public void ExecuteForCommand()
{
ICommand setX = new SetVariableCommand("x", new ConstantExpression(0));
ICommand setY = new SetVariableCommand("y", new ConstantExpression(0));
List<ICommand> commands = new List<ICommand>();
commands.Add(setX);
commands.Add(setY);
ICommand initialCommand = new CompositeCommand(commands);
IExpression condition = new CompareExpression(ComparisonOperator.Less, new VariableExpression("x"), new ConstantExpression(6));
IExpression addXtoY = new ArithmeticBinaryExpression(ArithmeticOperator.Add, new VariableExpression("y"), new VariableExpression("x"));
ICommand addToY = new SetVariableCommand("y", addXtoY);
ICommand endCommand = new SetVariableCommand("x", new ArithmeticBinaryExpression(ArithmeticOperator.Add, new VariableExpression("x"), new ConstantExpression(1)));
ForCommand forcmd = new ForCommand(initialCommand, condition, endCommand, addToY);
BindingEnvironment environment = new BindingEnvironment();
environment.SetValue("y", null);
forcmd.Execute(environment);
Assert.AreEqual(15, environment.GetValue("y"));
}
private static ICallable BuildFactorialFunction()
{
IExpression condition = new CompareExpression(ComparisonOperator.LessEqual, new VariableExpression("n"), new ConstantExpression(1));
ICommand return1 = new ReturnCommand(new ConstantExpression(1));
ICommand return2 = new ReturnCommand(new ArithmeticBinaryExpression(
ArithmeticOperator.Multiply,
new VariableExpression("n"),
new InvokeExpression("Factorial", new IExpression[] { new ArithmeticBinaryExpression(ArithmeticOperator.Subtract, new VariableExpression("n"), new ConstantExpression(1)) })));
ICommand ifcmd = new IfCommand(condition, return1, return2);
ICallable factorial = new Function(new string[] { "n" }, ifcmd);
return factorial;
}
private static bool EvaluateComparisonOperator(ComparisonOperator operation, object left, object right)
{
IExpression expression = new CompareExpression(operation, new ConstantExpression(left), new ConstantExpression(right));
return (bool)expression.Evaluate(null);
}
private IExpression ParseBinaryExpressionZerothLevel()
{
IExpression expression = this.ParseBinaryExpressionFirstLevel();
if (expression == null)
return null;
while (this.TryParse(TokenType.Operator, "<", ">", "==", ">=", "<=", "!="))
{
Token oper = this.lexer.NextToken();
IExpression right = this.ParseBinaryExpressionFirstLevel();
ComparisonOperator op = 0;
if (oper.Value == "<")
op = ComparisonOperator.Less;
if (oper.Value == ">")
op = ComparisonOperator.Greater;
if (oper.Value == "<=")
op = ComparisonOperator.LessEqual;
if (oper.Value == ">=")
op = ComparisonOperator.GreaterEqual;
if (oper.Value == "==")
op = ComparisonOperator.Equal;
if (oper.Value == "!=")
op = ComparisonOperator.NotEqual;
expression = new CompareExpression(op, expression, right);
}
return expression;
}
