Fix bug #20910.

[pspp-builds.git] / src / data / casereader.c

diff --git a/src/data/casereader.c b/src/data/casereader.c
index 3c062d9068b6355ace4f8e3caf005b89cd7c25ad..27c6148bc1c538e2e308edafc42ee4c3f203b236 100644 (file)
--- a/src/data/casereader.c
+++ b/src/data/casereader.c
@@ -1,20 +1,18 @@
-/* PSPP - computes sample statistics.
+/* PSPP - a program for statistical analysis.
    Copyright (C) 2007 Free Software Foundation, Inc.
 
-   This program is free software; you can redistribute it and/or
-   modify it under the terms of the GNU General Public License as
-   published by the Free Software Foundation; either version 2 of the
-   License, or (at your option) any later version.
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
 
-   This program is distributed in the hope that it will be useful, but
-   WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   General Public License for more details.
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
-   along with this program; if not, write to the Free Software
-   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
-   02110-1301, USA. */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>. */
 
 #include <config.h>
 
@@ -60,7 +58,7 @@ casereader_read (struct casereader *reader, struct ccase *c)
 {
   if (reader->case_cnt != 0 && reader->class->read (reader, reader->aux, c))
     {
-      assert (case_get_value_cnt (c) == reader->value_cnt);
+      assert (case_get_value_cnt (c) >= reader->value_cnt);
       if (reader->case_cnt != CASENUMBER_MAX)
         reader->case_cnt--;
       return true;
@@ -313,6 +311,26 @@ casereader_create_sequential (const struct taint *taint,
   reader->aux = aux;
   return reader;
 }
+
+/* If READER is a casereader of the given CLASS, returns its
+   associated auxiliary data; otherwise, returns a null pointer.
+
+   This function is intended for use from casereader
+   implementations, not by casereader users.  Even within
+   casereader implementations, its usefulness is quite limited,
+   for at least two reasons.  First, every casereader member
+   function already receives a pointer to the casereader's
+   auxiliary data.  Second, a casereader's class can change
+   (through a call to casereader_swap) and this is in practice
+   quite common (e.g. any call to casereader_clone on a
+   casereader that does not directly support clone will cause the
+   casereader to be replaced by a shim caseader). */
+void *
+casereader_dynamic_cast (struct casereader *reader,
+                         struct casereader_class *class)
+{
+  return reader->class == class ? reader->aux : NULL;
+}
 \f
 /* Random-access casereader implementation.