From 7f4007a7c4587d737da4b7a2da9de462f0e8831d Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Tue, 3 Sep 2013 12:49:14 +0200
Subject: Handling of dynamic empty statements as result of versioning

---
 odb/statement-processing.cxx | 57 ++++++++++++++++++++++++++------------------
 1 file changed, 34 insertions(+), 23 deletions(-)

diff --git a/odb/statement-processing.cxx b/odb/statement-processing.cxx
index ed5bad5..f17e9ca 100644
--- a/odb/statement-processing.cxx
+++ b/odb/statement-processing.cxx
@@ -480,31 +480,14 @@ namespace odb
       }
     }
 
-    // Trailer.
-    //
-    const char* trailer_begin (0);
-    size_t trailer_size (0);
-    if (e - p != 0)
-    {
-      trailer_begin = p;
-      trailer_size = e - p;
-    }
-
     // Empty case.
     //
     if (empty)
     {
-      r.reserve (header_size + (trailer_size == 0 ? 0 : trailer_size + 1));
-      r.assign (s, header_size);
-
-      if (trailer_size != 0)
-      {
-        r += ' ';
-        r.append (trailer_begin, trailer_size);
-      }
+      r.clear ();
 
 #ifdef LIBODB_TRACE_STATEMENT_PROCESSING
-      if (r.size () != n)
+      if (n != 0)
         cerr << endl
              << "old: '" << s << "'" << endl << endl
              << "new: '" << r << "'" << endl << endl;
@@ -513,6 +496,16 @@ namespace odb
       return;
     }
 
+    // Trailer.
+    //
+    const char* trailer_begin (0);
+    size_t trailer_size (0);
+    if (e - p != 0)
+    {
+      trailer_begin = p;
+      trailer_size = e - p;
+    }
+
     // Assume the same size as the original. It can only shrink, and in
     // most cases only slightly. So this is a good approximation.
     //
@@ -575,13 +568,32 @@ namespace odb
 #endif
                   string& r)
   {
-    bool fast (true); // Fast case (if all present).
-    for (size_t i (0); i != bind_size && fast; ++i)
+    bool empty (true); // Empty case (if none present).
+    bool fast (true);  // Fast case (if all present).
+    for (size_t i (0); i != bind_size && (empty || fast); ++i)
     {
-      if (bind_at (i, bind, bind_skip) == 0)
+      if (bind_at (i, bind, bind_skip) != 0)
+        empty = false;
+      else
         fast = false;
     }
 
+    // Empty.
+    //
+    if (empty)
+    {
+      r.clear ();
+
+#ifdef LIBODB_TRACE_STATEMENT_PROCESSING
+      if (*s != '\0')
+        cerr << endl
+             << "old: '" << s << "'" << endl << endl
+             << "new: '" << r << "'" << endl << endl;
+#endif
+
+      return;
+    }
+
     // Fast path: just remove the "structure".
     //
 #ifndef LIBODB_DEBUG_STATEMENT_PROCESSING
@@ -620,7 +632,6 @@ namespace odb
     if (p != e)
       p++;
 
-
     // JOIN list.
     //
     const char* joins_begin (0), *joins_end (0);
-- 
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