lex & parse the operator

brag/rules/lexer.rkt

@@ -64,8 +64,11 @@
     (token-SPLICE lexeme)]
    ["|"
     (token-PIPE lexeme)]
-   [(:or "+" "*")
+   [(:or "+" "*"
-    (token-REPEAT lexeme)]
+         ;; todo: consolidate next two patterns?
+         (:: "{" (:* digit) "}")
+         (:: "{" (:* digit) "," (:* digit) "}"))
+    (token-REPEAT (let () (println lexeme) lexeme))]
    [whitespace
     ;; Skip whitespace
     (return-without-pos (lex/1 input-port))]

brag/rules/parser.rkt

@@ -162,6 +162,12 @@
              (pattern-repeat (position->pos $1-start-pos)
                              (position->pos $2-end-pos)
                              1 $1)]
+            [(regexp-match #px"^\\{(\\d+)?,?(\\d+)?\\}$" $2)
+             => (λ (m)
+                  (define pr (match m
+                      [(list _ min max) (cons (and min (string->number min))
+                                                (and max (string->number max)))]))
+                  (error (format "~a" pr)))]
             [else
              (error 'grammar-parse "unknown repetition operator ~e" $2)])]
      [(atomic-pattern)