify_map(|s| u16::from_str_radix(s, 16).ok())
+        .parse_next(input)
+}
+
+/// Some combinators, like `separated` or `repeat`, will call a parser repeatedly,
+/// accumulating results in a `Vec`, until it encounters an error.
+/// If you want more control on the parser application, check out the `iterator`
+/// combinator (cf `examples/iterator.rs`)
+fn array<'i, E: ParserError<Stream<'i>> + AddContext<Stream<'i>, StrContext>>(
+    input: &mut Stream<'i>,
+) -> ModalResult<Vec<JsonValue>, E> {
+    preceded(
+        ('[', ws),
+        cut_err(terminated(
+            separated(0.., json_value, (ws, ',', ws)),
+            (ws, ']'),
+        )),
+    )
+    .context(StrContext::Expected("array".into()))
+    .parse_next(input)
+}
+
+fn object<'i, E: ParserError<Stream<'i>> + AddContext<Stream<'i>, StrContext>>(
+    input: &mut Stream<'i>,
+) -> ModalResult<HashMap<String, JsonValue>, E> {
+    preceded(
+        ('{', ws),
+        cut_err(terminated(
+            separated(0.., key_value, (ws, ',', ws)),
+            (ws, '}'),
+        )),
+    )
+    .context(StrContext::Expected("object".into()))
+    .parse_next(input)
+}
+
+fn key_value<'i, E: ParserError<Stream<'i>> + AddContext<Stream<'i>, StrContext>>(
+    input: &mut Stream<'i>,
+) -> ModalResult<(String, JsonValue), E> {
+    separated_pair(string, cut_err((ws, ':', ws)), json_value).parse_next(input)
+}
+
+/// Parser combinators are constructed from the bottom up:
+/// first we write parsers for the smallest elements (here a space character),
+/// then we'll combine them in larger parsers
+fn ws<'i, E: ParserError<Stream<'i>>>(input: &mut Stream<'i>) -> ModalResult<&'i str, E> {
+    // Combinators like `take_while` return a function. That function is the
+    // parser,to which we can pass the input
+    take_while(0.., WS).parse_next(input)
+}
+
+const WS: &[char] = &[' ', '\t', '\r', '\n'];
+
+#[cfg(test)]
+mod test {
+    #[allow(clippy::useless_attribute)]
+    #[allow(unused_imports)] // its dead for benches
+    use super::*;
+
+    #[allow(clippy::useless_attribute)]
+    #[allow(dead_code)] // its dead for benches
+    type Error = winnow::error::ContextError;
+
+    #[test]
+    fn json_string() {
+        assert_eq!(string::<Error>.parse_peek("\"\""), Ok(("", "".to_owned())));
+        assert_eq!(
+            string::<Error>.parse_peek("\"abc\""),
+            Ok(("", "abc".to_owned()))
+        );
+        assert_eq!(
+            string::<Error>
+                .parse_peek("\"abc\\\"\\\\\\/\\b\\f\\n\\r\\t\\u0001\\u2014\u{2014}def\""),
+            Ok(("", "abc\"\\/\x08\x0C\n\r\t\x01——def".to_owned())),
+        );
+        assert_eq!(
+            string::<Error>.parse_peek("\"\\uD83D\\uDE10\""),
+            Ok(("", "😐".to_owned()))
+        );
+
+        assert!(string::<Error>.parse_peek("\"").is_err());
+        assert!(string::<Error>.parse_peek("\"abc").is_err());
+        assert!(string::<Error>.parse_peek("\"\\\"").is_err());
+        assert!(string::<Error>.parse_peek("\"\\u123\"").is_err());
+        assert!(string::<Error>.parse_peek("\"\\uD800\"").is_err());
+        assert!(string::<Error>.parse_peek("\"\\uD800\\uD800\"").is_err());
+        assert!(string::<Error>.parse_peek("\"\\uDC00\"").is_err());
+    }
+
+    #[test]
+    fn json_object() {
+        use JsonValue::{Num, Object, Str};
+
+        let input = r#"{"a":42,"b":"x"}"#;
+
+        let expected = Object(
+            vec![
+                ("a".to_owned(), Num(42.0)),
+                ("b".to_owned(), Str("x".to_owned())),
+            ]
+            .into_iter()
+            .collect(),
+        );
+
+        assert_eq!(json::<Error>.parse_peek(input), Ok(("", expected)));
+    }
+
+    #[test]
