X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Fdata%2Fcasewriter-translator.c;h=e80b9d68187b3f65e33b35051b0b6d891ca5f312;hb=ebbfbe937906e4b4ca577478965cf06d1a812715;hp=f2a0b68e6a5683d6c903ed40de0510ca4f88742c;hpb=43b1296aafe7582e7dbe6c2b6a8b478d7d9b0fcf;p=pspp-builds.git

diff --git a/src/data/casewriter-translator.c b/src/data/casewriter-translator.c
index f2a0b68e..e80b9d68 100644
--- a/src/data/casewriter-translator.c
+++ b/src/data/casewriter-translator.c
@@ -1,5 +1,5 @@
 /* PSPP - a program for statistical analysis.
-   Copyright (C) 2007 Free Software Foundation, Inc.
+   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
@@ -29,19 +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)
 {
@@ -51,7 +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;
@@ -62,10 +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
@@ -88,7 +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,