Move all command implementations into a single 'commands' directory.

[pspp] / src / language / commands / delete-variables.c

diff --git a/src/language/commands/delete-variables.c b/src/language/commands/delete-variables.c
new file mode 100644 (file)
index 0000000..03ccd11
--- /dev/null
+++ b/src/language/commands/delete-variables.c
@@ -0,0 +1,113 @@
+/* PSPP - a program for statistical analysis.
+   Copyright (C) 2006, 2007, 2010, 2011, 2013 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 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.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+
+#include <config.h>
+
+#include <stdlib.h>
+
+#include "data/casereader.h"
+#include "data/dataset.h"
+#include "data/dictionary.h"
+#include "language/command.h"
+#include "language/lexer/lexer.h"
+#include "language/lexer/variable-parser.h"
+#include "libpspp/message.h"
+
+#include "gettext.h"
+#define _(msgid) gettext (msgid)
+
+/* Performs DELETE VARIABLES command. */
+int
+cmd_delete_variables (struct lexer *lexer, struct dataset *ds)
+{
+  struct variable **vars;
+  size_t n_vars;
+  bool ok;
+
+  if (proc_make_temporary_transformations_permanent (ds))
+    lex_ofs_error (lexer, 0, lex_ofs (lexer) - 1,
+                   _("%s may not be used after %s.  "
+                     "Temporary transformations will be made permanent."),
+                   "DELETE VARIABLES", "TEMPORARY");
+
+  if (!parse_variables (lexer, dataset_dict (ds), &vars, &n_vars, PV_NONE))
+    goto error;
+  if (n_vars == dict_get_n_vars (dataset_dict (ds)))
+    {
+      lex_ofs_error (lexer, 0, lex_ofs (lexer) - 1,
+                     _("%s may not be used to delete all variables "
+                       "from the active dataset dictionary.  "
+                       "Use %s instead."), "DELETE VARIABLES", "NEW FILE");
+      goto error;
+    }
+
+  ok = casereader_destroy (proc_open_filtering (ds, false));
+  ok = proc_commit (ds) && ok;
+  if (!ok)
+    goto error;
+
+  dict_delete_vars (dataset_dict (ds), vars, n_vars);
+
+  /* XXX A bunch of bugs conspire to make executing transformations again here
+     necessary, even though it shouldn't be.
+
+     Consider the following (which is included in delete-variables.at):
+
+        DATA LIST NOTABLE /s1 TO s2 1-2(A).
+        BEGIN DATA
+        12
+        END DATA.
+        DELETE VARIABLES s1.
+        NUMERIC n1.
+        LIST.
+
+     The DATA LIST gives us a caseproto with widths 1,1.  DELETE VARIABLES
+     deletes the first variable so we now have -1,1.  This already is
+     technically a problem because proc_casereader_read() calls
+     case_unshare_and_resize() from the former to the latter caseproto, and
+     these caseprotos are not conformable (which is a requirement for
+     case_resize()).  It doesn't cause an assert by default because
+     case_resize() uses expensive_assert() to check for it though.  However, in
+     practice we don't see a problem yet because case_resize() only does work
+     if the number of widths in the source and dest caseproto are different.
+
+     Executing NUMERIC adds a third variable, though, so we have -1,1,0.  This
+     makes caseproto_resize() notice that there are fewer strings in the new
+     caseproto.  Therefore it destroys the second one (s2).  It should destroy
+     the first one (s1), but if the caseprotos were really conformable then it
+     would have destroyed the right one.  This mistake eventually causes a bad
+     memory reference.
+
+     Executing transformations a second time after DELETE VARIABLES, like we do
+     below, works around the problem because we can never run into a situation
+     where we've got both new variables (triggering a resize) and deleted
+     variables (triggering the bad free).
+
+     We should fix this in a better way.  Doing it cleanly seems hard.  This
+     seems to work for now. */
+  ok = casereader_destroy (proc_open_filtering (ds, false));
+  ok = proc_commit (ds) && ok;
+  if (!ok)
+    goto error;
+
+  free (vars);
+
+  return CMD_SUCCESS;
+
+ error:
+  free (vars);
+  return CMD_CASCADING_FAILURE;
+}