From 3fc691acf28ceb2eeb5c2a63d9b16159fe6dbeb2 Mon Sep 17 00:00:00 2001
From: Michael Sippel <micha@fragmental.art>
Date: Mon, 2 Oct 2023 02:01:15 +0200
Subject: [PATCH] lexer: allow escaped characters in char-token

---
 src/lexer.rs      | 20 ++++++++++++++++++--
 src/test/lexer.rs |  6 ++++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/src/lexer.rs b/src/lexer.rs
index d03b2f5..4644ae6 100644
--- a/src/lexer.rs
+++ b/src/lexer.rs
@@ -90,8 +90,24 @@ where It: Iterator<Item = char>
                 }
 
                 LexerState::Char(val) => {
-                    // todo escape characters
-                    *val = self.chars.next();
+                    *val = Some(
+                        match self.chars.next() {
+                            Some('\\') => {
+                                match self.chars.next() {
+                                    Some('0') => '\0',
+                                    Some('n') => '\n',
+                                    Some('t') => '\t',
+                                    Some(c) => c,
+                                    None => {
+                                        return Some(Err(LexError::InvalidChar));
+                                    }
+                                }
+                            }
+                            Some(c) => c,
+                            None => {
+                                return Some(Err(LexError::InvalidChar));
+                            }
+                        });
 
                     match self.chars.next() {
                         Some('\'') => {
diff --git a/src/test/lexer.rs b/src/test/lexer.rs
index 7cba4db..a7ce90b 100644
--- a/src/test/lexer.rs
+++ b/src/test/lexer.rs
@@ -30,6 +30,12 @@ fn test_lexer_char() {
 
     assert_eq!( lex.next(), Some(Ok(LadderTypeToken::Char('x'))) );
     assert_eq!( lex.next(), None );
+
+    assert_eq!( LadderTypeLexer::from("'\\0'".chars()).next(), Some(Ok(LadderTypeToken::Char('\0'))) );
+    assert_eq!( LadderTypeLexer::from("'\\n'".chars()).next(), Some(Ok(LadderTypeToken::Char('\n'))) );
+    assert_eq!( LadderTypeLexer::from("'\\t'".chars()).next(), Some(Ok(LadderTypeToken::Char('\t'))) );
+    assert_eq!( LadderTypeLexer::from("'\\\''".chars()).next(), Some(Ok(LadderTypeToken::Char('\''))) );
+    assert_eq!( LadderTypeLexer::from("'\\\\'".chars()).next(), Some(Ok(LadderTypeToken::Char('\\'))) );
 }
 
 #[test]