[Utilities] add shift_constant for Parameter set (#2105)

Author: odow

src/Utilities/sets.jl

@@ -61,6 +61,11 @@ function shift_constant(set::MOI.Interval, offset)
 end
 supports_shift_constant(::Type{<:MOI.Interval}) = true
 
+function shift_constant(set::MOI.Parameter, offset)
+    return MOI.Parameter(MOI.constant(set) + offset)
+end
+supports_shift_constant(::Type{<:MOI.Parameter}) = true
+
 """
     ScalarLinearSet{T}
 

test/Utilities/sets.jl

@@ -61,6 +61,8 @@ function test_shifts()
     @test MOIU.shift_constant(MOI.Interval(-2, 3), 1) == MOI.Interval(-1, 4)
     @test MOIU.supports_shift_constant(MOI.ZeroOne) == false
     @test_throws MethodError MOIU.shift_constant(MOI.ZeroOne(), 1.0)
+    @test MOIU.supports_shift_constant(MOI.Parameter{Int})
+    @test MOIU.shift_constant(MOI.Parameter(3), 1) == MOI.Parameter(4)
     return
 end