Method build

gapil/bapi/decode.go:1953–1983

build calls cb to decode an object instance from a proto. The output of cb is cached into s so each instance is only built once. i is the proto instances slice (d.content.Instances.Foo) s is a pointer to the decoder instances slice (&d.inst.Foo) p is the object's proto ID outPtr is a pointer to the

(i, s, p, outPtr, cb interface{})

// outPtr is a pointer to the output value
// cb is a func with the signature: func(InputType, *OutputType)
func (*decoder) build(i, s, p, outPtr, cb interface{}) {
	sV := reflect.ValueOf(s)
	pV := reflect.ValueOf(p)

	outPtrV := reflect.ValueOf(outPtr)
	outV := outPtrV.Elem()

	id := int(pV.Interface().(uint64))
	if id == 0 {
		return // 0 means nil
	}

	idx := id - 1

	if existing := sV.Elem().Index(idx); !existing.IsNil() {
		// Already built this object.
		outV.Set(existing)
		return
	}

	in := reflect.ValueOf(i).Index(idx)
	out := reflect.New(outPtrV.Type().Elem().Elem())
	outV.Set(out)

	// Store the id into the decoder instances slice before building to handle
	// cyclic dependencies.
	sV.Elem().Index(idx).Set(out)

	// Build
	reflect.ValueOf(cb).Call([]reflect.Value{in, out})
}