protected override Expression Transform(CallExpression lx)
{
if (!Operators.WildcardComparators.Contains(lx.OperatorName) || lx.Operands.Length != 2)
{
return(base.Transform(lx));
}
var lhsIs = WildcardSearch.FindElementAtWildcard(lx.Operands[0]);
var rhsIs = WildcardSearch.FindElementAtWildcard(lx.Operands[1]);
if (lhsIs != null && rhsIs != null || lhsIs == null && rhsIs == null)
{
return(base.Transform(lx)); // N/A, or invalid
}
var wildcardPath = lhsIs != null ? lx.Operands[0] : lx.Operands[1];
var comparand = lhsIs != null ? lx.Operands[1] : lx.Operands[0];
var indexer = lhsIs ?? rhsIs !;
var px = new ParameterExpression("p" + _nextParameter++);
var nestedComparand = NodeReplacer.Replace(wildcardPath, indexer, px);
var coll = indexer.Receiver;
var wc = ((IndexerWildcardExpression)indexer.Index).Wildcard;
var comparisonArgs = lhsIs != null ? new[] { nestedComparand, comparand } : new[] { comparand, nestedComparand };
var body = new CallExpression(lx.IgnoreCase, lx.OperatorName, comparisonArgs);
var lambda = new LambdaExpression(new[] { px }, body);
var op = Operators.ToRuntimeWildcardOperator(wc);
var call = new CallExpression(false, op, coll, lambda);
return(Transform(call));
}
// Reduces the size of a supplied expression tree by compiling parts of the tree into individual
// delegates. Besides preventing the CLR from throwing stack overflow exceptions (which will happen
// when the tree gets somewhere between 20,000 and 50,000 nodes), this can reduce the amount of code
// that needs to be JITted and can therefore reduce the memory footprint of the application.
private static Expression ReduceObjectGraphSize(Expression expression, Container container,
Dictionary <Expression, InvocationExpression> reducedNodes = null)
{
var results = NodeSizeCalculator.Calculate(expression);
while (results.TotalSize > container.Options.MaximumNumberOfNodesPerDelegate)
{
reducedNodes = reducedNodes ?? new Dictionary <Expression, InvocationExpression>(16);
Expression mostReductiveNode = FindMostReductiveNodeOrNull(results,
container.Options.MaximumNumberOfNodesPerDelegate);
if (mostReductiveNode == null)
{
// In case mostReductiveNode is null, there's no good candidate to reduce the object
// graph. In that case we break out.
break;
}
// If the found mostReductiveNode has been reduced before, we use the previously compiled
// value (instead of doing the compilation all over again). Otherwise we compile that node.
InvocationExpression replacementNode = reducedNodes.ContainsKey(mostReductiveNode)
? reducedNodes[mostReductiveNode]
: CompileToInvocation(mostReductiveNode, container, reducedNodes);
reducedNodes[mostReductiveNode] = replacementNode;
expression = NodeReplacer.Replace(expression, oldNode: mostReductiveNode, newNode: replacementNode);
results = NodeSizeCalculator.Calculate(expression);
}
return(expression);
}
