Allow custom count query

mcintyre321 · Sep 5, 2014 · 8ef888e · 8ef888e
1 parent ee86808
commit 8ef888e
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Showing 6 changed files with 30 additions and 30 deletions.
diff --git a/LinqToAnything.Tests/Tests.cs b/LinqToAnything.Tests/Tests.cs
@@ -293,6 +293,16 @@ public void CanHandleAProjectionASkipAndAnOrderByAsc()
             var pq = new DelegateQueryable<SomeEntity>(getPageFromDataSource);
             pq.OrderBy(e => e.Name).ToArray();
         }
+        [Test]
+        public void CanDoAnOptimizedCount()
+        {
+            DataQuery<SomeEntity> getPageFromDataSource = (info) =>
+            {
+                throw new NotImplementedException();
+            };
+            var pq = new DelegateQueryable<SomeEntity>(getPageFromDataSource, qi => 15);
+            Assert.AreEqual(15, pq.Count(x => x.Index > 1));
+        }
 
 
 

diff --git a/LinqToAnything/DataQuery.cs b/LinqToAnything/DataQuery.cs
@@ -3,4 +3,5 @@
 namespace LinqToAnything
 {
     public delegate IEnumerable<T> DataQuery<out T>(QueryInfo info);
+    public delegate int CountQuery(QueryInfo info);
 }
diff --git a/LinqToAnything/DelegateQueryable.cs b/LinqToAnything/DelegateQueryable.cs
@@ -11,16 +11,17 @@ public class DelegateQueryable<T> : IOrderedQueryable<T>
         QueryProvider<T> provider;
         Expression expression;
 
-        public DelegateQueryable(DataQuery<T> dataQuery)
+        public DelegateQueryable(DataQuery<T> dataQuery, CountQuery countQuery = null)
         {
-            this.provider = new QueryProvider<T>(dataQuery);
+
+            this.provider = new QueryProvider<T>(dataQuery, countQuery ?? (qi => dataQuery(qi).Count()));
             this.expression = Expression.Constant(this);
         }
 
-        public DelegateQueryable(DataQuery<T> dataQuery, Expression expression, QueryVisitor ev)
+        internal DelegateQueryable(DataQuery<T> dataQuery, CountQuery countQuery, Expression expression, QueryVisitor ev)
         {
 
-            this.provider = new QueryProvider<T>(dataQuery, ev);
+            this.provider = new QueryProvider<T>(dataQuery, countQuery, ev);
             this.expression = expression ?? Expression.Constant(this);
 
         }

diff --git a/LinqToAnything/Extension.cs b/LinqToAnything/Extension.cs
diff --git a/LinqToAnything/LinqToAnything.csproj b/LinqToAnything/LinqToAnything.csproj
@@ -49,7 +49,6 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="ExpressionUtils.cs" />
-    <Compile Include="Extension.cs" />
     <Compile Include="QueryInfo.cs" />
     <Compile Include="DelegateQueryable.cs" />
     <Compile Include="DataQuery.cs" />

diff --git a/LinqToAnything/QueryProvider.cs b/LinqToAnything/QueryProvider.cs
@@ -9,13 +9,15 @@ namespace LinqToAnything
     public class QueryProvider<T> : IQueryProvider
     {
         private readonly DataQuery<T> _dataQuery;
+        private readonly CountQuery countQuery;
         private QueryVisitor _queryVisitor;
 
 
-        public QueryProvider(DataQuery<T> dataQuery, QueryVisitor _queryVisitor = null)
+        public QueryProvider(DataQuery<T> dataQuery, CountQuery countQuery, QueryVisitor queryVisitor = null)
         {
             _dataQuery = dataQuery;
-            this._queryVisitor = _queryVisitor ?? new QueryVisitor();
+            this.countQuery = countQuery;
+            this._queryVisitor = queryVisitor ?? new QueryVisitor();
         }
 
         public IQueryable CreateQuery(Expression expression)
@@ -30,9 +32,9 @@ public IQueryable<TElement> CreateQuery<TElement>(Expression expression)
             if (typeof(TElement) != typeof(T))
             {
                 DataQuery<TElement> q = info => _dataQuery(info).Select(queryVisitor.Transform<T, TElement>());
-                return new DelegateQueryable<TElement>(q, null, queryVisitor);
+                return new DelegateQueryable<TElement>(q, countQuery, null, queryVisitor);
             }
-            return new DelegateQueryable<TElement>((DataQuery<TElement>)((object)_dataQuery), expression, queryVisitor);
+            return new DelegateQueryable<TElement>((DataQuery<TElement>)((object)_dataQuery), countQuery, expression, queryVisitor);
 
         }
 
@@ -41,9 +43,9 @@ public IEnumerable<TResult> GetEnumerable<TResult>()
         {
             var queryVisitor = new QueryVisitor(_queryVisitor.QueryInfo.Clone());
             var results = _dataQuery(queryVisitor.QueryInfo);
-            //if (queryVisitor.Select != null)
+            //if (countQuery.Select != null)
             //{
-            //    var projectionFunc = (Func<T, TResult>)queryVisitor.Select.Lambda.Compile();
+            //    var projectionFunc = (Func<T, TResult>)countQuery.Select.Lambda.Compile();
             //    return results.Select(projectionFunc);
             //}
             return (IEnumerable<TResult>) results;
@@ -57,8 +59,14 @@ object IQueryProvider.Execute(Expression expression)
         public TResult Execute<TResult>(Expression expression)
         {
             var methodCallExpression = (MethodCallExpression)expression;
+
             var queryVisitor = new QueryVisitor(_queryVisitor.QueryInfo.Clone());
             queryVisitor.Visit(expression);
+            if (methodCallExpression.Method.Name == "Count" && typeof(TResult) == typeof(int))
+            {
+                return (TResult) (object) countQuery(queryVisitor.QueryInfo);
+            }
+
             var array = _dataQuery(queryVisitor.QueryInfo).ToList();
             var data = array.AsQueryable();