X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?p=ginac.git;a=blobdiff_plain;f=ginac%2Farchive.h;h=53c45437e4e5e439c92d7de92932e418c402af98;hp=1d60f5317748f08d41e818b111acf90ccb56da57;hb=8cffcdf13d817a47f217f1a1043317d95969e070;hpb=e40d45d3bbeda09cc1f42b4d8abfa4e75c55ade9

diff --git a/ginac/archive.h b/ginac/archive.h
index 1d60f531..53c45437 100644
--- a/ginac/archive.h
+++ b/ginac/archive.h
@@ -3,7 +3,7 @@
  *  Archiving of GiNaC expressions. */
 
 /*
- *  GiNaC Copyright (C) 1999-2007 Johannes Gutenberg University Mainz, Germany
+ *  GiNaC Copyright (C) 1999-2019 Johannes Gutenberg University Mainz, Germany
  *
  *  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
@@ -20,15 +20,15 @@
  *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
  */
 
-#ifndef __GINAC_ARCHIVE_H__
-#define __GINAC_ARCHIVE_H__
+#ifndef GINAC_ARCHIVE_H
+#define GINAC_ARCHIVE_H
 
 #include "ex.h"
 
 #include <iosfwd>
+#include <map>
 #include <string>
 #include <vector>
-#include <map>
 
 namespace GiNaC {
 
@@ -83,7 +83,6 @@ public:
 	};
 	typedef std::vector<property>::const_iterator archive_node_cit;
 
-	archive_node() : a(*dummy_ar_creator()), has_expression(false) {} // hack for cint which always requires a default constructor
 	archive_node(archive &ar) : a(ar), has_expression(false) {}
 	archive_node(archive &ar, const ex &expr);
 
@@ -143,8 +142,6 @@ public:
 	void printraw(std::ostream &os) const;
 
 private:
-	static archive* dummy_ar_creator();
-
 	/** Reference to the archive to which this node belongs. */
 	archive &a;
 
@@ -158,6 +155,86 @@ private:
 	mutable ex e;
 };
 
+typedef basic* (*synthesize_func)();
+typedef std::map<std::string, synthesize_func> unarchive_map_t;
+
+class unarchive_table_t
+{
+	static int usecount;
+	static unarchive_map_t* unarch_map;
+public:
+	unarchive_table_t();
+	~unarchive_table_t();
+	synthesize_func find(const std::string& classname) const;
+	void insert(const std::string& classname, synthesize_func f);
+};
+static unarchive_table_t unarch_table_instance;
+
+/** Helper macros to register a class with (un)archiving (a.k.a.
+ * (de)serialization).
+ *
+ * Usage: put 
+ *
+ * GINAC_DECLARE_UNARCHIVER(myclass);
+ *
+ * into the header file (in the global or namespace scope), and
+ *
+ * GINAC_BIND_UNARCHIVER(myclass);
+ *
+ * into the source file.
+ *
+ * Effect: the `myclass' (being a class derived directly or indirectly
+ * from GiNaC::basic) can be archived and unarchived.
+ *
+ * Note: you need to use GINAC_{DECLARE,BIND}_UNARCHIVER incantations
+ * in order to make your class (un)archivable _even if your class does
+ * not overload `read_archive' method_. Sorry for inconvenience.
+ *
+ * How it works: 
+ *
+ * The `basic' class has a `read_archive' virtual method which reads an
+ * expression from archive. Derived classes can overload that method.
+ * There's a small problem, though. On unarchiving all we have is a set
+ * of named byte streams. In C++ the class name (as written in the source
+ * code) has nothing to do with its actual type. Thus, we need establish
+ * a correspondence ourselves. To do so we maintain a `class_name' =>
+ * `function_pointer' table (see the unarchive_table_t class above).
+ * Every function in this table is supposed to create a new object of
+ * the `class_name' type. The `archive_node' class uses that table to
+ * construct an object of correct type. Next it invokes read_archive
+ * virtual method of newly created object, which does the actual job.
+ *
+ * Note: this approach is very simple-minded (it does not handle classes
+ * with same names from different namespaces, multiple inheritance, etc),
+ * but it happens to work surprisingly well.
+ */
+#define GINAC_DECLARE_UNARCHIVER(classname)			\
+class classname ## _unarchiver					\
+{								\
+	static int usecount;					\
+public:								\
+	static GiNaC::basic* create();				\
+	classname ## _unarchiver();				\
+	~ classname ## _unarchiver();				\
+};								\
+static classname ## _unarchiver classname ## _unarchiver_instance
+
+#define GINAC_BIND_UNARCHIVER(classname)			\
+classname ## _unarchiver::classname ## _unarchiver()		\
+{								\
+	static GiNaC::unarchive_table_t table;			\
+	if (usecount++ == 0) {					\
+		table.insert(std::string(#classname),		\
+			&(classname ## _unarchiver::create));	\
+	}							\
+}								\
+GiNaC::basic* classname ## _unarchiver::create()		\
+{								\
+	return new classname();					\
+}								\
+classname ## _unarchiver::~ classname ## _unarchiver() { }	\
+int classname ## _unarchiver::usecount = 0
+
 
 /** This class holds archived versions of GiNaC expressions (class ex).
  *  An archive can be constructed from an expression and then written to
@@ -249,7 +326,6 @@ private:
 	mutable std::map<std::string, archive_atom> inverse_atoms;
 
 	/** Map of stored expressions to nodes for faster archiving */
-	typedef std::map<ex, archive_node_id, ex_is_less>::iterator mapit;
 	mutable std::map<ex, archive_node_id, ex_is_less> exprtable;
 };
 
@@ -257,7 +333,6 @@ private:
 std::ostream &operator<<(std::ostream &os, const archive &ar);
 std::istream &operator>>(std::istream &is, archive &ar);
 
-
 } // namespace GiNaC
 
-#endif // ndef __GINAC_ARCHIVE_H__
+#endif // ndef GINAC_ARCHIVE_H