From 8ef888e8fc3ad081d38d0354ea368bf5bd5fb92c Mon Sep 17 00:00:00 2001
From: mcintyre321 <mcintyre321@gmail.com>
Date: Fri, 5 Sep 2014 11:48:19 +0100
Subject: [PATCH] Allow custom count query

---
 LinqToAnything.Tests/Tests.cs        | 10 ++++++++++
 LinqToAnything/DataQuery.cs          |  1 +
 LinqToAnything/DelegateQueryable.cs  |  9 +++++----
 LinqToAnything/Extension.cs          | 19 -------------------
 LinqToAnything/LinqToAnything.csproj |  1 -
 LinqToAnything/QueryProvider.cs      | 20 ++++++++++++++------
 6 files changed, 30 insertions(+), 30 deletions(-)
 delete mode 100644 LinqToAnything/Extension.cs

diff --git a/LinqToAnything.Tests/Tests.cs b/LinqToAnything.Tests/Tests.cs
index be08dac..7cd48f6 100644
--- 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
index a2f11f6..eff4fa2 100644
--- 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);
 }
\ No newline at end of file
diff --git a/LinqToAnything/DelegateQueryable.cs b/LinqToAnything/DelegateQueryable.cs
index 1e6a077..1e919b8 100644
--- 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
deleted file mode 100644
index c2d72ca..0000000
--- a/LinqToAnything/Extension.cs
+++ /dev/null
@@ -1,19 +0,0 @@
-using System.Linq;
-
-namespace LinqToAnything
-{
-    public static class Extension
-    {
-        public static IQueryable<T> ToDelegateQueryable<T>(this IQueryable<T> inner)
-        {
-            DataQuery<T> query = info =>
-            {
-                var q = inner;
-                if (info.Skip > 0) q = q.Skip(info.Skip);
-                if (info.Take.HasValue) q = q.Take(info.Take.Value);
-                return q;
-            };
-            return new DelegateQueryable<T>(query);
-        } 
-    }
-}
diff --git a/LinqToAnything/LinqToAnything.csproj b/LinqToAnything/LinqToAnything.csproj
index a38c0e4..2af28a9 100644
--- 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
index 40594e2..139902e 100644
--- 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();