[lexer] Add Quote token

lexer/src/chars.rs

@@ -10,6 +10,7 @@ pub trait Lexable {
     fn is_identifier_initial(&self) -> bool;
     fn is_identifier_subsequent(&self) -> bool;
     fn is_left_paren(&self) -> bool;
+    fn is_quote(&self) -> bool;
     fn is_radix(&self) -> bool;
     fn is_right_paren(&self) -> bool;
 }
@@ -43,6 +44,10 @@ impl Lexable for char {
         self.is_whitespace() || self.is_left_paren() || self.is_right_paren()
     }
 
+    fn is_quote(&self) -> bool {
+        *self == '\''
+    }
+
     fn is_radix(&self) -> bool {
         let radishes = &['b', 'd', 'o', 'x'];
         radishes.contains(self)

lexer/src/states/begin.rs

@@ -36,6 +36,8 @@ impl State for Begin {
             StateResult::advance(Box::new(Hash::new()))
         } else if let Some(st) = Digit::with_char(&Builder::new(), c) {
             StateResult::advance(Box::new(st))
+        } else if c.is_quote() {
+            StateResult::Emit(Token::Quote, Resume::AtNext)
         } else {
             StateResult::fail(Error::invalid_char(c))
         }

lexer/src/token.rs

@@ -14,10 +14,11 @@ pub struct Lex {
 pub enum Token {
     Bool(bool),
     Dot,
-    Num(i64),
+    Id,
     LeftParen,
+    Num(i64),
+    Quote,
     RightParen,
-    Id
 }
 
 impl Lex {

lexer/tests/single_tokens.rs

@@ -95,3 +95,10 @@ fn dot() {
     assert_eq!(lex.next(), Some(Ok(Lex::new(Token::Dot, ".", 0, 0))));
     assert_eq!(lex.next(), None);
 }
+
+#[test]
+fn quote() {
+    let mut lex = Lexer::new("'".chars());
+    assert_eq!(lex.next(), Some(Ok(Lex::new(Token::Quote, "'", 0, 0))));
+    assert_eq!(lex.next(), None);
+}