+    fn json_array() {
+        use JsonValue::{Array, Num, Str};
+
+        let input = r#"[42,"x"]"#;
+
+        let expected = Array(vec![Num(42.0), Str("x".to_owned())]);
+
+        assert_eq!(json::<Error>.parse_peek(input), Ok(("", expected)));
+    }
+
+    #[test]
+    fn json_whitespace() {
+        use JsonValue::{Array, Boolean, Null, Num, Object, Str};
+
+        let input = r#"
+  {
+    "null" : null,
+    "true"  :true ,
+    "false":  false  ,
+    "number" : 123e4 ,
+    "string" : " abc 123 " ,
+    "array" : [ false , 1 , "two" ] ,
+    "object" : { "a" : 1.0 , "b" : "c" } ,
+    "empty_array" : [  ] ,
+    "empty_object" : {   }
+  }
+  "#;
+
+        assert_eq!(
+            json::<Error>.parse_peek(input),
+            Ok((
+                "",
+                Object(
+                    vec![
+                        ("null".to_owned(), Null),
+                        ("true".to_owned(), Boolean(true)),
+                        ("false".to_owned(), Boolean(false)),
+                        ("number".to_owned(), Num(123e4)),
+                        ("string".to_owned(), Str(" abc 123 ".to_owned())),
+                        (
+                            "array".to_owned(),
+                            Array(vec![Boolean(false), Num(1.0), Str("two".to_owned())])
+                        ),
+                        (
+                            "object".to_owned(),
+                            Object(
+                                vec![
+                                    ("a".to_owned(), Num(1.0)),
+                                    ("b".to_owned(), Str("c".to_owned())),
+                                ]
+                                .into_iter()
+                                .collect()
+                            )
+                        ),
+                        ("empty_array".to_owned(), Array(vec![]),),
+                        ("empty_object".to_owned(), Object(HashMap::new()),),
+                    ]
+                    .into_iter()
+                    .collect()
+                )
+            ))
+        );
+    }
+}

vendor/winnow/examples/json/parser_dispatch.rs

@@ -0,0 +1,319 @@
+use std::collections::HashMap;
+use std::str;
+
+use winnow::prelude::*;
+use winnow::Result;
+use winnow::{
+    ascii::float,
+    combinator::empty,
+    combinator::fail,
+    combinator::peek,
+    combinator::{alt, dispatch},
+    combinator::{delimited, preceded, separated_pair, terminated},
+    combinator::{repeat, separated},
+    error::{AddContext, ParserError, StrContext},
+    token::{any, none_of, take, take_while},
+};
+
+use crate::json::JsonValue;
+
+pub(crate) type Stream<'i> = &'i str;
+
+/// The root element of a JSON parser is any value
+///
+/// A parser has the following signature:
+/// `&mut Stream -> Result<Output ContextError>`
+///
+/// most of the times you can ignore the error type and use the default (but this
+/// examples shows custom error types later on!)
+///
+/// Here we use `&str` as input type, but parsers can be generic over
+/// the input type, work directly with `&[u8]`, or any other type that
+/// implements the required traits.
+pub(crate) fn json<'i, E: ParserError<Stream<'i>> + AddContext<Stream<'i>, StrContext>>(
+    input: &mut Stream<'i>,
+) -> Result<JsonValue, E> {
+    delimited(ws, json_value, ws).parse_next(input)
+}
+
+/// `alt` is a combinator that tries multiple parsers one by one, until
+/// one of them succeeds
+fn json_value<'i, E: ParserError<Stream<'i>> + AddContext<Stream<'i>, StrContext>>(
+    input: &mut Stream<'i>,
+) -> Result<JsonValue, E> {
+    // `dispatch` gives you `match`-like behavior compared to `alt` successively trying different
+    // implementations.
