Fix support for external sets in loadfromstring (#2177)

Author: odow

src/Utilities/parser.jl

@@ -267,6 +267,36 @@ function _parsed_to_moi(model, f::_ParsedVariableIndex)
     return _parsed_to_moi(model, f.variable)
 end
 
+_walk_expr(f::F, expr) where {F<:Function} = f(expr)
+
+function _walk_expr(f::F, expr::Expr) where {F<:Function}
+    for (i, arg) in enumerate(expr.args)
+        expr.args[i] = _walk_expr(f, arg)
+    end
+    return expr
+end
+
+function _parse_set(expr::Expr)
+    expr = _walk_expr(expr) do arg
+        if arg isa Symbol && arg in (:MOI, :MathOptInterface)
+            return MOI
+        end
+        return arg
+    end
+    @assert Meta.isexpr(expr, :call)
+    if expr.args[1] isa Symbol
+        # If the set is a Symbol, it must be one of the MOI sets. We need to
+        # eval this in the MOI module.
+        return Core.eval(MOI, expr)
+    elseif Meta.isexpr(expr.args[1], :curly) && expr.args[1].args[1] isa Symbol
+        # Something like Indicator{}()
+        return Core.eval(MOI, expr)
+    end
+    # If the set is an expression, it must be something like
+    # `SCS.ScaledPSDCone()`. We need to eval this in `Main`.
+    return Core.eval(Main, expr)
+end
+
 # Ideally, this should be load_from_string
 """
     loadfromstring!(model, s)
@@ -333,7 +363,7 @@ function loadfromstring!(model, s)
         elseif label == :constrainedvariable
             @assert length(ex.args) == 3
             @assert ex.args[1] == :in
-            set = Core.eval(MOI, ex.args[3])
+            set = _parse_set(ex.args[3])
             if isa(ex.args[2], Symbol)
                 # constrainedvariable: x in LessThan(1.0)
                 x, _ = MOI.add_constrained_variable(model, set)
@@ -362,7 +392,7 @@ function loadfromstring!(model, s)
             f = _parsed_to_moi(model, _parse_function(ex.args[2], T))
             if ex.args[1] == :in
                 # Could be safer here
-                set = Core.eval(MOI, ex.args[3])
+                set = _parse_set(ex.args[3])
             elseif ex.args[1] == :<=
                 set = MOI.LessThan(Core.eval(Base, ex.args[3]))
             elseif ex.args[1] == :>=

test/Utilities/parser.jl

@@ -399,6 +399,42 @@ function test_eltypes_complex_float64()
     return
 end
 
+struct Set2175 <: MOI.AbstractScalarSet end
+
+function test_parse_external_set_constraint()
+    model = MOI.Utilities.UniversalFallback(MOI.Utilities.Model{Float64}())
+    MOI.Utilities.loadfromstring!(
+        model,
+        "variables: x\nx in $(@__MODULE__).Set2175()",
+    )
+    constraints = MOI.get(model, MOI.ListOfConstraintTypesPresent())
+    @test (MOI.VariableIndex, Set2175) in constraints
+    return
+end
+
+function test_parse_external_set_constrained_variable()
+    model = MOI.Utilities.UniversalFallback(MOI.Utilities.Model{Float64}())
+    MOI.Utilities.loadfromstring!(
+        model,
+        "constrainedvariable: x in $(@__MODULE__).Set2175()",
+    )
+    constraints = MOI.get(model, MOI.ListOfConstraintTypesPresent())
+    @test (MOI.VariableIndex, Set2175) in constraints
+    return
+end
+
+function test_parse_scope()
+    @test !isdefined(@__MODULE__, :MathOptInterface)
+    model = MOI.Utilities.UniversalFallback(MOI.Utilities.Model{Float64}())
+    MOI.Utilities.loadfromstring!(
+        model,
+        "variables: x\nx in MathOptInterface.ZeroOne()",
+    )
+    attr = MOI.NumberOfConstraints{MOI.VariableIndex,MOI.ZeroOne}()
+    @test MOI.get(model, attr) == 1
+    return
+end
+
 end  # module
 
 TestParser.runtests()