Use Aho-Corasick for alts of literals during regexp AST compilation #221
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It's difficult to see the structure for unanchored strings (because we have no way to inform graphviz to weight the backwards edges differently). But here's the simpler case for anchored strings, showing 100 alts of {3,20} characters in length. The same (randomly generated) data for each. Hopefully you can see the difference in the structure, with the trie shape visible.
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…`re_strings()`, which is already a convenience.
…e()`. This was neglected for the previous commit (of passing in an fsm for `ast_compile()`). Here I am attempting to rectify that by passing along the start states explicitly.
This avoids needing to construct an intermediate string, and allocating storage for it.
When a single end state is provided, we cannot set these as accepting. So here I'm hooking them up with epsilons, instead. Yes, this means we don't always produce a DFA. To do this, we need to identify leaf nodes, so I've introduced `has_child()` for that.
…ode. This allows for accepting states in the middle of branches in the trie, rather than hooking them up using epsilons.
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I'll have more to say about this, but I'm too tired to write about it at the moment.