basic implementation complete. still need to work on a select clause …

…that's mroe complex than just "select obj"
foretagsplatsen · Sep 15, 2009 · 6fd7e61 · 6fd7e61
1 parent b478c3f
commit 6fd7e61
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Showing 5 changed files with 147 additions and 53 deletions.
diff --git a/samples/Trivial/Program.cs b/samples/Trivial/Program.cs
@@ -5,6 +5,7 @@
 using Divan;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Linq;
+using Divan.Linq;
 
 namespace Trivial
 {
@@ -20,7 +21,7 @@ namespace Trivial
     class Program
     {
         static void Main(string[] args) {
-            string host = "localhost";
+            string host = "172.16.10.78";
             int port = 5984;
 
             // Lets you see all HTTP requests made by Divan
@@ -29,7 +30,7 @@ static void Main(string[] args) {
             // Trivial parse of args to get host and port
             switch (args.Length) {
                 case 0:
-                    Console.WriteLine("Using localhost:5984");
+                    Console.WriteLine("Using " + host + ":" + port);
                     break;
                 case 1:
                     Console.WriteLine("Using " + args[0] + ":5984");
@@ -89,6 +90,18 @@ static void Main(string[] args) {
             var cars = db.GetAllDocuments<Car>();
             Console.WriteLine("Loaded all Cars: " + cars.Count);
 
+            // Now try some linq
+            var tempQuery = CreateTempView("if (doc.docType && doc.docType == 'car') emit(doc.Hps, doc);", db);
+            var linqProvider = new CouchQueryProvider(db, tempQuery);
+            var linqCars = new CouchLinqQuery<Car>(linqProvider);
+
+            var fastCars = from c in linqCars where c.HorsePowers >= 175 select c;//.Make + " " + c.Model;
+            foreach (var fastCar in fastCars)
+                Console.WriteLine(fastCar);
+
+            // cleanup for later
+            db.DeleteDocument(tempQuery.Doc);
+
             // Delete some Cars one by one. CouchDB is an MVCC database which means that for every operation that modifies a document
             // we need to supply not only its document id, but also the revision that we are aware of. This means that we must supply id/rev
             // for each document we want to delete.
@@ -107,7 +120,18 @@ static void Main(string[] args) {
 
             // Delete the db itself
             db.Delete();
-            Console.WriteLine("Deleted database");
+            Console.WriteLine("Deleted database\r\n\r\n. Press enter to close. ");
+
+            Console.ReadLine();
+        }
+
+        private static CouchViewDefinition CreateTempView(string mapText, CouchDatabase db)
+        {
+            var designDoc = new CouchDesignDocument("test", db);
+            var def = designDoc.AddView("test", "function (doc) {" + mapText + "}");
+            designDoc.Synch();
+
+            return def;
         }
 
         /// <summary>
@@ -138,6 +162,8 @@ public override void WriteJson(JsonWriter writer)
                 // This will write id and rev
                 base.WriteJson(writer);
 
+                writer.WritePropertyName("docType");
+                writer.WriteValue("car");
                 writer.WritePropertyName("Make");
                 writer.WriteValue(Make);
                 writer.WritePropertyName("Model");

diff --git a/src/Linq/CouchLinqQuery.cs b/src/Linq/CouchLinqQuery.cs
@@ -1,8 +1,12 @@
-using System;
+// adapted from sample code at http://linqinaction.net/files/folders/linqinaction/entry1952.aspx
+
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Linq.Expressions;
+using System.Collections;
+using System.Reflection;
 
 namespace Divan.Linq
 {
@@ -17,60 +21,80 @@ public CouchLinqQuery(Expression expression, CouchQueryProvider provider)
             this.provider = provider;
         }
 
-        #region IEnumerable<T> Members
-
-        public IEnumerator<T> GetEnumerator()
+        public CouchLinqQuery(CouchQueryProvider provider)
         {
-            throw new NotImplementedException();
+            this.expression = Expression.Constant(this);
+            this.provider = provider;
         }
 
-        #endregion
-
-        #region IEnumerable Members
-
-        System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator()
+        Expression IQueryable.Expression
         {
-            throw new NotImplementedException();
+            get { return this.expression; }
         }
 
-        #endregion
-
-        #region IQueryable Members
-
-        public Type ElementType
+        Type IQueryable.ElementType
         {
-            get { throw new NotImplementedException(); }
+            get { return typeof(T); }
         }
 
-        public System.Linq.Expressions.Expression Expression
+        IQueryProvider IQueryable.Provider
         {
-            get { throw new NotImplementedException(); }
+            get { return this.provider; }
         }
 
