dictomaton VS sdsl-lite

Say you want to compute all strings of length 5 that the automaton can generate. Conceptually the nicest way is to create an automaton that matches any five characters and then compute the intersection between that automaton and the regex automaton. Then you can generate all the strings in the intersection automaton. Of course, IRL, you wouldn't actually generate the intersection (you can easily do this on the fly), but you get the idea.

Automata are really a lost art in modern natural language processing. We used to do things like store a large vocabulary in an deterministic acyclic minimized automaton (nice and compact, so-called dictionary automaton). And then to find, say all words within Levenshtein distance 2 of hacker, create a Levenshtein automaton for hacker and then compute (on the fly) the intersection between the Levenshtein automaton and the dictionary automaton. The language of the automaton is then all words within the intersection automaton.

I wrote a Java package a decade ago that implements some of this stuff:

https://github.com/danieldk/dictomaton

Also related: Levenshtein automata - automata for words that match every word within a given Levenshtein distance. The intersection of a Levenshtein automaton of a word and a DAWG gives you an automaton of all words within the given edit distance.

I haven't done any Java in years, but I made a Java package in 2013 that supports: DAWGs, Levenshtein automata and perfect hash automata:

https://github.com/danieldk/dictomaton

Succinct Data Structures [0] [1]. It encompass many different underlying data structure types but the overarching idea is that you want small data size while still keeping "big O" run time.

In other words, data structures that effectively reach a 'practical' entropy lower bound while still keeping asymptotic run time.

[0] https://en.wikipedia.org/wiki/Succinct_data_structure

[1] https://github.com/simongog/sdsl-lite

The book mentioned in another comment is probably the best way to go. But FYI, documentation for some data structures include references. An SDSL-lite example can be found here. And its equivalent in SDSL-RS can be found here.