public void TestThe()
{
NumExpression n = new NumVariable("n");
var two = new NumConstant(2);
NumExpression test = new NumThe("n", n == two);
Assert.AreEqual("2", testAsync(test, 1000).Result);
test = new NumThe("n", n == two + two);
Assert.AreEqual("4", testAsync(test, 1000).Result);
test = new NumThe("n", n + n == n * n); // not valid since it has two results, but we ignore this
Assert.AreEqual("0", testAsync(test, 1000).Result);
// Find the positive natural such that 2n=n^2
test = new NumThe("n", (logicLoop | (n + n == n * n) & (n > zero)) | logicLoop);
Assert.AreEqual("2", testAsync(test, 1000).Result);
// Should fail
test = new NumThe("n", (n == zero) & (n > zero));
Assert.AreEqual(False, testAsync(test, 1000).Result);
test = new NumThe("n", (logicLoop | n == new NumConstant(50) | logicLoop));
Assert.AreEqual("50", testAsync(test, 1000).Result);
// Find the positive natural such that 2n=n^2 this time with logicFalse
test = new NumThe("n", ((n + n == n * n) & (n > zero)) | logicFalse);
Assert.AreEqual("2", testAsync(test, 1000).Result);
test = new NumThe("n", (n == new NumConstant(50) | logicFalse));
Assert.AreEqual("50", testAsync(test, 1000).Result);
}
public SortedSet <string> Visit(NumThe expression)
{
// 'the' is a binder, so it binds its variable
var vars = Run(expression.Expression);
vars.Remove(expression.VariableName);
return(vars);
}
public Expression Visit(NumThe expression)
{
if (expression.VariableName == VariableName)
{
return(expression); // variable is shadowed
}
else
{
var expr = (LogicExpression)expression.Expression.Accept(this);
return(new NumThe(expression.VariableName, expr));
}
}
public T Visit(NumThe expression)
{
expression.Expression.Accept(this);
return(default(T));
}
public async Task <Value> Visit(NumThe expression)
{
// The idea here is similar to VisitNumExists, except this time we remember
// which number we found.
// The number we are currently up to
int nextNum = 0;
bool foundValue = false;
List <Task <Value> > runningTasks = new List <Task <Value> >();
// Setup a new token source so we can cancel all the tasks we have created
CancellationTokenSource tokenSource = new CancellationTokenSource();
// When this task is cancelled make sure all the descendent ones are cancelled too
if (CancelToken != null)
{
CancelToken.Register(() => tokenSource.Cancel());
}
// Store a mapping of tasks to their values
Dictionary <Task <Value>, int> taskDictionary = new Dictionary <Task <Value>, int>();
while (!foundValue)
{
// See if we have been canceled. If so cancel everything
if (CancelToken != null && CancelToken.IsCancellationRequested)
{
tokenSource.Cancel();
}
// Clone the context
Dictionary <string, Value> newContext = (from x in Context
select x).ToDictionary(x => x.Key, x => x.Value);
newContext[expression.VariableName] = new NumValue(nextNum);
// Construct a new evaluator with an updated context
ExpressionEvaluator nextEvaluator = new ExpressionEvaluator(newContext);
nextEvaluator.CancelToken = tokenSource.Token;
// Add the new evaluator to our list of tasks
Task <Value> newTask = expression.Expression.Accept(nextEvaluator);
runningTasks.Add(newTask);
taskDictionary[newTask] = nextNum;
// create a new delay task to add to the list
Task <Value> delay = Delay <Value>(ExistsTimeout, CancelToken);
runningTasks.Add(delay);
// Run the tasks until one completes
Task <Value> resultTask = await Task.WhenAny(runningTasks);
// If it is not the delay task we have a true result, so return it
if (resultTask != delay)
{
Value resultValue = await resultTask;
runningTasks.Remove(resultTask);
if (resultValue is BoolValue)
{
if (((BoolValue)resultValue).Value)
{
// cancel all running tasks
tokenSource.Cancel();
return(new NumValue(taskDictionary[resultTask]));
}
else
{
// expression is false, so remove from dictionary
taskDictionary.Remove(resultTask);
}
}
else
{
throw new ArgumentException("For 'the' the predicate should have a logic value");
}
}
else // delay has fired, so remove it and loop to the next number
{
runningTasks.Remove(delay);
nextNum++;
}
}
throw new NotImplementedException("This code should not be reached");
}
