Reuse internals to create a compactDescription for OSCMessage and create message from compactDescription

[DoubleBaroness]

I’d like to reuse the convenient message shorthand of specifying the address, type tag, and arguments as a string that liblo's bundled oscsend and oscdump command-line tools use:

/sample/address iTfs 1 3.14 hello

If I only care about a subset of types, the string parsing seems straightforward. But is there a convenient way to:

• Get the tag identity character for a given value?
• Know if a particular tag identity requires an argument?
• Fetch a tag identity from the character?

[orchetect]

address, type tag, and arguments as a string that liblo's tools use

I'm not familiar with liblo but just had a look at the command line tools.

If you're looking for a way to both construct an OSCMessage from liblo's string format as well as generate the string from an OSCMessage, there are some resources that can help in OSCKit but a fair amount of custom logic would be needed.

OSC tag characters are, for the most part, obfuscated from the user in OSCKit in favor of using Swift language concrete value types.

OSC value types, including their tag characters and encoding/decoding logic is found within Sources/OSCKitCore/OSCValue.

For example, Int32 (i tag) is defined here: Int32.swift.

As such, tag characters aren't defined in a single enumeration. Part of the reason is that certain OSC types have variable tag identities and are not static.

• Fetch a tag identity from the character?

OSCSerialization could otherwise help here. It is a global singleton that registers OSC types, but most methods are internal. The tagIdentities(for character: Character) method would return the concrete type for a given OSC type character, but it's currently not a public method (but could be made public):

let char = Character("i")

// array: should contain one entry if there is a match, or empty if no types match.
let types = OSCSerialization.shared.tagIdentities(for: char)

(Although, this will be renamed concreteTypes(for:))

• Get the tag identity character for a given value?

If a concrete value conforms to OSCValue (which values in an OSCMessage implicitly do), it will gain an oscTagIdentity property which will return a OSCValueTagIdentity case defining its tag character(s).

let value: Double = 3.14 // Double conforms to OSCValue
let id = value.oscTagIdentity
switch id {
case let .atomic(char):
    // char is a Character instance; atomic (static) character for this OSC value type
case let .variable(chars):
    // chars is a Character array of possible characters for the given value type (ie: Bool can be T or F)
case let .variadic(minCount, maxCount):
    // characters may vary depending on value's contents, such as an OSC Array
}

• Know if a particular tag identity requires an argument?

And there is no direct way to determine if an OSC value type encodes data ('an argument') or not, apart from whether its concrete type's static oscEncoding property returns nil for the data portion.