/// <summary>
/// Limit the output of the query.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="esperQuery">The esper query.</param>
/// <param name="whenExpression">the expression that returns true to trigger output</param>
/// <returns>clause</returns>
public static EsperQuery <T> OutputLimit <T>(
this EsperQuery <T> esperQuery,
Expression whenExpression)
{
var parentObjectModel = esperQuery.ObjectModel;
var deriveObjectModel = parentObjectModel.ShallowCopy();
deriveObjectModel.OutputLimitClause = OutputLimitClause.Create(whenExpression);
return(new EsperQuery <T>(esperQuery.ServiceProvider, deriveObjectModel));
}
/// <summary>
/// Groups the results of the expression.
/// </summary>
/// <typeparam name="TSource">The type of the source.</typeparam>
/// <typeparam name="TKey">The type of the key.</typeparam>
/// <param name="esperQuery">The esper query.</param>
/// <param name="keySelectionExpression">The key selection expression.</param>
/// <returns></returns>
public static EsperQuery <TSource> GroupBy <TSource, TKey>(
this EsperQuery <TSource> esperQuery,
Expression <Func <TSource, TKey> > keySelectionExpression)
{
var parentObjectModel = esperQuery.ObjectModel;
var deriveObjectModel = parentObjectModel.ShallowCopy();
// Adapt or set the where clause according to the expression contents
using (ScopedInstance <EPStatementObjectModel> .Set(deriveObjectModel)) {
var sodaExpression = LinqToSoda.LinqToSodaExpression(keySelectionExpression);
deriveObjectModel.GroupByClause = GroupByClause.Create(sodaExpression);
return(new EsperQuery <TSource>(esperQuery.ServiceProvider, deriveObjectModel));
}
}
/// <summary>
/// Adds the property.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="esperQuery">The esper query.</param>
/// <param name="propertyName">Name of the property.</param>
/// <param name="expression">The expression.</param>
/// <returns></returns>
public static EsperQuery <T> AddProperty <T>(
this EsperQuery <T> esperQuery,
string propertyName,
Expression <Func <object> > expression)
{
var parentObjectModel = esperQuery.ObjectModel;
var deriveObjectModel = parentObjectModel.ShallowCopy();
using (ScopedInstance <EPStatementObjectModel> .Set(deriveObjectModel)) {
deriveObjectModel.SelectClause.Add(
LinqToSoda.LinqToSodaExpression(expression),
propertyName);
return(new EsperQuery <T>(esperQuery.ServiceProvider, deriveObjectModel));
}
}
/// <summary>
/// Selects the specified "item" from the esper query.
/// </summary>
/// <typeparam name="T1">The type of the 1.</typeparam>
/// <typeparam name="T2">The type of the 2.</typeparam>
/// <param name="esperQuery">The esper query.</param>
/// <param name="expression">The expression.</param>
/// <returns></returns>
public static DisposableObservableCollection <T2> Select <T1, T2>(
this EsperQuery <T1> esperQuery,
Expression <Func <T1, T2> > expression)
{
var transform = expression.Compile();
esperQuery.Compile();
if (typeof(T1) == typeof(T2))
{
return(esperQuery.Statement.AsObservableCollection <T2>(true));
}
return(new CascadeObservableCollection <T1, T2>(
esperQuery.Statement.AsObservableCollection <T1>(true),
transform,
true));
}
/// <summary>
/// Constrains the specified esper query.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="esperQuery">The esper query.</param>
/// <param name="expression">The expression.</param>
/// <returns></returns>
public static EsperQuery <T> Where <T>(
this EsperQuery <T> esperQuery,
Expression <Func <T, bool> > expression)
{
var parentObjectModel = esperQuery.ObjectModel;
var deriveObjectModel = parentObjectModel.ShallowCopy();
// Adapt or set the where clause according to the expression contents
using (ScopedInstance <EPStatementObjectModel> .Set(deriveObjectModel)) {
var sodaExpression = LinqToSoda.LinqToSodaExpression(expression);
deriveObjectModel.WhereClause = deriveObjectModel.WhereClause == null
? sodaExpression
: Expressions.And(deriveObjectModel.WhereClause, sodaExpression);
deriveObjectModel.FromClause.Streams[0].StreamName =
expression.Parameters[0].Name;
return(new EsperQuery <T>(esperQuery.ServiceProvider, deriveObjectModel));
}
}
/// <summary>
/// Joins the specified outer.
/// </summary>
/// <typeparam name="TOuter">The type of the outer.</typeparam>
/// <typeparam name="TInner">The type of the inner.</typeparam>
/// <typeparam name="TKey">The type of the key.</typeparam>
/// <typeparam name="TResult">The type of the result.</typeparam>
/// <param name="outer">The outer.</param>
/// <param name="inner">The inner.</param>
/// <param name="outerKeySelector">The outer key selector.</param>
/// <param name="innerKeySelector">The inner key selector.</param>
/// <param name="resultSelector">The result selector.</param>
/// <returns></returns>
public static EsperQuery <TResult> Join <TOuter, TInner, TKey, TResult>(
this EsperQuery <TOuter> outer,
EsperQuery <TInner> inner,
Expression <Func <TOuter, TKey> > outerKeySelector,
Expression <Func <TInner, TKey> > innerKeySelector,
Expression <Func <TOuter, TInner, TResult> > resultSelector)
{
var parentObjectModel = outer.ObjectModel;
var deriveObjectModel = new EPStatementObjectModel();
using (ScopedInstance <EPStatementObjectModel> .Set(deriveObjectModel)) {
deriveObjectModel.Annotations = parentObjectModel.Annotations;
var innerKey = LinqToSoda.LinqToSodaExpression(innerKeySelector);
var outerKey = LinqToSoda.LinqToSodaExpression(outerKeySelector);
deriveObjectModel.FromClause = new FromClause(
outer.ObjectModel.FromClause.Streams.Concat(
inner.ObjectModel.FromClause.Streams)
.ToArray());
var parametersArray = resultSelector.Parameters.ToArray();
for (var ii = 0; ii < parametersArray.Length; ii++)
{
deriveObjectModel.FromClause.Streams[ii].StreamName =
parametersArray[ii].Name;
}
deriveObjectModel.FromClause.OuterJoinQualifiers = new List <OuterJoinQualifier>();
deriveObjectModel.FromClause.OuterJoinQualifiers.Add(
new OuterJoinQualifier(
OuterJoinType.LEFT,
outerKey,
innerKey,
new PropertyValueExpressionPair[0]));
deriveObjectModel.SelectClause = LinqToSoda.LinqToSelectClause(resultSelector);
var toEPL = deriveObjectModel.ToEPL();
return(new EsperQuery <TResult>(outer.ServiceProvider, deriveObjectModel));
}
}
