From dc2a89f853987f4aa2ab0fdad3ffd7f5a46bc105 Mon Sep 17 00:00:00 2001
From: Alexandre Duret-Lutz <adl@lrde.epita.fr>
Date: Mon, 17 Jan 2011 21:52:59 +0100
Subject: [PATCH] Do not output empty parse error blocks in the CGI script.

* wrap/python/spot.i: Provide a __nonzero__() method for
parse_error_list.
* wrap/python/cgi-bin/ltl2tgba.in: Do not call format_parse_errors()
unconditionally.
---
 ChangeLog                       |  9 +++++++++
 wrap/python/cgi-bin/ltl2tgba.in |  7 ++++---
 wrap/python/spot.i              | 10 ++++++++++
 3 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 646c7184a..130835ad5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2011-01-17  Alexandre Duret-Lutz  <adl@lrde.epita.fr>
+
+	Do not output empty parse error blocks in the CGI script.
+
+	* wrap/python/spot.i: Provide a __nonzero__() method for
+	parse_error_list.
+	* wrap/python/cgi-bin/ltl2tgba.in: Do not call format_parse_errors()
+	unconditionally.
+
 2011-01-12  Alexandre Duret-Lutz  <adl@lrde.epita.fr>
 
 	Fix "unused function" warnings reported by clang++.
diff --git a/wrap/python/cgi-bin/ltl2tgba.in b/wrap/python/cgi-bin/ltl2tgba.in
index 173665cc6..c0a7fad70 100755
--- a/wrap/python/cgi-bin/ltl2tgba.in
+++ b/wrap/python/cgi-bin/ltl2tgba.in
@@ -497,9 +497,10 @@ pel = spot.empty_parse_error_list()
 f = spot.parse(formula, pel, env, show_parse)
 if show_parse: print '</pre>'
 
-print '<font color="red"><pre>'
-err = spot.format_parse_errors(spot.get_cout(), formula, pel)
-print '</pre></font>'
+if pel:
+    print '<font color="red"><pre>'
+    err = spot.format_parse_errors(spot.get_cout(), formula, pel)
+    print '</pre></font>'
 
 if not f:
     print '<p><b>Aborting...</b></p>'
diff --git a/wrap/python/spot.i b/wrap/python/spot.i
index 5d44707e9..de4866e62 100644
--- a/wrap/python/spot.i
+++ b/wrap/python/spot.i
@@ -280,3 +280,13 @@ unblock_signal(int signum)
 }
 
 %}
+
+%extend spot::ltl::parse_error_list {
+
+bool
+__nonzero__()
+{
+  return !self->empty();
+}
+
+}
-- 
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