add setall() (#68)

Author: aplavin

Project.toml

@@ -1,7 +1,7 @@
 name = "Accessors"
 uuid = "7d9f7c33-5ae7-4f3b-8dc6-eff91059b697"
 authors = ["Takafumi Arakaki <[email protected]>", "Jan Weidner <[email protected]> and contributors"]
-version = "0.1.21"
+version = "0.1.22"
 
 [deps]
 Compat = "34da2185-b29b-5c13-b0c7-acf172513d20"

src/getsetall.jl

@@ -3,7 +3,10 @@
 
 Extract all parts of `obj` that are selected by `optic`.
 Returns a flat `Tuple` of values, or an `AbstractVector` if the selected parts contain arrays.
-This function is experimental and we might change the precise output container in future.
+
+This function is experimental and we might change the precise output container in the future.
+
+See also [`setall`](@ref).
 
 
 ```jldoctest
@@ -20,6 +23,34 @@ julia> getall(obj, @optic _ |> Elements() |> last)
 """
 function getall end
 
+"""
+    setall(obj, optic, values)
+
+Replace a part of `obj` that is selected by `optic` with `values`.
+The `values` collection should have the same number of elements as selected by `optic`.
+
+This function is experimental and might change in the future.
+
+See also [`getall`](@ref), [`set`](@ref). The former is dual to `setall`:
+
+```jldoctest
+julia> using Accessors
+
+julia> obj = (a=1, b=(2, 3));
+
+julia> optic = @optic _ |> Elements() |> last;
+
+julia> getall(obj, optic)
+(1, 3)
+
+julia> setall(obj, optic, (4, 5))
+(a = 4, b = (2, 5))
+```
+"""
+function setall end
+
+# implementations for individual noncomposite optics
+
 getall(obj::Union{Tuple, AbstractVector}, ::Elements) = obj
 getall(obj::Union{NamedTuple}, ::Elements) = values(obj)
 getall(obj::AbstractArray, ::Elements) = vec(obj)
@@ -29,17 +60,63 @@ getall(obj, ::Properties) = getproperties(obj) |> values
 getall(obj, o::If) = o.modify_condition(obj) ? (obj,) : ()
 getall(obj, f) = (f(obj),)
 
+function setall(obj, ::Properties, vs)
+    names = propertynames(obj)
+    setproperties(obj, NamedTuple{names}(NTuple{length(names)}(vs)))
+end
+setall(obj::NamedTuple{NS}, ::Elements, vs) where {NS} = NamedTuple{NS}(NTuple{length(NS)}(vs))
+setall(obj::NTuple{N, Any}, ::Elements, vs) where {N} = (@assert length(vs) == N; NTuple{N}(vs))
+setall(obj::AbstractArray, ::Elements, vs::AbstractArray) = (@assert length(obj) == length(vs); reshape(vs, size(obj)))
+setall(obj::AbstractArray, ::Elements, vs) = setall(obj, Elements(), collect(vs))
+setall(obj, o::If, vs) = error("Not supported")
+setall(obj, o, vs) = set(obj, o, only(vs))
+
+
+# implementations for composite optics
+
+# A straightforward recursive approach doesn't actually infer,
+# see https://github.com/JuliaObjects/Accessors.jl/pull/64 and https://github.com/JuliaObjects/Accessors.jl/pull/68.
+# Instead, we need to generate separate functions for each recursion level.
 
-# A recursive implementation of getall doesn't actually infer,
-# see https://github.com/JuliaObjects/Accessors.jl/pull/64.
-# Instead, we need to generate unrolled code explicitly.
 function getall(obj, optic::ComposedFunction)
     N = length(decompose(optic))
-    _GetAll{N}()(obj, optic)
+    _getall(obj, optic, Val(N))
+end
+
+function setall(obj, optic::ComposedFunction, vs)
+    N = length(decompose(optic))
+    vss = to_nested_shape(vs, Val(getall_lengths(obj, optic, Val(N))), Val(N))
+    _setall(obj, optic, vss, Val(N))
+end
+
+
+# _getall: the actual workhorse for getall
+_getall(_, _, ::Val{N}) where {N} = error("Too many chained optics: $N is not supported for now. See also https://github.com/JuliaObjects/Accessors.jl/pull/64.")
+_getall(obj, optic, ::Val{1}) = getall(obj, optic)