-        public IQueryProvider Provider
+        class TransformingEnumerator<T> : IEnumerator<T>
         {
-            get { throw new NotImplementedException(); }
-        }
+            private IEnumerator<T> e;
+            private MethodInfo transformer;
 
-        #endregion
+            public TransformingEnumerator(IEnumerator<T> e, MethodInfo transformer)
+            {
+                this.e = e;
+                this.transformer = transformer;
+            }
 
-        #region IQueryable Members
+            public T Current { get { return (T)transformer.Invoke(e.Current, null); } }
+            object IEnumerator.Current { get { return transformer.Invoke(e.Current, null); } }
 
-        Type IQueryable.ElementType
+            public void Dispose() { e.Dispose(); }
+            public bool MoveNext() { return e.MoveNext(); }
+            public void Reset() { e.Reset(); }
+        }
+
+        protected virtual IEnumerator<T> DoGetEnumerator<T>()
         {
-            get { throw new NotImplementedException(); }
+            var expVisitor = this.provider.Prepare(expression);
+            var viewResult = (CouchGenericViewResult)expVisitor.Query.GetResult();
+
+            var dynamicResult =
+                viewResult
+                    .GetType()
+                    .GetMethods()
+                    .First(m => m.Name == "ValueDocuments" && m.IsGenericMethodDefinition)
+                    .MakeGenericMethod(new Type[] { typeof(T) })
+                    .Invoke(viewResult, null);
+
+            if (expVisitor.SelectExpression == null)
+                return ((IEnumerable<T>)dynamicResult).GetEnumerator();
+
+            return
+                new TransformingEnumerator<T>(
+                    ((IEnumerable<T>)dynamicResult).GetEnumerator(),
+                    ((MethodCallExpression)expVisitor.SelectExpression).Method);
         }
 
-        System.Linq.Expressions.Expression IQueryable.Expression
+        public IEnumerator<T> GetEnumerator()
         {
-            get { throw new NotImplementedException(); }
+            return DoGetEnumerator<T>();
         }
 
-        IQueryProvider IQueryable.Provider
+        IEnumerator IEnumerable.GetEnumerator()
         {
-            get { throw new NotImplementedException(); }
+            return DoGetEnumerator<CouchDocument>();
         }
 
-        #endregion
+        public override string ToString() { return this.provider.GetQueryText(this.expression); }
+        public override bool Equals(object obj) { return obj == null ? false : ToString().Equals(obj.ToString()); }
+        public override int GetHashCode() { return ToString().GetHashCode(); }
     }
 }
diff --git a/src/Linq/CouchQueryProvider.cs b/src/Linq/CouchQueryProvider.cs
@@ -1,4 +1,6 @@
-using System;
+// adapted from sample code at http://linqinaction.net/files/folders/linqinaction/entry1952.aspx
+
+using System;
 using System.Collections.Generic;
 using System.Linq.Expressions;
 using System.Text;
@@ -13,13 +15,21 @@ public class CouchQueryProvider: IQueryProvider
         string view;
         string design;
 
+        CouchViewDefinition definition;
+
         public CouchQueryProvider(CouchDatabase db, string design, string view)
         {
             this.db = db;
             this.view = view;
             this.design = design;
         }
 
+        public CouchQueryProvider(CouchDatabase db, CouchViewDefinition definition)
+        {
+            this.db = db;
+            this.definition = definition;
+        }
+
         #region IQueryProvider Members
 
         public IQueryable<TElement> CreateQuery<TElement>(Expression expression)
@@ -42,19 +52,36 @@ public IQueryable CreateQuery(Expression expression)
             }
         }
 
-        protected virtual CouchQuery Prepare(Expression expression)
+        public virtual ExpressionVisitor Prepare(Expression expression)
         {
-            return new ExpressionVisitor().ProcessExpression(expression, db, design, view);
+            return 
+                definition == null ?
+                new ExpressionVisitor().ProcessExpression(expression, db, design, view) :
+                new ExpressionVisitor().ProcessExpression(expression, db, definition);
         }
 
         public TResult Execute<TResult>(Expression expression)
         {
-            return (TResult)Execute(expression);// return Prepare(expression).GetResult<TResult>();
+            if (!typeof(CouchViewResult).IsAssignableFrom(typeof(TResult)))
+                throw new InvalidCastException("Only subclasses of CouchViewResult are supported. " + typeof(TResult).ToString() + " is not a valid result type.");
+
+            return (TResult)Execute(expression);
         }
 
         public object Execute(Expression expression)
         {
-            return Prepare(expression).GetResult();
+            var expVisitor = Prepare(expression);
+            var result = expVisitor.Query.GetResult().RowDocuments().First();
+
+            if (expVisitor.SelectExpression == null)
+                return result;
+
+            return ((MethodCallExpression)expVisitor.SelectExpression).Method.Invoke(result, null);
+        }
+
+        public string GetQueryText(Expression expression)
+        {
+            return Prepare(expression).ToString();
         }
 
