* casereader-translator.c (struct casereader_translator): Change

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

diff --git a/src/data/casereader-translator.c b/src/data/casereader-translator.c
index b409beeb1c166541b7d4f98469303f904b6ad40c..5a717da8252a15de221728734e39e0d6f4210aab 100644 (file)
--- a/src/data/casereader-translator.c
+++ b/src/data/casereader-translator.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>
 
@@ -27,22 +25,37 @@
 
 #include "xalloc.h"
 
+/* Casereader that applies a user-supplied function to translate
+   each case into another in an arbitrary fashion. */
+
+/* A translating casereader. */
 struct casereader_translator
   {
-    struct casereader *subreader;
+    struct casereader *subreader; /* Source of input cases. */
 
-    void (*translate) (const struct ccase *input, struct ccase *output,
-                       void *aux);
+    void (*translate) (struct ccase *input, struct ccase *output, void *aux);
     bool (*destroy) (void *aux);
     void *aux;
   };
 
 static struct casereader_class casereader_translator_class;
 
+/* Creates and returns a new casereader whose cases are produced
+   by reading from SUBREADER and passing through TRANSLATE, which
+   must create case OUTPUT, with OUTPUT_VALUE_CNT values, and
+   populate it based on INPUT and auxiliary data AUX.  TRANSLATE
+   must also destroy INPUT.
+
+   When the translating casereader is destroyed, DESTROY will be
+   called to allow any state maintained by TRANSLATE to be freed.
+
+   After this function is called, SUBREADER must not ever again
+   be referenced directly.  It will be destroyed automatically
+   when the translating casereader is destroyed. */
 struct casereader *
 casereader_create_translator (struct casereader *subreader,
                               size_t output_value_cnt,
-                              void (*translate) (const struct ccase *input,
+                              void (*translate) (struct ccase *input,
                                                  struct ccase *output,
                                                  void *aux),
                               bool (*destroy) (void *aux),
@@ -62,6 +75,7 @@ casereader_create_translator (struct casereader *subreader,
   return reader;
 }
 
+/* Internal read function for translating casereader. */
 static bool
 casereader_translator_read (struct casereader *reader UNUSED,
                             void *ct_, struct ccase *c)
@@ -78,6 +92,7 @@ casereader_translator_read (struct casereader *reader UNUSED,
     return false;
 }
 
+/* Internal destroy function for translating casereader. */
 static void
 casereader_translator_destroy (struct casereader *reader UNUSED, void *ct_)
 {
@@ -87,6 +102,7 @@ casereader_translator_destroy (struct casereader *reader UNUSED, void *ct_)
   free (ct);
 }
 
+/* Casereader class for translating casereader. */
 static struct casereader_class casereader_translator_class =
   {
     casereader_translator_read,