Andreas Pokorny wrote:
I guess I'm still not clear about "attributes". What are those, really? And why will attributes not work with segmented sequences? or not required?
An attribute is a compile time or compile time and runtime information stored for an expression tree, and identified by a key type.
[snip example]
This information is stored inside a container and wrapped inside key-value pairs, to be able to write generic rules. Rules not coupled to the attribues they process. So rule can simply take all attributes of either operands and combine them where possible, or update their values/types if required and store the results inside the expression encoding data structure returned by the rule.
To define an attribute one needs a key type, and some meta functions which get called by the rule, e.g. if an attribute occurs on both operands of a node, a combine meta function is called.
My statement about attributes and segmented sequences is probably wrong. Attributes just need a fusion::map and rules that invoke the automated attribute processing.
Ah! Pretty cool! Regards, -- Joel de Guzman http://www.boost-consulting.com http://spirit.sf.net