chore: checkpoint before Python removal

vendor/nom/tests/reborrow_fold.rs

@@ -0,0 +1,33 @@
+#![allow(dead_code)]
+// #![allow(unused_variables)]
+
+use std::str;
+
+use nom::bytes::complete::is_not;
+use nom::character::complete::char;
+use nom::combinator::{map, map_res};
+use nom::multi::fold;
+use nom::sequence::delimited;
+use nom::{IResult, Parser};
+
+fn atom(_tomb: &mut ()) -> impl for<'a> FnMut(&'a [u8]) -> IResult<&'a [u8], String> {
+  move |input| {
+    map(
+      map_res(is_not(" \t\r\n"), str::from_utf8),
+      ToString::to_string,
+    )
+    .parse(input)
+  }
+}
+
+// FIXME: should we support the use case of borrowing data mutably in a parser?
+fn list<'a>(i: &'a [u8], tomb: &mut ()) -> IResult<&'a [u8], String> {
+  delimited(
+    char('('),
+    fold(0.., atom(tomb), String::new, |acc: String, next: String| {
+      acc + next.as_str()
+    }),
+    char(')'),
+  )
+  .parse(i)
+}