math: Avoid unneeded extra allocations for fixed-size data structures.

[pspp] / src / math / interaction.h

diff --git a/src/math/interaction.h b/src/math/interaction.h
index 4e709818f59c6336294790e4a257e4bb90010832..8229083f860f7cf0a7b86e5f4268b9a1551623cf 100644 (file)
--- a/src/math/interaction.h
+++ b/src/math/interaction.h
@@ -1,21 +1,73 @@
-/* PSPP - Creates data structures to store interactions for
-   statistical routines.  
+/* PSPP - a program for statistical analysis.
+   Copyright (C) 2011 Free Software Foundation, Inc.
 
-   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 3 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 2 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. */
-gsl_vector *
-get_interaction (union value **, const struct variable **, size_t);
+   along with this program.  If not, see <http://www.gnu.org/licenses/>. */
+
+
+#ifndef _INTERACTION_H__
+#define _INTERACTION_H__ 1
+
+#include <stdbool.h>
+#include "libpspp/compiler.h"
+#include "data/missing-values.h"
+
+struct ccase;
+struct interaction;
+struct string;
+struct variable;
+
+#include <stddef.h>
+
+/* An interaction is a structure containing a "product" of other variables.
+   The variables can be either string or numeric.
+
+   Interaction is commutative.  That means, that from a mathematical point of
+   view, the order of the variables is irrelevant.  However, for display
+   purposes, and for matching with an interaction's value the order is
+   pertinent.  Therefore, when using these functions, make sure the orders of
+   variables and values match when appropriate.
+
+   Some functions for interactions will not work properly for interactions that
+   contain a given variable more than once, so this should be regarded as an
+   invariant.  The functions to modify interactions don't check for this
+   invariant. */
+struct interaction
+  {
+    const struct variable **vars;
+    size_t n_vars;
+  };
+
+struct interaction *interaction_create (const struct variable *);
+struct interaction *interaction_clone (const struct interaction *);
+void interaction_destroy (struct interaction *);
+void interaction_add_variable (struct interaction *, const struct variable *);
+void interaction_dump (const struct interaction *);
+void interaction_to_string (const struct interaction *, struct string *str);
+bool interaction_is_proper_subset (const struct interaction *,
+                                   const struct interaction *);
+bool interaction_is_subset (const struct interaction *,
+                            const struct interaction *);
+
+
+unsigned int interaction_case_hash (const struct interaction *,
+                                    const struct ccase *,
+                                   unsigned int base) WARN_UNUSED_RESULT;
+bool interaction_case_equal (const struct interaction *, const struct ccase *,
+                             const struct ccase *);
+bool interaction_case_is_missing (const struct interaction *,
+                                  const struct ccase *, enum mv_class);
+int interaction_case_cmp_3way (const struct interaction *,
+                               const struct ccase *, const struct ccase *);
+
+#endif