On Fri, 19 May 2006, Derek M Jones wrote: > likely; as least I think so until my figures show otherwise; > which they cannot until I have have access to both parse > trees when an ambiguity occurs).
If you construct parse trees (a parse forest really) in your semantic actions, you will have access to them all in your %merge functions. > One possible solution would be to allow the grammar writer to > specify weights for a particular reduction. When a conflict > occurred the one with the greatest weight would be chosen. A conflict action (which we proposed earlier) could be encoded with these weights so it could choose a reduction before a split could occur. > Preferably these weights could change as the parse progressed. > Using the above example, both id1 and id2 would both initially > be given the same is_identifier weight. However, when reduced > thorough declaration_specifier_list the weights would be changed > to reflect the fact that the extra information (two ids in sequence) > indicates that one is a typedef-name and the other an identifier. Now it's starting to sound like a job for semantic actions and semantic values to track the weights. %merge could ultimately make the choice. Joel _______________________________________________ help-bison@gnu.org http://lists.gnu.org/mailman/listinfo/help-bison
