From 0e15e68f9ec493ca0eb660ce891579932d070df9 Mon Sep 17 00:00:00 2001
From: Ben Pfaff <blp@cs.stanford.edu>
Date: Mon, 20 Feb 2023 14:56:34 -0800
Subject: [PATCH] work on DELETE VARS

---
 src/data/case-map.c | 16 ++++++++++++++++
 src/data/case-map.h |  2 +-
 src/data/dataset.c  | 13 +++++++++++++
 src/data/dataset.h  |  2 ++
 4 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/src/data/case-map.c b/src/data/case-map.c
index 87174f1fb3..5d2a347472 100644
--- a/src/data/case-map.c
+++ b/src/data/case-map.c
@@ -72,6 +72,22 @@ insert_mapping (struct case_map *map, size_t from, size_t to)
   map->map[to] = from;
 }
 
+/* Returns a copy of OLD, if OLD is nonnull, and otherwise returns NULL.  */
+struct case_map *
+case_map_clone (const struct case_map *old)
+{
+  if (!old)
+    return NULL;
+
+  size_t n_values = caseproto_get_n_widths (old->proto);
+  struct case_map *new = xmalloc (sizeof *new);
+  *new = (struct case_map) {
+    .proto = caseproto_ref (old->proto),
+    .map = xmemdup (old->proto, n_values * sizeof *new->map),
+  };
+  return new;
+}
+
 /* Destroys case map MAP. */
 void
 case_map_destroy (struct case_map *map)
diff --git a/src/data/case-map.h b/src/data/case-map.h
index 0e9970a873..13e2ef190f 100644
--- a/src/data/case-map.h
+++ b/src/data/case-map.h
@@ -32,7 +32,7 @@ struct casewriter;
 struct ccase;
 struct dictionary;
 
-struct case_map *case_map_create (void);
+struct case_map *case_map_clone (const struct case_map *);
 void case_map_destroy (struct case_map *);
 struct ccase *case_map_execute (const struct case_map *, struct ccase *);
 
diff --git a/src/data/dataset.c b/src/data/dataset.c
index aa196f2850..ded7c7ab02 100644
--- a/src/data/dataset.c
+++ b/src/data/dataset.c
@@ -347,6 +347,19 @@ dataset_steal_source (struct dataset *ds)
   return reader;
 }
 
+bool
+dataset_delete_vars (struct dataset *ds, struct variable **vars, size_t n)
+{
+  dict_delete_vars (ds->dict, vars, n);
+
+  if (ds->source)
+    {
+      struct case_map *map = case_map_to_compact_dict (ds->d, 0);
+      ds->source = case_map_create_input_translator (map, ds->source);
+    }
+  dict_compact_values (ds->dict);
+}
+
 /* Returns a number unique to DS.  It can be used to distinguish one dataset
    from any other within a given program run, even datasets that do not exist
    at the same time. */
diff --git a/src/data/dataset.h b/src/data/dataset.h
index dfa444356e..87fe1c3831 100644
--- a/src/data/dataset.h
+++ b/src/data/dataset.h
@@ -48,6 +48,8 @@ bool dataset_has_source (const struct dataset *ds);
 bool dataset_set_source (struct dataset *, struct casereader *);
 struct casereader *dataset_steal_source (struct dataset *);
 
+bool dataset_delete_vars (struct dataset *, struct variable **, size_t n);
+
 unsigned int dataset_seqno (const struct dataset *);
 
 struct dataset_callbacks
-- 
2.30.2