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# This file is a part of Julia. License is MIT: https://julialang.org/license
### Methods for a Ref object that can store a single value of any type
mutable struct RefValue{T} <: Ref{T}
x::T
RefValue{T}() where {T} = new()
RefValue{T}(x) where {T} = new(x)
end
RefValue(x::T) where {T} = RefValue{T}(x)
isassigned(x::RefValue) = isdefined(x, :x)
function unsafe_convert(P::Type{Ptr{T}}, b::RefValue{T}) where T
if datatype_pointerfree(RefValue{T})
p = pointer_from_objref(b)
elseif isconcretetype(T) && T.mutable
p = pointer_from_objref(b.x)
else
# If the slot is not leaf type, it could be either immutable or not.
# If it is actually an immutable, then we can't take it's pointer directly
# Instead, explicitly load the pointer from the `RefValue`,
# which also ensures this returns same pointer as the one rooted in the `RefValue` object.
p = pointerref(Ptr{Ptr{Cvoid}}(pointer_from_objref(b)), 1, Core.sizeof(Ptr{Cvoid}))
end
return convert(P, p)
end
function unsafe_convert(P::Type{Ptr{Any}}, b::RefValue{Any})
return convert(P, pointer_from_objref(b))
end
unsafe_convert(::Type{Ptr{Cvoid}}, b::RefValue{T}) where {T} = convert(Ptr{Cvoid}, unsafe_convert(Ptr{T}, b))
getindex(b::RefValue) = b.x
setindex!(b::RefValue, x) = (b.x = x; b)
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