add `apply-lexer`

beautiful-racket-demo/basic-demo/lexer.rkt

@@ -1,11 +1,11 @@
 #lang br
-(require brag/support racket/contract)
+(require brag/support)
 
 (define basic-lexer
   (lexer-srcloc
    [(eof) (return-without-srcloc eof)]
    [whitespace (token lexeme #:skip? #t)]
-   [(from/to "rem" "\n") (token 'REM lexeme)]
+   [(from/to "rem" #\newline) (token 'REM lexeme)]
    [(:or "print" "goto" "end" "+" ":") lexeme]
    [(:+ numeric) (token 'INTEGER (string->number lexeme))]
    [(:or (:seq (:+ numeric) ".")
@@ -15,10 +15,3 @@
     (token 'STRING (trim-ends "\"" lexeme "\""))]))
 
 (provide basic-lexer)
-
-
-(define (apply-lexer lexer str)
-(for/list ([t (in-port lexer (open-input-string str))])
-  t))
-
-(apply-lexer basic-lexer "10 rem")

brag/brag/support.rkt

@@ -60,6 +60,11 @@
                                 (exn:fail:parsing-srclocs instance)))
 
 
+(provide apply-lexer)
+(define (apply-lexer lexer val)
+  (for/list ([t (in-port lexer (if (string? val) (open-input-string val) val))])
+    t))
+
 (provide apply-tokenizer-maker
          (rename-out [apply-tokenizer-maker apply-tokenizer]))
 (define (apply-tokenizer-maker tokenize in)
@@ -76,7 +81,7 @@
                                                              [(srcloc-token? tok)
                                                               (srcloc-token-token tok)]
                                                              [else tok]))))])
-            token))
+    token))
 
 (provide trim-ends)
 (define (trim-ends left lexeme right)