From 79d2daaaeb4e9c8e274752cba02fe73f177bd393 Mon Sep 17 00:00:00 2001
From: Matthew Butterick <mb@mbtype.com>
Date: Sat, 27 Jun 2015 13:22:30 -0700
Subject: [PATCH] correct handling of `valid-char?` for 6.0

---
 txexpr/core-predicates.rkt | 19 +++++++++++++++++--
 txexpr/tests.rkt           |  2 ++
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/txexpr/core-predicates.rkt b/txexpr/core-predicates.rkt
index 0a077b3..270fbaf 100644
--- a/txexpr/core-predicates.rkt
+++ b/txexpr/core-predicates.rkt
@@ -1,6 +1,21 @@
 #lang racket/base
-(require sugar/define xml racket/match)
-(provide (all-defined-out) valid-char? cdata? cdata xexpr->string xexpr?)
+(require sugar/define (prefix-in xml: xml) racket/match)
+(provide (all-defined-out) cdata? cdata xexpr->string xexpr?)
+
+; Section 2.2 of XML 1.1
+; (XML 1.0 is slightly different and more restrictive)
+(define (valid-char? i)
+  (and (exact-nonnegative-integer? i)
+       (or (<= #x1     i #xD7FF)
+           (<= #xE000  i #xFFFD)
+           (<= #x10000 i #x10FFFF))))
+
+(define (xexpr? x)
+  (or (txexpr? x) (xml:xexpr? x) (valid-char? x)))
+
+(define cdata xml:cdata)
+(define cdata? xml:cdata?)
+(define xexpr->string xml:xexpr->string)
 
 (define (txexpr-short? x)
   (match x
diff --git a/txexpr/tests.rkt b/txexpr/tests.rkt
index 3b74fa4..8d28317 100644
--- a/txexpr/tests.rkt
+++ b/txexpr/tests.rkt
@@ -68,6 +68,8 @@
  (check-false (txexpr-elements? '("foo" "bar" ((key "value"))))) ; malformed
  
  (check-true (txexpr? '(p)))
+ (check-true (txexpr? '(div 2)))
+ (check-true (txexpr? '(div (div ((foo "bar")) 2))))
  (check-true (txexpr? '(p "foo" "bar")))
  (check-true (txexpr? '(p ((key "value")) "foo" "bar")))
  (check-true (txexpr? '(p 123))) ; content is a number