protected override Expression VisitConstant(ConstantExpression c)
{
IWmiQueryable q = c.Value as IWmiQueryable;
if (q != null)
{
// assume constant nodes w/ IQueryables are table references
if (sb.Length == 0)
{
sb.Append("SELECT ");
if (m_FetchAllFields)
{
sb.Append("*");
}
else
{
sb.Append(string.Join(",", WmiObject.GetWmiPropertyNames(q.ElementType)));
}
sb.Append(" FROM ");
}
sb.Append(WmiObject.GetClassName(q.ElementType));
}
else if (c.Value == null)
{
sb.Append("NULL");
}
else
{
switch (Type.GetTypeCode(c.Value.GetType()))
{
case TypeCode.Boolean:
sb.Append(((bool)c.Value) ? 1 : 0);
break;
case TypeCode.String:
sb.AppendFormat("\"{0}\"", WmiObject.GetWmiQueryValue(c.Value));
break;
case TypeCode.Object:
throw new NotSupportedException(string.Format("The constant for '{0}' is not supported", c.Value));
default:
sb.Append(c.Value);
break;
}
}
return(c);
}
public string Translate(IWmiQueryable query, bool fetchAllFields = false)
{
m_FetchAllFields = fetchAllFields;
var a = query.ElementType.GetCustomAttribute <WmiClassAttribute>(false);
if (a == null)
{
throw new InvalidOperationException();
}
sb = new StringBuilder();
var e = Evaluator.PartialEval(query.Expression);
Visit(e);
return(sb.ToString());
}
public IEnumerator <TResult> Execute <TResult>(IWmiQueryable query)
where TResult : WmiObject <TResult>, new()
{
if (m_QueryBuilder == null)
{
m_QueryBuilder = new WmiQueryBuilder(this);
}
var querystring = m_QueryBuilder.Translate(query, m_FetchAllFields);
var objQuery = new ObjectQuery(querystring);
var wmiSearcher = new ManagementObjectSearcher(m_Scope, objQuery);
Debug.WriteLine(querystring);
foreach (ManagementObject o in wmiSearcher.Get().Cast <ManagementObject>())
{
yield return(WmiObject.CreateObject <TResult>(this, o));
}
wmiSearcher.Dispose();
}
public static IEnumerable <T> Where <T>(this IWmiQueryable <T> source, Expression <Func <T, bool> > predicate)
where T : WmiObject <T>, new()
{
return(new WmiQuery <T>(source.Context, Expression.Call(((MethodInfo)MethodBase.GetCurrentMethod()).MakeGenericMethod(typeof(T)),
source.Expression, Expression.Quote(predicate))));
}
