Fix parser for index and call exprs, remove old test that didn't work, add visitor pattern

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

src/syn/parser.y

@@ -19,6 +19,7 @@ Body -> Result<Vec<Stmt>>:
 
 Stmt -> Result<Stmt>:
         Expr { Ok(Stmt::Expr($1?)) }
+    //|   Assign { todo!() }
     ;
 
 Expr -> Result<Expr>: BinExpr { $1 };
@@ -42,31 +43,24 @@ BinExpr -> Result<Expr>:
 UnExpr -> Result<Expr>:
         '+' UnExpr { Ok(UnExpr::new_expr(UnOp::Plus, $2?)) }
     |   '-' UnExpr { Ok(UnExpr::new_expr(UnOp::Minus, $2?)) }
+    |   CallIndexExpr { $1 }
+    ;
+
+// TODO - add CallExpr and IndexExpr, allow them to nest
+//      - UnExpr will point to CallIndexExpr
+//      - Call/Index exprs are based on an AccessExpr
+//      - AccessExpr will retain ExprTrailing in between its items, but should end in a .ident
+
+CallIndexExpr -> Result<Expr>:
+        IndexExpr { $1 }
+    |   CallExpr { $1 }
     |   AccessExpr { $1 }
     ;
 
-AccessExpr -> Result<Expr>:
-        AtomExpr AccessExprTail {
-            Ok(AccessExpr::new_expr($1?, $2?))
+CallExpr -> Result<Expr>:
+        CallIndexExpr '(' FunArgs ')' {
+            Ok(CallExpr::new_expr($1?, $3?))
         }
-    |   AtomExpr {
-            Ok(AccessExpr::new_expr($1?, Default::default()))
-        }
-    ;
-
-AccessExprTail -> Result<Vec<Access>>: 
-        AccessExprTail '.' Ident ExprTrailing {
-            flatten($1, Ok(Access { access: $3?, trailing: $4? }))
-        }
-    |   '.' Ident ExprTrailing {
-            Ok(vec![Access { access: $2?, trailing: $3? }])
-        }
-    ;
-
-ExprTrailing -> Result<Vec<ExprTrail>>:
-        ExprTrailing '(' FunArgs ')' { flatten($1, Ok(ExprTrail::Call($3?))) }
-    |   ExprTrailing '[' Expr ']' { flatten($1, Ok(ExprTrail::Index($3?))) }
-    |   { Ok(Vec::new()) }
     ;
 
 FunArgs -> Result<Vec<Expr>>:
@@ -79,6 +73,17 @@ FunArgsTail -> Result<Vec<Expr>>:
     |   Expr { Ok(vec![$1?]) }
     ;
 
+IndexExpr -> Result<Expr>:
+        CallIndexExpr '[' Expr ']' {
+            Ok(IndexExpr::new_expr($1?, $3?))
+        }
+    ;
+
+AccessExpr -> Result<Expr>:
+        AtomExpr { $1 }
+    |   CallIndexExpr '.' Ident { Ok(AccessExpr::new_expr($1?, $3?)) }
+    ;
+
 AtomExpr -> Result<Expr>:
         Atom { $1.map(Expr::Atom) }
     |   '(' Expr ')' { $2 }