Concurrent incremental attribute evaluation

The design of a concurrent incremental combined static/dynamic attribute evaluator is presented. The static part is an incremental version of the ordered attribute evaluation scheme. The dynamic part is an incremental version of the dynamic evaluation scheme. To remove the restriction that every transformation of an attributed syntax tree should immediately be followed by a reevaluation of the tree, criteria have been formulated which permit a delay in calling the reevaluator. These criteria allow multiple asynchronous tree transformations and multiple asynchronous reevaluations. Transformation and reevaluation processes are distributed over regions of the tree. Each region is either in its transformation phase or in its reevaluation phase. Different regions can be in different phases at the same time