Properly lex ?, |, \f, and =

src/common.rs

@@ -62,6 +62,10 @@ pub enum Symbol {
     DoubleQuote,
     /// '
     SingleQuote,
+    /// ?
+    QuestionMark,
+    /// \
+    BackSlash,
 }
 
 impl Display for Symbol {
@@ -94,6 +98,8 @@ impl Display for Symbol {
             Self::Percent => write!(f, "%"),
             Self::DoubleQuote => write!(f, "\""),
             Self::SingleQuote => write!(f, "'"),
+            Self::QuestionMark => write!(f, "?"),
+            Self::BackSlash => write!(f, "\\"),
         }
     }
 }
@@ -130,6 +136,8 @@ impl TryFrom<char> for Symbol {
             '%' => Ok(Self::Percent),
             '"' => Ok(Self::DoubleQuote),
             '\'' => Ok(Self::SingleQuote),
+            '?' => Ok(Self::QuestionMark),
+            '\\' => Ok(Self::BackSlash),
             _ => Err("invalid symbol"),
         }
     }

src/lexer.rs

@@ -43,12 +43,15 @@ impl<'a> Iterator for Lexer<'a> {
             '(' => symbol!(self, OpenParen),
             ')' => symbol!(self, CloseParen),
             '+' => symbol!(self, Plus),
+            '=' => symbol!(self, Equal),
+            '?' => symbol!(self, QuestionMark),
+            '\\' => symbol!(self, BackSlash),
             '~' => symbol!(self, Tilde),
             '\'' => symbol!(self, SingleQuote),
             '"' => symbol!(self, DoubleQuote),
             ' ' => whitespace!(self, Space),
             '\t' => whitespace!(self, Tab),
-            '\n' => {
+            '\n' | '\x0C' => {
                 self.buf.next();
                 self.pos.newline();
                 TokenKind::Whitespace(Whitespace::Newline)
@@ -62,6 +65,7 @@ impl<'a> Iterator for Lexer<'a> {
             '*' => symbol!(self, Mul),
             '}' => symbol!(self, CloseCurlyBrace),
             '&' => symbol!(self, BitAnd),
+            '|' => symbol!(self, BitOr),
             '/' => self.lex_forward_slash(),
             '%' => {
                 self.buf.next();