From ad9748feb30d4b1f72861e1f7ed53b54139f10a0 Mon Sep 17 00:00:00 2001
From: Matthew Butterick <mb@mbtype.com>
Date: Tue, 19 Mar 2019 13:55:18 -0700
Subject: [PATCH] steps

---
 quad/quad/wrap.rkt | 385 +++++++++++++++++++++++----------------------
 1 file changed, 199 insertions(+), 186 deletions(-)

diff --git a/quad/quad/wrap.rkt b/quad/quad/wrap.rkt
index 6e208b5d..803ad8ea 100644
--- a/quad/quad/wrap.rkt
+++ b/quad/quad/wrap.rkt
@@ -18,6 +18,16 @@
   ;; drop any soft breaks that wouldn't print (e.g., unused soft hyphens)
   (append partial (dropf wrap nonprinting-soft-break-in-middle?)))
 
+(define (default-finish-wrap-func wrap-qs q0 q idx) (list wrap-qs))
+(define ((make-finish-wrap finish-wrap-func) qs previous-wrap-ender wrap-idx [wrap-triggering-q (car qs)])
+  ;; reverse because quads accumulated in reverse
+  ;; wrap-triggering-q is ordinarily the last accumulated q
+  ;; unless it's the last wrap, in which case it's #f
+  ;; but we capture it separately because it's likely to get trimmed away by `nonprinting-at-end?`
+  ;; note: we don't trim `soft-break?` or `hard-break?` because that's an orthogonal consideration
+  ;; for instance, a hyphen is `soft-break?` but shouldn't be trimmed.
+  (finish-wrap-func (reverse (dropf qs nonprinting-at-end?)) previous-wrap-ender wrap-triggering-q wrap-idx))
+
 (define (wrap qs
               [target-size-proc-arg (current-wrap-distance)]
               [debug #f]
@@ -34,7 +44,7 @@
                                           (+ last-dist (if (printable? q) (distance q) 0)))]
               ;; called when wrap counter increments.
               ;; perhaps should reset after paragraph breaks, etc.
-              #:wrap-count [wrap-count (λ (idx q) (add1 idx))]
+              #:wrap-count [wrap-count (λ (idx wrap-triggering-q) (add1 idx))]
               ;; starting value when wrap counter resets.
               ;; could use an arbitrary data structure (then incremented with `wrap-count`
               #:initial-wrap-count [initial-wrap-idx 1]
@@ -44,21 +54,14 @@
               ;; q that caused this one, or #f at end.
               ;; (q0 is not part of this wrap, but q is)
               ;; idx is current wrap-count value.
-              #:finish-wrap [finish-wrap-func (λ (wrap-qs q0 q idx) (list wrap-qs))])
+              #:finish-wrap [finish-wrap-func default-finish-wrap-func])
   (define (hard-break? x) (and (hard-break-func x) (or (not no-break-func) (not (no-break-func x)))))
   (define (soft-break? x) (and (soft-break-func x) (or (not no-break-func) (not (no-break-func x)))))
   (define target-size-proc (match target-size-proc-arg
                              [(? procedure? proc) proc]
                              [val (λ (q idx) val)]))
   ; takes quads in wrap, triggering quad, and wrap idx; returns list containing wrap (and maybe other things)
-  (define (finish-wrap qs previous-wrap-ender wrap-idx [wrap-triggering-q (car qs)])
-    ;; reverse because quads accumulated in reverse
-    ;; wrap-triggering-q is ordinarily the last accumulated q
-    ;; unless it's the last wrap, in which case it's #f
-    ;; but we capture it separately because it's likely to get trimmed away by `nonprinting-at-end?`
-    ;; note: we don't trim `soft-break?` or `hard-break?` because that's an orthogonal consideration
-    ;; for instance, a hyphen is `soft-break?` but shouldn't be trimmed.
