// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

namespace Microsoft.CodeAnalysis;

internal enum StateMachineState
{
    /// <summary>
    /// First state of an async iterator state machine that is used to resume the machine after yield return.
    /// Initial state is not used to resume state machine that yielded. State numbers decrease as the iterator makes progress.
    /// </summary>
    FirstResumableAsyncIteratorState = InitialAsyncIteratorState - 1,

    /// <summary>
    /// Initial iterator state of an async iterator.
    /// Distinct from <see cref="NotStartedOrRunningState"/> so that DisposeAsync can throw in latter case.
    /// </summary>
    InitialAsyncIteratorState = -3,

    /// <summary>
    /// First state of an iterator state machine. State numbers decrease for subsequent finalize states.
    /// </summary>
    FirstIteratorFinalizeState = -3,

    FinishedState = -2,
    NotStartedOrRunningState = -1,
    FirstUnusedState = 0,

    /// <summary>
    /// First state in async state machine that is used to resume the machine after await.
    /// State numbers increase as the async computation makes progress.
    /// </summary>
    FirstResumableAsyncState = 0,

    /// <summary>
    /// Initial iterator state of an iterator.
    /// </summary>
    InitialIteratorState = 0,

    /// <summary>
    /// First state in iterator state machine that is used to resume the machine after yield return.
    /// Initial state is not used to resume state machine that yielded. State numbers increase as the iterator makes progress.
    /// </summary>
    FirstResumableIteratorState = InitialIteratorState + 1,
}