Add graph references

references/igraph-1.0.1/include/igraph_config.h.in

@@ -0,0 +1,51 @@
+/*
+   igraph library.
+   Copyright (C) 2011-2025  The igraph development team <igraph@igraph.org>
+
+   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, see <https://www.gnu.org/licenses/>.
+*/
+
+#ifndef IGRAPH_CONFIG_H
+#define IGRAPH_CONFIG_H
+
+#include "igraph_decls.h"
+
+IGRAPH_BEGIN_C_DECLS
+
+/**
+ * \define IGRAPH_INTEGER_SIZE
+ *
+ * Specifies the size of igraph's integer data type; must be one of 32 (for
+ * 32-bit integers) or 64 (for 64-bit integers).
+ */
+#define IGRAPH_INTEGER_SIZE @IGRAPH_INTEGER_SIZE@
+
+#define IGRAPH_DEPRECATED_ENUMVAL @IGRAPH_DEPRECATED_ENUMVAL@
+
+/**
+ * \define IGRAPH_BOOL_TYPE
+ *
+ * Specifies the C type to be used for igraph_bool_t. This is added here _only_
+ * to support the R interface, where we want to be able to create views into
+ * R boolean vectors and treat them as an igraph_vector_bool_t, which requires
+ * us to align igraph_bool_t with R's boolean type.
+ *
+ * Any other use-case of overriding igraph's bool type is completely
+ * unsupported.
+ */
+#define IGRAPH_BOOL_TYPE bool
+
+IGRAPH_END_C_DECLS
+
+#endif