-    (finish-wrap-func (reverse (dropf qs nonprinting-at-end?)) previous-wrap-ender wrap-triggering-q wrap-idx))
+  (define finish-wrap (make-finish-wrap finish-wrap-func))
   (let loop ([wraps null] ; list of (list of quads)
              [wrap-idx initial-wrap-idx] ; wrap count (could be (length wraps) but we'd rather avoid `length`)
              [next-wrap-head null] ; list of quads ending in previous `soft-break?` or `hard-break?`
@@ -201,24 +204,43 @@
                    ;; q that caused this one, or #f at end.
                    ;; (q0 is not part of this wrap, but q is)
                    ;; idx is current wrap-count value.
-                   #:finish-wrap [finish-wrap-func (λ (wrap-qs q0 q idx) (list wrap-qs))])
-
+                   #:finish-wrap [finish-wrap-func default-finish-wrap-func])
+  (define (hard-break? x) (and (hard-break-func x) (or (not no-break-func) (not (no-break-func x)))))
+  (define (soft-break? x) (and (soft-break-func x) (or (not no-break-func) (not (no-break-func x)))))
+  (define finish-wrap (make-finish-wrap finish-wrap-func))
+  
   (define measure target-size-proc-arg)
+  (struct $penalty (val idx) #:transparent)
   (define (penalty i j)
-    (define line-width (- j i))
-    (define underflow (- measure line-width))
-    (+ (ocm-min-value ocm i) ; include penalty so far
-       (if (negative? underflow)
-           ;; overfull line: huge penalty prevents break; multiplier is essential for monotonicity.
-           (* underflow -1e8)
-           ;; standard penalty, optionally also applied to last line (by changing operator)
-           (expt underflow 2))))
-
-  (define ocm (make-ocm penalty))
+    (match-define ($penalty last-val last-idx) (ocm-min-value ocm i))
+    (cond
+      [(> j (vector-length pieces)) ($penalty (- i) last-idx)]
+      [else
+       (define first-q (vector-ref pieces i))
+       (define last-q (vector-ref pieces (sub1 j)))
+       (define this-idx (wrap-count last-idx last-q))
+       (cond
+         [(hard-break? last-q) ($penalty 0 this-idx)]
+         [(soft-break? last-q)
+          #R (pieces-sublist i j)
+          (define line-width (- j i))
+          (define underflow (- measure line-width))
+          ($penalty
+           (+  last-val ; include penalty so far
+               (if (negative? underflow)
+                   ;; overfull line: huge penalty prevents break; multiplier is essential for monotonicity.
+                   (* 1e8 (- underflow))
+                   ;; standard penalty
+                   (expt underflow 2)))
+           this-idx)]
+         [else ($penalty last-val last-idx)])]))
+
+  (define ocm (make-ocm penalty ($penalty 0 (sub1 initial-wrap-idx)) $penalty-val))
   ;; starting from last position, ask ocm for position of row minimum (= new-pos)
   ;; collect this value, and use it as the input next time
   ;; until you reach first position.
