public static Expression <Hoisted <TIn, TOut> > Hoist(Expression <Func <TIn, TOut> > expr)
{
HoistingExpressionVisitor <TIn, TOut> hoistingExpressionVisitor = new HoistingExpressionVisitor <TIn, TOut>();
Expression body = hoistingExpressionVisitor.Visit(expr.Body);
return(Expression.Lambda <Hoisted <TIn, TOut> >(body, new ParameterExpression[]
{
expr.Parameters[0],
HoistingExpressionVisitor <TIn, TOut> ._hoistedConstantsParamExpr
}));
}
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 fingerprintChain = FingerprintingExpressionVisitor.GetFingerprintChain(expr, out capturedConstants);
if (fingerprintChain != null)
{
Hoisted <TIn, TOut> del = CachedExpressionCompiler.Compiler <TIn, TOut> ._fingerprintedCache.GetOrAdd(fingerprintChain, delegate(ExpressionFingerprintChain _)
{
Expression <Hoisted <TIn, TOut> > expression = HoistingExpressionVisitor <TIn, TOut> .Hoist(expr);
return(expression.Compile());
});
return((TIn model) => del(model, capturedConstants));
}
return(null);
}
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);
}