public static Expression <Hoisted <TIn, TOut> > Hoist(Expression <Func <TIn, TOut> > expr)
{
// rewrite Expression<Func<TIn, TOut>> as Expression<Hoisted<TIn, TOut>>
var visitor = new HoistingExpressionVisitor <TIn, TOut>();
var rewrittenBodyExpr = visitor.Visit(expr.Body);
var rewrittenLambdaExpr = Expression.Lambda <Hoisted <TIn, TOut> >(rewrittenBodyExpr, expr.Parameters[0], hoistedConstantsParamExpr);
return(rewrittenLambdaExpr);
}
private static Func <TIn, TOut> CompileFromFingerprint(Expression <Func <TIn, TOut> > expr)
{
List <object> capturedConstants;
ExpressionFingerprintChain fingerprint = FingerprintingExpressionVisitor.GetFingerprintChain(expr, out capturedConstants);
if (fingerprint != null)
{
var del = fingerprintedCache.GetOrAdd(fingerprint, _ =>
{
// Fingerprinting succeeded, but there was a cache miss. Rewrite the expression
// and add the rewritten expression to the cache.
var hoistedExpr = HoistingExpressionVisitor <TIn, TOut> .Hoist(expr);
return(hoistedExpr.Compile());
});
return(model => del(model, capturedConstants));
}
// couldn't be fingerprinted
return(null);
}