Flux.jl/src/treelike.jl

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import Adapt: adapt, adapt_storage
import Zygote: IdSet
children(x) = ()
mapchildren(f, x) = x
children(x::Tuple) = x
children(x::NamedTuple) = x
mapchildren(f, x::Tuple) = map(f, x)
mapchildren(f, x::NamedTuple) = map(f, x)
function treelike(m::Module, T, fs = fieldnames(T))
@eval m begin
Flux.children(x::$T) = ($([:(x.$f) for f in fs]...),)
Flux.mapchildren(f, x::$T) = $T(f.($children(x))...)
end
end
macro treelike(T, fs = nothing)
fs == nothing || isexpr(fs, :tuple) || error("@treelike T (a, b)")
fs = fs == nothing ? [] : [:($(map(QuoteNode, fs.args)...),)]
:(treelike(@__MODULE__, $(esc(T)), $(fs...)))
end
isleaf(x) = isempty(children(x))
function mapleaves(f, x; cache = IdDict())
haskey(cache, x) && return cache[x]
cache[x] = isleaf(x) ? f(x) : mapchildren(x -> mapleaves(f, x, cache = cache), x)
end
function prefor(f, x; seen = IdSet())
x seen && return
push!(seen, x)
f(x)
foreach(x -> prefor(f, x, seen = seen), children(x))
return
end
function params(m)
ps = Params()
prefor(p ->
p isa AbstractArray{<:Real} &&
!any(p -> p === p, ps) && push!(ps, p),
m)
return ps
end
params(m...) = params(m)
function loadparams!(m, xs)
for (p, x) in zip(params(m), xs)
size(p) == size(x) ||
error("Expected param size $(size(p)), got $(size(x))")
copyto!(p, x)
end
end
# CPU/GPU movement conveniences
cpu(m) = mapleaves(x -> adapt(Array, x), m)
const gpu_adaptor = if has_cuarrays()
CuArrays.cu
else
identity
end
gpu(x) = mapleaves(gpu_adaptor, x)
# Precision
adapt_storage(T::Type{<:Real}, xs::AbstractArray{<:Real}) = convert.(T, xs)
paramtype(T::Type{<:Real}, m) = mapleaves(x -> adapt(T, x), m)
f32(m) = paramtype(Float32, m)
f64(m) = paramtype(Float64, m)
# General parameter map
function mapparams(f, m)
mapleaves(m) do x
x isa Union{AbstractArray,Number} ? f(x) : x
end
end