ProjectedSlot.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / DataEntity / System / Data / Map / ViewGeneration / Structures / ProjectedSlot.cs / 1305376 / ProjectedSlot.cs
                        
                        
                            //---------------------------------------------------------------------- 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// 
// @owner [....]
// @backupOwner [....] 
//--------------------------------------------------------------------- 

using System.Data.Common.Utils; 
using System.Collections.Generic;
using System.Text;
using System.Data.Mapping.ViewGeneration.CqlGeneration;
using System.Data.Mapping.ViewGeneration.Utils; 
using System.Diagnostics;
using System.Data.Entity; 
 
namespace System.Data.Mapping.ViewGeneration.Structures
{ 

    /// 
    /// This class represents the constants or members that that can be referenced in a C or S Cell query
    /// In addition to fields, may represent constants such as types of fields, booleans, etc. 
    /// 
    internal abstract class ProjectedSlot : InternalBase, IEquatable 
    { 

        #region Fields 
        // A comparer object for comparing slots
        internal static readonly IEqualityComparer EqualityComparer = new ProjectedSlotComparer();
        #endregion
 
        #region Abstract methods
 
        // effects: Given a slot and the new mapping, returns the 
        // corresponding nw slot
        internal virtual ProjectedSlot RemapSlot(Dictionary remap) 
        {
            Debug.Fail("Should not be called.");
            return null; // To keep the compiler happy
        } 

        // effects: Returns true if this is semantically equivalent to s2 
        protected virtual bool IsEqualTo(ProjectedSlot right) 
        {
            return base.Equals(right); 
        }

        protected virtual int GetHash()
        { 
            return base.GetHashCode();
        } 
 
        public bool Equals(ProjectedSlot right)
        { 
            return EqualityComparer.Equals(this, right);
        }

        public override bool Equals(object obj) 
        {
            ProjectedSlot right = obj as ProjectedSlot; 
            if (obj == null) 
            {
                return false; 
            }
            return Equals(right);
        }
 
        public override int GetHashCode()
        { 
            return EqualityComparer.GetHashCode(this); 
        }
 
        // effects: Converts all "relevant" ProjectedSlots in this (including
        // this) to aliased slots for CqlBlock "block". A slot type is
        // relevant if it is not a constant. "outputPath" is the output path
        // of this slot in the final view 

        internal virtual ProjectedSlot MakeAliasedSlot(CqlBlock block, MemberPath outputPath, int slotNum) 
        { 
            AliasedSlot result = new AliasedSlot(block, this, outputPath, slotNum);
            return result; 
        }

        // requires: outputMember is non-null if slot is ConstantSlot (it can be
        // null otherwise). indentLevel indicates the appropriate 
        // indentation level (method can ignore it)
        // effects: Given a slot and a tableAlias, generates the Cql 
        // corresponding to it.  If slot is an Aliased slot, tableAlias is ignored 
        // Returns the modified builder
        internal abstract StringBuilder AsCql(StringBuilder builder, MemberPath outputMember, 
                                              string blockAlias, int indentLevel);
        #endregion

        #region Helper Methods for slots and ProjectedSlotMap 
        // effects: Returns the alias corresponding to slot. outputMember is
        // the member to which this slot is ultimately contributing to, e.g., 
        // CPerson1_pid 
        internal virtual string CqlFieldAlias(MemberPath outputMember)
        { 
            // Subclasses that don't want the outputMember will override this method
            return outputMember.CqlFieldAlias;
        }
 
        // effects: Given a slot number, slotNum, returns the output member path
        // that this slot contributes/corresponds to in the extent view. If 
        // the slot corresponds to one of the boolean variables, returns null 
        internal static MemberPath GetMemberPath(int slotNum, MemberProjectionIndex projectedSlotMap,
                                                 int numBoolSlots) 
        {
            MemberPath result = IsBoolSlot(slotNum, projectedSlotMap, numBoolSlots) ?
                                null : projectedSlotMap[slotNum];
            return result; 
        }
 
        // effects: Given the index of a boolean variable (e.g., of from1), 
        // returns the slot number for that boolean in this
        internal static int BoolIndexToSlot(int boolIndex, MemberProjectionIndex projectedSlotMap, int numBoolSlots) 
        {
            // Booleans appear after the regular slot
            Debug.Assert(boolIndex >= 0 && boolIndex < numBoolSlots,
                         "No such boolean in this node"); 
            return projectedSlotMap.Count + boolIndex;
        } 
 
