public object Execute(ParseTree.Node node)
{
if (PreCondition != null && !PreCondition(node))
{
throw new ParseErrorException();
}
if (node.Parent == null)
{
return(null);
}
var operandStack = node.Parent.OperandStack;
var capturedValue = node.Value;
var productions = node.ChildProductions;
// pop-out rule operands from operand stack
object[] ruleOperands = FetchOperands(operandStack);
// calculate order of actions taking child productions into account
var actionScheduling = ScheduleActions(productions);
// run actions in the calculated order
T production = default(T);
foreach (var actionSchedule in actionScheduling)
{
var a = actionSchedule.Action;
var childProduction = actionSchedule.Production;
// if production is null and action is update, init with default production
if (production == null && a.ActionInfo.ReturnType == typeof(void))
{
production = DefaultProduction(capturedValue, operandStack, productions);
}
// if action uses child production, use it as input instead of the rule operands
if (childProduction != null)
{
a.Execute(ref production, capturedValue, childProduction);
}
else
{
a.Execute(ref production, capturedValue, ruleOperands);
}
}
// if no production was created by rule actions, create default production
if (production == null)
{
production = DefaultProduction(capturedValue, operandStack, productions);
}
return(production);
}
protected virtual bool TestPreCondition(
ParseTree.Node node,
string capturedValue,
Stack <ParseTree.Node> operandStack,
ProductionObjects productions)
{
if (PreCondition == null)
{
return(true);
}
return(PreCondition(node));
}
