private static bool CanInline(Expression context, ParameterExpression parameter, Expression expression)
{
var fvs = FreeVariableScanner.Scan(expression).AsCollection();
if (fvs.Count > 0)
{
var ca = new CaptureAnalyzer(parameter, fvs);
ca.Visit(context);
return(!ca.HasCapture);
}
return(true);
}
/// <summary>
/// Throws an unbound parameter exception if the specified expression contains unbound parameters.
/// </summary>
/// <param name="expression">Expression to check for unbound parameters.</param>
/// <param name="message">Exception message to use for signaling unbound parameters.</param>
public static void ThrowIfOpen(Expression expression, string message)
{
if (expression == null)
{
throw new ArgumentNullException(nameof(expression));
}
var variables = FreeVariableScanner.Scan(expression);
if (variables.Any())
{
throw new UnboundParameterException(message, expression, variables);
}
}
/// <summary>
/// Evaluates the specified expression.
/// </summary>
/// <param name="expression">Expression to evaluate.</param>
/// <returns>Expression containing the evaluation result.</returns>
protected virtual Expression Evaluate(Expression expression)
{
// NOTE: Scope analysis could be improved by tracking use sites of variables on a lookaside stack.
// However, in typical usage patterns the number of subtrees that can be partially evaluated
// is expected to be low, so the number of times free variables have to be scanned is going
// to be relatively small.
if (expression != null && expression.NodeType != ExpressionType.Constant && !FreeVariableScanner.HasFreeVariables(expression))
{
return(EvaluateCore(expression));
}
return(expression);
}
