Add support for query continuations.

ICSharpCode.Decompiler/Ast/Transforms/CombineQueryExpressions.cs

@@ -27,6 +27,13 @@ namespace ICSharpCode.Decompiler.Ast.Transforms
 			CombineQueries(compilationUnit);
 		}
 		
+		static readonly InvocationExpression castPattern = new InvocationExpression {
+			Target = new MemberReferenceExpression {
+				Target = new AnyNode("inExpr"),
+				MemberName = "Cast",
+				TypeArguments = { new AnyNode("targetType") }
+			}};
+		
 		void CombineQueries(AstNode node)
 		{
 			for (AstNode child = node.FirstChild; child != null; child = child.NextSibling) {
@@ -39,6 +46,17 @@ namespace ICSharpCode.Decompiler.Ast.Transforms
 				if (innerQuery != null) {
 					if (TryRemoveTransparentIdentifier(query, fromClause, innerQuery)) {
 						RemoveTransparentIdentifierReferences(query);
+					} else {
+						QueryContinuationClause continuation = new QueryContinuationClause();
+						continuation.PrecedingQuery = innerQuery.Detach();
+						continuation.Identifier = fromClause.Identifier;
+						fromClause.ReplaceWith(continuation);
+					}
+				} else {
+					Match m = castPattern.Match(fromClause.Expression);
+					if (m != null) {
+						fromClause.Type = m.Get<AstType>("targetType").Single().Detach();
+						fromClause.Expression = m.Get<Expression>("inExpr").Single().Detach();
 					}
 				}
 			}

ICSharpCode.Decompiler/Ast/Transforms/IntroduceQueryExpressions.cs

@@ -64,6 +64,8 @@ namespace ICSharpCode.Decompiler.Ast.Transforms
 		void DecompileQueries(AstNode node)
 		{
 			QueryExpression query = DecompileQuery(node as InvocationExpression);
+			if (query != null)
+				node.ReplaceWith(query);
 			for (AstNode child = (query ?? node).FirstChild; child != null; child = child.NextSibling) {
 				DecompileQueries(child);
 			}
@@ -87,26 +89,33 @@ namespace ICSharpCode.Decompiler.Ast.Transforms
 							QueryExpression query = new QueryExpression();
 							query.Clauses.Add(new QueryFromClause { Identifier = parameterName, Expression = mre.Target.Detach() });
 							query.Clauses.Add(new QuerySelectClause { Expression = body.Detach() });
-							invocation.ReplaceWith(query);
 							return query;
 						}
 						return null;
 					}
 				case "GroupBy":
 					{
-						if (invocation.Arguments.Count != 2)
-							return null;
-						string parameterName1, parameterName2;
-						Expression keySelector, elementSelector;
-						if (MatchSimpleLambda(invocation.Arguments.ElementAt(0), out parameterName1, out keySelector)
-						    && MatchSimpleLambda(invocation.Arguments.ElementAt(1), out parameterName2, out elementSelector)
-						    && parameterName1 == parameterName2)
-						{
-							QueryExpression query = new QueryExpression();
-							query.Clauses.Add(new QueryFromClause { Identifier = parameterName1, Expression = mre.Target.Detach() });
-							query.Clauses.Add(new QueryGroupClause { Projection = elementSelector.Detach(), Key = keySelector.Detach() });
-							invocation.ReplaceWith(query);
-							return query;
+						if (invocation.Arguments.Count == 2) {
+							string parameterName1, parameterName2;
+							Expression keySelector, elementSelector;
+							if (MatchSimpleLambda(invocation.Arguments.ElementAt(0), out parameterName1, out keySelector)
+							    && MatchSimpleLambda(invocation.Arguments.ElementAt(1), out parameterName2, out elementSelector)
+							    && parameterName1 == parameterName2)
+							{
+								QueryExpression query = new QueryExpression();
+								query.Clauses.Add(new QueryFromClause { Identifier = parameterName1, Expression = mre.Target.Detach() });
+								query.Clauses.Add(new QueryGroupClause { Projection = elementSelector.Detach(), Key = keySelector.Detach() });
+								return query;
+							}
+						} else if (invocation.Arguments.Count == 1) {
+							string parameterName;
+							Expression keySelector;
+							if (MatchSimpleLambda(invocation.Arguments.Single(), out parameterName, out keySelector)) {
+								QueryExpression query = new QueryExpression();
+								query.Clauses.Add(new QueryFromClause { Identifier = parameterName, Expression = mre.Target.Detach() });
+								query.Clauses.Add(new QueryGroupClause { Projection = new IdentifierExpression(parameterName), Key = keySelector.Detach() });
+								return query;
+							}
 						}
 						return null;
 					}
@@ -127,7 +136,6 @@ namespace ICSharpCode.Decompiler.Ast.Transforms
 								query.Clauses.Add(new QueryFromClause { Identifier = p1.Name, Expression = mre.Target.Detach() });
 								query.Clauses.Add(new QueryFromClause { Identifier = p2.Name, Expression = collectionSelector.Detach() });
 								query.Clauses.Add(new QuerySelectClause { Expression = ((Expression)lambda.Body).Detach() });
-								invocation.ReplaceWith(query);
 								return query;
 							}
 						}
@@ -143,7 +151,6 @@ namespace ICSharpCode.Decompiler.Ast.Transforms
 							QueryExpression query = new QueryExpression();
 							query.Clauses.Add(new QueryFromClause { Identifier = parameterName, Expression = mre.Target.Detach() });
 							query.Clauses.Add(new QueryWhereClause { Condition = body.Detach() });
-							invocation.ReplaceWith(query);
 							return query;
 						}
 						return null;
@@ -183,7 +190,6 @@ namespace ICSharpCode.Decompiler.Ast.Transforms
 								QueryExpression query = new QueryExpression();
 								query.Clauses.Add(new QueryFromClause { Identifier = parameterName, Expression = mre.Target.Detach() });
 								query.Clauses.Add(orderClause);
-								invocation.ReplaceWith(query);
 								return query;
 							}
 						}
@@ -219,7 +225,6 @@ namespace ICSharpCode.Decompiler.Ast.Transforms
 								}
 								query.Clauses.Add(joinClause);
 								query.Clauses.Add(new QuerySelectClause { Expression = ((Expression)lambda.Body).Detach() });
-								invocation.ReplaceWith(query);
 								return query;
 							}
 						}

