/// <summary>Matches simple lambdas of the form "a => b"</summary> bool MatchSimpleLambda(Expression expr, out string parameterName, out Expression body) { expr = StripCastAndParenthasis(expr); LambdaExpression lambda = expr as LambdaExpression; if (lambda != null && lambda.Parameters.Count == 1 && lambda.Body is Expression) { ParameterDeclaration p = lambda.Parameters.Single(); if (p.ParameterModifier == ParameterModifier.None) { parameterName = p.Name; body = (Expression)lambda.Body; return(true); } } parameterName = null; body = null; return(false); }
QueryExpression DecompileQuery(InvocationExpression invocation) { if (invocation == null) { return(null); } if (invocation.Parent is ParenthesizedExpression == false && invocation.Parent is QueryClause == false) { return(null); } MemberReferenceExpression mre = invocation.Target as MemberReferenceExpression; if (mre == null) { return(null); } switch (mre.MemberName) { case "Select": { if (invocation.Arguments.Count != 1) { return(null); } string parameterName; Expression body; if (MatchSimpleLambda(invocation.Arguments.Single(), out parameterName, out body)) { QueryExpression query = new QueryExpression(); query.Clauses.Add(new QueryFromClause { Identifier = parameterName, Expression = Detach(mre.Target) }); query.Clauses.Add(new QuerySelectClause { Expression = Detach(body) }); return(query); } return(null); } case "GroupBy": { 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 = Detach(mre.Target) }); query.Clauses.Add(new QueryGroupClause { Projection = Detach(elementSelector), Key = Detach(keySelector) }); 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 = Detach(mre.Target) }); query.Clauses.Add(new QueryGroupClause { Projection = new IdentifierExpression(parameterName), Key = Detach(keySelector) }); return(query); } } return(null); } case "SelectMany": { if (invocation.Arguments.Count != 2) { return(null); } string parameterName; Expression collectionSelector; if (!MatchSimpleLambda(invocation.Arguments.ElementAt(0), out parameterName, out collectionSelector)) { return(null); } LambdaExpression lambda = invocation.Arguments.ElementAt(1) as LambdaExpression; if (lambda != null && lambda.Parameters.Count == 2 && lambda.Body is Expression) { ParameterDeclaration p1 = lambda.Parameters.ElementAt(0); ParameterDeclaration p2 = lambda.Parameters.ElementAt(1); if (p1.Name == parameterName) { QueryExpression query = new QueryExpression(); query.Clauses.Add(new QueryFromClause { Identifier = p1.Name, Expression = Detach(mre.Target) }); query.Clauses.Add(new QueryFromClause { Identifier = p2.Name, Expression = Detach(collectionSelector) }); query.Clauses.Add(new QuerySelectClause { Expression = Detach(((Expression)lambda.Body)) }); return(query); } } return(null); } case "Where": { if (invocation.Arguments.Count != 1) { return(null); } string parameterName; Expression body; if (MatchSimpleLambda(invocation.Arguments.Single(), out parameterName, out body)) { QueryExpression query = new QueryExpression(); query.Clauses.Add(new QueryFromClause { Identifier = parameterName, Expression = Detach(mre.Target) }); query.Clauses.Add(new QueryWhereClause { Condition = Detach(body) }); return(query); } return(null); } case "OrderBy": case "OrderByDescending": case "ThenBy": case "ThenByDescending": { if (invocation.Arguments.Count != 1) { return(null); } string parameterName; Expression orderExpression; if (MatchSimpleLambda(invocation.Arguments.Single(), out parameterName, out orderExpression)) { if (ValidateThenByChain(invocation, parameterName)) { QueryOrderClause orderClause = new QueryOrderClause(); InvocationExpression tmp = invocation; while (mre.MemberName == "ThenBy" || mre.MemberName == "ThenByDescending") { // insert new ordering at beginning orderClause.Orderings.InsertAfter( null, new QueryOrdering { Expression = Detach(orderExpression), Direction = (mre.MemberName == "ThenBy" ? QueryOrderingDirection.None : QueryOrderingDirection.Descending) }); tmp = (InvocationExpression)mre.Target; mre = (MemberReferenceExpression)tmp.Target; MatchSimpleLambda(tmp.Arguments.Single(), out parameterName, out orderExpression); } // insert new ordering at beginning orderClause.Orderings.InsertAfter( null, new QueryOrdering { Expression = Detach(orderExpression), Direction = (mre.MemberName == "OrderBy" ? QueryOrderingDirection.None : QueryOrderingDirection.Descending) }); QueryExpression query = new QueryExpression(); query.Clauses.Add(new QueryFromClause { Identifier = parameterName, Expression = Detach(mre.Target) }); query.Clauses.Add(orderClause); return(query); } } return(null); } case "Join": case "GroupJoin": { if (invocation.Arguments.Count != 4) { return(null); } Expression source1 = mre.Target; Expression source2 = invocation.Arguments.ElementAt(0); string elementName1, elementName2; Expression key1, key2; if (!MatchSimpleLambda(invocation.Arguments.ElementAt(1), out elementName1, out key1)) { return(null); } if (!MatchSimpleLambda(invocation.Arguments.ElementAt(2), out elementName2, out key2)) { return(null); } LambdaExpression lambda = invocation.Arguments.ElementAt(3) as LambdaExpression; if (lambda != null && lambda.Parameters.Count == 2 && lambda.Body is Expression) { ParameterDeclaration p1 = lambda.Parameters.ElementAt(0); ParameterDeclaration p2 = lambda.Parameters.ElementAt(1); if (p1.Name == elementName1 && (p2.Name == elementName2 || mre.MemberName == "GroupJoin")) { QueryExpression query = new QueryExpression(); query.Clauses.Add(new QueryFromClause { Identifier = elementName1, Expression = Detach(source1) }); QueryJoinClause joinClause = new QueryJoinClause(); joinClause.JoinIdentifier = elementName2; // join elementName2 joinClause.InExpression = Detach(source2); // in source2 joinClause.OnExpression = Detach(key1); // on key1 joinClause.EqualsExpression = Detach(key2); // equals key2 if (mre.MemberName == "GroupJoin") { joinClause.IntoIdentifier = p2.Name; // into p2.Name } query.Clauses.Add(joinClause); query.Clauses.Add(new QuerySelectClause { Expression = Detach(((Expression)lambda.Body)) }); return(query); } } return(null); } default: return(null); } }