public Func <Document, bool> CompileRule(EnabledRule r)
{
var paramDoc = Expression.Parameter(typeof(Document));
Expression expr = BuildExpr(r, paramDoc);
return(Expression.Lambda <Func <Document, bool> >(expr, paramDoc).Compile());
}
Expression BuildExpr(EnabledRule r, ParameterExpression paramDoc)
{
var left = MemberExpression.Property(paramDoc, r.StatusName);
ExpressionType tBinary;
// is the operator a known .NET operator?
if (ExpressionType.TryParse(r.StatusOperator, out tBinary))
{
var right = Expression.Constant(r.StatusValue);
// use a binary operation, e.g. 'Equal' -> 'doc.Status == 1'
var exp = Expression.MakeBinary(tBinary, left, right);
return(exp);
}
throw new Exception("Неизвестное выражение");
}