Frama_c_kernel.WtoWeak topological orderings (WTOs) are a hierarchical decomposition of the a graph where each layer is topologically ordered and strongly connected components are aggregated and ordered recursively. This is a very convenient representation to describe an evaluation order to reach a fixpoint.
type 'n component = | Component of 'n * 'n partition | (* A strongly connected component, described by its head node and the remaining sub-components topologically ordered *) |
| Node of 'n | (* A single node without self loop *) |
Each component of the graph is either an individual node of the graph (without) self loop, or a strongly connected component where a node is designed as the head of the component and the remaining nodes are given by a list of components topologically ordered.
and 'n partition = 'n component listA list of strongly connected components, sorted topologically
val head : 'n partition -> 'n optionReturn the first node of a partition or None if the partition is empty
val flatten : 'n partition -> 'n listTransform the partition into a list
val fold_heads : ( 'a -> 'n -> 'a ) -> 'a -> 'n partition -> 'a