Index: obj_subc_list.h
===================================================================
--- obj_subc_list.h	(nonexistent)
+++ obj_subc_list.h	(revision 8990)
@@ -0,0 +1,81 @@
+/*
+ *                            COPYRIGHT
+ *
+ *  pcb-rnd, interactive printed circuit board design
+ *  Copyright (C) 2017 Tibor 'Igor2' Palinkas
+ *
+ *  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.
+ *
+ *  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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+#ifndef PCB_OBJ_SUBC_LIST_H
+#define PCB_OBJ_SUBC_LIST_H
+
+#include "obj_subc.h"
+
+/* List of Elements */
+#define TDL(x)      pcb_subclist_ ## x
+#define TDL_LIST_T  pcb_subclist_t
+#define TDL_ITEM_T  pcb_subc_t
+#define TDL_FIELD   link
+#define TDL_SIZE_T  size_t
+#define TDL_FUNC
+
+#define subclist_foreach(list, iterator, loop_elem) \
+	gdl_foreach_((&((list)->lst)), (iterator), (loop_elem))
+
+#include "ht_subc.h"
+#include <genht/hash.h>
+
+/* Calculate a hash value using the content of the subc. The hash value
+   represents the actual content of an subc */
+unsigned int pcb_subc_hash(const pcb_subc_t *e);
+
+/* Compare two subcs and return 1 if they contain the same objects. */
+int pcb_subc_eq(const pcb_subc_t *e1, const pcb_subc_t *e2);
+
+/* Create a new local variable to be used for deduplication */
+#define pcb_subclist_dedup_initializer(state) htep_t *state = NULL;
+
+/* Do a "continue" if an subc matching loop_elem has been seen already;
+   Typically this is invoked as the first statement of an subclist_foreach()
+   loop. */
+#define pcb_subclist_dedup_skip(state, loop_elem) \
+switch(1) { \
+	case 1: { \
+		if (state == NULL) \
+			state = htep_alloc(pcb_subc_hash, pcb_subc_eq); \
+		if (htep_has(state, loop_elem)) \
+			continue; \
+		htep_set(state, loop_elem, 1); \
+	} \
+}
+
+/* use this after the loop to free all memory used by state */
+#define pcb_subclist_dedup_free(state) \
+	do { \
+		if (state != NULL) { \
+			htep_free(state); \
+			state = NULL; \
+		} \
+	} while(0)
+
+
+#ifndef LIST_SUBCENT_NOINSTANT
+#include <genlist/gentdlist_impl.h>
+#include <genlist/gentdlist_undef.h>
+#endif
+
+#endif