Added Base.keepat! for StructVector (#301)

Co-authored-by: Pietro Vertechi <pietro.vertechi@protonmail.com>
Co-authored-by: Alexander Plavin <alexander@plav.in>

src/structarray.jl

@@ -413,6 +413,13 @@ function Base.deleteat!(s::StructVector{T}, idxs) where T
     return StructVector{T}(t)
 end
 
+@static if VERSION >= v"1.7.0"
+    function Base.keepat!(s::StructVector{T}, idxs) where T
+        t = map(Base.Fix2(keepat!, idxs), components(s))
+        return StructVector{T}(t)
+    end
+end
+
 Base.copyto!(I::StructArray, J::StructArray) = (foreachfield(copyto!, I, J); I)
 
 function Base.copyto!(I::StructArray, doffs::Integer, J::StructArray, soffs::Integer, n::Integer)

test/runtests.jl

@@ -259,6 +259,10 @@ end
     @test d == c == StructArray(a=[1,10,2,3], b=[2,20,3,4], c=["a","A","b","c"])
     d = deleteat!(c, 2)
     @test d == c == StructArray(a=[1,2,3], b=[2,3,4], c=["a","b","c"])
+    if Base.VERSION >= v"1.7.0"
+        d = keepat!(c, 2)
+        @test d == c == StructArray(a=[2], b=[3], c=["b"])
+    end
 
     c = StructArray(a=[1], b=[2], c=["a"])
     d = [(a=10, b=20, c="A")]
@@ -295,6 +299,10 @@ end
     @test d == c == StructArray{C}(a=[1,10,2,3], b=[2,20,3,4], c=["a","A","b","c"])
     d = deleteat!(c, 2)
     @test d == c == StructArray{C}(a=[1,2,3], b=[2,3,4], c=["a","b","c"])
+    if Base.VERSION >= v"1.7.0"
+        d = keepat!(c, 2)
+        @test d == c == StructArray{C}(a=[2], b=[3], c=["b"])
+    end
 
     c = StructArray{C}(a=[1], b=[2], c=["a"])
     d = [C(10, 20, "A")]