Support vectors as indices to NamedTuple

Fix #32662, #27021

Author: cmcaine

base/namedtuple.jl

@@ -103,6 +103,8 @@ firstindex(t::NamedTuple) = 1
 lastindex(t::NamedTuple) = nfields(t)
 getindex(t::NamedTuple, i::Int) = getfield(t, i)
 getindex(t::NamedTuple, i::Symbol) = getfield(t, i)
+getindex(t::NamedTuple, v::AbstractVector{<:Integer}) = (; map(i->keys(t)[i] => t[i], v)...)
+getindex(t::NamedTuple, v::AbstractVector{Symbol}) = (; map(i->i => t[i], v)...)
 indexed_iterate(t::NamedTuple, i::Int, state=1) = (getfield(t, i), i+1)
 isempty(::NamedTuple{()}) = true
 isempty(::NamedTuple) = false

test/namedtuple.jl

@@ -21,6 +21,10 @@
 @test (a=3,)[:a] == 3
 @test (x=4, y=5, z=6).y == 5
 @test (x=4, y=5, z=6).z == 6
+@test (x=4, y=5, z=6)[1:1] == (x=4,)
+@test (x=4, y=5, z=6)[1:2] == (x=4, y=5)
+@test (x=4, y=5, z=6)[[1,3]] == (x=4, z=6)
+@test (x=4, y=5, z=6)[[:x,:y]] == (x=4, y=5)
 @test_throws ErrorException (x=4, y=5, z=6).a
 @test_throws BoundsError (a=2,)[0]
 @test_throws BoundsError (a=2,)[2]