   (define pieces (list->vector qs))
+  (define (pieces-sublist i j) (vector->list (vector-copy pieces i j)))
   (define last-j (vector-length pieces))
   (define bps
     (let loop ([j last-j][bps (list last-j)]) ; start from end
@@ -226,9 +248,16 @@
       (if (zero? i) ; zero means we're at first position, and therefore done
           (cons i bps)
           (loop i (cons i bps)))))
-  (for/list ([i (in-list bps)]
+  (for/fold ([wraps null]
+             [wrap-idx initial-wrap-idx]
+             #:result (reverse wraps))
+            ([i (in-list bps)]
              [j (in-list (cdr bps))])
-    (vector->list (vector-copy pieces i j))))
+    (define wrap-qs (reverse (pieces-sublist i j))) ; first-fit gets wrap-qs in reverse, so be consistent
+    (define previous-wrap-ender (and (positive? i) (vector-ref pieces (sub1 i))))
+    (define wrap-triggering-q (and (not (= j (vector-length pieces))) (car wrap-qs)))
+    (values (cons (finish-wrap wrap-qs previous-wrap-ender wrap-idx wrap-triggering-q) wraps)
+            (wrap-count wrap-idx (car wrap-qs)))))
 
 (define q-zero (q #:size (pt 0 0)))
 (define q-one (q #:size (pt 1 1) #:printable #t))
@@ -276,101 +305,6 @@
 (module+ test
   (require rackunit))
 
-(module+ test
-  (test-case
-   "chars"
-   (check-equal? (linewrap (list) 1) (list))  
-   (check-equal? (linewrap (list a) 1) (list (list a)))
-   (check-equal? (linewrap (list a b) 1) (list (list a) lbr (list b)))
-   (check-equal? (linewrap (list a b c) 1) (list (list a) lbr (list b) lbr (list c)))
-   (check-equal? (linewrap (list a b c) 2) (list (list a b) lbr (list c)))
-   (check-equal? (linewrap (list x x x x) 2) (list (list x x) lbr (list x x)))
-   (check-equal? (linewrap (list x x x x x) 3) (list (list x x x) lbr (list x x)))
-   (check-equal? (linewrap (list x x x x x) 1)
-                 (list (list x) lbr (list x) lbr (list x) lbr (list x) lbr (list x)))
-   (check-equal? (linewrap (list x x x x x) 10) (list (list x x x x x)))))
-
-(module+ test
-  (test-case
-   "chars and spaces"
-   (check-equal? (linewrap (list a sp b) 1) (list (list a) lbr (list b)))
-   (check-equal? (linewrap (list a b sp c) 2) (list (list a b) lbr (list c)))
-   (check-equal? (linewrap (list a sp b) 3) (list (list a sp b)))
-   (check-equal? (linewrap (list a sp b c) 3) (list (list a) lbr (list b c)))))
-
-(module+ test
-  (test-case
-   "leading & trailing spaces"
-   (check-equal? (linewrap (list sp x) 2) (list (list x)))
-   (check-equal? (linewrap (list x sp) 2) (list (list x)))
-   (check-equal? (linewrap (list sp x sp) 2) (list (list x)))
-   (check-equal? (linewrap (list sp sp x sp sp) 2) (list (list x)))
-   (check-equal? (linewrap (list sp sp x sp sp x sp) 1) (list (list x) lbr (list x)))))
-
-(module+ test
-  (test-case
-   "hard hyphens"
-   (check-equal? (linewrap (list hyph) 1) (list (list hyph)))
-   (check-equal? (linewrap (list hyph hyph) 1) (list (list hyph) lbr (list hyph)))
-   (check-equal? (linewrap (list hyph hyph) 2) (list (list hyph hyph)))
-   (check-equal? (linewrap (list hyph hyph hyph) 2) (list (list hyph hyph) lbr (list hyph)))
-   (check-equal? (linewrap (list x hyph) 1) (list (list x) lbr (list hyph)))
-   (check-equal? (linewrap (list a b hyph c d) 1)
-                 (list (list a) lbr (list b) lbr (list hyph) lbr (list c) lbr (list d)))
-   (check-equal? (linewrap (list a b hyph c d) 2) (list (list a b) lbr (list hyph c) lbr (list d)))
-   (check-equal? (linewrap (list a b hyph c d) 3) (list (list a b hyph) lbr (list c d)))
