Give keywords their own token types

src/lexer.rs

     static ref WHITESPACE_REGEX: Regex = Regex::new(r"\s").unwrap();
     static ref MATCHERS: Vec<Matcher> = vec![
         Matcher::new(r#""(.*)""#, TokenType::String),
-        Matcher::new(r#"(SELECT|FROM)"#, TokenType::Keyword),
+        Matcher::new(r#"SELECT"#, TokenType::Select),
+        Matcher::new(r#"FROM"#, TokenType::From),
         Matcher::new(r#"[a-z][a-zA-Z_\-]*"#, TokenType::Identfiier),
         Matcher::new(r#"[0-9]+"#, TokenType::Number),
         Matcher::new(r#"\*"#, TokenType::Star),
     fn it_scans_a_keyword() {
         assert_eq!(
             scan("SELECT").unwrap(),
-            vec![Token::new(TokenType::Keyword, "SELECT")]
+            vec![Token::new(TokenType::Select, "SELECT")]
         )
     }
 
         assert_eq!(
             scan("SELECT FROM").unwrap(),
             vec![
-                Token::new(TokenType::Keyword, "SELECT"),
-                Token::new(TokenType::Keyword, "FROM")
+                Token::new(TokenType::Select, "SELECT"),
+                Token::new(TokenType::From, "FROM")
             ]
         )
     }

src/token.rs

 
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub enum TokenType {
+    From,
     Identfiier,
-    Keyword,
     Number,
+    Select,
     Star,
     String,
 }
             "{}",
             match self {
                 TokenType::Identfiier => "Identifier",
-                TokenType::Keyword => "Keyword",
                 TokenType::Number => "Number",
                 TokenType::Star => "Star",
                 TokenType::String => "String",
+
+                TokenType::Select => "SELECT",
+                TokenType::From => "FROM",
             }
         )
     }