Bunch of improvements

src/parse/string.rs

@@ -0,0 +1,42 @@
+use chumsky::{self, prelude::*, Parser};
+
+fn text_parser(delim: char) -> impl Parser<char, char, Error = Simple<char>> {
+    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
+                            })
+                    }),
+            )),
+    );
+    filter(move |&c| c != '\\' && c != delim).or(escape)
+}
+
+pub fn char_parser() -> impl Parser<char, char, Error = Simple<char>> {
+    just('\'').ignore_then(text_parser('\'')).then_ignore(just('\''))
+}
+
+pub fn str_parser() -> impl Parser<char, String, Error = Simple<char>> {
+    just('"')
+    .ignore_then(
+        text_parser('"').map(Some)
+        .or(just("\\\n").map(|_| None))
+        .repeated()
+    ).then_ignore(just('"'))
+    .flatten().collect()
+}