Support struct functions with ToValue

[shoriwe]

Is your feature request related to a problem? Please describe.

Map Struct function to Plasma Objects

Describe the solution you'd like

Using reflection, also scan for the functions of an struct an map them to the plasma object

[shoriwe]

The basic idea is that type functions don't directly compile as they look like, the first argument is always the pointer or value to the type that implements it. For example:

type MyType struct{}

func (mt *MyType) SayHello(arg1 int) {}

// Will compile to something like...

func MyType_SayHello(mt *MyType, arg1 int) {}

Having this in consideration, the solution will need some kind of callback since the current implementation only has Value assignment mapping to Plasma Objects, a conceptual workaround could be:

// This is passed to the VM as plasma.ToValue(objVirtualTable, newMemberCaller(self, function))
type memberCaller func(arguments ...any) []any

func newMemberCaller(self, function reflect.Value) memberCaller {
    return func(arguments ...any) []any {
        callArguments := make([]reflect.Value, 0, function.Type().NumIn())
        callArguments = append(callArguments, self) // Add self
        for index := 0; index < function.Type().NumIn(); index++ {
            in := function.Type().In(index)
            asValue := reflect.ValueOf(arguments[index])
            asValue = asValue.Convert(in)
            callArguments = append(callArguments, asValue)
        }
        // Some corrections need to be made to also support Variadic function calls
        asValuesResults := function.Call(callArguments)
        result := make([]any, 0, len(asValueResults))
        for _, v := range asValuesResults {
            result = append(result, v.Interface())
        }
        return result
    }
}