AnarchoSystems/process-kit

Usage Example

Consider the following structs:

struct Echo : Proc {
    typealias Input = VoidPipe
    typealias Output = StringPipe
    let msg : String
    func path() throws -> URL {
        // convenience to look up files in PATH
        try .findExecutable(named: "echo")
    }
    var arguments: [String] {
        [msg]
    }
}

struct Grep : Proc {
    typealias Input = StringPipe
    typealias Output = StringPipe
    let pattern : String
    func path() throws -> URL {
        // will of course also work with other urls
        if let path = Bundle.module.path(forResource: "MyGrep", ofType: "sh") {
            return URL(filePath: path)
        }
        throw NSError()
    }
    var arguments: [String] {
        [pattern]
    }
}

What the ``Proc` protocol expects is an `Input`, an `Output`, a `path()` and `arguments`. From there, it can automatically set up a process that can be executed. Also, the `Input` and `Output`` types make it so that you can only chain processes that naturally form a pipeline.

Here's how:

let proc = Echo(msg: snooper) |> Grep(pattern: "bug")

Alternatively, you can use builder syntax:

let proc = Pipeline {
        Echo(msg: snooper)
        Grep(pattern: "b")
        Grep(pattern: "u")
        Grep(pattern: "g")
        Grep(pattern: "bug")
    }

You may have noticed that input and output have the suffix "Pipe". That's because they're typed wrappers around ``Pipes`. If they conform to `PipeEncodable` and/or `PipeDecodable` (which is true for the example implementations `VoidPipe`, `StringPipe` and `JSONPipe``), you can even get the plain swift types back or instantiate them with a plain swift type:

let inPipe = try StringPipe("Lorem ipsum...")
let outPipe = try await Grep(pattern: "Lo").run(inPipe)
let result = try outPipe.read()

And finally, there's a way to just directly run a pipeline:

let result = try await runProcess(()) {
        Echo(msg: snooper)
        Grep(pattern: "b")
        Grep(pattern: "u")
        Grep(pattern: "g")
        Grep(pattern: "bug")
    }

Package Metadata

Repository: AnarchoSystems/process-kit

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Forks: 0

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Default branch: main

Primary language: swift

README: README.md