+    dispatch!(peek(any);
+        'n' => null.value(JsonValue::Null),
+        't' => true_.map(JsonValue::Boolean),
+        'f' => false_.map(JsonValue::Boolean),
+        '"' => string.map(JsonValue::Str),
+        '+' => float.map(JsonValue::Num),
+        '-' => float.map(JsonValue::Num),
+        '0'..='9' => float.map(JsonValue::Num),
+        '[' => array.map(JsonValue::Array),
+        '{' => object.map(JsonValue::Object),
+        _ => fail,
+    )
+    .parse_next(input)
+}
+
+/// `literal(string)` generates a parser that takes the argument string.
+///
+/// This also shows returning a sub-slice of the original input
+fn null<'i, E: ParserError<Stream<'i>>>(input: &mut Stream<'i>) -> Result<&'i str, E> {
+    // This is a parser that returns `"null"` if it sees the string "null", and
+    // an error otherwise
+    "null".parse_next(input)
+}
+
+/// We can combine `tag` with other functions, like `value` which returns a given constant value on
+/// success.
+fn true_<'i, E: ParserError<Stream<'i>>>(input: &mut Stream<'i>) -> Result<bool, E> {
+    // This is a parser that returns `true` if it sees the string "true", and
+    // an error otherwise
+    "true".value(true).parse_next(input)
+}
+
+/// We can combine `tag` with other functions, like `value` which returns a given constant value on
+/// success.
+fn false_<'i, E: ParserError<Stream<'i>>>(input: &mut Stream<'i>) -> Result<bool, E> {
+    // This is a parser that returns `false` if it sees the string "false", and
+    // an error otherwise
+    "false".value(false).parse_next(input)
+}
+
+/// This parser gathers all `char`s up into a `String`with a parse to take the double quote
+/// character, before the string (using `preceded`) and after the string (using `terminated`).
+fn string<'i, E: ParserError<Stream<'i>> + AddContext<Stream<'i>, StrContext>>(
+    input: &mut Stream<'i>,
+) -> Result<String, E> {
+    preceded(
+        '\"',
+        terminated(
+            repeat(0.., character).fold(String::new, |mut string, c| {
+                string.push(c);
+                string
+            }),
+            '\"',
+        ),
+    )
+    // `context` lets you add a static string to errors to provide more information in the
+    // error chain (to indicate which parser had an error)
+    .context(StrContext::Expected("string".into()))
+    .parse_next(input)
+}
+
+/// You can mix the above declarative parsing with an imperative style to handle more unique cases,
+/// like escaping
+fn character<'i, E: ParserError<Stream<'i>>>(input: &mut Stream<'i>) -> Result<char, E> {
+    let c = none_of('\"').parse_next(input)?;
+    if c == '\\' {
+        dispatch!(any;
+          '"' => empty.value('"'),
+          '\\' => empty.value('\\'),
+          '/'  => empty.value('/'),
+          'b' => empty.value('\x08'),
+          'f' => empty.value('\x0C'),
+          'n' => empty.value('\n'),
+          'r' => empty.value('\r'),
+          't' => empty.value('\t'),
+          'u' => unicode_escape,
+          _ => fail,
+        )
+        .parse_next(input)
+    } else {
+        Ok(c)
+    }
+}
+
+fn unicode_escape<'i, E: ParserError<Stream<'i>>>(input: &mut Stream<'i>) -> Result<char, E> {
+    alt((
+        // Not a surrogate
+        u16_hex
+            .verify(|cp| !(0xD800..0xE000).contains(cp))
+            .map(|cp| cp as u32),
+        // See https://en.wikipedia.org/wiki/UTF-16#Code_points_from_U+010000_to_U+10FFFF for details
+        separated_pair(u16_hex, "\\u", u16_hex)
+            .verify(|(high, low)| (0xD800..0xDC00).contains(high) && (0xDC00..0xE000).contains(low))
+            .map(|(high, low)| {
+                let high_ten = (high as u32) - 0xD800;
+                let low_ten = (low as u32) - 0xDC00;
+                (high_ten << 10) + low_ten + 0x10000
+            }),
+    ))
+    .verify_map(
+        // Could be probably replaced with .unwrap() or _unchecked due to the verify checks
+        std::char::from_u32,
+    )
+    .parse_next(input)
+}
+
+fn u16_hex<'i, E: ParserError<Stream<'i>>>(input: &mut Stream<'i>) -> Result<u16, E> {
+    take(4usize)
+        .verify_map(|s| u16::from_str_radix(s, 16).ok())
+        .parse_next(input)
+}
+
+/// Some combinators, like `separated` or `repeat`, will call a parser repeatedly,
+/// accumulating results in a `Vec`, until it encounters an error.
