Performance issues related to memory

[mikolasstuchlik]

Hello,

I have been playing with the package recently and I have experienced some issues.

The program seems to struggle with larger texts. At first I suspected, there might be an unreasonable amount of copying involved. After some debugging, I've came to conclusion, that this is in fact a problem with stack related to usage of recursion.

Reproduction example:

        let grammar = Grammar(start: "initial") {
            "initial"       --> n("initial") <+> t("a")
                            <|> t()
        }

        let parser = EarleyParser(grammar: grammar)
        let text = String.init(repeating: "a", count: 2500)
        let syntaxTree = try parser.syntaxTree(for: text )

I'm trying to work with files aroung 10K characters. At this time, I am able to work with 2000 characters long texts using this simple grammar.

For the time being, I will try to find a workaroud. I might have time to fix the issue in the future.

[mikolasstuchlik]

My work so far is here: https://github.com/mikolasstuchlik/Covfefe/tree/fix/stack-overflow

I have been able to solve recursion of EarleyParser.buildSyntaxTrees( ~~~ ).resolve( ~~~ ) but my stress test still does not work, since there is also a recursion on EarleyParser.buildSyntaxTrees( ~~~ ) which now crashes the program.

Since performace is not my main objective, there is a significant performace degradation.