===================================================================
RCS file: /home/cvs/GiNaC/ginac/archive.cpp,v
retrieving revision 1.19.2.3
diff -r1.19.2.3 archive.cpp
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< 	// Search for node in nodes vector
< 	std::vector<archive_node>::const_iterator i = nodes.begin(), iend = nodes.end();
< 	archive_node_id id = 0;
< 	while (i != iend) {
< 		if (i->has_same_ex_as(n))
< 			return id;
< 		i++; id++;
---
> 	// Look if expression is known to be in some node already.
> 	if(n.has_ex())
> 	{	mapit i=exprtable.find(n.get_ex());
> 		if(i != exprtable.end())
> 			return i->second;
> 		nodes.push_back(n);
> 		exprtable[n.get_ex()]=nodes.size()-1;
> 		return nodes.size()-1;
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< 	return id;
---
> 	return nodes.size()-1;
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> /** Check if node is known to store an unarchived exression */
> bool archive_node::has_ex() const
> {
> 	return has_expression;
> }
> 
> /** Return unarchived version of expression stored in this node */
> ex archive_node::get_ex() const
> {
> 	return e;
> }
> 
> 
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> 	exprtable.clear();
Index: archive.h
===================================================================
RCS file: /home/cvs/GiNaC/ginac/archive.h,v
retrieving revision 1.17.2.3
diff -r1.17.2.3 archive.h
30a31
> #include <map>
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> 	bool has_ex() const;
> 	ex get_ex() const;
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> 
> 	/** 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;