+/// If you want more control on the parser application, check out the `iterator`
+/// combinator (cf `examples/iterator.rs`)
+fn array<'i, E: ParserError<Stream<'i>> + AddContext<Stream<'i>, StrContext>>(
+    input: &mut Stream<'i>,
+) -> Result<Vec<JsonValue>, E> {
+    preceded(
+        ('[', ws),
+        terminated(separated(0.., json_value, (ws, ',', ws)), (ws, ']')),
+    )
+    .context(StrContext::Expected("array".into()))
+    .parse_next(input)
+}
+
+fn object<'i, E: ParserError<Stream<'i>> + AddContext<Stream<'i>, StrContext>>(
+    input: &mut Stream<'i>,
+) -> Result<HashMap<String, JsonValue>, E> {
+    preceded(
+        ('{', ws),
+        terminated(separated(0.., key_value, (ws, ',', ws)), (ws, '}')),
+    )
+    .context(StrContext::Expected("object".into()))
+    .parse_next(input)
+}
+
+fn key_value<'i, E: ParserError<Stream<'i>> + AddContext<Stream<'i>, StrContext>>(
+    input: &mut Stream<'i>,
+) -> Result<(String, JsonValue), E> {
+    separated_pair(string, (ws, ':', ws), json_value).parse_next(input)
+}
+
+/// Parser combinators are constructed from the bottom up:
+/// first we write parsers for the smallest elements (here a space character),
+/// then we'll combine them in larger parsers
+fn ws<'i, E: ParserError<Stream<'i>>>(input: &mut Stream<'i>) -> Result<&'i str, E> {
+    // Combinators like `take_while` return a function. That function is the
+    // parser,to which we can pass the input
+    take_while(0.., WS).parse_next(input)
+}
+
+const WS: &[char] = &[' ', '\t', '\r', '\n'];
+
+#[cfg(test)]
+mod test {
+    #[allow(clippy::useless_attribute)]
+    #[allow(unused_imports)] // its dead for benches
+    use super::*;
+
+    #[allow(clippy::useless_attribute)]
+    #[allow(dead_code)] // its dead for benches
+    type Error = winnow::error::ContextError;
+
+    #[test]
+    fn json_string() {
+        assert_eq!(string::<Error>.parse_peek("\"\""), Ok(("", "".to_owned())));
+        assert_eq!(
+            string::<Error>.parse_peek("\"abc\""),
+            Ok(("", "abc".to_owned()))
+        );
+        assert_eq!(
+            string::<Error>
+                .parse_peek("\"abc\\\"\\\\\\/\\b\\f\\n\\r\\t\\u0001\\u2014\u{2014}def\""),
+            Ok(("", "abc\"\\/\x08\x0C\n\r\t\x01——def".to_owned())),
+        );
+        assert_eq!(
+            string::<Error>.parse_peek("\"\\uD83D\\uDE10\""),
+            Ok(("", "😐".to_owned()))
+        );
+
+        assert!(string::<Error>.parse_peek("\"").is_err());
+        assert!(string::<Error>.parse_peek("\"abc").is_err());
+        assert!(string::<Error>.parse_peek("\"\\\"").is_err());
+        assert!(string::<Error>.parse_peek("\"\\u123\"").is_err());
+        assert!(string::<Error>.parse_peek("\"\\uD800\"").is_err());
+        assert!(string::<Error>.parse_peek("\"\\uD800\\uD800\"").is_err());
+        assert!(string::<Error>.parse_peek("\"\\uDC00\"").is_err());
+    }
+
+    #[test]
+    fn json_object() {
+        use JsonValue::{Num, Object, Str};
+
+        let input = r#"{"a":42,"b":"x"}"#;
+
+        let expected = Object(
+            vec![
+                ("a".to_owned(), Num(42.0)),
+                ("b".to_owned(), Str("x".to_owned())),
+            ]
+            .into_iter()
+            .collect(),
+        );
+
