From 5de6ff2ada89c94e0f854dfd44e95471b6df0dc5 Mon Sep 17 00:00:00 2001
From: Robby Findler <robby@racket-lang.org>
Date: Tue, 24 Aug 2010 13:45:53 -0500
Subject: [PATCH] Adjusts the prompt handling so that it submits expressions
 that signal arbitrary read errors, but does not submit those that raise eof
 errors. closes PR 11126

---
 collects/framework/main.rkt           |  7 +++++--
 collects/framework/private/scheme.rkt | 15 +++++++++------
 collects/tests/framework/scheme.rkt   |  7 ++++---
 3 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/collects/framework/main.rkt b/collects/framework/main.rkt
index 7568e710ff..c4e3fe8bbc 100644
--- a/collects/framework/main.rkt
+++ b/collects/framework/main.rkt
@@ -1327,10 +1327,13 @@
                @scheme[end] in @scheme[text] has at least one complete s-expression and
                there are no incomplete s-expressions.  If
                @scheme[end] is @scheme[#f], it defaults to the last position of the
-               @scheme[text].
+               @scheme[text]. The designation ``complete'' is defined to be something that does not
+               cause @racket[read] to raise a @racket[exn:fail:read:eof?] exception,
+               so there may be all kinds of strange read-level (not to speak of parse level) 
+               errors in the expressions.
                
                The implementation of this function creates a port with
-               @scheme[open-input-text-editor] and then uses `read' to parse the
+               @scheme[open-input-text-editor] and then uses @racket[read] to parse the
                range of the buffer.})
  
  (proc-doc/names
diff --git a/collects/framework/private/scheme.rkt b/collects/framework/private/scheme.rkt
index 836d1e8e97..07e72d9232 100644
--- a/collects/framework/private/scheme.rkt
+++ b/collects/framework/private/scheme.rkt
@@ -44,13 +44,16 @@
     (let* ([end (or in-end (send text last-position))]
            [port (open-input-text-editor text start end)])
       (with-handlers ([exn:fail:read:eof? (λ (x) #f)]
-                      [exn:fail:read? (λ (x) #f)])
+                      [exn:fail:read? (λ (x) #t)])
         (let ([first (read port)])
-          (and (not (eof-object? first))
-               (let loop ()
-                 (let ([s (read port)])
-                   (or (eof-object? s)
-                       (loop))))))))))
+          (cond
+            [(eof-object? first) #f]
+            [else
+             (let loop ()
+               (let ([s (read port)])
+                 (cond
+                   [(eof-object? s) #t]
+                   [else (loop)])))]))))))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;                                                                  ;;
diff --git a/collects/tests/framework/scheme.rkt b/collects/tests/framework/scheme.rkt
index c31c5cc6ab..6f5129a63b 100644
--- a/collects/tests/framework/scheme.rkt
+++ b/collects/tests/framework/scheme.rkt
@@ -21,10 +21,11 @@
 
 (test-text-balanced? 0 "" 0 #f #f)
 (test-text-balanced? 1 "  \n " 0 #f #f)
-(test-text-balanced? 2 "foo)" 0 #f #f)
+(test-text-balanced? 2 "foo)" 0 #f #t)
 (test-text-balanced? 3 "(foo" 0 #f #f)
 (test-text-balanced? 4 "(foo)" 0 #f #t)
-(test-text-balanced? 5 "(foo 'bar))" 0 #f #f)
+(test-text-balanced? 5 "(foo 'bar))" 0 #f #t)
 (test-text-balanced? 6 "(foo) bar ([buz])" 0 #f #t)
-(test-text-balanced? 7 "(foo]" 0 #f #f)
+(test-text-balanced? 7 "(foo]" 0 #f #t)
 (test-text-balanced? 8 "{foo} ((bar) [5.9])" 0 #f #t)
+(test-text-balanced? 9 "#(1 2 . 3)" 0 #f #t)