major refactor of IndexAutomaton??

[kalmarek]

Just collecting some ideas after #38 is merged.

1. walk(::Automaton, ::AbstractWord)
   • I think this should be renamed to trace
   • I think there is little advantage of breaking prematurely and returning the last (non-failed) state (even though I suggested this): maybe a simpler solution like below is better?

     function trace(a::AbstractAutomaton, signature::AbstractWord, state=initialstate(a))
     for k in signature
     next = outedges(state)[k]
     isfailstate(next) ? return next : state = next
     end
     return state
     end

2. outedges(state) → this doesn't return an edge but a neighboring state ;) LightGraphs.jl use outneighbors: https://github.com/JuliaGraphs/LightGraphs.jl/blob/ce533729381a6c0b0d8a1eb5f0c3e058833cb55b/src/interface.jl#L336 (I don't mean using LightGraphs directly, but adopting their naming)

[mikolajpabiszczak]

• I agree trace is nice.
• As to the break (or lack of it) in walk/trace - I have no feelings about it.
• outneighbors is better.

[kalmarek]

Continuing point 1 from above:

• I'd be best if this push!(::Automaton, ::W) would actually return the state created, otherwise we leak the implementation detail (at least in one or two places) that this push! actually pushes the newly created state to the last place in some internal vector, see e.g. https://github.com/kalmarek/KnuthBendix.jl/pull/38/files#diff-ba45e2be10d1f5b03e3f0f6145c6c34920b4a89ad7aa6c0be65fcb6c15d47e66R268.
• deprecate addedge!(at::Automaton, label::Integer, src::Integer, dst::Integer) in favour of `addedge!(at::Automaton, label::Integer, src::State, dst::State)

[mikolajpabiszczak]

The first seems sensible.

The second is also sensible - I believe there is only one place in which this addedge! method you want to depreciate is used and it can be easily substituted with the other one. In fact two methods exist just because at the time I was writing them I had no idea which one will be more useful.

[kalmarek]

rendered invalid by #54