Implement ADD FILES and UPDATE.

[pspp-builds.git] / src / data / case-matcher.c

diff --git a/src/data/case-matcher.c b/src/data/case-matcher.c
new file mode 100644 (file)
index 0000000..9cfc008
--- /dev/null
+++ b/src/data/case-matcher.c
@@ -0,0 +1,152 @@
+/* PSPP - a program for statistical analysis.
+   Copyright (C) 2008 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 <data/case-matcher.h>
+
+#include <stdlib.h>
+
+#include <data/case.h>
+#include <data/subcase.h>
+#include <data/value.h>
+#include <libpspp/assertion.h>
+
+#include "xalloc.h"
+
+struct case_matcher_input
+  {
+    struct subcase by_vars;
+    const struct ccase *data;
+    bool *is_minimal;
+  };
+
+struct case_matcher
+  {
+    struct case_matcher_input *inputs;
+    size_t n_inputs, allocated_inputs;
+    union value *by_values;
+  };
+
+/* Creates and returns a new case matcher. */
+struct case_matcher *
+case_matcher_create (void)
+{
+  struct case_matcher *cm = xmalloc (sizeof *cm);
+  cm->inputs = NULL;
+  cm->n_inputs = 0;
+  cm->allocated_inputs = 0;
+  cm->by_values = NULL;
+  return cm;
+}
+
+/* Adds a new input file to case matcher CM.
+   case_matcher_match() will compare the variables specified in
+   BY in case DATA and set *IS_MINIMAL appropriately.
+
+   All of the BY subcases provided to this function for a given
+   CM must be conformable (see subcase_conformable()). */
+void
+case_matcher_add_input (struct case_matcher *cm, const struct subcase *by,
+                        const struct ccase *data, bool *is_minimal)
+{
+  struct case_matcher_input *input;
+
+  if (cm->n_inputs == 0)
+    cm->by_values = xmalloc (subcase_get_n_values (by)
+                             * sizeof *cm->by_values);
+  else
+    assert (subcase_conformable (by, &cm->inputs[0].by_vars));
+
+  if (cm->n_inputs >= cm->allocated_inputs)
+    cm->inputs = x2nrealloc (cm->inputs, &cm->allocated_inputs,
+                             sizeof *cm->inputs);
+  input = &cm->inputs[cm->n_inputs++];
+  subcase_clone (&input->by_vars, by);
+  input->data = data;
+  input->is_minimal = is_minimal;
+}
+
+/* Destroys case matcher CM. */
+void
+case_matcher_destroy (struct case_matcher *cm)
+{
+  if (cm != NULL)
+    {
+      size_t i;
+
+      for (i = 0; i < cm->n_inputs; i++)
+        {
+          struct case_matcher_input *input = &cm->inputs[i];
+          subcase_destroy (&input->by_vars);
+        }
+      free (cm->inputs);
+      free (cm);
+    }
+}
+
+static int
+compare_BY_3way (struct case_matcher_input *a, struct case_matcher_input *b)
+{
+  return subcase_compare_3way (&a->by_vars, a->data, &b->by_vars, b->data);
+}
+
+/* Compares the values of the BY variables in all of the nonnull
+   cases provided to case_matcher_add_input() for CM, sets
+   *IS_MINIMAL for each one to true if it has the minimum BY
+   values among those cases or to false if its BY values are
+   greater than the minimum.  Also sets *IS_MINIMAL to false for
+   null cases.  Sets *BY to the BY values extracted from the
+   minimum case.  (The caller must not free *BY.)
+
+   Returns true if at least one of the cases is nonnull, false
+   if they are all null.*/
+bool
+case_matcher_match (struct case_matcher *cm, union value **by)
+{
+  struct case_matcher_input *file, *min;
+
+  min = NULL;
+  for (file = cm->inputs; file < &cm->inputs[cm->n_inputs]; file++)
+    if (!case_is_null (file->data))
+      {
+        int cmp = min != NULL ? compare_BY_3way (min, file) : 1;
+        if (cmp < 0)
+          *file->is_minimal = false;
+        else
+          {
+            *file->is_minimal = true;
+            if (cmp > 0)
+              min = file;
+          }
+      }
+    else
+      *file->is_minimal = false;
+
+  if (min != NULL)
+    {
+      for (file = cm->inputs; file < min; file++)
+        *file->is_minimal = false;
+      subcase_extract (&min->by_vars, min->data, cm->by_values);
+      *by = cm->by_values;
+      return true;
+    }
+  else
+    {
+      *by = NULL;
+      return false;
+    }
+}