touchup

brag/rules/lexer.rkt

@@ -32,31 +32,30 @@
 (define-lex-abbrev id (:& (complement (:+ digit)) (:+ id-char)))
 (define-lex-abbrev id-separator (:or ":" "::="))
 
-(define-lex-abbrev esc-chars (char-set "\\a\\b\\t\\n\\v\\f\\r\\e"))
+(define-lex-abbrev esc-chars (union "\\a" "\\b" "\\t" "\\n" "\\v" "\\f" "\\r" "\\e"))
 
-(define (escape-lexeme lexeme quote-char)
+(define (unescape-lexeme lexeme quote-char)
   ;; convert the literal string representation back into an escape char with lookup table
-  ;; maybe use `read` instead?
-  (define escapes (hash "a" 7 "b" 8 "t" 9 "n" 10 "v" 11 "f" 12 "r" 13 "e" 27 "\"" 34 "'" 39))
+  (define unescapes (hash "a" 7 "b" 8 "t" 9 "n" 10 "v" 11 "f" 12 "r" 13 "e" 27 "\"" 34 "'" 39))
   (define pat (regexp (format "(?<=^~a\\\\).(?=~a$)" quote-char quote-char)))
   (cond
     [(regexp-match pat lexeme)
-     => (λ (m) (string quote-char (integer->char (hash-ref escapes (car m))) quote-char))]
+     => (λ (m) (string quote-char (integer->char (hash-ref unescapes (car m))) quote-char))]
     [else lexeme]))
 
 
 (define lex/1
   (lexer-src-pos
-   ;; handle whitespace chars within quotes as literal tokens: "\n" "\t" '\n' '\t'
-   ;; by matching the escaped version, and then unescaping them before they become token-LITs
+   ;; handle whitespace & escape chars within quotes as literal tokens: "\n" "\t" '\n' '\t'
+   ;; match the escaped version, and then unescape them before they become token-LITs
    [(:: "'"
         (:* (:or "\\'" esc-chars (:~ "'" "\\")))
         "'")
-    (token-LIT (escape-lexeme lexeme #\'))]
+    (token-LIT (unescape-lexeme lexeme #\'))]
    [(:: "\""
         (:* (:or "\\\"" esc-chars (:~ "\"" "\\")))
         "\"")
-    (token-LIT (escape-lexeme lexeme #\"))]
+    (token-LIT (unescape-lexeme lexeme #\"))]
    ["("
     (token-LPAREN lexeme)]
    ["["
@@ -81,7 +80,6 @@
    [(:: (:or "#" ";")
         (complement (:: (:* any-char) NL (:* any-char)))
         (:or NL ""))
-    ;; Skip comments up to end of line.
     (return-without-pos (lex/1 input-port))]
    [(eof)
     (token-EOF lexeme)]
@@ -119,7 +117,7 @@
 
 
 ;; position->pos: position -> pos
-;; Coerses position structures from br-parser-tools/lex to our own pos structures.
+;; Converts position structures from br-parser-tools/lex to our own pos structures.
 (define (position->pos a-pos)
   (pos (position-offset a-pos)
        (position-line a-pos)
@@ -128,8 +126,6 @@
 
 
 ;; tokenize: input-port -> (-> token)
-(define (tokenize ip
-                  #:source [source (object-name ip)])
-  (lambda ()
-    (parameterize ([file-path source])
-      (lex/1 ip))))
+(define (tokenize ip #:source [source (object-name ip)])
+  (λ () (parameterize ([file-path source])
+          (lex/1 ip))))