Axiom.Runtime.Instructions.UnifyConstantInstruction.Execute C# (CSharp) Method

        public override void Execute(AbstractMachineState state)
        {
            AMProgram program = (AMProgram)state.Program;
            AMHeap heap = (AMHeap)state.DataArea;
            AMTrail trail = (AMTrail)state.Trail;

            if (state.IsReadMode)
            {
                AbstractTerm addr = ((AbstractTerm)state.S).Dereference();
                state.S = state.S.Next;
                if (addr.IsReference)
                {
                    addr.Assign(new ConstantTerm(_constant));
                    trail.Trail(addr);

                }
                else if (addr.IsConstant)
                {
                    state.Fail = !_constant.Equals(addr.Data());
                }
                else
                {
                    state.Fail = true;
                }
            }
            else
            {
                heap.Push(new ConstantTerm(_constant));
            }

            if (state.Fail)
            {
                state.Backtrack();
            }
            else
            {
                program.Next();
            }
        }

        public void UnifyConstant()
        {
            AbstractMachineState state = SetupMachine();

            UnifyConstantInstruction i = new UnifyConstantInstruction();

            object[] args = { "ali" };

            state.S = new AbstractTerm();

            i.Process(args);
            i.Execute(state);

            Assert.AreEqual("unify_constant", i.Name());
            Assert.AreEqual(1, i.NumberOfArguments());
            Assert.AreEqual("ali", ((AbstractTerm)state.S).Data());
        }