123 lines
5.5 KiB
C#
123 lines
5.5 KiB
C#
// Animancer // https://kybernetik.com.au/animancer // Copyright 2018-2023 Kybernetik //
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using System;
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namespace Animancer.FSM
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{
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/// <summary>A static access point for the details of a key change in a <see cref="StateMachine{TKey, TState}"/>.</summary>
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/// <remarks>
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/// This system is thread-safe.
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/// <para></para>
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/// Documentation: <see href="https://kybernetik.com.au/animancer/docs/manual/fsm/changing-states">Changing States</see>
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/// </remarks>
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/// https://kybernetik.com.au/animancer/api/Animancer.FSM/KeyChange_1
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///
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public struct KeyChange<TKey> : IDisposable
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{
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/************************************************************************************************************************/
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[ThreadStatic]
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private static KeyChange<TKey> _Current;
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private IKeyedStateMachine<TKey> _StateMachine;
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private TKey _PreviousKey;
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private TKey _NextKey;
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/************************************************************************************************************************/
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/// <summary>Is a <see cref="KeyChange{TKey}"/> of this type currently occurring?</summary>
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public static bool IsActive => _Current._StateMachine != null;
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/// <summary>The <see cref="KeyChange{TKey}"/> in which the current change is occurring.</summary>
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/// <remarks>This will be null if no change is currently occurring.</remarks>
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public static IKeyedStateMachine<TKey> StateMachine => _Current._StateMachine;
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/************************************************************************************************************************/
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/// <summary>The key being changed from.</summary>
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/// <exception cref="InvalidOperationException">[Assert-Only]
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/// <see cref="IsActive"/> is false so this property is likely being accessed on the wrong generic type.
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/// </exception>
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public static TKey PreviousKey
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{
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get
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{
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#if UNITY_ASSERTIONS
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if (!IsActive)
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throw new InvalidOperationException(StateExtensions.GetChangeError(typeof(TKey), typeof(StateMachine<,>), "Key"));
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#endif
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return _Current._PreviousKey;
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}
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}
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/************************************************************************************************************************/
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/// <summary>The key being changed into.</summary>
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/// <exception cref="InvalidOperationException">[Assert-Only]
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/// <see cref="IsActive"/> is false so this property is likely being accessed on the wrong generic type.
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/// </exception>
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public static TKey NextKey
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{
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get
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{
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#if UNITY_ASSERTIONS
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if (!IsActive)
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throw new InvalidOperationException(StateExtensions.GetChangeError(typeof(TKey), typeof(StateMachine<,>), "Key"));
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#endif
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return _Current._NextKey;
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}
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}
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/************************************************************************************************************************/
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/// <summary>[Internal]
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/// Assigns the parameters as the details of the currently active change and creates a new
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/// <see cref="KeyChange{TKey}"/> containing the details of the previously active change so that disposing
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/// it will re-assign those previous details to be current again in case of recursive state changes.
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/// </summary>
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/// <example><code>
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/// using (new KeyChange<TState>(previousKey, nextKey))
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/// {
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/// // Do the actual key change.
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/// }
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/// </code></example>
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internal KeyChange(IKeyedStateMachine<TKey> stateMachine, TKey previousKey, TKey nextKey)
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{
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this = _Current;
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_Current._StateMachine = stateMachine;
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_Current._PreviousKey = previousKey;
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_Current._NextKey = nextKey;
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}
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/************************************************************************************************************************/
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/// <summary>[<see cref="IDisposable"/>]
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/// Re-assigns the values of this change (which were the previous values from when it was created) to be the
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/// currently active change. See the constructor for recommended usage.
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/// </summary>
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/// <remarks>
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/// Usually this will be returning to default values (nulls), but if one state change causes another then the
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/// second one ending will return to the first which will then return to the defaults.
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/// </remarks>
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public void Dispose()
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{
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_Current = this;
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}
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/************************************************************************************************************************/
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/// <summary>Returns a string describing the contents of this <see cref="KeyChange{TKey}"/>.</summary>
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public override string ToString() => IsActive ?
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$"{nameof(KeyChange<TKey>)}<{typeof(TKey).FullName}" +
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$">({nameof(PreviousKey)}={PreviousKey}" +
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$", {nameof(NextKey)}={NextKey})" :
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$"{nameof(KeyChange<TKey>)}<{typeof(TKey).FullName}(Not Currently Active)";
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/// <summary>Returns a string describing the contents of the current <see cref="KeyChange{TKey}"/>.</summary>
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public static string CurrentToString() => _Current.ToString();
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/************************************************************************************************************************/
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}
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}
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