diff --git a/brag/brag/codegen/runtime.rkt b/brag/brag/codegen/runtime.rkt
index 1229a30..980bec2 100755
--- a/brag/brag/codegen/runtime.rkt
+++ b/brag/brag/codegen/runtime.rkt
@@ -158,44 +158,45 @@ This would be the place to check a syntax property for hiding.
(datum->syntax #f d (positions->srcloc start-pos end-pos) stx-with-original?-property))
-(require sugar/debug)
+(define (remove-rule-name component-stx [splice #f])
+ ;; when removing a rule name, we apply it as a syntax property to the remaining elements
+ ;; for possible later usage (aka, why throw away information)
+ (with-syntax ([(name . subcomponents) component-stx])
+ (let ([name-datum (syntax->datum #'name)])
+ (if splice
+ ;; when splicing, returned list is a regular list, with each element having the property.
+ (map (λ(sc) (syntax-property sc name-datum #'name)) (syntax->list #'subcomponents))
+ ;; when hiding, returned list should be a syntaxed list with the property
+ ;; iow, basically the same as `component-stx`, minus the name
+ (syntax-property (datum->syntax component-stx #'subcomponents component-stx component-stx) name-datum #'name)))))
+
+
+(define (preprocess-component-lists component-lists)
+ ; "preprocess" means splicing and rule-name-hiding where indicated
+ (append*
+ ;; each `component-list` is a list that's either empty, or has a single component-stx object
+ ;; inside `component-stx` is a name followed by subcomponents
+ (for*/list ([component-list (in-list component-lists)]
+ [component-stx (in-list component-list)]) ; this has the effect of omitting empty component-lists
+ (list
+ (cond
+ [(eq? (syntax-property component-stx 'hide-or-splice) 'hide)
+ (list (remove-rule-name component-stx))] ; hidden version still wrapped in a sublist
+ [(or (eq? (syntax-property component-stx 'hide-or-splice) 'splice)
+ (syntax-property component-stx 'splice-rh-id))
+ (remove-rule-name component-stx #t)] ; spliced version is lifted out of the sublist
+ [else (list component-stx)])))))
+
;; rule-components->syntax: (U symbol false) (listof stx) ... #:srcloc (U #f (list src line column offset span)) -> stx
;; Creates an stx out of the rule name and its components.
;; The location information of the rule spans that of its components.
-(define (rule-components->syntax rule-name/false #:srcloc [srcloc #f] #:hide-or-splice? [hide-or-splice #f] . componentss)
- (define (remove-rule-name components-stx)
- ;; when removing a rule name, we apply it as a syntax property to the remaining elements
- ;; for possible later usage (aka, why throw away information)
- ;; todo: distinguish hiding and splicing behavior.
- ;; when hiding, returned list should be a syntaxed list with the property (?)
- ;; when splicing, returned list should be a regular list, with each element having the property.
- (let* ([name+elements (syntax->list components-stx)]
- [name-datum (syntax->datum (car name+elements))]
- [elements (cdr name+elements)])
- (map (λ(e) (syntax-property e name-datum #t)) elements)))
- (define componentss-hoisted
- (apply append
- (for/list ([css (in-list componentss)])
- (list
- ;; each `css` is a list that's either empty, or has a single syntaxed component list
- (let ([components-stx (and (pair? css) (car css))])
- (if components-stx
- (cond
- [(eq? (syntax-property components-stx 'hide-or-splice) 'hide)
- (list (remove-rule-name components-stx))] ; hidden version still wrapped in a sub-`list`
- [(or (eq? (syntax-property components-stx 'hide-or-splice) 'splice)
- (syntax-property components-stx 'splice-rh-id))
- (remove-rule-name components-stx)] ; spliced version is "delisted"
- [else css])
- css))))))
- (syntax-property
- (datum->syntax #f
- (cons
- (datum->syntax #f rule-name/false srcloc stx-with-original?-property)
- (apply append componentss-hoisted))
- srcloc
- stx-with-original?-property)
- ;; not 'hide-or-splice-lhs-id, because it is now a component in a different rule
- ;; actual splicing happens when the parent rule is processed (with procedure above)
- 'hide-or-splice hide-or-splice))
\ No newline at end of file
+(define (rule-components->syntax rule-name/false #:srcloc [srcloc #f] #:hide-or-splice? [hide-or-splice #f] . component-lists)
+ (define new-rule-name (datum->syntax #f rule-name/false srcloc stx-with-original?-property))
+ (define new-rule-components (append* (preprocess-component-lists component-lists)))
+ (define rule-result (cons new-rule-name new-rule-components))
+ (define syntaxed-rule-result (datum->syntax #f rule-result srcloc stx-with-original?-property))
+ ;; not 'hide-or-splice-lhs-id, because this will now become a (right-hand) component in a different (left-hand) rule
+ ;; actual splicing happens when the parent rule is processed (with procedure above)
+ (syntax-property syntaxed-rule-result 'hide-or-splice hide-or-splice))
+
diff --git a/brag/brag/examples/baby-json-hider.rkt b/brag/brag/examples/baby-json-hider.rkt
index acbe349..b1bdfc8 100755
--- a/brag/brag/examples/baby-json-hider.rkt
+++ b/brag/brag/examples/baby-json-hider.rkt
@@ -13,4 +13,6 @@ array: "[" [json ("," json)*] "]"
object: /"{" [kvpair ("," kvpair)*] /"}"
-@kvpair : /ID ":" /json
+@kvpair : /ID colon /json
+
+/colon : ":"
diff --git a/brag/brag/test/test-all.rkt b/brag/brag/test/test-all.rkt
index f23fabe..fb6b365 100755
--- a/brag/brag/test/test-all.rkt
+++ b/brag/brag/test/test-all.rkt
@@ -6,6 +6,7 @@
"test-01-equal.rkt"
"test-simple-arithmetic-grammar.rkt"
"test-baby-json.rkt"
+ "test-baby-json-hider.rkt"
"test-wordy.rkt"
"test-simple-line-drawing.rkt"
"test-flatten.rkt"
diff --git a/brag/brag/test/test-baby-json-hider.rkt b/brag/brag/test/test-baby-json-hider.rkt
index ffd28e9..b7580d6 100755
--- a/brag/brag/test/test-baby-json-hider.rkt
+++ b/brag/brag/test/test-baby-json-hider.rkt
@@ -8,10 +8,10 @@
":"
(token 'STRING "'hello world'")
"}")))
-(check-equal? (syntax->datum parse-result) '(json ":"))
+(check-equal? (syntax->datum parse-result) '(json (":")))
-(define syntaxed-colon (cadr (syntax->list parse-result)))
-(check-true (syntax-property syntaxed-colon 'kvpair))
+(define syntaxed-colon-parens (cadr (syntax->list parse-result)))
+(check-equal? (syntax->datum (syntax-property syntaxed-colon-parens 'kvpair)) 'kvpair)
(check-equal?
(syntax->datum