use ! instead of <> for grammar hiding

beautiful-racket/br/demo/txtadv/parser.rkt

@@ -2,26 +2,26 @@
 
 txtadv-program : verb-section everywhere-section things-section places-section start-section
 
-verb-section : <"===VERBS==="> verb-item+
+verb-section : !"===VERBS===" verb-item+
 
-<verb-item> : verb-name+ s-exp
+!verb-item : verb-name+ s-exp
 
-<verb-name> : [<",">] ID ["_"]
+!verb-name : [!","] ID ["_"]
 
-everywhere-section : <"===EVERYWHERE==="> id-desc+
+everywhere-section : !"===EVERYWHERE===" id-desc+
 
-things-section : <"===THINGS==="> thing-item+
+things-section : !"===THINGS===" thing-item+
 
-<thing-item> : DASHED-NAME id-desc+
+!thing-item : DASHED-NAME id-desc+
 
-places-section : <"===PLACES==="> place-item+
+places-section : !"===PLACES===" place-item+
 
-<place-item> : DASHED-NAME STRING place-items id-desc+
+!place-item : DASHED-NAME STRING place-items id-desc+
 
-<place-items> : <"["> ([<",">] ID)* <"]">
+!place-items : !"[" ([!","] ID)* !"]"
 
-start-section : <"===START==="> ID
+start-section : !"===START===" ID
 
-<id-desc> : ID s-exp
+!id-desc : ID s-exp
 
-s-exp : ID | STRING | <"("> s-exp* <")">
+s-exp : ID | STRING | !"(" s-exp* !")"

brag/brag/examples/baby-json-hider.rkt

@@ -11,6 +11,6 @@ string: STRING
 
 array: "[" [json ("," json)*] "]"
 
-object: <"{"> [kvpair ("," kvpair)*] <"}">
+object: !"{" [kvpair ("," kvpair)*] !"}"
 
-<kvpair>: <ID> ":" <json>
+!kvpair : !ID ":" !json

brag/brag/rules/lexer.rkt

@@ -14,7 +14,7 @@
 (define-lex-abbrevs
    [letter (:or (:/ "a" "z") (:/ #\A #\Z))]
    [digit (:/ #\0 #\9)]
-   [id-char (:or letter digit (char-set "-.!$%&/=?^_~@"))]
+   [id-char (:or letter digit (char-set "-.$%&/=?^_~<>"))]
  )
 
 (define-lex-abbrev id
@@ -36,14 +36,14 @@
     (token-LPAREN lexeme)]
    ["["
     (token-LBRACKET lexeme)]
-   ["<"
-    (token-LANGLE lexeme)]
    [")"
     (token-RPAREN lexeme)]
    ["]"
     (token-RBRACKET lexeme)]
-   [">"
-    (token-RANGLE lexeme)]
+   ["!"
+    (token-BANG lexeme)]
+   ["@"
+    (token-ATSIGN lexeme)]
    ["|"
     (token-PIPE lexeme)]
    [(:or "+" "*")
@@ -61,7 +61,7 @@
     (token-EOF lexeme)]
    [(:: id (:* whitespace) ":")
     (token-RULE_HEAD lexeme)]
-   [(:: "<" id ">" (:* whitespace) ":")
+   [(:: "!" id (:* whitespace) ":")
     (token-RULE_HEAD_HIDDEN lexeme)]
    [id
     (token-ID lexeme)]

brag/brag/rules/parser.rkt

@@ -10,8 +10,8 @@
 (provide tokens
          token-LPAREN
          token-RPAREN
-         token-LANGLE ; for elider
-         token-RANGLE ; for elider
+         token-BANG ; for hider
+         token-ATSIGN ; for splicer
          token-LBRACKET
          token-RBRACKET
          token-PIPE
@@ -41,8 +41,8 @@
                        RPAREN
                        LBRACKET
                        RBRACKET
-                       LANGLE
-                       RANGLE
+                       BANG
+                       ATSIGN
                        PIPE
                        REPEAT
                        RULE_HEAD
@@ -88,10 +88,10 @@
                       #f)
               $2))]
      
-     ;; angles indicate splicing. set splice value to #t
+     ;; bang indicates hiding. set hide value to #t
      [(RULE_HEAD_HIDDEN pattern)
       (begin
-        (define trimmed (cadr (regexp-match #px"<(.+)>\\s*:$" $1)))
+        (define trimmed (cadr (regexp-match #px"!(\\S+)\\s*:$" $1)))
         (rule (position->pos $1-start-pos)
               (position->pos $2-end-pos)
               (lhs-id (position->pos $1-start-pos)
@@ -168,9 +168,9 @@
      [(LPAREN pattern RPAREN)
       (relocate-pattern $2 (position->pos $1-start-pos) (position->pos $3-end-pos))]
      
-     [(LANGLE pattern RANGLE)
-      ;; angles indicate hiding. set hide value to #t
-      (relocate-pattern $2 (position->pos $1-start-pos) (position->pos $3-end-pos) #t)]])
+     [(BANG atomic-pattern)
+      ;; bang indicates hiding. set hide value to #t
+      (relocate-pattern $2 (position->pos $1-start-pos) (position->pos $2-end-pos) #t)]])
    
    
    (error (lambda (tok-ok? tok-name tok-value start-pos end-pos)