VVMExecutionContext.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "Blueprint/BlueprintExceptionInfo.h"
#include "Misc/AssertionMacros.h"
 
#if !WITH_VERSE_BPVM
#include "VerseVM/VVMContext.h"
#endif
 
namespace verse
{
 
#if WITH_VERSE_BPVM
struct FExecutionContextImpl
{
private:
    friend struct FExecutionContext;
 
    FExecutionContextImpl() = default;
 
    COREUOBJECT_API static FExecutionContextImpl* Claim();
    COREUOBJECT_API void Release();
 
    COREUOBJECT_API static FExecutionContextImpl* GetCurrent();
 
    bool bActive = false;
};
#endif
 
// A thread must have an active execution context to run Verse code.
struct FExecutionContext
{
    FExecutionContext(const FExecutionContext& Other)
        : Impl(Other.Impl)
    {
        ensure(!bBlockAllExecution);
    }
 
#if WITH_VERSE_BPVM
    static FExecutionContext Create()
    {
        ensure(!bBlockAllExecution);
        return FExecutionContext(FExecutionContextImpl::Claim());
    }
#endif
 
    static FExecutionContext GetActiveContext()
    {
        ensure(!bBlockAllExecution);
#if WITH_VERSE_BPVM
        return FExecutionContext(FExecutionContextImpl::GetCurrent());
#else
        return FExecutionContext(::Verse::FRunningContextPromise{});
#endif
    }
 
#if WITH_VERSE_VM || defined(__INTELLISENSE__)
    ::Verse::FRunningContext GetContext()
    {
        return Impl;
    }
#endif
 
    static bool SetBlockExecution(bool ShouldBlock)
    {
        bool bWasBlocked = bBlockAllExecution;
        bBlockAllExecution = ShouldBlock;
        return bWasBlocked;
    }
    static bool IsExecutionBlocked() { return bBlockAllExecution; }
 
private:
#if WITH_VERSE_BPVM
    explicit FExecutionContext(FExecutionContextImpl* InImpl)
        : Impl(InImpl)
    {
        ensureMsgf(Impl != nullptr && Impl->bActive, TEXT("Running Verse code outside of an execution context!"));
    }
#else
    explicit FExecutionContext(::Verse::FRunningContext InImpl)
        : Impl(InImpl)
    {
    }
#endif
 
    COREUOBJECT_API static bool bBlockAllExecution;
 
#if WITH_VERSE_BPVM
    FExecutionContextImpl* Impl;
#else
    ::Verse::FRunningContext Impl;
#endif
};
 
} // namespace verse