Is there a "kotlin" way to do something like `Scan...

# getting-started

[eygraber]

Is there a "kotlin" way to do something like Scanner(myFile).findAll(myPattern) that returns a `Sequence<String>`(I know I can call asSequence on the returned Stream but I'm wondering if there's a specific Kotlin API for that)?

[Paul Griffith]

Since Scanner is implemented in Java, you're not going to get any better than an extension method that returns a sequence by calling asSequence on the stream. Unless someone has implemented a Scanner-like class for KMM, that's probably as good as you'll get

[Rein T]

something like

fun Scanner.all(matching : Pattern) = findAll(matching).asSequence()

[eygraber]

Right, I guess my question is really is there a KMP function for this?

[Stephan Schroeder]

Scanner is also JVM-only, isn't it?
Here's the extension function that'll work on a line-sequence:

fun Sequence<String>.findMatches(pattern: String): Sequence<String> {
    val regex = pattern.toRegex()
    return this.flatMap{line->regex.findAll(line).map{match->match.value}}
}

Here the Playground with some testdata: https://pl.kotl.in/yoF7jx5pv
Now you only have to figure out how to convert your file into a Sequence<String>.

[Joffrey]

There is no Kotlin multiplatform facilities for files, because in JS browser environment you don't have access to the file system. You can work on Sequence<String> as others mentioned, and on JVM you can simply use Path.useLines or File.useLines like this:

Path("yourpath").useLines { seq ->
    // do something with the sequence of lines
}
// here the file is closed automatically

[eygraber]

So if the regex needed to look across lines this wouldn't work right?

[Joffrey]

Correct, so this might not be what you want

[eygraber]

Ok thanks