71 lines
2.7 KiB
C#
71 lines
2.7 KiB
C#
using System;
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namespace UnityEngine.InputSystem.Utilities
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{
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/// <summary>
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/// Provides type erasure and an abstraction of a saved state that
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/// will (must) be restored at a later point.
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/// </summary>
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internal interface ISavedState
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{
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/// <summary>
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/// Dispose current state, should be invoked before RestoreSavedState()
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/// to dispose the current state before restoring a saved state.
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/// </summary>
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void StaticDisposeCurrentState();
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/// <summary>
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/// Restore previous state, should be invoked after StaticDisposeCurrentState().
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/// </summary>
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void RestoreSavedState();
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}
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/// <summary>
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/// Provides functionality to store and support later restoration of a saved
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/// state. The state is expected to be a value-type. If the state is not restored
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/// it must be disposed to not leak resources.
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/// </summary>
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/// <typeparam name="T">The value-type representing the state to be stored.</typeparam>
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internal sealed class SavedStructState<T> : ISavedState where T : struct
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{
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public delegate void TypedRestore(ref T state);
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/// <summary>
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/// Constructs a SavedStructState.
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/// </summary>
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/// <param name="state">The value-type state to be saved.</param>
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/// <param name="restoreAction">The action to be carried out to restore state.</param>
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/// <param name="staticDisposeCurrentState">The action to be carried out to dispose current state. May be null.</param>
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internal SavedStructState(ref T state, TypedRestore restoreAction, Action staticDisposeCurrentState = null)
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{
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Debug.Assert(restoreAction != null, "Restore action is required");
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m_State = state; // copy
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m_RestoreAction = restoreAction;
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m_StaticDisposeCurrentState = staticDisposeCurrentState;
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}
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public void StaticDisposeCurrentState()
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{
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if (m_StaticDisposeCurrentState != null)
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{
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m_StaticDisposeCurrentState();
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m_StaticDisposeCurrentState = null;
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}
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}
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public void RestoreSavedState()
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{
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Debug.Assert(m_StaticDisposeCurrentState == null,
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$"Should have been disposed via {nameof(StaticDisposeCurrentState)} before invoking {nameof(RestoreSavedState)}");
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Debug.Assert(m_RestoreAction != null, $"Only invoke {nameof(RestoreSavedState)} once ");
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m_RestoreAction(ref m_State);
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m_RestoreAction = null;
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}
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private T m_State;
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private TypedRestore m_RestoreAction;
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private Action m_StaticDisposeCurrentState;
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}
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}
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