Implement explicit_basis_covering for same basis (#48)

* Implement explicit_basis_covering for same basis

* Fix format

Author: blegat

src/monomial.jl

@@ -64,6 +64,10 @@ function Base.getindex(basis::SubBasis{B,M}, value::Polynomial{B,M}) where {B,M}
     return mono
 end
 
+function explicit_basis_covering(::FullBasis{B}, target::SubBasis{B}) where {B}
+    return SubBasis{B}(target.monomials)
+end
+
 const MonomialIndexedBasis{B,M} = Union{SubBasis{B,M},FullBasis{B,M}}
 
 MP.monomial_type(::Type{<:SubBasis{B,M}}) where {B,M} = M
@@ -295,6 +299,14 @@ function explicit_basis_covering(
     return SubBasis{B}(target.monomials)
 end
 
+# To break ambiguity
+function explicit_basis_covering(
+    ::FullBasis{B},
+    target::SubBasis{B},
+) where {B<:AbstractMonomial}
+    return SubBasis{B}(target.monomials)
+end
+
 function Base.adjoint(p::Polynomial{B}) where {B<:AbstractMonomialIndexed}
     return Polynomial{B}(adjoint(p.monomial))
 end

test/runtests.jl

@@ -56,6 +56,10 @@ function api_test(B::Type{<:MB.AbstractMonomialIndexed}, degree)
             full_basis,
             MB.SubBasis{ScaledMonomial}(monomials(x, 0:degree)),
         ),
+        explicit_basis_covering(
+            full_basis,
+            MB.SubBasis{B}(monomials(x, 0:degree)),
+        ),
     ]
         _test_basis(basis)
         @test basis isa MB.explicit_basis_type(typeof(full_basis))