protected override CrawlSyntaxNode VisitMultiChildExpression(MultiChildExpressionNode multiChildExpression)
{
var expr = (MultiChildExpressionNode)base.VisitMultiChildExpression(multiChildExpression);
if (!(expr.ExpressionType == ExpressionType.Add ||
expr.ExpressionType == ExpressionType.Multiply ||
expr.ExpressionType == ExpressionType.ShortCircuitAnd ||
expr.ExpressionType == ExpressionType.ShortCircuitOr))
{
return(expr);
}
List <ExpressionNode> literals = new List <ExpressionNode>();
List <ExpressionNode> restOfIt = new List <ExpressionNode>();
foreach (ExpressionNode expression in expr.Arguments)
{
var literal = expression as LiteralNode;
if (literal != null)
{
literals.Add(literal);
}
else
{
restOfIt.Add(expression);
}
}
List <ExpressionNode> newArguments = literals.Concat(restOfIt).ToList();
return(CrawlSyntaxNode.MultiChildExpression(expr.Interval, expr.ExpressionType, expr.ResultType,
newArguments));
}
protected override CrawlSyntaxNode VisitMultiChildExpression(MultiChildExpressionNode multiChildExpression)
{
CrawlSyntaxNode expr = base.VisitMultiChildExpression(multiChildExpression);
MultiChildExpressionNode multuExpr = expr as MultiChildExpressionNode;
if (multuExpr == null)
{
return(expr);
}
if (multuExpr.Arguments.ChildCount == 1)
{
OptimizationsWereMade = true;
return(multuExpr.Arguments.First());
}
List <ExpressionNode> newArguments = new List <ExpressionNode>();
ListNode <ExpressionNode> arguments = multuExpr.Arguments;
//Algorithm ahead. Strap in.
//Go through the node's arguments, building list of new arguments,
//where any pair of neighboring literals have been folded into one.
int i = 0;
while (i < arguments.Count())
{
//If this is the last in the sequence, there is nothing left to fold.
if (i == arguments.Count() - 1)
{
newArguments.Add(arguments[i]);
break;
}
//Only literal nodes can be folded.
LiteralNode current = arguments[i] as LiteralNode;
if (current != null)
{
//If both the current node and the next node is a literal, then
//fold them, add them to the new list,
//and jump to the argument after them.
LiteralNode next = arguments[i + 1] as LiteralNode;
if (next != null)
{
newArguments.Add(FoldMultuPair(current, multuExpr.ExpressionType, next));
OptimizationsWereMade = true;
i += 2;
}
//If the next argument is not a literal, it cannot be folded.
//move on to the argument after that.
else
{
newArguments.Add(arguments[i]);
newArguments.Add(arguments[i + 1]);
i += 2;
}
}
//If the current node isn't a literal,
//move on to consider the next
else
{
newArguments.Add(arguments[i]);
i += 1;
}
}
return(CrawlSyntaxNode.MultiChildExpression(multuExpr.Interval, multuExpr.ExpressionType,
multuExpr.ResultType, newArguments));
}
