append-boq-and-eoq

signals beginning & end of a list of quads

quad2/linearize.rkt

@@ -13,11 +13,11 @@
   #:post (list-of simple-quad?)
   (append*
    (for/list ([q (in-list qs)])
-     (match q
-       [(quad _ _ (list (? string? str)) _)
-        (for/list ([c (in-string str)])
-          (struct-copy quad q [elems (list (string c))]))]
-       [_ (list q)]))))
+             (match q
+               [(quad _ _ (list (? string? str)) _)
+                (for/list ([c (in-string str)])
+                          (struct-copy quad q [elems (list (string c))]))]
+               [_ (list q)]))))
 
 (define-pass (linearize qs)
   ;; convert a single quad into a list of quads, with the attributes propagated downward
@@ -101,4 +101,13 @@
   qs)
 
 (module+ test
-  (mark-text-runs smlqs))
+  (mark-text-runs smlqs))
+
+(define-pass (append-boq-and-eoq qs)
+  #:pre (list-of simple-quad?)
+  #:post (λ (qs) (match qs
+                   [(list (? boq-quad?) (? simple-quad?) ... (? eoq-quad?)) #true]
+                   [_ #false]))
+  (set-quad-attrs! boq (quad-attrs (first qs)))
+  (set-quad-attrs! eoq (quad-attrs (last qs)))
+  (append (list boq) qs (list eoq)))

quad2/main.rkt

@@ -38,6 +38,8 @@
    resolve-font-sizes
    resolve-font-features
    parse-page-sizes
+   resolve-font-paths
+   complete-attr-paths
 
    ;; linearization =============
    ;; we postpone this step until we're certain any
@@ -45,11 +47,10 @@
    ;; has been absorbed into the attrs
    ;; (e.g., cascading font sizes)
    ;; because once we linearize, that information is gone.
-   (print-pass linearize)
+   linearize
+   (print-pass append-boq-and-eoq)
 
    ;; post-linearization resolutions & parsings =============
-   resolve-font-paths
-   complete-attr-paths
                     
    mark-text-runs
    merge-adjacent-strings
@@ -59,7 +60,7 @@
    remove-font-without-char
    insert-fallback-font
    layout
-   make-drawing-insts
+   (print-pass make-drawing-insts)
    stackify))
 
 (module+ main

quad2/quad.rkt

@@ -25,7 +25,7 @@
                              (? quad-attrs?)
                              (? quad-elems?)) #true]
                       [_ #false])
-              (error 'no-dice))
+              (raise-user-error 'quad-constructor (format "failed: ~v" (list tag attrs elems posn))))
             (values tag attrs elems posn)))
              
 (define (quad-tag? x) (match x
@@ -108,4 +108,11 @@
       [(? string? str) (loop (make-quad #:elems (list str)))])))
 
 (module+ test
-  (define q (make-quad #:tag 'div #:attrs (make-hasheq '((hello . "world"))) #:elems (list "fine"))))
+  (define q (make-quad #:tag 'div #:attrs (make-hasheq '((hello . "world"))) #:elems (list "fine"))))
+
+
+
+(struct boq-quad quad ())
+(define boq (boq-quad #f (make-hasheq) null #f))
+(struct eoq-quad quad ())
+(define eoq (eoq-quad #f (make-hasheq) null #f))