From 992141878227439cd517d05b68f15e57d77452a5 Mon Sep 17 00:00:00 2001
From: Akshay <nerdy@peppe.rs>
Date: Mon, 29 Mar 2021 10:24:49 +0530
Subject: fix: handle unterminated strings gracefully

---
 src/app.rs        | 13 +++++++++++--
 src/lisp/error.rs |  4 ++--
 src/lisp/lex.rs   |  8 +++++++-
 3 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/src/app.rs b/src/app.rs
index 016349b..eef896d 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -4,7 +4,7 @@ use crate::{
     command::CommandBox,
     consts::{colors::*, FONT_PATH},
     dither,
-    lisp::{eval, lex::Lexer, parse::Parser, prelude, EnvList},
+    lisp::{error::LispError, eval, lex::Lexer, parse::Parser, prelude, EnvList},
     message::Message,
     rect,
     symmetry::Symmetry,
@@ -284,7 +284,7 @@ impl<'ctx, 'file> AppState<'ctx, 'file> {
                 Ok(val) => self.message.set_info(format!("{}", val)),
                 Err(eval_err) => self.message.set_error(format!("{}", eval_err)),
             },
-            Err(parse_err) => self.message.set_error(format!("{}", parse_err)),
+            Err(err) => self.message = AppState::handle_error(err, &lisp_expr),
         }
         self.command_box.hist_append();
 
@@ -292,6 +292,15 @@ impl<'ctx, 'file> AppState<'ctx, 'file> {
         self.mode = Mode::Draw;
     }
 
+    fn handle_error(err: LispError, src: &str) -> Message {
+        let mut message = Message::new();
+        match err {
+            LispError::Parse(p) => message.set_error(p.display(&src)),
+            eval_err => message.set_error(eval_err.to_string()),
+        }
+        message
+    }
+
     fn draw_grid(&mut self) {
         let cs = self.zoom as u32;
         let (width, height) = (self.width(), self.height());
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 {
-- 
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