+        assert_eq!(json::<Error>.parse_peek(input), Ok(("", expected)));
+    }
+
+    #[test]
+    fn json_array() {
+        use JsonValue::{Array, Num, Str};
+
+        let input = r#"[42,"x"]"#;
+
+        let expected = Array(vec![Num(42.0), Str("x".to_owned())]);
+
+        assert_eq!(json::<Error>.parse_peek(input), Ok(("", expected)));
+    }
+
+    #[test]
+    fn json_whitespace() {
+        use JsonValue::{Array, Boolean, Null, Num, Object, Str};
+
+        let input = r#"
+  {
+    "null" : null,
+    "true"  :true ,
+    "false":  false  ,
+    "number" : 123e4 ,
+    "string" : " abc 123 " ,
+    "array" : [ false , 1 , "two" ] ,
+    "object" : { "a" : 1.0 , "b" : "c" } ,
+    "empty_array" : [  ] ,
+    "empty_object" : {   }
+  }
+  "#;
+
+        assert_eq!(
+            json::<Error>.parse_peek(input),
+            Ok((
+                "",
+                Object(
+                    vec![
+                        ("null".to_owned(), Null),
+                        ("true".to_owned(), Boolean(true)),
+                        ("false".to_owned(), Boolean(false)),
+                        ("number".to_owned(), Num(123e4)),
+                        ("string".to_owned(), Str(" abc 123 ".to_owned())),
+                        (
+                            "array".to_owned(),
+                            Array(vec![Boolean(false), Num(1.0), Str("two".to_owned())])
+                        ),
+                        (
+                            "object".to_owned(),
+                            Object(
+                                vec![
+                                    ("a".to_owned(), Num(1.0)),
+                                    ("b".to_owned(), Str("c".to_owned())),
+                                ]
+                                .into_iter()
+                                .collect()
+                            )
+                        ),
+                        ("empty_array".to_owned(), Array(vec![]),),
+                        ("empty_object".to_owned(), Object(HashMap::new()),),
+                    ]
+                    .into_iter()
+                    .collect()
+                )
+            ))
+        );
+    }
+}

vendor/winnow/examples/json/parser_partial.rs

@@ -0,0 +1,350 @@
+use std::collections::HashMap;
+use std::str;
+
+use winnow::prelude::*;
+use winnow::{
+    ascii::float,
+    combinator::alt,
+    combinator::cut_err,
+    combinator::{delimited, preceded, separated_pair, terminated},
+    combinator::{repeat, separated},
+    error::{AddContext, ParserError, StrContext},
+    stream::Partial,
+    token::{any, none_of, rest, take, take_while},
+};
+
+use crate::json::JsonValue;
+
+pub(crate) type Stream<'i> = Partial<&'i str>;
+
+/// The root element of a JSON parser is any value
+///
+/// A parser has the following signature:
+/// `&mut Stream -> ModalResult<Output, ContextError>`, with `ModalResult` defined as:
+/// `type ModalResult<O, E = ErrorKind> = Result<O, ErrMode<E>>;`
+///
+/// most of the times you can ignore the error type and use the default (but this
+/// examples shows custom error types later on!)
+///
+/// Here we use `&str` as input type, but parsers can be generic over
+/// the input type, work directly with `&[u8]`, or any other type that
+/// implements the required traits.
