improve tables support (#276)

* support more table types in the constructor
* add fromtable() and Tables.materializer()
* only run doctests on a single Julia version

---------

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

src/tables.jl

@@ -12,6 +12,14 @@ function _schema(::Type{T}) where {T<:NTuple{N, Any}} where N
     return Tables.Schema{ntuple(identity, N), T}
 end
 
+StructArray(cols::Tables.AbstractColumns) = StructArray(Tables.columntable(cols))
+StructArray{T}(cols::Tables.AbstractColumns) where {T} = StructArray{T}(Tables.columntable(cols))
+
+# convert from any Tables-compliant object
+fromtable(cols) = StructArray(Tables.columntable(cols))
+Tables.materializer(::Type{<:StructArray}) = fromtable
+Tables.materializer(::StructArray) = fromtable  # Tables documentation says it's not needed, but actually it is
+
 function try_compatible_columns(rows::R, s::StructArray) where {R}
     Tables.isrowtable(rows) && Tables.columnaccess(rows) || return nothing
     T = eltype(rows)

test/runtests.jl

@@ -14,7 +14,7 @@ using SparseArrays
 using InfiniteArrays
 
 using Documenter: doctest
-if Base.VERSION >= v"1.6" && Int === Int64
+if Base.VERSION == v"1.6" && Int === Int64
     doctest(StructArrays)
 end
 
@@ -717,6 +717,22 @@ end
     # Testing integer column "names":
     @test invoke(append!, Tuple{StructVector,Any}, StructArray(([0],)), StructArray(([1],))) ==
         StructArray(([0, 1],))
+
+    dtab = (a=[1,2],) |> Tables.dictcolumntable
+    @test StructArray(dtab) == [(a=1,), (a=2,)]
+    @test StructArray{NamedTuple{(:a,), Tuple{Float64}}}(dtab) == [(a=1.,), (a=2.,)]
+    @test StructVector{NamedTuple{(:a,), Tuple{Float64}}}(dtab) == [(a=1,), (a=2,)]
+
+    tblbase = (a=[1,2], b=["3", "4"])
+    @testset for tblfunc in [Tables.columntable, Tables.rowtable, Tables.dictcolumntable, Tables.dictrowtable]
+        tbl = tblfunc(tblbase)
+        sa = StructArrays.fromtable(tbl)
+        @test sa::StructArray == [(a=1, b="3"), (a=2, b="4")]
+        sa = Tables.materializer(StructArray)(tbl)
+        @test sa::StructArray == [(a=1, b="3"), (a=2, b="4")]
+        sa = Tables.materializer(sa)(tbl)
+        @test sa::StructArray == [(a=1, b="3"), (a=2, b="4")]
+    end
 end
 
 struct S