|int LibGFX_ConstAttrFold (||AST_Node ||*||root,|
walks the tree and retrieves the currently applicable value/attribute to a simple extent
|root||the node to start checking|
|const_val||a pointer to an integer to receive the constant value|
|attr_val||a pointer to an integer to receive the attribute index|
|return||0 if there is no match, 1 for a constant match, 2 for an attribute match|
All arguments may be NULL without impeding functionality. const_val/attr_val will only be written if non-null and the corresponding match was found.