         #endregion

diff --git a/src/Linq/ExpressionVisitor.cs b/src/Linq/ExpressionVisitor.cs
@@ -1,4 +1,6 @@
-using System;
+// adapted from sample code at http://linqinaction.net/files/folders/linqinaction/entry1952.aspx
+
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Linq.Expressions;
@@ -7,15 +9,23 @@
 
 namespace Divan.Linq
 {
-    internal class ExpressionVisitor
+    public class ExpressionVisitor
     {
-        CouchQuery query;
+        public virtual CouchQuery Query { get; protected set; }
+        public virtual MethodCallExpression SelectExpression { get; protected set; }
+
+        public ExpressionVisitor ProcessExpression(Expression expression, CouchDatabase db, string design, string view)
+        {
+            Query = db.Query(design, view);
+            VisitExpression(expression);
+            return this;
+        }
 
-        public CouchQuery ProcessExpression(Expression expression, CouchDatabase db, string design, string view)
+        public ExpressionVisitor ProcessExpression(Expression expression, CouchDatabase db, CouchViewDefinition definition)
         {
-            query = db.Query(design, view);
+            Query = db.Query(definition);
             VisitExpression(expression);
-            return query;
+            return this;
         }
 
         private void VisitExpression(Expression expression)
@@ -26,13 +36,13 @@ private void VisitExpression(Expression expression)
                     VisitAndAlso((BinaryExpression)expression);
                     break;
                 case ExpressionType.Equal:
-                    CallIfPresent((BinaryExpression)expression, (val) => query.Key(val));
+                    CallIfPresent((BinaryExpression)expression, (val) => Query.Key(val));
                     break;
                 case ExpressionType.LessThanOrEqual:
-                    CallIfPresent((BinaryExpression)expression, (val) => query.EndKey(val));
+                    CallIfPresent((BinaryExpression)expression, (val) => Query.EndKey(val));
                     break;
                 case ExpressionType.GreaterThanOrEqual:
-                    CallIfPresent((BinaryExpression)expression, (val) => query.StartKey(val));
+                    CallIfPresent((BinaryExpression)expression, (val) => Query.StartKey(val));
                     break;
                 default:
                     if (expression is MethodCallExpression)
@@ -51,9 +61,12 @@ private void VisitAndAlso(BinaryExpression andAlso)
 
         private void VisitMethodCall(MethodCallExpression expression)
         {
-            if ((expression.Method.DeclaringType == typeof(Queryable)) && 
+            if ((expression.Method.DeclaringType == typeof(Queryable)) &&
                 (expression.Method.Name == "Where"))
                 VisitExpression(((UnaryExpression)expression.Arguments[1]).Operand);
+            else if ((expression.Method.DeclaringType == typeof(Queryable)) &&
+                (expression.Method.Name == "Select"))
+                SelectExpression = expression;
             else
                 throw new NotSupportedException("Method not supported: " + expression.Method.Name);
         }
@@ -69,8 +82,10 @@ private void CallIfPresent(Expression expression, Action<object> callback)
 
         private object GetRightExpressionValue(BinaryExpression expression)
         {
-            if ((expression.Left.NodeType != ExpressionType.MemberAccess) ||
-              (((MemberExpression)expression.Left).Member.Name != "Key"))
+            // since all things will have to translate to "key", and the only
+            // place where we know what "key" really is is within the view,
+            // just check that it's a member access expression
+            if ((expression.Left.NodeType != ExpressionType.MemberAccess))
                 return null;
 
             object key;
@@ -79,7 +94,7 @@ private object GetRightExpressionValue(BinaryExpression expression)
             else if (expression.Right.NodeType == ExpressionType.MemberAccess)
                 key = GetMemberValue((MemberExpression)expression.Right);
             else
-                throw new NotSupportedException("Expression type not supported for publisher: " + expression.Right.NodeType.ToString());
+                throw new NotSupportedException("Expression type not supported: " + expression.Right.NodeType.ToString());
 
             return key;
         }

diff --git a/src/Linq/TypeSystem.cs b/src/Linq/TypeSystem.cs
@@ -1,4 +1,6 @@
-// The code in this file comes from Matt Warren's series of blog posts on how to build a LINQ provider
+// adapted from sample code at http://linqinaction.net/files/folders/linqinaction/entry1952.aspx
+
+// The code in this file comes from Matt Warren's series of blog posts on how to build a LINQ provider
 // http://blogs.msdn.com/mattwar/archive/2007/08/09/linq-building-an-iqueryable-provider-part-i.aspx
 
 using System;