From d6332dfe78f687ab77050c4c03452cb514ca297c Mon Sep 17 00:00:00 2001
From: Matthew Butterick <mb@mbtype.com>
Date: Wed, 17 Feb 2016 10:22:15 -0800
Subject: [PATCH] fix some defective logic with handling empty strings

---
 pollen/decode.rkt         | 13 +++++--------
 pollen/private/splice.rkt | 14 ++++++++++++--
 pollen/private/ts.rktd    |  2 +-
 3 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/pollen/decode.rkt b/pollen/decode.rkt
index 4375eda..42f0da3 100644
--- a/pollen/decode.rkt
+++ b/pollen/decode.rkt
@@ -1,13 +1,9 @@
 #lang racket/base
 (require xml txexpr racket/list sugar/list sugar/define sugar/test)
-(require "setup.rkt"
-         "private/whitespace.rkt")
+(require "setup.rkt" "private/splice.rkt")
 
 (require "unstable/typography.rkt")
-(provide (all-from-out "unstable/typography.rkt")) ; bw compat
-
-(require "private/whitespace.rkt")
-(provide (all-from-out "private/whitespace.rkt")) ; bw compat
+(provide (all-from-out "unstable/typography.rkt")) ; bw compat, includes `whitespace?`
 
 (define (->list/tx x)
   ;; same as ->list but catches special case of single txexpr,
@@ -170,7 +166,7 @@
         xs))
   (define not-empty-string? (λ(x) (not (and (string? x) (= (string-length x) 0)))))
   (let loop ([x x])
-    (if (pair? x)
+    (if (and (pair? x) (not (attrs? x)))
         (let ([xs (map loop (filter not-empty-string? x))])
           (append-map merge-if-newlines (slicef xs newlines?)))
         x)))
@@ -178,7 +174,8 @@
 (module-test-external
  (require racket/list)
  (check-equal? (merge-newlines empty) empty)
- (check-equal? (merge-newlines '(p "\n" "" "\n")) '(p "\n\n"))
+(check-equal? (merge-newlines '((p ((id "")) "\n" "" "\n"))) '((p ((id "")) "\n\n")))
+ (check-equal? (merge-newlines '((p "\n" "" "\n"))) '((p "\n\n")))
  (check-equal? (merge-newlines '(p "\n" "\n" "foo" "\n" "\n\n" "bar" (em "\n" "\n" "\n"))) 
                '(p "\n\n" "foo" "\n\n\n" "bar" (em "\n\n\n"))))
 
diff --git a/pollen/private/splice.rkt b/pollen/private/splice.rkt
index 9a9e4fb..20bbb36 100644
--- a/pollen/private/splice.rkt
+++ b/pollen/private/splice.rkt
@@ -4,12 +4,21 @@
 ;; (string->symbol (format "~a" #\u200B))
 (define splice-signal-tag '@)
 
+(define (attrs? x)
+  (and (list? x)
+       (andmap (λ(xi)
+                 (and (list? xi)
+                      (= (length xi) 2)
+                      (symbol? (car xi))
+                      (string? (cadr xi)))) x)))
+
+
 (define (splice x [splicing-tag splice-signal-tag])
   ;  (listof txexpr-elements?) . -> . (listof txexpr-elements?))
   (define spliceable? (λ(x) (and (pair? x) (eq? (car x) splicing-tag))))
   (define not-null-string? (λ(x) (not (and (string? x) (= (string-length x) 0)))))
   (let loop ([x x])
-    (if (list? x)
+    (if (and (list? x) (not (attrs? x))) ; don't splice null strings inside attrs
         (apply append (map (λ(x) ((if (spliceable? x)
                                       cdr
                                       list) (loop x))) (filter not-null-string? x)))
@@ -22,7 +31,8 @@
   (check-equal? (splice `((,splice-signal-tag 1 (,splice-signal-tag 2 "" (,splice-signal-tag 3 (div 4 (,splice-signal-tag 5))) 6) "" 7)))
                 '(1 2 3 (div 4 5) 6 7))
   (check-equal? (splice `((,splice-signal-tag "foo" "" "bar"))) '("foo" "bar"))
-  (check-equal? (splice null) null))
+  (check-equal? (splice null) null)
+  (check-equal? (splice '(a ((href "")(foo "bar")) "zam")) '(a ((href "")(foo "bar")) "zam")))
 
 
 (define (strip-empty-attrs x)
diff --git a/pollen/private/ts.rktd b/pollen/private/ts.rktd
index 42584b1..8311203 100644
--- a/pollen/private/ts.rktd
+++ b/pollen/private/ts.rktd
@@ -1 +1 @@
-1455676575
+1455733334