-   (check-equal? (linewrap (list x x hyph x x) 4) (list (list x x hyph) lbr (list x x)))
-   (check-equal? (linewrap (list x x hyph x x) 5) (list (list x x hyph x x)))))
-
-(module+ test
-  (test-case
-   "soft hyphens"
-   (check-equal? (linewrap (list shy) 1) (list))
-   (check-equal? (linewrap (list shy shy) 2) (list))
-   (check-equal? (linewrap (list shy shy shy) 2) (list))
-   (check-equal? (linewrap (list x shy) 1) (list (list x)))
-   (check-equal? (linewrap (list x shy shy shy shy) 1) (list (list x)))
-   ;; todo: degenerate cases that don't work without continuations
-   ;(check-equal? (linewrap (list x x shy x x) 1) (list x br x br x br x))
-   ;(check-equal? (linewrap (list x x shy x x) 2) (list x x br x x))
-   (check-equal? (linewrap (list x x shy x x) 3) (list (list x x shy) lbr (list x x)))
-   (check-equal? (linewrap (list x x shy x x) 4) (list (list x x x x)))
-   (check-equal? (linewrap (list x x shy x x) 5) (list (list x x x x)))
-   (check-equal? (linewrap (list x x shy x sp x) 4) (list (list x x x) lbr (list x)))))
-
-(module+ test
-  (test-case
-   "zero width nonbreakers"
-   (check-equal? (linewrap (list sp zwx) 2) (list (list zwx)))
-   (check-equal? (linewrap (list zwx sp) 2) (list (list zwx)))
-   (check-equal? (linewrap (list sp zwx sp) 2) (list (list zwx)))
-   (check-equal? (linewrap (list sp sp zwx sp sp) 2) (list (list zwx)))
-   (check-equal? (linewrap (list sp sp zwx sp sp zwx sp) 2) (list (list zwx sp sp zwx)))))
-
-(module+ test
-  (test-case
-   "hard breaks"
-   (check-equal? (linewrap (list lbr) 2) (list)) ;; only insert a break if it's between things
-   (check-equal? (linewrap (list a lbr b) 2) (list (list a) lbr (list b)))
-   (check-equal? (linewrap (list a b lbr) 2) (list (list a b)))
-   (check-equal? (linewrap (list a b lbr lbr) 2) (list (list a b) lbr (list)))
-   (check-equal? (linewrap (list x lbr x x) 3) (list (list x) lbr (list x x)))
-   (check-equal? (linewrap (list x x lbr x) 3) (list (list x x) lbr (list x)))
-   (check-equal? (linewrap (list x x x x) 3) (list (list x x x) lbr (list x)))
-   (check-equal? (linewrap (list x x x sp x x) 2) (list (list x x) lbr (list x) lbr (list x x)))
-   (check-equal? (linewrap (list x x x sp x x) 3) (list (list x x x) lbr (list x x)))))
-
-(module+ test
-  (test-case
-   "hard breaks and spurious spaces"
-   (check-equal? (linewrap (list a sp sp sp lbr b) 2) (list (list a) lbr (list b)))
-   (check-equal? (linewrap (list a sp lbr sp sp b c sp) 3) (list (list a) lbr (list b c)))
-   (check-equal? (linewrap (list sp sp x x sp sp lbr sp sp sp x) 3) (list (list x x) lbr (list x)))
-   (check-equal? (linewrap (list a sp b sp sp lbr sp c) 3) (list (list a sp b) lbr (list c)))
-   (check-equal? (linewrap (list x x x x) 3) (list (list x x x) lbr (list x)))
-   (check-equal? (linewrap (list x x x sp x x) 2) (list (list x x) lbr (list x) lbr (list x x)))
-   (check-equal? (linewrap (list x x x sp x x) 3) (list (list x x x) lbr (list x x)))))
-
 (define (visual-wrap str int [debug #f] #:wrapper [wrap-proc wrap])
   (string-join
    (for/list ([x (in-list (linewrap (for/list ([c (in-string str)])
@@ -385,32 +319,6 @@
      (list->string (map car (map quad-elems x))))
    "|"))
 
-(module+ test
-  (test-case
-   "kp linebreaking"
-   (check-equal? (visual-wrap "Meg is an ally." 6) "Meg is|an|ally.")
-   (check-equal? (visual-wrap "Meg is an ally." 6 #:wrapper wrap-best) "Meg i|s an |ally.")))
