public LambdaExpression Construct()
{
var entry = Nodes.First(n => n.Type == FunctionNames.Entry);
Dictionary <int, bool> visited = new Dictionary <int, bool>();
visited[entry.Id] = true;
// Storing self pointer in case if there will be recursive calls
CallStackTreePointers[FunctionName] = Self;
Expression body = GetControlExpression(entry.Outputs[0][0].Node, visited);
// Outside of the current function's scope self pointer is no longer usable
CallStackTreePointers.Remove(FunctionName);
ConstructedExpression = Expression.Lambda(
Self.Type,
Expression.Block(
LocalVars.Values.Concat(new[] { Self }),
Expression.Assign(
Self,
Expression.Lambda(
Expression.Block(
ReturnParam.Type,
body,
Expression.Label(ReturnTarget, Expression.Default(ReturnParam.Type))
),
EntryParams
)
),
Expression.Invoke(Self, EntryParams)
),
EntryParams
);
CachedTrees[FunctionName] = ConstructedExpression;
return(ConstructedExpression);
}
private Expression GetDataExpression(int?node, int?output, Dictionary <int, bool> visited)
{
if (visited.ContainsKey(node.Value) && visited[node.Value])
{
throw new InvalidGraphException("Infinite data loop");
}
var currentNode = GetNode(node.Value);
if (FunctionsFacade.IsPureFunction(currentNode.Type))
{
visited[node.Value] = true;
var inputExpressions = new Expression[currentNode.Inputs.Length];
for (int i = 0; i < currentNode.Inputs.Length; i++)
{
var connection = currentNode.Inputs[i][0];
if (connection == null)
{
inputExpressions[i] = GetDefaultValueOfEmptyInput(currentNode.Type, i, currentNode.Data.Value);
}
else
{
inputExpressions[i] = GetDataExpression(connection.Node, connection.Output, visited);
}
}
visited[node.Value] = false;
if (currentNode.Type == FunctionNames.Number)
{
return(Expression.Constant((double?)Convert.ToDouble(currentNode.Data.Value), typeof(double?)));
}
else if (currentNode.Type == FunctionNames.Boolean)
{
return(Expression.Constant((bool?)Convert.ToBoolean(currentNode.Data.Value), typeof(bool?)));
}
else if (currentNode.Type == FunctionNames.NumberArray)
{
return(Expression.Constant(JsonConvert.DeserializeObject <double?[]>(currentNode.Data.Value), typeof(double?[])));
}
if (currentNode.Type == FunctionNames.Get)
{
return(LocalVars[currentNode.Data.Value]);
}
else
{
try
{
var tree = FunctionsFacade.GetExpressionTree(currentNode.Type, inputExpressions);
return(tree);
}
catch (NeedToConstructExpressionTreeException)
{
// If the function has been constructed before use that
if (CachedTrees.ContainsKey(currentNode.Type))
{
return(Expression.Invoke(CachedTrees[currentNode.Type], inputExpressions));
}
// If this is a recursive call of a function that hasn't been constructed yet use self pointer
else if (CallStackTreePointers.ContainsKey(currentNode.Type))
{
return(Expression.Invoke(CallStackTreePointers[currentNode.Type], inputExpressions));
}
// Otherwise construct a tree for the function
else
{
var graph = FunctionsFacade.GetFunctionGraph(currentNode.Type);
var constructor = new ExpressionTreeConstructor(currentNode.Type, graph, FunctionsFacade, CachedTrees);
var tree = constructor.Construct();
return(Expression.Invoke(tree, inputExpressions));
}
}
}
}
else
{
switch (currentNode.Type)
{
case FunctionNames.Entry:
return(EntryParams[output.Value - 1]);
case FunctionNames.ForEach:
case FunctionNames.For:
return(LoopVars[Tuple.Create(currentNode.Id, output.Value)]);
case FunctionNames.Set:
return(LocalVars[currentNode.Data.Value]);
}
}
throw new InvalidGraphException($"Couldn't recognize node {currentNode.Type}");
}