ICSharpCode.Decompiler/Tests/QueryExpressions.cs

@@ -10,9 +10,10 @@ public class QueryExpressions
 	public class Customer
 	{
 		public int CustomerID;
-		public IEnumerable<Order> Orders;
+		public IEnumerable<QueryExpressions.Order> Orders;
 		public string Name;
 		public string Country;
+		public string City;
 	}
 	
 	public class Order
@@ -22,7 +23,7 @@ public class QueryExpressions
 		public Customer Customer;
 		public int CustomerID;
 		public decimal Total;
-		public IEnumerable<OrderDetail> Details;
+		public IEnumerable<QueryExpressions.OrderDetail> Details;
 	}
 	
 	public class OrderDetail
@@ -31,8 +32,8 @@ public class QueryExpressions
 		public int Quantity;
 	}
 	
-	public IEnumerable<Customer> customers;
-	public IEnumerable<Order> orders;
+	public IEnumerable<QueryExpressions.Customer> customers;
+	public IEnumerable<QueryExpressions.Order> orders;
 	
 	public object MultipleWhere()
 	{
@@ -129,4 +130,20 @@ public class QueryExpressions
 			from c in customers
 			group c.Name by c.Country;
 	}
+	
+	public object ExplicitType()
+	{
+		return
+			from Customer c in customers
+			where c.City == "London"
+			select c;
+	}
+	
+	public object QueryContinuation()
+	{
+		return
+			from c in customers
+			group c by c.Country into g
+			select new { Country = g.Key, CustCount = g.Count() };
+	}
 }

ICSharpCode.Decompiler/Tests/TestRunner.cs

@@ -94,6 +94,12 @@ namespace ICSharpCode.Decompiler.Tests
 			TestFile(@"..\..\Tests\YieldReturn.cs");
 		}
 		
+		[Test, Ignore("Formatting differences")]
+		public void QueryExpressions()
+		{
+			TestFile(@"..\..\Tests\QueryExpressions.cs");
+		}
+		
 		static void TestFile(string fileName)
 		{
 			string code = File.ReadAllText(fileName);