cleanup: delete internal type VectorAffineFunctionAsMatrix (#660)

* delete VectorAffineFunctionAsMatrix

* fix

Author: ericphanson

src/Convex.jl

@@ -224,7 +224,7 @@ for (root, _, files) in walkdir(joinpath(@__DIR__, "constraints"))
 end
 
 include("SparseTape.jl")
-include("VectorAffineFunctionAsMatrix.jl")
+include("to_MOI.jl")
 include("ComplexTape.jl")
 include("operate.jl")
 include("complex_operate.jl")

src/VectorAffineFunctionAsMatrix.jl

@@ -0,0 +1,35 @@
+# Copyright (c) 2014: Madeleine Udell and contributors
+#
+# Use of this source code is governed by a BSD-style license that can be found
+# in the LICENSE file or at https://opensource.org/license/bsd-2-clause
+
+# This is a variant of MOI.VectorAffineFunction which represents
+# the transformation `matrix * variables + vector` lazily.
+to_vaf(tape::SPARSE_VECTOR) = tape
+
+# convert to a usual VAF
+function to_vaf(tape::SparseTape{T}) where {T}
+    I, J, V = SparseArrays.findnz(tape.operation.matrix)
+    vats = Vector{MOI.VectorAffineTerm{T}}(undef, length(I))
+    for (idx, n) in enumerate(eachindex(I, J, V))
+        i = I[n]
+        j = J[n]
+        v = V[n]
+
+        vats[idx] = MOI.VectorAffineTerm{T}(
+            i,
+            MOI.ScalarAffineTerm{T}(v, tape.variables[j]),
+        )
+    end
+
+    return MOI.VectorAffineFunction{T}(vats, tape.operation.vector)
+end
+
+# method for adding constraints and converting to standard VAFs as needed
+function MOI_add_constraint(model, f, set)
+    return MOI.add_constraint(model, f, set)
+end
+
+function MOI_add_constraint(model, f::SparseTape, set)
+    return MOI_add_constraint(model, to_vaf(f), set)
+end