Change "union value" to dynamically allocate long strings.

[pspp-builds.git] / src / data / casewriter-translator.c

diff --git a/src/data/casewriter-translator.c b/src/data/casewriter-translator.c
index 7252eaa50542bafdd627ce44c56eda881a8c6351..e80b9d68187b3f65e33b35051b0b6d891ca5f312 100644 (file)
--- a/src/data/casewriter-translator.c
+++ b/src/data/casewriter-translator.c
@@ -1,20 +1,18 @@
-/* PSPP - computes sample statistics.
-   Copyright (C) 2007 Free Software Foundation, Inc.
+/* PSPP - a program for statistical analysis.
+   Copyright (C) 2007, 2009 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>
 
@@ -31,19 +29,36 @@ struct casewriter_translator
   {
     struct casewriter *subwriter;
 
-    void (*translate) (const struct ccase *input, struct ccase *output,
-                       void *aux);
+    struct ccase *(*translate) (struct ccase *, void *aux);
     bool (*destroy) (void *aux);
     void *aux;
   };
 
-static struct casewriter_class casewriter_translator_class;
+static const struct casewriter_class casewriter_translator_class;
 
+/* Creates and returns a new casewriter whose cases are passed
+   through TRANSLATE, based on INPUT and auxiliary data AUX.
+   (TRANSLATE may also return a null pointer, in which case no
+   case is written to the output.)  The translated cases are then
+   written to SUBWRITER.
+
+   The cases returned by TRANSLATE must match OUTPUT_PROTO.
+
+   TRANSLATE takes ownership of each case passed to it.  Thus, it
+   should either unref each case and return a new case, or
+   (unshare and then) modify and return the same case.
+
+   When the translating casewriter is destroyed, DESTROY will be
+   called to allow any state maintained by TRANSLATE to be freed.
+
+   After this function is called, SUBWRITER must not ever again
+   be referenced directly.  It will be destroyed automatically
+   when the translating casewriter is destroyed. */
 struct casewriter *
 casewriter_create_translator (struct casewriter *subwriter,
-                              void (*translate) (const struct ccase *input,
-                                                 struct ccase *output,
-                                                 void *aux),
+                              const struct caseproto *translated_proto,
+                              struct ccase *(*translate) (struct ccase *,
+                                                          void *aux),
                               bool (*destroy) (void *aux),
                               void *aux)
 {
@@ -53,7 +68,8 @@ casewriter_create_translator (struct casewriter *subwriter,
   ct->translate = translate;
   ct->destroy = destroy;
   ct->aux = aux;
-  writer = casewriter_create (&casewriter_translator_class, ct);
+  writer = casewriter_create (translated_proto,
+                              &casewriter_translator_class, ct);
   taint_propagate (casewriter_get_taint (ct->subwriter),
                    casewriter_get_taint (writer));
   return writer;
@@ -64,10 +80,9 @@ casewriter_translator_write (struct casewriter *writer UNUSED,
                              void *ct_, struct ccase *c)
 {
   struct casewriter_translator *ct = ct_;
-  struct ccase tmp;
-
-  ct->translate (c, &tmp, ct->aux);
-  casewriter_write (ct->subwriter, &tmp);
+  c = ct->translate (c, ct->aux);
+  if (c != NULL)
+    casewriter_write (ct->subwriter, c);
 }
 
 static void
@@ -90,7 +105,7 @@ casewriter_translator_convert_to_reader (struct casewriter *writer UNUSED,
   return reader;
 }
 
-static struct casewriter_class casewriter_translator_class =
+static const struct casewriter_class casewriter_translator_class =
   {
     casewriter_translator_write,
     casewriter_translator_destroy,