1 files changed, 112 insertions, 0 deletions
diff --git a/src/parser/key.rs b/src/parser/key.rs
new file mode 100644
index 0000000..12715da
--- /dev/null
+++ b/src/parser/key.rs
@@ -0,0 +1,112 @@
+use std::ops::RangeInclusive;
+
+use winnow::combinator::peek;
+use winnow::combinator::separated1;
+use winnow::token::any;
+use winnow::token::take_while;
+use winnow::trace::trace;
+
+use crate::key::Key;
+use crate::parser::errors::CustomError;
+use crate::parser::prelude::*;
+use crate::parser::strings::{basic_string, literal_string};
+use crate::parser::trivia::{from_utf8_unchecked, ws};
+use crate::repr::{Decor, Repr};
+use crate::InternalString;
+use crate::RawString;
+
+// key = simple-key / dotted-key
+// dotted-key = simple-key 1*( dot-sep simple-key )
+pub(crate) fn key(input: &mut Input<'_>) -> PResult<Vec<Key>> {
+    trace(
+        "dotted-key",
+        separated1(
+            (ws.span(), simple_key, ws.span()).map(|(pre, (raw, key), suffix)| {
+                Key::new(key)
+                    .with_repr_unchecked(Repr::new_unchecked(raw))
+                    .with_decor(Decor::new(
+                        RawString::with_span(pre),
+                        RawString::with_span(suffix),
+                    ))
+            }),
+            DOT_SEP,
+        )
+        .context(StrContext::Label("key"))
+        .try_map(|k: Vec<_>| {
+            // Inserting the key will require recursion down the line
+            RecursionCheck::check_depth(k.len())?;
+            Ok::<_, CustomError>(k)
+        }),
+    )
+    .parse_next(input)
+}
+
+// simple-key = quoted-key / unquoted-key
+// quoted-key = basic-string / literal-string
+pub(crate) fn simple_key(input: &mut Input<'_>) -> PResult<(RawString, InternalString)> {
+    trace(
+        "simple-key",
+        dispatch! {peek(any);
+            crate::parser::strings::QUOTATION_MARK => basic_string
+                .map(|s: std::borrow::Cow<'_, str>| s.as_ref().into()),
+            crate::parser::strings::APOSTROPHE => literal_string.map(|s: &str| s.into()),
+            _ => unquoted_key.map(|s: &str| s.into()),
+        }
+        .with_span()
+        .map(|(k, span)| {
+            let raw = RawString::with_span(span);
+            (raw, k)
+        }),
+    )
+    .parse_next(input)
+}
+
+// unquoted-key = 1*( ALPHA / DIGIT / %x2D / %x5F ) ; A-Z / a-z / 0-9 / - / _
+fn unquoted_key<'i>(input: &mut Input<'i>) -> PResult<&'i str> {
+    trace(
+        "unquoted-key",
+        take_while(1.., UNQUOTED_CHAR)
+            .map(|b| unsafe { from_utf8_unchecked(b, "`is_unquoted_char` filters out on-ASCII") }),
+    )
+    .parse_next(input)
+}
+
+pub(crate) fn is_unquoted_char(c: u8) -> bool {
+    use winnow::stream::ContainsToken;
+    UNQUOTED_CHAR.contains_token(c)
+}
+
+const UNQUOTED_CHAR: (
+    RangeInclusive<u8>,
+    RangeInclusive<u8>,
+    RangeInclusive<u8>,
+    u8,
+    u8,
+) = (b'A'..=b'Z', b'a'..=b'z', b'0'..=b'9', b'-', b'_');
+
+// dot-sep   = ws %x2E ws  ; . Period
+const DOT_SEP: u8 = b'.';
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn keys() {
+        let cases = [
+            ("a", "a"),
+            (r#""hello\n ""#, "hello\n "),
+            (r#"'hello\n '"#, "hello\\n "),
+        ];
+
+        for (input, expected) in cases {
+            dbg!(input);
+            let parsed = simple_key.parse(new_input(input));
+            assert_eq!(
+                parsed,
+                Ok((RawString::with_span(0..(input.len())), expected.into())),
+                "Parsing {input:?}"
+            );
+        }
+    }
+}