[jgrapht-users] Getting an ordered set of edges for graph cycles?

[<org...@io...>]

Hello.

I'm attempting to use jgrapht to handle dependencies in a small
programming language.

Essentially, I want to ensure that a "module" can only import known
modules and that imports cannot introduce cyclic dependencies. I want
to give good error messages when the user manages either of the
previous errors: A list of the import statements that caused the cycle.

Something like:

error: cyclic import detected
     import of N at m.z:23
  -> import of M at n.z:12
  -> import of N at m.z:23

I've tried the following:

1. Use a DirectedGraph where modules are the vertices and import
declarations are the edges. This allows me to catch imports of unknown
modules by catching IllegalArgumentExceptions raised by addEdge. I
then run the CycleDetector after each addition of an edge.
Unfortunately, the CycleDetector can only return a set of vertices
rather than the edges (so I can't directly tell the user exactly which
series of import declarations caused the cycle). It also comes with a
rather scary warning that it might not actually catch all cycles (and
recommends the use of the StrongConnectivityInspector, but doesn't say
exactly how to use it and the documentation is non-obvious).

2. Use a DirectedAcyclicGraph. This allows me to catch imports of
unknown modules by checking to see if an edge could actually be
inserted (the boolean return value of addDagEdge). It also raises
exceptions when cycles are introduced, but this gives me even less
information than the CycleDetector (it just tells me that they've
happened, not why).

Is there some better way to achieve what I want? My ideal scenario is
that I add edges to graphs and upon adding an edge, I get a list of all
the *edges and vertices* that led to a cycle in some well-defined order.

M