+for i in 2:10
+    @eval function _getall(obj, optic, ::Val{$i})
+        _reduce_concat(
+            map(getall(obj, optic.inner)) do obj
+                _getall(obj, optic.outer, Val($(i-1)))
+            end
+        )
+    end
+end
+
+# _setall: the actual workhorse for setall
+# takes values as a nested tuple with proper leaf lengths, prepared in setall above
+_setall(_, _, _, ::Val{N}) where {N} = error("Too many chained optics: $N is not supported for now. See also https://github.com/JuliaObjects/Accessors.jl/pull/68.")
+_setall(obj, optic, vs, ::Val{1}) = setall(obj, optic, vs)
+for i in 2:10
+    @eval function _setall(obj, optic, vs, ::Val{$i})
+        setall(obj, optic.inner, map(getall(obj, optic.inner), vs) do obj, vss
+            _setall(obj, optic.outer, vss, Val($(i - 1)))
+        end)
+    end
 end
 
-struct _GetAll{N} end
-(::_GetAll{N})(_) where {N} = error("Too many chained optics: $N is not supported for now. See also https://github.com/JuliaObjects/Accessors.jl/pull/64.")
+
+# helper functions
 
 _concat(a::Tuple, b::Tuple) = (a..., b...)
 _concat(a::Tuple, b::AbstractVector) = vcat(collect(a), b)
@@ -51,26 +128,48 @@ _reduce_concat(xs::AbstractVector) = reduce(append!, xs; init=eltype(eltype(xs))
 _reduce_concat(xs::Tuple{AbstractVector, Vararg{AbstractVector}}) = reduce(vcat, xs)
 _reduce_concat(xs::AbstractVector{<:AbstractVector}) = reduce(vcat, xs)
 
-function _generate_getall(N::Int)
-    syms = [Symbol(:f_, i) for i in 1:N]
-
-    expr = :( getall(obj, $(syms[end])) )
-    for s in syms[1:end - 1] |> reverse
-        expr = :(
-            _reduce_concat(
-                map(getall(obj, $(s))) do obj
-                    $expr
-                end
-            )
-        )
-    end
+_staticlength(::NTuple{N, <:Any}) where {N} = Val(N)
+_staticlength(x::AbstractVector) = length(x)
 
-    :(function (::_GetAll{$N})(obj, optic)
-        ($(syms...),) = deopcompose(optic)
-        $expr
-    end)
+getall_lengths(obj, optic, ::Val{1}) = _staticlength(getall(obj, optic))
+for i in 2:10
+    @eval function getall_lengths(obj, optic, ::Val{$i})
+        # convert to Tuple: vectors cannot be put into Val
+        map(getall(obj, optic.inner) |> Tuple) do o
+            getall_lengths(o, optic.outer, Val($(i - 1)))
+        end
+    end
 end
 
+_val(N::Int) = N
+_val(::Val{N}) where {N} = N
+
+nestedsum(ls::Int) = ls
+nestedsum(ls::Val) = ls
+nestedsum(ls::Tuple) = sum(_val ∘ nestedsum, ls)
+
+# to_nested_shape() definition uses both @eval and @generated
+#
+# @eval is needed because the code for different recursion depths should be different for inference,
+# not the same method with different parameters.
+#
+# @generated is used to unpack target lengths from the second argument at compile time to make to_nested_shape() as cheap as possible.
+#
+# Note: to_nested_shape() only operates on plain Julia types and won't be affected by user lens definition, unlike setall for example.
+# That's why it's safe to make it @generated.
+to_nested_shape(vs, ::Val{LS}, ::Val{1}) where {LS} = (@assert length(vs) == _val(LS); vs)
 for i in 2:10
-    eval(_generate_getall(i))
+    @eval @generated function to_nested_shape(vs, ls::Val{LS}, ::Val{$i}) where {LS}
+        vi = 1
+        subs = map(LS) do lss
+            n = nestedsum(lss)
+            elems = map(vi:vi+_val(n)-1) do j
+                :( vs[$j] )
+            end
+            res = :( to_nested_shape(($(elems...),), $(Val(lss)), $(Val($(i - 1)))) )
+            vi += _val(n)
+            res
+        end
+        :( ($(subs...),) )
+    end
 end

