using System;
using System.Collections.Generic;
using System.Text;
using System.Reflection;
using System.Linq.Expressions;

namespace System.Data.Linq {
    /// <summary>
    /// Encodes the rules for subqueries.
    /// </summary>
    static class SubqueryRules {
        /// <summary>
        /// This list of top-level methods that are supported in subqueries.
        /// </summary>
        /// <param name="mi"></param>
        /// <returns></returns>
        static internal bool IsSupportedTopLevelMethod(MethodInfo mi) {
            if (!IsSequenceOperatorCall(mi))
                return false;
            switch (mi.Name) {
                case "Where":
                case "OrderBy":
                case "OrderByDescending":
                case "ThenBy":
                case "ThenByDescending":
                case "Take":
                    return true;
            }
            return false;
        }
        private static bool IsSequenceOperatorCall(MethodInfo mi) {
            Type declType = mi.DeclaringType;
            if (declType == typeof(System.Linq.Enumerable) ||
                declType == typeof(System.Linq.Queryable)) {
                return true;
            }
            return false;
        }
    }
}