Added Base.sizehint! (#221)

* Added Base.sizehint! implementation

* Added sizehint! test

* Apply suggestions from code review

Co-authored-by: Pietro Vertechi <pietro.vertechi@protonmail.com>

Co-authored-by: kaandocal <>
Co-authored-by: Pietro Vertechi <pietro.vertechi@protonmail.com>

Author: kaandocal

src/structarray.jl

@@ -411,6 +411,13 @@ function Base.empty!(s::StructArray)
     foreachfield(empty!, s)
 end
 
+function Base.sizehint!(s::StructArray, i::Integer)
+    for a in components(s)
+        sizehint!(a, i)
+    end
+    return s
+end
+
 for op in [:cat, :hcat, :vcat]
     @eval begin
         function Base.$op(args::StructArray...; kwargs...)

test/runtests.jl

@@ -397,7 +397,15 @@ end
     t[5] = p
     @test t[5] == p
 end
-
+@testset "sizehint!" begin
+    t = StructArray{Pair}(([3, 5], [:a, :b]))
+    sizehint!(t, 5)
+    @test @allocated(resize!(t, 5)) == 0
+    @test length(t) == 5
+    p = 1 => :c
+    t[5] = p
+    @test t[5] == p
+end
 @testset "concat" begin
     t = StructArray{Pair}(([3, 5], ["a", "b"]))
     push!(t, (2 => "d"))
@@ -1019,4 +1027,4 @@ end
     A = @inferred StructArrays.map_params(zero, namedtypes)
     C = map(zero, NamedTuple{(:a, :b, :c)}(map(zero, fieldtypes(types))))
     @test A === C
-end
+end