-
-(module+ test
-  (test-case
-   "visual breaks"
-   (check-equal? (visual-wrap "My dog has fleas" 1) "M|y|d|o|g|h|a|s|f|l|e|a|s")
-   (check-equal? (visual-wrap "My dog has fleas" 2) "My|do|g|ha|s|fl|ea|s")
-   (check-equal? (visual-wrap "My dog has fleas" 3) "My|dog|has|fle|as")
-   (check-equal? (visual-wrap "My dog has fleas" 4) "My|dog|has|flea|s")
-   (check-equal? (visual-wrap "My dog has fleas" 5) "My|dog|has|fleas")
-   (check-equal? (visual-wrap "My dog has fleas" 6) "My dog|has|fleas")
-   (check-equal? (visual-wrap "My dog has fleas" 7) "My dog|has|fleas")
-   (check-equal? (visual-wrap "My dog has fleas" 8) "My dog|has|fleas")
-   (check-equal? (visual-wrap "My dog has fleas" 9) "My dog|has fleas")
-   (check-equal? (visual-wrap "My dog has fleas" 10) "My dog has|fleas")
-   (check-equal? (visual-wrap "My dog has fleas" 11) "My dog has|fleas")
-   (check-equal? (visual-wrap "My dog has fleas" 12) "My dog has|fleas")
-   (check-equal? (visual-wrap "My dog has fleas" 13) "My dog has|fleas")
-   (check-equal? (visual-wrap "My dog has fleas" 14) "My dog has|fleas")
-   (check-equal? (visual-wrap "My dog has fleas" 15) "My dog has|fleas")
-   (check-equal? (visual-wrap "My dog has fleas" 16) "My dog has fleas")))
-
 (define (pagewrap xs size [debug #f])
   (add-between
    (wrap (flatten xs) size debug
@@ -420,37 +328,6 @@
                #:printable #false
                #:elems '(#\page)))
 
-(module+ test
-  (require rackunit)
-  (test-case
-   "soft page breaks"
-   (check-equal? (pagewrap null 2) (list))
-   (check-equal? (pagewrap (list x) 2) (list (list x)))
-   (check-equal? (pagewrap (list x x) 2) (list (list x x)))
-   (check-equal? (pagewrap (list x x x) 1) (list (list x) pbr (list x) pbr (list x)))
-   (check-equal? (pagewrap (list x x x) 2) (list (list x x) pbr (list x)))
-   (check-equal? (pagewrap (list x x x) 3) (list (list x x x)))
-   (check-equal? (pagewrap (list x x x) 4) (list (list x x x)))
-   (check-equal? (pagewrap (list x lbr x x) 2) (list (list x) pbr (list x x)))))
-
-(module+ test
-  (test-case
-   "hard page breaks"
-   (check-equal? (pagewrap (list a pbr b c) 2) (list (list a) pbr (list b c)))
-   (check-equal? (pagewrap (list x pbr x x) 1) (list (list x) pbr (list x) pbr (list x)))
-   (check-equal? (pagewrap (list x pbr pbr x x) 1) (list (list x) pbr (list) pbr (list x) pbr (list x)))
-   (check-equal? (pagewrap (list x pbr pbr x x) 2) (list (list x) pbr (list) pbr (list x x)))
-   (check-equal? (pagewrap (list lbr x lbr lbr pbr lbr x x lbr) 2) (list (list x) pbr (list x x)))))
-
-(module+ test
-  (test-case
-   "composed line breaks and page breaks"
-   (check-equal? (pagewrap (linewrap null 1) 2) (list))
-   (check-equal? (pagewrap (linewrap (list x) 1) 2) (list (list x)))
-   (check-equal? (pagewrap (linewrap (list x x x) 1) 2) (list (list x lbr x) pbr (list x)))
-   (check-equal? (pagewrap (linewrap (list x x x) 2) 2) (list (list x x) pbr (list x)))
-   (check-equal? (pagewrap (linewrap (list x x x) 2) 1) (list (list x) pbr (list x) pbr (list x)))))
-
 (define (linewrap2 xs size [debug #f])
   (add-between
    (wrap xs size debug
@@ -459,14 +336,150 @@
          #:finish-wrap (λ (pcs . _) (list (apply q pcs))))
    lbr))
 
