Reconnaissance des tokens de deux caractères

src/rlox/scanner.rs

@@ -12,7 +12,7 @@ struct Scanner {
 
 impl Scanner {
     fn scan_tokens(&mut self) {
-        while (!self.is_at_end()) {
+        while !self.is_at_end() {
             self.start = self.current;
             self.scan_token();
         }
@@ -38,7 +38,11 @@ impl Scanner {
             '+' => self.add_simple_token( TokenType::Plus ),
             ';' => self.add_simple_token( TokenType::Semicolon ),
             '*' => self.add_simple_token( TokenType::Star ),
-            _ => ()
+            '!' => { if self.matchnext('=') { self.add_simple_token( TokenType::BangEqual ) } else { self.add_simple_token( TokenType::Bang ) } },
+            '=' => { if self.matchnext('=') { self.add_simple_token( TokenType::EqualEqual ) } else { self.add_simple_token( TokenType::Equal ) } },
+            '<' => { if self.matchnext('=') { self.add_simple_token( TokenType::LessEqual ) } else { self.add_simple_token( TokenType::Less ) } },
+            '>' => { if self.matchnext('=') { self.add_simple_token( TokenType::GreaterEqual ) } else { self.add_simple_token( TokenType::Greater ) } },
+            _ => (), // report error
         }
     }
 
@@ -47,6 +51,14 @@ impl Scanner {
         self.source[self.current]
     }
 
+    fn matchnext(&mut self, expected: char) -> bool {
+        if self.is_at_end() { return false; }
+        if self.source[self.current]!=expected { return false; }
+
+        self.current += 1;
+        true
+    }
+
     fn add_simple_token(&mut self, t: TokenType) {
         self.add_token(t, String::from(""));
     }