fix: handle unterminated strings gracefully

2 files changed, 9 insertions, 3 deletions

diff --git a/src/lisp/error.rs b/src/lisp/error.rs
index a360eb2..6d28c22 100644
--- a/src/lisp/error.rs
+++ b/src/lisp/error.rs
@@ -30,9 +30,9 @@ impl ParseError {
     pub fn new(span: Span, kind: ParseErrorKind) -> Self {
         Self { span, kind }
     }
-    pub fn fmt(&self, f: &mut fmt::Formatter<'_>, text: &str) -> fmt::Result {
+    pub fn display(&self, text: &str) -> String {
         let SpanDisplay { line, col, .. } = SpanDisplay::highlight_span(self.span, text);
-        write!(f, "line {}, col {}: {}", line, col, self.kind)
+        format!("line {}, col {}: {}", line, col, self.kind)
     }
 }
 
diff --git a/src/lisp/lex.rs b/src/lisp/lex.rs
index 1a34e53..e514d7f 100644
--- a/src/lisp/lex.rs
+++ b/src/lisp/lex.rs
@@ -210,6 +210,7 @@ fn parse_number<'a>(mut input: &'a str) -> Result<(usize, Token<'a>), ParseError
 fn parse_string<'a>(input: &'a str) -> Result<(usize, Token<'a>), ParseErrorKind> {
     // count opening quote
     let mut size = 1;
+    let mut closed = false;
     let mut chars = input.char_indices().skip(1);
     while let Some((ind, chr)) = chars.next() {
         match chr {
@@ -218,12 +219,17 @@ fn parse_string<'a>(input: &'a str) -> Result<(usize, Token<'a>), ParseErrorKind
             }
             '"' => {
                 size += ind;
+                closed = true;
                 break;
             }
             _ => (),
         }
     }
-    return Ok((size, Token::String(&input[..size])));
+    if !closed {
+        Err(ParseErrorKind::UnterminatedString)
+    } else {
+        Ok((size, Token::String(&input[..size])))
+    }
 }
 
 fn is_ident(ch: char) -> bool {