-(module+ test
-  (test-case
-   "hard breaks and spurious spaces with slugs"
-   (check-equal? (linewrap2 (list a sp sp sp lbr b) 2) (list (q a) lbr (q b)))
-   (check-equal? (linewrap2 (list x sp lbr sp sp x x sp) 3) (list (q x) lbr (q x x)))
-   (check-equal? (linewrap2 (list sp sp x x sp sp lbr sp sp sp x) 3) (list (q x x) lbr (q x)))
-   (check-equal? (linewrap2 (list a sp b sp sp lbr sp c) 3) (list (q a sp b) lbr (q c)))
-   (check-equal? (linewrap2 (list x x x x) 3) (list (q x x x) lbr (q x)))
-   (check-equal? (linewrap2 (list x x x sp x x) 2) (list (q x x) lbr (q x) lbr (q x x)))
-   (check-equal? (linewrap2 (list x x x sp x x) 3) (list (q x x x) lbr (q x x)))))
+
+#;(module+ test
+    (test-begin
+     (test-case
+      "chars"
+      (check-equal? (linewrap (list) 1) (list))  
+      (check-equal? (linewrap (list a) 1) (list (list a)))
+      (check-equal? (linewrap (list a b) 1) (list (list a) lbr (list b)))
+      (check-equal? (linewrap (list a b c) 1) (list (list a) lbr (list b) lbr (list c)))
+      (check-equal? (linewrap (list a b c) 2) (list (list a b) lbr (list c)))
+      (check-equal? (linewrap (list x x x x) 2) (list (list x x) lbr (list x x)))
+      (check-equal? (linewrap (list x x x x x) 3) (list (list x x x) lbr (list x x)))
+      (check-equal? (linewrap (list x x x x x) 1)
+                    (list (list x) lbr (list x) lbr (list x) lbr (list x) lbr (list x)))
+      (check-equal? (linewrap (list x x x x x) 10) (list (list x x x x x))))
+
+     (test-case
+      "chars and spaces"
+      (check-equal? (linewrap (list a sp b) 1) (list (list a) lbr (list b)))
+      (check-equal? (linewrap (list a b sp c) 2) (list (list a b) lbr (list c)))
+      (check-equal? (linewrap (list a sp b) 3) (list (list a sp b)))
+      (check-equal? (linewrap (list a sp b c) 3) (list (list a) lbr (list b c))))
+
+     (test-case
+      "leading & trailing spaces"
+      (check-equal? (linewrap (list sp x) 2) (list (list x)))
+      (check-equal? (linewrap (list x sp) 2) (list (list x)))
+      (check-equal? (linewrap (list sp x sp) 2) (list (list x)))
+      (check-equal? (linewrap (list sp sp x sp sp) 2) (list (list x)))
+      (check-equal? (linewrap (list sp sp x sp sp x sp) 1) (list (list x) lbr (list x))))
+
+     (test-case
+      "hard hyphens"
+      (check-equal? (linewrap (list hyph) 1) (list (list hyph)))
+      (check-equal? (linewrap (list hyph hyph) 1) (list (list hyph) lbr (list hyph)))
+      (check-equal? (linewrap (list hyph hyph) 2) (list (list hyph hyph)))
+      (check-equal? (linewrap (list hyph hyph hyph) 2) (list (list hyph hyph) lbr (list hyph)))
+      (check-equal? (linewrap (list x hyph) 1) (list (list x) lbr (list hyph)))
+      (check-equal? (linewrap (list a b hyph c d) 1)
+                    (list (list a) lbr (list b) lbr (list hyph) lbr (list c) lbr (list d)))
+      (check-equal? (linewrap (list a b hyph c d) 2) (list (list a b) lbr (list hyph c) lbr (list d)))
+      (check-equal? (linewrap (list a b hyph c d) 3) (list (list a b hyph) lbr (list c d)))
+      (check-equal? (linewrap (list x x hyph x x) 4) (list (list x x hyph) lbr (list x x)))
+      (check-equal? (linewrap (list x x hyph x x) 5) (list (list x x hyph x x))))
+