+pub(crate) fn json<'i, E: ParserError<Stream<'i>> + AddContext<Stream<'i>, StrContext>>(
+    input: &mut Stream<'i>,
+) -> ModalResult<JsonValue, E> {
+    delimited(ws, json_value, ws_or_eof).parse_next(input)
+}
+
+/// `alt` is a combinator that tries multiple parsers one by one, until
+/// one of them succeeds
+fn json_value<'i, E: ParserError<Stream<'i>> + AddContext<Stream<'i>, StrContext>>(
+    input: &mut Stream<'i>,
+) -> ModalResult<JsonValue, E> {
+    // `alt` combines the each value parser. It returns the result of the first
+    // successful parser, or an error
+    alt((
+        null.value(JsonValue::Null),
+        boolean.map(JsonValue::Boolean),
+        string.map(JsonValue::Str),
+        float.map(JsonValue::Num),
+        array.map(JsonValue::Array),
+        object.map(JsonValue::Object),
+    ))
+    .parse_next(input)
+}
+
+/// `literal(string)` generates a parser that takes the argument string.
+///
+/// This also shows returning a sub-slice of the original input
+fn null<'i, E: ParserError<Stream<'i>>>(input: &mut Stream<'i>) -> ModalResult<&'i str, E> {
+    // This is a parser that returns `"null"` if it sees the string "null", and
+    // an error otherwise
+    "null".parse_next(input)
+}
+
+/// We can combine `tag` with other functions, like `value` which returns a given constant value on
+/// success.
+fn boolean<'i, E: ParserError<Stream<'i>>>(input: &mut Stream<'i>) -> ModalResult<bool, E> {
+    // This is a parser that returns `true` if it sees the string "true", and
+    // an error otherwise
+    let parse_true = "true".value(true);
+
+    // This is a parser that returns `false` if it sees the string "false", and
+    // an error otherwise
+    let parse_false = "false".value(false);
+
+    alt((parse_true, parse_false)).parse_next(input)
+}
+
+/// This parser gathers all `char`s up into a `String`with a parse to take the double quote
+/// character, before the string (using `preceded`) and after the string (using `terminated`).
+fn string<'i, E: ParserError<Stream<'i>> + AddContext<Stream<'i>, StrContext>>(
+    input: &mut Stream<'i>,
+) -> ModalResult<String, E> {
+    preceded(
+        '\"',
+        // `cut_err` transforms an `ErrMode::Backtrack(e)` to `ErrMode::Cut(e)`, signaling to
+        // combinators like  `alt` that they should not try other parsers. We were in the
+        // right branch (since we found the `"` character) but encountered an error when
+        // parsing the string
+        cut_err(terminated(
+            repeat(0.., character).fold(String::new, |mut string, c| {
+                string.push(c);
+                string
+            }),
+            '\"',
+        )),
+    )
+    // `context` lets you add a static string to errors to provide more information in the
+    // error chain (to indicate which parser had an error)
+    .context(StrContext::Expected("string".into()))
+    .parse_next(input)
+}
+
+/// You can mix the above declarative parsing with an imperative style to handle more unique cases,
+/// like escaping
+fn character<'i, E: ParserError<Stream<'i>>>(input: &mut Stream<'i>) -> ModalResult<char, E> {
+    let c = none_of('\"').parse_next(input)?;
+    if c == '\\' {
+        alt((
+            any.verify_map(|c| {
+                Some(match c {
+                    '"' | '\\' | '/' => c,
+                    'b' => '\x08',
+                    'f' => '\x0C',
+                    'n' => '\n',
+                    'r' => '\r',
+                    't' => '\t',
+                    _ => return None,
+                })
+            }),
+            preceded('u', unicode_escape),
+        ))
+        .parse_next(input)
+    } else {
+        Ok(c)
+    }
+}
+
+fn unicode_escape<'i, E: ParserError<Stream<'i>>>(input: &mut Stream<'i>) -> ModalResult<char, E> {
+    alt((
+        // Not a surrogate
+        u16_hex
+            .verify(|cp| !(0xD800..0xE000).contains(cp))
+            .map(|cp| cp as u32),
+        // See https://en.wikipedia.org/wiki/UTF-16#Code_points_from_U+010000_to_U+10FFFF for details
+        separated_pair(u16_hex, "\\u", u16_hex)
+            .verify(|(high, low)| (0xD800..0xDC00).contains(high) && (0xDC00..0xE000).contains(low))
+            .map(|(high, low)| {
+                let high_ten = (high as u32) - 0xD800;
+                let low_ten = (low as u32) - 0xDC00;
+                (high_ten << 10) + low_ten + 0x10000
+            }),
+    ))
+    .verify_map(
+        // Could be probably replaced with .unwrap() or _unchecked due to the verify checks
+        std::char::from_u32,
+    )
+    .parse_next(input)
+}
+
+fn u16_hex<'i, E: ParserError<Stream<'i>>>(input: &mut Stream<'i>) -> ModalResult<u16, E> {
+    take(4usize)
+        .verify_map(|s| u16::from_str_radix(s, 16).ok())
+        .parse_next(input)
+}
+
+/// Some combinators, like `separated` or `repeat`, will call a parser repeatedly,
+/// accumulating results in a `Vec`, until it encounters an error.
