pulumi/sdk/dotnet/Pulumi/Output.cs

using System;
using System.Threading.Tasks;

namespace Pulumi {

    public class OutputState<T> {
        public T Value { get; private set; }
        public bool IsKnown { get; private set; }

        public Resource[] DependsOn { get; private set; }

        public OutputState(T value, bool isKnown, params Resource[] dependsOn) {
            Serilog.Log.Debug("Creating new OutputState {value} {isKnown} {dependsOn}", value, isKnown, dependsOn);
            Value = value;
            IsKnown = isKnown;
            DependsOn = dependsOn;
        }
    }
    interface IOutput {
        Task<OutputState<object>> GetOutputStateAsync();
    }

    public sealed class Output<T> : IOutput{
        Task<OutputState<T>> m_stateTask;

        public Output(Task<OutputState<T>> stateTask) {
            m_stateTask = stateTask;
        }

        async Task<OutputState<object>> IOutput.GetOutputStateAsync() {
            var resolvedState = await m_stateTask;
            return new OutputState<object>(resolvedState.Value, resolvedState.IsKnown, resolvedState.DependsOn);
        }

        public void Apply(Action<T> fn) {
            if (this.m_stateTask.Result.IsKnown) {
                fn(this.m_stateTask.Result.Value);
            }
        }

        public Output<U> Apply<U>(Func<T, U> fn) {
            return new Output<U>(this.m_stateTask.ContinueWith(x => new OutputState<U>(
                x.Result.IsKnown ? fn(x.Result.Value) : default(U),
                x.Result.IsKnown,
                x.Result.DependsOn)));
        }
    }
}