+     (test-case
+      "soft hyphens"
+      (check-equal? (linewrap (list shy) 1) (list))
+      (check-equal? (linewrap (list shy shy) 2) (list))
+      (check-equal? (linewrap (list shy shy shy) 2) (list))
+      (check-equal? (linewrap (list x shy) 1) (list (list x)))
+      (check-equal? (linewrap (list x shy shy shy shy) 1) (list (list x)))
+      ;; todo: degenerate cases that don't work without continuations
+      ;(check-equal? (linewrap (list x x shy x x) 1) (list x br x br x br x))
+      ;(check-equal? (linewrap (list x x shy x x) 2) (list x x br x x))
+      (check-equal? (linewrap (list x x shy x x) 3) (list (list x x shy) lbr (list x x)))
+      (check-equal? (linewrap (list x x shy x x) 4) (list (list x x x x)))
+      (check-equal? (linewrap (list x x shy x x) 5) (list (list x x x x)))
+      (check-equal? (linewrap (list x x shy x sp x) 4) (list (list x x x) lbr (list x))))
+
+     (test-case
+      "zero width nonbreakers"
+      (check-equal? (linewrap (list sp zwx) 2) (list (list zwx)))
+      (check-equal? (linewrap (list zwx sp) 2) (list (list zwx)))
+      (check-equal? (linewrap (list sp zwx sp) 2) (list (list zwx)))
+      (check-equal? (linewrap (list sp sp zwx sp sp) 2) (list (list zwx)))
+      (check-equal? (linewrap (list sp sp zwx sp sp zwx sp) 2) (list (list zwx sp sp zwx))))
+
+     (test-case
+      "hard breaks"
+      (check-equal? (linewrap (list lbr) 2) (list)) ;; only insert a break if it's between things
+      (check-equal? (linewrap (list a lbr b) 2) (list (list a) lbr (list b)))
+      (check-equal? (linewrap (list a b lbr) 2) (list (list a b)))
+      (check-equal? (linewrap (list a b lbr lbr) 2) (list (list a b) lbr (list)))
+      (check-equal? (linewrap (list x lbr x x) 3) (list (list x) lbr (list x x)))
+      (check-equal? (linewrap (list x x lbr x) 3) (list (list x x) lbr (list x)))
+      (check-equal? (linewrap (list x x x x) 3) (list (list x x x) lbr (list x)))
+      (check-equal? (linewrap (list x x x sp x x) 2) (list (list x x) lbr (list x) lbr (list x x)))
+      (check-equal? (linewrap (list x x x sp x x) 3) (list (list x x x) lbr (list x x))))
+
+
+     (test-case
+      "hard breaks and spurious spaces"
+      (check-equal? (linewrap (list a sp sp sp lbr b) 2) (list (list a) lbr (list b)))
+      (check-equal? (linewrap (list a sp lbr sp sp b c sp) 3) (list (list a) lbr (list b c)))
+      (check-equal? (linewrap (list sp sp x x sp sp lbr sp sp sp x) 3) (list (list x x) lbr (list x)))
+      (check-equal? (linewrap (list a sp b sp sp lbr sp c) 3) (list (list a sp b) lbr (list c)))
+      (check-equal? (linewrap (list x x x x) 3) (list (list x x x) lbr (list x)))
+      (check-equal? (linewrap (list x x x sp x x) 2) (list (list x x) lbr (list x) lbr (list x x)))
+      (check-equal? (linewrap (list x x x sp x x) 3) (list (list x x x) lbr (list x x))))
+
+     (test-case
+      "visual breaks"
+      (check-equal? (visual-wrap "My dog has fleas" 1) "M|y|d|o|g|h|a|s|f|l|e|a|s")
+      (check-equal? (visual-wrap "My dog has fleas" 2) "My|do|g|ha|s|fl|ea|s")
+      (check-equal? (visual-wrap "My dog has fleas" 3) "My|dog|has|fle|as")
+      (check-equal? (visual-wrap "My dog has fleas" 4) "My|dog|has|flea|s")
