Add lexing of '?'

Signed-off-by: Marcel Müller <neikos@neikos.email>

src/lexer/mod.rs

@@ -238,6 +238,7 @@ pub enum TokenOperator {
     GreaterOrEqual,
     Lesser,
     LesserOrEqual,
+    QuestionMark,
 }
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
@@ -567,6 +568,7 @@ fn parse_operator<'input>(input: &mut Input<'input>) -> PResult<'input, Template
                 "=".value(TokenOperator::Equal),
                 cut_err(fail),
             )),
+            '?' => empty.value(TokenOperator::QuestionMark),
             _ => fail,
         },
     )
@@ -604,6 +606,7 @@ fn ident_terminator_check<'input>(input: &mut Input<'input>) -> PResult<'input,
 fn ident_terminator<'input>(input: &mut Input<'input>) -> PResult<'input, ()> {
     alt((
         eof.void(),
+        parse_operator.void(),
         one_of(('{', '}')).void(),
         one_of(('(', ',', ')')).void(),
         one_of((' ', '\t', '\r', '\n')).void(),
@@ -905,4 +908,26 @@ mod tests {
         )
         "#);
     }
+
+    #[test]
+    fn parse_question_mark() {
+        let input = "{{= foo? }}";
+        let output = parse(input.into());
+
+        insta::assert_debug_snapshot!(output, @r#"
+        Ok(
+            ParsedTemplate {
+                tokens: [
+                    [LeftDelim]"{{" (0..2),
+                    [WantsOutput]"=" (2..3),
+                    [Whitespace]" " (3..4),
+                    [Ident]"foo" (4..7),
+                    [Operator(QuestionMark)]"?" (7..8),
+                    [Whitespace]" " (8..9),
+                    [RightDelim]"}}" (9..11),
+                ],
+            },
+        )
+        "#);
+    }
 }

src/parser/mod.rs

@@ -7,6 +7,7 @@ use winnow::combinator::cut_err;
 use winnow::combinator::delimited;
 use winnow::combinator::dispatch;
 use winnow::combinator::expression;
+use winnow::combinator::fail;
 use winnow::combinator::not;
 use winnow::combinator::opt;
 use winnow::combinator::peek;
@@ -685,8 +686,9 @@ fn parse_expression<'input>(
                         op: TokenOperator::$val,
                         lhs: Box::new(lhs),
                         rhs: Box::new(rhs)
-                    }))
-                ),*
+                    })),
+                )*
+                _ => fail
             }
         };
     }
@@ -737,6 +739,7 @@ mod tests {
     use winnow::combinator::fail;
     use winnow::stream::TokenSlice;
 
+    use crate::lexer::TokenKind;
     use crate::parser::AstError;
     use crate::parser::AstFailure;
     use crate::parser::TemplateAst;
@@ -744,7 +747,6 @@ mod tests {
     use crate::parser::parse;
     use crate::parser::parse_block;
     use crate::parser::parse_end;
-    use crate::lexer::TokenKind;
 
     fn panic_pretty<'a>(
         input: &'_ str,