        // effects: Given a slotNum corresponding to a boolean slot, returns
        // the cel number that the cell corresponds to 
        internal static int SlotToBoolIndex(int slotNum, MemberProjectionIndex projectedSlotMap, int numBoolSlots)
        {
            Debug.Assert(slotNum < projectedSlotMap.Count +
                         numBoolSlots && slotNum >= projectedSlotMap.Count, "No such boolean slot"); 
            return slotNum - projectedSlotMap.Count;
        } 
 
        // effects: Returns true if slotNum corresponds to a key slot in the
        // output extent view 
        internal static bool IsKeySlot(int slotNum, MemberProjectionIndex projectedSlotMap, int numBoolSlots)
        {
            Debug.Assert(slotNum < projectedSlotMap.Count + numBoolSlots, "No such slot in tree");
            return slotNum < projectedSlotMap.Count && projectedSlotMap[slotNum].IsPartOfKey; 
        }
 
        // effects: Returns true if slotNum corresponds to a bool slot and 
        // not a regular field
        internal static bool IsBoolSlot(int slotNum, MemberProjectionIndex projectedSlotMap, int numBoolSlots) 
        {
            Debug.Assert(slotNum < projectedSlotMap.Count + numBoolSlots, "Boolean slot does not exist in tree");
            return slotNum >= projectedSlotMap.Count;
        } 
        #endregion
 
        #region Other Methods 
        // effects: Given fields slots1 and slot2, remap then using "remap" and merge them
        internal static bool TryMergeRemapSlots(ProjectedSlot[] slots1, 
                                                ProjectedSlot[] slots2,
                                                out ProjectedSlot[] result)
        {
            // First merge them and then remp them 
            ProjectedSlot[] mergedSlots;
            if (!TryMergeSlots(slots1, slots2, out mergedSlots)) 
            { 
                result = null;
                return false; 
            }

            result = mergedSlots;
            return true; 
        }
 
        // effects: Given two lists of slots1 and slot2, merges them and returns 
        // the resulting slots, i.e., empty slots from one are overridden by
        // the slots from the other 
        private static bool TryMergeSlots(ProjectedSlot[] slots1,
                                          ProjectedSlot[] slots2,
                                          out ProjectedSlot[] slots)
        { 
            Debug.Assert(slots1.Length == slots2.Length, "Merged slots of two cells must be same size");
            slots = new ProjectedSlot[slots1.Length]; 
 
            for (int i = 0; i < slots.Length; i++)
            { 
                ProjectedSlot slot1 = slots1[i];
                ProjectedSlot slot2 = slots2[i];
                if (slot1 == null)
                { 
                    slots[i] = slot2;
                } 
                else if (slot2 == null) 
                {
                    slots[i] = slot1; 
                }
                else
                {
                    // Both slots are non-null: Either both are the same 
                    // members or one of them is a constant
                    // Note: if both are constants (even different constants) 
                    // it does not matter which one we pick because the CASE statement will override it 
                    MemberProjectedSlot memberSlot1 = slot1 as MemberProjectedSlot;
                    MemberProjectedSlot memberSlot2 = slot2 as MemberProjectedSlot; 

                    if (memberSlot1 != null && memberSlot2 != null &&
                       false == EqualityComparer.Equals(memberSlot1, memberSlot2))
                    { 
                        // Illegal combination of slots; non-constant fields disagree
                        return false; 
                    } 

                    // If one of them is a field we have to get the field 
                    ProjectedSlot pickedSlot = (memberSlot1 != null) ? slot1 : slot2;
                    slots[i] = pickedSlot;
                }
            } 
            return true;
        } 
 
        #endregion
 
        #region Comparer class
        // summary: A class that can compare slots basd on their contents
        internal class ProjectedSlotComparer : IEqualityComparer
        { 
            // effects: Returns true if left and right are semantically equivalent
            public bool Equals(ProjectedSlot left, ProjectedSlot right) 
            { 
                // Quick check with references
                if (object.ReferenceEquals(left, right)) 
                {
                    // Gets the Null and Undefined case as well
                    return true;
                } 
                // One of them is non-null at least. So if the other one is
                // null, we cannot be equal 
                if (left == null || right == null) 
                {
                    return false; 
                }
                // Both are non-null at this point
                return left.IsEqualTo(right);
            } 

            public int GetHashCode(ProjectedSlot key) 
            { 
                EntityUtil.CheckArgumentNull(key, "key");
                return key.GetHash(); 
            }
        }
        #endregion
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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