Support escaping backslash in sexp.

src/parser/sexp.rs

@@ -175,7 +175,7 @@ fn quoted_atom<'s>(input: &'s str) -> Res<&'s str, Token<'s>> {
             _ => false,
         }),
         '\\',
-        one_of(r#""n"#),
+        one_of(r#""n\\"#),
     )(remaining)?;
     let (remaining, _) = tag(r#"""#)(remaining)?;
     let source = get_consumed(input, remaining);
@@ -298,4 +298,27 @@ mod tests {
             r#"baz"#
         );
     }
+
+    #[test]
+    fn string_containing_escaped_characters() {
+        let input = r#"  (foo "\\( x=2 \\)" bar)  "#;
+        let (remaining, parsed) = sexp_with_padding(input).expect("Parse the input");
+        assert_eq!(remaining, "");
+        assert!(match parsed {
+            Token::Atom(_) => false,
+            Token::List(_) => true,
+            Token::TextWithProperties(_) => false,
+        });
+        let children = match parsed {
+            Token::List(children) => children,
+            _ => panic!("Should be a list."),
+        };
+        assert_eq!(
+            match children.get(1) {
+                Some(Token::Atom(body)) => *body,
+                _ => panic!("First child should be an atom."),
+            },
+            r#""\\( x=2 \\)""#
+        )
+    }
 }