--- /dev/null
+/* PSPP - computes sample statistics.
+ Copyright (C) 1997-9, 2000, 2006 Free Software Foundation, Inc.
+ Written by Ben Pfaff <blp@gnu.org>.
+
+ 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 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. */
+
+#ifndef CASE_SINK_H
+#define CASE_SINK_H 1
+
+#include <stdbool.h>
+#include <stddef.h>
+
+struct ccase;
+struct dictionary;
+
+/* A case sink. */
+struct case_sink
+ {
+ const struct case_sink_class *class; /* Class. */
+ void *aux; /* Auxiliary data. */
+ size_t value_cnt; /* Number of `union value's in case. */
+ };
+
+/* A case sink class. */
+struct case_sink_class
+ {
+ const char *name; /* Identifying name. */
+
+ /* Opens the sink for writing. */
+ void (*open) (struct case_sink *);
+
+ /* Writes a case to the sink. */
+ bool (*write) (struct case_sink *, const struct ccase *);
+
+ /* Closes and destroys the sink. */
+ void (*destroy) (struct case_sink *);
+
+ /* Closes the sink and returns a source that can read back
+ the cases that were written, perhaps transformed in some
+ way. The sink must still be separately destroyed by
+ calling destroy(). */
+ struct case_source *(*make_source) (struct case_sink *);
+ };
+
+extern const struct case_sink_class null_sink_class;
+
+struct case_sink *create_case_sink (const struct case_sink_class *,
+ const struct dictionary *,
+ void *);
+void free_case_sink (struct case_sink *);
+
+#endif /* case-sink.h */