From 58b937521f3e459089c0d475551bf9a49f930657 Mon Sep 17 00:00:00 2001
From: Tolmachev Igor <me@igorek.dev>
Date: Fri, 8 May 2026 15:25:55 +0300
Subject: Fold unclosed string error into Token variant

UnclosedString was the only error variant, making lexer::Error redundant. Also removes Result from
the Iterator impl.
---
 compiler/src/lexer/mod.rs | 31 ++++++++++++++++++-------------
 1 file changed, 18 insertions(+), 13 deletions(-)

(limited to 'compiler/src/lexer/mod.rs')

diff --git a/compiler/src/lexer/mod.rs b/compiler/src/lexer/mod.rs
index 2ef4922..ff7d51d 100644
--- a/compiler/src/lexer/mod.rs
+++ b/compiler/src/lexer/mod.rs
@@ -1,7 +1,4 @@
-mod error;
-
 use crate::span::{Pos, Span};
-pub use error::{Error, Result};
 
 #[cfg(test)]
 mod tests;
@@ -17,6 +14,7 @@ pub enum Token<'a> {
     Quote,
     Number(&'a str),
     String(&'a str),
+    UnclosedString(&'a str),
     Symbol(&'a str),
 }
 
@@ -82,7 +80,7 @@ impl<'a> Lexer<'a> {
         self.next_while(|ch| !is_terminator(ch))
     }
 
-    fn next_string(&mut self) -> Result<&'a str> {
+    fn next_string(&mut self) -> Result<&'a str, &'a str> {
         debug_assert_eq!(self.peek(), Some('"'));
         self.consume();
 
@@ -95,7 +93,11 @@ impl<'a> Lexer<'a> {
                     self.consume();
                     return Ok(string);
                 }
-                '\n' => return Err(Error::UnclosedString),
+                '\n' => {
+                    let string = &self.input[start..self.cursor];
+                    self.consume();
+                    return Err(string);
+                }
                 '\\' => {
                     self.consume();
                     self.consume();
@@ -106,12 +108,12 @@ impl<'a> Lexer<'a> {
             }
         }
 
-        Err(Error::UnclosedString)
+        Err(&self.input[start..self.cursor])
     }
 }
 
 impl<'a> Iterator for Lexer<'a> {
-    type Item = Span<Result<Token<'a>>>;
+    type Item = Span<Token<'a>>;
 
     fn next(&mut self) -> Option<Self::Item> {
         loop {
@@ -131,15 +133,15 @@ impl<'a> Iterator for Lexer<'a> {
         let token = match self.peek()? {
             '(' => {
                 self.consume();
-                Ok(Token::LeftPar)
+                Token::LeftPar
             }
             ')' => {
                 self.consume();
-                Ok(Token::RightPar)
+                Token::RightPar
             }
             '\'' => {
                 self.consume();
-                Ok(Token::Quote)
+                Token::Quote
             }
 
             // Number
@@ -147,14 +149,17 @@ impl<'a> Iterator for Lexer<'a> {
                 || matches!(ch, '+' | '-' | '.')
                     && self.peek_nth(1).is_some_and(|ch| ch.is_ascii_digit()) =>
             {
-                Ok(Token::Number(self.next_atom()))
+                Token::Number(self.next_atom())
             }
 
             // String
-            '"' => self.next_string().map(Token::String),
+            '"' => match self.next_string() {
+                Ok(string) => Token::String(string),
+                Err(string) => Token::UnclosedString(string),
+            },
 
             // Symbol
-            _ => Ok(Token::Symbol(self.next_atom())),
+            _ => Token::Symbol(self.next_atom()),
         };
 
         let end = Pos::new(self.line, self.column, self.cursor);
-- 
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