Matching a keyword

[Tam]

Hey, great library!

Sorry if I'm being a bit dumb, but I'm struggling with how I would match a keyword without it being part of another word. Essentially, what I'm trying to achieve is they way the var keyword is highlighted below:

var my_var;var anothervar; var yet1varmore;

I want it to match the word exactly, but taking into consideration what came before it (i.e. anything that isn't an alphanumeric or _ character).

So far I've got:

"key": /^(var|true|false)\b/

but that highlights the matches, no matter where they are.

[J-Cake]

I think what you should do is create a proxy object of a regex. from there, when you call the test or match function, you can add traps to decide based on context if the token is a variable or a keyword.

const patterns: [{
    match: new Proxy(/^[$_a-zA-Z][$_a-zA-Z0-9]*\b/, {
        get(target: any[], prop: string, receiver: any) {
            if (prop in RegExp.prototype)
                if (prop === "test")
                    return function (param: string): boolean {
                        // do logic here
                    }
                else
                    return Reflect.get(target, prop, receiver); // do the expected behaviour
            else
                return null; // the requested parameter doesn't exit
        }
    }),
    name: "KeyWord"
}];

highlight(patterns);

it's not elegant but it'll work...

EDIT: Upon further scrolling down the page (I kid you not, 10 lines) I realised that the match property takes a function as well. So it's probably best to make use of these as you'll be able to look at the previous token (you'll need to store a reference to each in an array as I don't think there is a way of looking at this information yet) and access the previous token and decide then, what to label it as.