[lexer] move char::is_hash() to chars::Lexable

lexer/src/chars.rs

@@ -11,6 +11,7 @@ pub trait Lexable {
 
     fn is_exactness(&self) -> bool;
     fn is_radix(&self) -> bool;
+    fn is_hash(&self) -> bool;
 }
 
 impl Lexable for char {
@@ -42,6 +43,10 @@ impl Lexable for char {
         let radishes = &['b', 'd', 'o', 'x'];
         radishes.contains(self)
     }
+
+    fn is_hash(&self) -> bool {
+        *self == '#'
+    }
 }
 
 trait LexableSpecial {

lexer/src/states/begin.rs

@@ -29,11 +29,3 @@ impl State for Begin {
         Ok(None)
     }
 }
-
-trait BeginLexable {
-    fn is_hash(&self) -> bool;
-}
-
-impl BeginLexable for char {
-    fn is_hash(&self) -> bool { *self == '#' }
-}