6 files changed, 43 insertions, 4 deletions
diff --git a/ext/psych/psych.c b/ext/psych/psych.c
index a218117..3333ab1 100644
--- a/ext/psych/psych.c
+++ b/ext/psych/psych.c
@@ -26,4 +26,5 @@ void Init_psych()
   Init_psych_parser();
   Init_psych_emitter();
   Init_psych_to_ruby();
+  Init_psych_yaml_tree();
 }
diff --git a/ext/psych/psych.h b/ext/psych/psych.h
index eea82f8..76a826b 100644
--- a/ext/psych/psych.h
+++ b/ext/psych/psych.h
@@ -6,6 +6,8 @@
 
 #include <parser.h>
 #include <emitter.h>
+#include <to_ruby.h>
+#include <yaml_tree.h>
 
 extern VALUE mPsych;
 
diff --git a/ext/psych/to_ruby.h b/ext/psych/to_ruby.h
index d4936a8..7b8e757 100644
--- a/ext/psych/to_ruby.h
+++ b/ext/psych/to_ruby.h
@@ -3,6 +3,6 @@
 
 #include <psych.h>
 
-void Init_psych_to_ruby();
+void Init_psych_to_ruby(void);
 
 #endif
diff --git a/ext/psych/yaml_tree.c b/ext/psych/yaml_tree.c
new file mode 100644
index 0000000..500883d
--- /dev/null
+++ b/ext/psych/yaml_tree.c
@@ -0,0 +1,23 @@
+#include <psych.h>
+
+VALUE cPsychVisitorsYamlTree;
+
+/*
+ * call-seq: private_iv_get(target, prop)
+ *
+ * Get the private instance variable +prop+ from +target+
+ */
+static VALUE private_iv_get(VALUE self, VALUE target, VALUE prop)
+{
+  return rb_attr_get(target, rb_intern(StringValuePtr(prop)));
+}
+
+void Init_psych_yaml_tree(void)
+{
+  VALUE psych     = rb_define_module("Psych");
+  VALUE visitors  = rb_define_module_under(psych, "Visitors");
+  VALUE visitor   = rb_define_class_under(visitors, "Visitor", rb_cObject);
+  cPsychVisitorsYamlTree = rb_define_class_under(visitors, "YAMLTree", visitor);
+
+  rb_define_private_method(cPsychVisitorsYamlTree, "private_iv_get", private_iv_get, 2);
+}
diff --git a/ext/psych/yaml_tree.h b/ext/psych/yaml_tree.h
new file mode 100644
index 0000000..4628a69
--- /dev/null
+++ b/ext/psych/yaml_tree.h
@@ -0,0 +1,8 @@
+#ifndef PSYCH_YAML_TREE_H
+#define PSYCH_YAML_TREE_H
+
+#include <psych.h>
+
+void Init_psych_yaml_tree(void);
+
+#endif
diff --git a/lib/psych/visitors/yaml_tree.rb b/lib/psych/visitors/yaml_tree.rb
index 0f0e3ba..57d23e2 100644
--- a/lib/psych/visitors/yaml_tree.rb
+++ b/lib/psych/visitors/yaml_tree.rb
@@ -62,11 +62,16 @@ module Psych
       end
 
       def visit_Exception o
-        tag = ['!ruby/exception', o.class.name].compact.join(':')
+        tag = ['!ruby/exception', o.class.name].join ':'
         @stack.push append Nodes::Mapping.new(nil, tag, false)
 
-        ['message', o.message].each do |m|
-          accept m
+        {
+          'message'   => private_iv_get(o, 'mesg'),
+          'backtrace' => private_iv_get(o, 'backtrace'),
+        }.each do |k,v|
+          next unless v
+          append Nodes::Scalar.new k
+          accept v
         end
 
         if o.respond_to? :to_yaml_properties