src/optics.jl

@@ -1,6 +1,6 @@
 export @optic
 export PropertyLens, IndexLens
-export set, modify, delete, insert, getall
+export set, modify, delete, insert, getall, setall
 export ∘, opcompose, var"⨟"
 export Elements, Recursive, If, Properties
 export setproperties

src/testing.jl

@@ -22,3 +22,19 @@ function test_modify_law(f, lens, obj)
     obj_setfget = set(obj, lens, val)
     @test obj_modify == obj_setfget
 end
+
+function test_getsetall_laws(optic, obj, vals1, vals2; cmp=(==))
+
+    # setall ⨟ getall
+    vals = getall(obj, optic)
+    @test cmp(setall(obj, optic, vals), obj)
+
+    # getall ⨟ setall
+    obj1 = setall(obj, optic, vals1)
+    @test cmp(collect(getall(obj1, optic)), collect(vals1))
+
+    # setall idempotent
+    obj12 = setall(obj1, optic, vals2)
+    obj2 = setall(obj12, optic, vals2)
+    @test obj12 == obj2
+end

test/test_getsetall.jl

@@ -64,6 +64,49 @@ if VERSION >= v"1.6"  # for ComposedFunction
     obj = ([1, 2], [:a, :b])
     @test [1, 2, :a, :b] == @inferred getall(obj, @optic _ |> Elements() |> Elements())
 end
+
+@testset "setall" begin
+    for o in [Elements(), Properties()]
+        @test (a=2, b=3) === @inferred setall((a=1, b="2"), o, (2, 3))
+        @test (a=2, b="3") === @inferred setall((a=1, b="2"), o, (2, "3"))
+        @test (a=2, b=3) === @inferred setall((a=1, b="2"), o, [2, 3])
+    end
+    @test (2, 3) === @inferred setall((1, "2"), Elements(), (2, 3))
+    @test (2, "3") === @inferred setall((1, "2"), Elements(), (2, "3"))
+    @test (2, 3) === @inferred setall((1, "2"), Elements(), [2, 3])
+    @test [2, 3] == @inferred setall([1, "2"], Elements(), (2, 3))
+    @test [2, "3"] == @inferred setall([1, "2"], Elements(), (2, "3"))
+    @test [2, 3] == @inferred setall([1, "2"], Elements(), [2, 3])
+
+    obj = (a=1, b=2.0, c='3')
+    @test (a="aa", b=2.0, c='3') === @inferred setall(obj, @optic(_.a), ("aa",))
+    @test (a=9, b=19.0, c='4') === @inferred setall(obj, @optic(_ |> Elements() |> _ + 1), (10, 20.0, '5'))
+
+    obj = (a=1, b=((c=3, d=4), (c=5, d=6)))
+    @test (a=1, b=(:x, :y)) === @inferred setall(obj, @optic(_.b |> Elements()), (:x, :y))
+    @test (a=1, b=((c=:x, d=4), (c=:y, d=6))) === @inferred setall(obj, @optic(_.b |> Elements() |> _.c), (:x, :y))
+    @test (a=1, b=((c=:x, d="y"), (c=:z, d=10))) === @inferred setall(obj, @optic(_.b |> Elements() |> Properties()), (:x, "y", :z, 10))
+    @test (a=1, b=((c=-3., d=-4.), (c=-5., d=-6.))) === @inferred setall(obj, @optic(_.b |> Elements() |> Properties() |> _ * 3), (-9, -12, -15, -18))
+    @test (a=1, b=((c=-3., d=-4.), (c=-5., d=-6.))) === @inferred setall(obj, @optic(_.b |> Elements() |> Properties() |> _ * 3), [-9, -12, -15, -18])
+
+    obj = ([1, 2], 3:5, (6,))
+    @test obj == setall(obj, @optic(_ |> Elements() |> Elements()), 1:6)
+    @test ([2, 3], 4:6, (7,)) == setall(obj, @optic(_ |> Elements() |> Elements() |> _ - 1), 1:6)
+    # can this infer?..
+    @test_broken obj == @inferred setall(obj, @optic(_ |> Elements() |> Elements()), 1:6)
+    @test_broken ([2, 3], 4:6, (7,)) == @inferred setall(obj, @optic(_ |> Elements() |> Elements() |> _ - 1), 1:6)
+end
+
+@testset "getall/setall consistency" begin
+    for (optic, obj, vals1, vals2) in [
+            (Elements(), (1, "2"), (2, 3), (4, 5)),
+            (Properties(), (a=1, b="2"), (2, 3), (4, 5)),
+            (@optic(_.b |> Elements() |> Properties() |> _ * 3), (a=1, b=((c=3, d=4), (c=5, d=6))), 1:4, (-9, -12, -15, -18)),
+        ]
+        Accessors.test_getsetall_laws(optic, obj, vals1, vals2)
+    end
+end
+        
 end
 
 end