ContentQueryProvider.cs :  » Content-Management-Systems-CMS » Kooboo » Everest » CmsServices » LINQ » C# / CSharp Open Source

/*
Kooboo is a content management system based on ASP.NET MVC framework. Copyright 2009 Yardi Technology Limited.

This program is free software: you can redistribute it and/or modify it under the terms of the
GNU General Public License version 3 as published by the Free Software Foundation.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program.
If not, see http://www.kooboo.com/gpl3/.
*/
using System;
using System.Web;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Linq.Expressions;
using System.Reflection;
using Everest.CmsServices.MvcHelper;

namespace Everest.CmsServices.LINQ{
    internal abstract class ContentQueryProvider : IQueryProvider
    {
        public ContentQueryProvider()
        {
            Translator = new ContentQueryTranslator();
        }
        #region IQueryProvider Members

        public abstract IQueryable<TElement> CreateQuery<TElement>(Expression expression);
        //{
        //    return (IQueryable<TElement>)new ContentQueryable<TElement>(expression);
        //}

        public abstract IQueryable CreateQuery(Expression expression);
        //{
        //    Type elementType = TypeSystem.GetElementType(expression.Type);
        //    try
        //    {
        //        return (IQueryable)Activator.CreateInstance(typeof(ContentQueryable<>).MakeGenericType(elementType), new object[] { this, expression });
        //    }
        //    catch (TargetInvocationException tie)
        //    {
        //        throw tie.InnerException;
        //    }
        //}

        public virtual TResult Execute<TResult>(Expression expression)
        {
            return (TResult)this.Execute(expression);
        }

        public virtual object Execute(Expression expression)
        {
            return ExecuteCall(expression);
        }

        #endregion
        protected virtual object ExecuteCall(Expression expression)
        {
            var statementExpression = Translator.Translate(expression);

            switch (statementExpression.QueryMethodType)
            {
                case SupportedQueryType.Count:
                    return Count(statementExpression);
                case SupportedQueryType.First:
                    return First(statementExpression);
                case SupportedQueryType.FirstOrDefault:
                    return FirstOrDefault(statementExpression);
                case SupportedQueryType.Last:
                    return Last(statementExpression);
                case SupportedQueryType.LastOrDefault:
                    return LastOrDefault(statementExpression);
                default:
                    return ExecuteCore(statementExpression);
            }
        }
        protected abstract object Count(StatementExpression exp);
        protected abstract object First(StatementExpression exp);
        protected abstract object FirstOrDefault(StatementExpression exp);
        protected abstract object Last(StatementExpression exp);
        protected abstract object LastOrDefault(StatementExpression exp);
        protected abstract object ExecuteCore(StatementExpression exp);

        public virtual ContentQueryTranslator Translator { get; private set; }


        protected virtual ContentService ContentService
        {
            get
            {
                return HttpContext.Current.GetCmsContext().ContentService;
            }
        }
    }
}