+/// If you want more control on the parser application, check out the `iterator`
+/// combinator (cf `examples/iterator.rs`)
+fn array<'i, E: ParserError<Stream<'i>> + AddContext<Stream<'i>, StrContext>>(
+    input: &mut Stream<'i>,
+) -> ModalResult<Vec<JsonValue>, E> {
+    preceded(
+        ('[', ws),
+        cut_err(terminated(
+            separated(0.., json_value, (ws, ',', ws)),
+            (ws, ']'),
+        )),
+    )
+    .context(StrContext::Expected("array".into()))
+    .parse_next(input)
+}
+
+fn object<'i, E: ParserError<Stream<'i>> + AddContext<Stream<'i>, StrContext>>(
+    input: &mut Stream<'i>,
+) -> ModalResult<HashMap<String, JsonValue>, E> {
+    preceded(
+        ('{', ws),
+        cut_err(terminated(
+            separated(0.., key_value, (ws, ',', ws)),
+            (ws, '}'),
+        )),
+    )
+    .context(StrContext::Expected("object".into()))
+    .parse_next(input)
+}
+
+fn key_value<'i, E: ParserError<Stream<'i>> + AddContext<Stream<'i>, StrContext>>(
+    input: &mut Stream<'i>,
+) -> ModalResult<(String, JsonValue), E> {
+    separated_pair(string, cut_err((ws, ':', ws)), json_value).parse_next(input)
+}
+
+/// Parser combinators are constructed from the bottom up:
+/// first we write parsers for the smallest elements (here a space character),
+/// then we'll combine them in larger parsers
+fn ws<'i, E: ParserError<Stream<'i>>>(input: &mut Stream<'i>) -> ModalResult<&'i str, E> {
+    // Combinators like `take_while` return a function. That function is the
+    // parser,to which we can pass the input
+    take_while(0.., WS).parse_next(input)
+}
+
+fn ws_or_eof<'i, E: ParserError<Stream<'i>>>(input: &mut Stream<'i>) -> ModalResult<&'i str, E> {
+    rest.verify(|s: &str| s.chars().all(|c| WS.contains(&c)))
+        .parse_next(input)
+}
+
+const WS: &[char] = &[' ', '\t', '\r', '\n'];
+
+#[cfg(test)]
+mod test {
+    #[allow(clippy::useless_attribute)]
+    #[allow(unused_imports)] // its dead for benches
+    use super::*;
+
+    #[allow(clippy::useless_attribute)]
+    #[allow(dead_code)] // its dead for benches
+    type Error = winnow::error::ContextError;
+
+    #[test]
+    fn json_string() {
+        assert_eq!(
+            string::<Error>.parse_peek(Partial::new("\"\"")),
+            Ok((Partial::new(""), "".to_owned()))
+        );
+        assert_eq!(
+            string::<Error>.parse_peek(Partial::new("\"abc\"")),
+            Ok((Partial::new(""), "abc".to_owned()))
+        );
+        assert_eq!(
+            string::<Error>.parse_peek(Partial::new(
+                "\"abc\\\"\\\\\\/\\b\\f\\n\\r\\t\\u0001\\u2014\u{2014}def\""
+            )),
+            Ok((
+                Partial::new(""),
+                "abc\"\\/\x08\x0C\n\r\t\x01——def".to_owned()
+            )),
+        );
+        assert_eq!(
+            string::<Error>.parse_peek(Partial::new("\"\\uD83D\\uDE10\"")),
+            Ok((Partial::new(""), "😐".to_owned()))
+        );
+
+        assert!(string::<Error>.parse_peek(Partial::new("\"")).is_err());
+        assert!(string::<Error>.parse_peek(Partial::new("\"abc")).is_err());
+        assert!(string::<Error>.parse_peek(Partial::new("\"\\\"")).is_err());