+      (check-equal? (visual-wrap "My dog has fleas" 5) "My|dog|has|fleas")
+      (check-equal? (visual-wrap "My dog has fleas" 6) "My dog|has|fleas")
+      (check-equal? (visual-wrap "My dog has fleas" 7) "My dog|has|fleas")
+      (check-equal? (visual-wrap "My dog has fleas" 8) "My dog|has|fleas")
+      (check-equal? (visual-wrap "My dog has fleas" 9) "My dog|has fleas")
+      (check-equal? (visual-wrap "My dog has fleas" 10) "My dog has|fleas")
+      (check-equal? (visual-wrap "My dog has fleas" 11) "My dog has|fleas")
+      (check-equal? (visual-wrap "My dog has fleas" 12) "My dog has|fleas")
+      (check-equal? (visual-wrap "My dog has fleas" 13) "My dog has|fleas")
+      (check-equal? (visual-wrap "My dog has fleas" 14) "My dog has|fleas")
+      (check-equal? (visual-wrap "My dog has fleas" 15) "My dog has|fleas")
+      (check-equal? (visual-wrap "My dog has fleas" 16) "My dog has fleas"))
+
+     (test-case
+      "soft page breaks"
+      (check-equal? (pagewrap null 2) (list))
+      (check-equal? (pagewrap (list x) 2) (list (list x)))
+      (check-equal? (pagewrap (list x x) 2) (list (list x x)))
+      (check-equal? (pagewrap (list x x x) 1) (list (list x) pbr (list x) pbr (list x)))
+      (check-equal? (pagewrap (list x x x) 2) (list (list x x) pbr (list x)))
+      (check-equal? (pagewrap (list x x x) 3) (list (list x x x)))
+      (check-equal? (pagewrap (list x x x) 4) (list (list x x x)))
+      (check-equal? (pagewrap (list x lbr x x) 2) (list (list x) pbr (list x x))))
+
+     (test-case
+      "hard page breaks"
+      (check-equal? (pagewrap (list a pbr b c) 2) (list (list a) pbr (list b c)))
+      (check-equal? (pagewrap (list x pbr x x) 1) (list (list x) pbr (list x) pbr (list x)))
+      (check-equal? (pagewrap (list x pbr pbr x x) 1) (list (list x) pbr (list) pbr (list x) pbr (list x)))
+      (check-equal? (pagewrap (list x pbr pbr x x) 2) (list (list x) pbr (list) pbr (list x x)))
+      (check-equal? (pagewrap (list lbr x lbr lbr pbr lbr x x lbr) 2) (list (list x) pbr (list x x))))
+
+     (test-case
+      "composed line breaks and page breaks"
+      (check-equal? (pagewrap (linewrap null 1) 2) (list))
+      (check-equal? (pagewrap (linewrap (list x) 1) 2) (list (list x)))
+      (check-equal? (pagewrap (linewrap (list x x x) 1) 2) (list (list x lbr x) pbr (list x)))
+      (check-equal? (pagewrap (linewrap (list x x x) 2) 2) (list (list x x) pbr (list x)))
+      (check-equal? (pagewrap (linewrap (list x x x) 2) 1) (list (list x) pbr (list x) pbr (list x))))
+
+     (test-case
+      "hard breaks and spurious spaces with slugs"
+      (check-equal? (linewrap2 (list a sp sp sp lbr b) 2) (list (q a) lbr (q b)))
+      (check-equal? (linewrap2 (list x sp lbr sp sp x x sp) 3) (list (q x) lbr (q x x)))
+      (check-equal? (linewrap2 (list sp sp x x sp sp lbr sp sp sp x) 3) (list (q x x) lbr (q x)))
+      (check-equal? (linewrap2 (list a sp b sp sp lbr sp c) 3) (list (q a sp b) lbr (q c)))
+      (check-equal? (linewrap2 (list x x x x) 3) (list (q x x x) lbr (q x)))
+      (check-equal? (linewrap2 (list x x x sp x x) 2) (list (q x x) lbr (q x) lbr (q x x)))
+      (check-equal? (linewrap2 (list x x x sp x x) 3) (list (q x x x) lbr (q x x))))))