NFA completion

[pazz]

This adds two methods to NFA,

• is_complete to check if the NFA is complete
• complete to turn it into a complete NFA.

The latter accepts an Option, which is the sink to be used in new
transitions. If None, self-loops will be added, otherwise new steps
point ot the given (sing) state.

New unit tests are included.

[pazz]

implementing this was challenging, because the alphaben needs to be computed lots as it is not explicitly represented in the NFA struct.

questions that came up while touching this code:

• why is NFA.states a vector of strings, not HashSet<State>?

[Copilot]

Pull Request Overview

Adds methods to verify and enforce completeness of NFAs, along with supporting helper and tests

• Implements is_complete to check that every state has an outgoing transition for each symbol in the alphabet
• Implements complete to fill in missing transitions with either self-loops or a designated sink state
• Adds get_alphabet helper and new unit tests covering both methods

Comments suppressed due to low confidence (1)

src/nfa.rs:62

• Comparing state_actions (Vec) with letters (Vec<&str>) will not compile due to a type mismatch. Consider converting one side to match the other (e.g., map letters to String).

if state_actions != letters {

[Copilot]

Pull Request Overview

Adds functionality to check whether an NFA is complete over its alphabet and to complete it by filling in missing transitions, along with tests.

• Introduce is_complete to verify that each state has transitions for every symbol.
• Introduce complete to add missing transitions, optionally targeting a sink state.
• Add unit tests for completeness checking and completion behavior.