+        assert!(string::<Error>
+            .parse_peek(Partial::new("\"\\u123\""))
+            .is_err());
+        assert!(string::<Error>
+            .parse_peek(Partial::new("\"\\uD800\""))
+            .is_err());
+        assert!(string::<Error>
+            .parse_peek(Partial::new("\"\\uD800\\uD800\""))
+            .is_err());
+        assert!(string::<Error>
+            .parse_peek(Partial::new("\"\\uDC00\""))
+            .is_err());
+    }
+
+    #[test]
+    fn json_object() {
+        use JsonValue::{Num, Object, Str};
+
+        let input = r#"{"a":42,"b":"x"}"#;
+
+        let expected = Object(
+            vec![
+                ("a".to_owned(), Num(42.0)),
+                ("b".to_owned(), Str("x".to_owned())),
+            ]
+            .into_iter()
+            .collect(),
+        );
+
+        assert_eq!(
+            json::<Error>.parse_peek(Partial::new(input)),
+            Ok((Partial::new(""), expected))
+        );
+    }
+
+    #[test]
+    fn json_array() {
+        use JsonValue::{Array, Num, Str};
+
+        let input = r#"[42,"x"]"#;
+
+        let expected = Array(vec![Num(42.0), Str("x".to_owned())]);
+
+        assert_eq!(
+            json::<Error>.parse_peek(Partial::new(input)),
+            Ok((Partial::new(""), expected))
+        );
+    }
+
+    #[test]
+    fn json_whitespace() {
+        use JsonValue::{Array, Boolean, Null, Num, Object, Str};
+
+        let input = r#"
+  {
+    "null" : null,
+    "true"  :true ,
+    "false":  false  ,
+    "number" : 123e4 ,
+    "string" : " abc 123 " ,
+    "array" : [ false , 1 , "two" ] ,
+    "object" : { "a" : 1.0 , "b" : "c" } ,
+    "empty_array" : [  ] ,
+    "empty_object" : {   }
+  }
+  "#;
+
+        assert_eq!(
+            json::<Error>.parse_peek(Partial::new(input)),
+            Ok((
+                Partial::new(""),
+                Object(
+                    vec![
+                        ("null".to_owned(), Null),
+                        ("true".to_owned(), Boolean(true)),
+                        ("false".to_owned(), Boolean(false)),
+                        ("number".to_owned(), Num(123e4)),
+                        ("string".to_owned(), Str(" abc 123 ".to_owned())),
+                        (
+                            "array".to_owned(),
+                            Array(vec![Boolean(false), Num(1.0), Str("two".to_owned())])
+                        ),
+                        (
+                            "object".to_owned(),
+                            Object(
+                                vec![
+                                    ("a".to_owned(), Num(1.0)),
+                                    ("b".to_owned(), Str("c".to_owned())),
+                                ]
+                                .into_iter()
+                                .collect()
+                            )
+                        ),
+                        ("empty_array".to_owned(), Array(vec![]),),
+                        ("empty_object".to_owned(), Object(HashMap::new()),),
+                    ]
+                    .into_iter()
+                    .collect()
+                )
+            ))
+        );
+    }
+}