Add model_filename option (#20)

Author: odow

README.md

@@ -102,3 +102,14 @@ model = Model(() -> MiniZinc.Optimizer{Float64}("gurobi"))
 optimize!(model)
 @show value.(x)
 ```
+
+## Options
+
+Set options using `MOI.RawOptimizerAttribute` in MOI or
+`set_optimizer_attribute` in JuMP.
+
+`MiniZinc.jl` supports the following options:
+
+ * `model_filename::String = ""`: the location at which to write out the `.mzn`
+   file during optimization. This option can be helpful during debugging. If
+   left empty, a temporary file will be used instead.

src/optimize.jl

@@ -34,8 +34,11 @@ mutable struct Optimizer{T} <: MOI.AbstractOptimizer
     inner::Model{T}
     has_solution::Bool
     primal_solution::Dict{MOI.VariableIndex,T}
+    options::Dict{String,Any}
     function Optimizer{T}(solver::String) where {T}
-        return new(solver, Model{T}(), false, Dict{MOI.VariableIndex,T}())
+        primal_solution = Dict{MOI.VariableIndex,T}()
+        options = Dict{String,Any}("model_filename" => "")
+        return new(solver, Model{T}(), false, primal_solution, options)
     end
 end
 
@@ -61,7 +64,10 @@ end
 
 function _run_minizinc(dest::Optimizer)
     dir = mktempdir()
-    filename = joinpath(dir, "model.mzn")
+    filename = dest.options["model_filename"]
+    if isempty(filename)
+        filename = joinpath(dir, "model.mzn")
+    end
     output = joinpath(dir, "model.ozn")
     open(filename, "w") do io
         return write(io, dest.inner)
@@ -86,6 +92,19 @@ function MOI.empty!(model::Optimizer)
     return
 end
 
+function MOI.supports(model::Optimizer, attr::MOI.RawOptimizerAttribute)
+    return haskey(model.options, attr.name)
+end
+
+function MOI.get(model::Optimizer, attr::MOI.RawOptimizerAttribute)
+    return get(model.options, attr.name, nothing)
+end
+
+function MOI.set(model::Optimizer, attr::MOI.RawOptimizerAttribute, value)
+    model.options[attr.name] = value
+    return
+end
+
 function MOI.supports_constraint(
     model::Optimizer,
     ::Type{F},

test/runtests.jl

@@ -1023,6 +1023,30 @@ function test_moi_tests()
     return
 end
 
+function test_model_filename()
+    model = MOI.Utilities.Model{Int}()
+    x, x_int = MOI.add_constrained_variable(model, MOI.Integer())
+    c1 = MOI.add_constraint(model, x, MOI.GreaterThan(1))
+    c2 = MOI.add_constraint(model, x, MOI.LessThan(3))
+    @test MOI.is_valid(model, x)
+    @test MOI.is_valid(model, x_int)
+    @test MOI.is_valid(model, c1)
+    @test MOI.is_valid(model, c2)
+    solver = MiniZinc.Optimizer{Int}(MiniZinc.Chuffed())
+    attr = MOI.RawOptimizerAttribute("model_filename")
+    @test MOI.supports(solver, attr)
+    @test MOI.get(solver, attr) == ""
+    MOI.set(solver, attr, "test.mzn")
+    @test MOI.get(solver, attr) == "test.mzn"
+    index_map, _ = MOI.optimize!(solver, model)
+    @test MOI.get(solver, MOI.TerminationStatus()) === MOI.OPTIMAL
+    @test MOI.get(solver, MOI.ResultCount()) >= 1
+    @test MOI.get(solver, MOI.VariablePrimal(), index_map[x]) in [1, 2, 3]
+    @test read("test.mzn", String) == "var 1 .. 3: x1;\nsolve satisfy;\n"
+    rm("test.mzn")
+    return
+end
+
 end
 
 TestMiniZinc.runtests()