added tuple fallback

Author: zsunberg

README.md

@@ -51,9 +51,9 @@ The interface for hybrid continuous-discrete spaces is currently planned, but no
 
 The Cartesian product of two spaces `a` and `b` can be constructed with `c = product(a, b)`.
 
-The exact form of the resulting space is unspecified and should be considered an implementation detail. The only guarantees are (1) that there will be one unique element of `c` for every combination of one object from `a` and one object from `b` and (2) that the resulting collection conforms to the interface above.
+The exact form of the resulting space is unspecified and should be considered an implementation detail. The only guarantees are (1) that there will be one unique element of `c` for every combination of one object from `a` and one object from `b` and (2) that the resulting space conforms to the interface above.
 
-The `TupleProductSpace` constructor provides a specialized Cartesian product where each element is a tuple, i.e. `TupleProductSpace(a, b)` has elements of type `Tuple{eltype(a), eltype(b)}`.
+The `TupleSpaceProduct` constructor provides a specialized Cartesian product where each element is a tuple, i.e. `TupleSpaceProduct(a, b)` has elements of type `Tuple{eltype(a), eltype(b)}`.
 
 ---
 

src/basic.jl

@@ -27,6 +27,9 @@ promote_spacestyle(::FiniteSpaceStyle, ::FiniteSpaceStyle) = FiniteSpaceStyle()
 promote_spacestyle(::ContinuousSpaceStyle, ::ContinuousSpaceStyle) = ContinuousSpaceStyle()
 promote_spacestyle(_, _) = UnknownSpaceStyle()
 
+# handle case of 3 or more
+promote_spacestyle(s1, s2, s3, others...) = foldl(promote_spacestyle, (s1, s2, s3, args...))
+
 function elsize end # note: different than Base.elsize
 
 function bounds end

src/product.jl

@@ -7,16 +7,34 @@ function product(b1::Box, b2::Box)
     if size(b1.lower, 2) == size(b2.lower, 2) # same number of columns
         return Box(vcat(b1.lower, b2.lower), vcat(b1.upper, b2.upper))
     else
-        return GenericrSpaceProduct((b1, b2))
+        return TupleSpaceProduct((b1, b2))
     end
 end
 
 # handle case of 3 or more
-product(s1, s2, s3, args...) = foldl(product, (s1, s2, s3, args...))
+product(s1, s2, s3, args...) = foldl(product, (s1, s2, s3, args...)) # not totally sure if this should be foldl or foldr
 
-struct TupleProductSpace{T<:Tuple}
-    members::T
+struct TupleSpaceProduct{T<:Tuple}
+    ss::T
 end
 
-# handle any case not covered above
-product(s1, s2) = TupleProductSpace((s1, s2))
+TupleSpaceProduct(s1, s2, others...) = TupleSpaceProduct((s1, s2, others...))
+
+subspaces(s::TupleSpaceProduct) = s.ss
+
+product(s1::TupleSpaceProduct, s2::TupleSpaceProduct) = TupleSpaceProduct(subspaces(s1)..., subspaces(s2)...)
+
+# handle any case not covered elsewhere by making a TupleSpaceProduct
+# if one of the members is already a TupleSpaceProduct, we add put them together in a new "flat" TupleSpaceProduct
+# note: if we had defined product(s1::TupleSpaceProduct, s2) it might be annoying because product(s1, s2::AnotherSpace) would be ambiguous with it
+function product(s1, s2)
+    if s1 isa TupleSpaceProduct
+        return TupleSpaceProduct(subspaces(s1)..., s2)
+    elseif s2 isa TupleSpaceProduct
+        return TupleSpaceProduct(s1, subspaces(s2)...)
+    else
+        return TupleSpaceProduct(s1, s2)
+    end
+end
+
+SpaceStyle(s::TupleSpaceProduct) = promote_spacestyle(subspaces(s)...)