Make cases simpler, faster, and easier to understand.

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

diff --git a/src/data/casewriter.c b/src/data/casewriter.c
index a30e50e20983f1f88adde7463931ad3ad4430c1b..56e6c291cbb4fb7722a310eeb504b20bb58a37d5 100644 (file)
--- a/src/data/casewriter.c
+++ b/src/data/casewriter.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
@@ -91,8 +91,7 @@ casewriter_get_value_cnt (const struct casewriter *writer)
 struct casereader *
 casewriter_make_reader (struct casewriter *writer)
 {
-  struct casereader *reader;
-  reader = writer->class->convert_to_reader (writer, writer->aux);
+  struct casereader *reader = writer->class->convert_to_reader (writer, writer->aux);
   taint_propagate (writer->taint, casereader_get_taint (reader));
   taint_destroy (writer->taint);
   free (writer);
@@ -241,27 +240,29 @@ casewriter_window_convert_to_reader (struct casewriter *writer UNUSED,
                                      void *window_)
 {
   struct casewindow *window = window_;
-  struct casereader *reader;
-  reader = casereader_create_random (casewindow_get_value_cnt (window),
-                                     casewindow_get_case_cnt (window),
-                                     &casereader_window_class, window);
+  struct casereader *reader =
+    casereader_create_random (casewindow_get_value_cnt (window),
+                             casewindow_get_case_cnt (window),
+                             &casereader_window_class, window);
+
   taint_propagate (casewindow_get_taint (window),
                    casereader_get_taint (reader));
   return reader;
 }
 
-/* Reads the case at the given 0-based OFFSET from the front of
-   WINDOW into C.  Returns true if successful, false if
-   OFFSET is beyond the end of file or upon I/O error. */
-static bool
+/* Reads and returns the case at the given 0-based OFFSET from
+   the front of WINDOW into C.  Returns a null pointer if OFFSET
+   is beyond the end of file or upon I/O error.  The caller must
+   call case_unref() on the returned case when it is no longer
+   needed.*/
+static struct ccase *
 casereader_window_read (struct casereader *reader UNUSED, void *window_,
-                        casenumber offset, struct ccase *c)
+                        casenumber offset)
 {
   struct casewindow *window = window_;
   if (offset >= casewindow_get_case_cnt (window))
-    return false;
-  else
-    return casewindow_get_case (window, offset, c);
+    return NULL;
+  return casewindow_get_case (window, offset);
 }
 
 /* Destroys casewindow reader WINDOW. */