VarInfo.cs source code in C# .NET

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

using System; 
using System.Collections.Generic;
//using System.Diagnostics; // Please use PlanCompiler.Assert instead of Debug.Assert in this class...
using System.Globalization;
 
using System.Data.Common;
using md = System.Data.Metadata.Edm; 
using System.Data.Query.InternalTrees; 
using System.Data.Query.PlanCompiler;
 
namespace System.Data.Query.PlanCompiler {

    /// 
    /// Information about a Var and its replacement 
    /// 
    internal abstract class VarInfo { 
 
        /// 
        /// Does this VarInfo represent a collection type 
        /// 
        internal virtual bool IsCollectionType { get { return false; } }

        ///  
        /// Get the list of new Vars introduced by this VarInfo
        ///  
        internal virtual List NewVars { get { return null; } } 
    }
 
    /// 
    /// Represents information about a collection typed Var.
    /// Each such Var is replaced by a Var with a new "mapped" type - the "mapped" type
    /// is simply a collection type where the element type has been "mapped" 
    /// 
    internal class CollectionVarInfo : VarInfo { 
        private List m_newVars; // always a singleton list 

        ///  
        /// Create a CollectionVarInfo
        /// 
        /// 
        internal CollectionVarInfo(Var newVar) { 
            m_newVars = new List();
            m_newVars.Add(newVar); 
        } 

        ///  
        /// Get the newVar
        /// 
        internal Var NewVar { get { return m_newVars[0]; } }
 
        /// 
        /// This is for a collection-type Var 
        ///  
        internal override bool IsCollectionType { get { return true; } }
 
        /// 
        /// Get the list of all NewVars - just one really
        /// 
        internal override List NewVars { get { return m_newVars; } } 
    }
 
    ///  
    /// The StructuredVarInfo class contains information about a structured type Var
    /// and how it can be replaced. This is targeted towards Vars of complex/record/ 
    /// entity/ref types, and the goal is to replace all such Vars in this module.
    /// 
    internal class StructuredVarInfo : VarInfo {
 
        private Dictionary m_propertyToVarMap;
        List m_newVars; 
        bool m_newVarsIncludeNullSentinelVar; 
        List m_newProperties;
        md.RowType m_newType; 
        md.TypeUsage m_newTypeUsage;

        /// 
        /// Constructor 
        /// 
        /// new "flat" record type corresponding to the Var's datatype 
        /// List of vars to replace current Var 
        /// List of properties in the "flat" record type
        /// Do the new vars include a var that represents a null sentinel either for this type or for any nested type 
        internal StructuredVarInfo(md.RowType newType, List newVars, List newTypeProperties, bool newVarsIncludeNullSentinelVar)
        {
            PlanCompiler.Assert(newVars.Count == newTypeProperties.Count, "count mismatch");
            // I see a few places where this is legal 
            // PlanCompiler.Assert(newVars.Count > 0, "0 vars?");
            m_newVars = newVars; 
            m_newProperties = newTypeProperties; 
            m_newType = newType;
            m_newVarsIncludeNullSentinelVar = newVarsIncludeNullSentinelVar; 
            m_newTypeUsage = md.TypeUsage.Create(newType);
        }

        ///  
        /// The NewVars property of the VarInfo is a list of the corresponding
        /// "scalar" Vars that can be used to replace the current Var. This is 
        /// mainly intended for use by other RelOps that maintain lists of Vars 
        /// - for example, the "Vars" property of ProjectOp and other similar
        /// locations. 
        /// 
        internal override List NewVars { get { return m_newVars; } }

        ///  
        /// The Fields property is matched 1-1 with the NewVars property, and
        /// specifies the properties of the record type corresponding to the 
        /// original VarType 
        /// 
        internal List Fields { get { return m_newProperties; } } 

        /// 
        /// Indicates whether any of the vars in NewVars 'derives'
        /// from a null sentinel. For example, for a type that is a Record with two 
        /// nested records, if any has a null sentinel, it would be set to true.
        /// It is used when expanding sort keys, to be able to indicate that there is a 
        /// sorting operation that includes null sentinels. This indication is later 
        /// used by transformation rules.
        ///  
        internal bool NewVarsIncludeNullSentinelVar { get { return m_newVarsIncludeNullSentinelVar; } }

        /// 
        /// Get the Var corresponding to a specific property 
        /// 
        /// the requested property 
        /// the corresponding Var 
        /// true, if the Var was found
        internal bool TryGetVar(md.EdmProperty p, out Var v) { 
            if (m_propertyToVarMap == null) {
                InitPropertyToVarMap();
            }
            return m_propertyToVarMap.TryGetValue(p, out v); 
        }
 
        ///  
        /// The NewType property describes the new "flattened" record type
        /// that is a replacement for the original type of the Var 
        /// 
        internal md.RowType NewType { get { return m_newType; } }

        ///  
        /// Returns the NewType wrapped in a TypeUsage
        ///  
        internal md.TypeUsage NewTypeUsage { get { return m_newTypeUsage; } } 

        ///  
        /// Initialize mapping from properties to the corresponding Var
        /// 
        private void InitPropertyToVarMap() {
            if (m_propertyToVarMap == null) { 
                m_propertyToVarMap = new Dictionary();
                IEnumerator newVarEnumerator = m_newVars.GetEnumerator(); 
                foreach (md.EdmProperty prop in m_newProperties) { 
                    newVarEnumerator.MoveNext();
                    m_propertyToVarMap.Add(prop, newVarEnumerator.Current); 
                }
                newVarEnumerator.Dispose();
            }
        } 
    }
 
    ///  
    /// The VarInfo map maintains a mapping from Vars to their corresponding VarInfo
    /// It is logically a Dictionary 
    /// 
    internal class VarInfoMap {
        private Dictionary m_map;
 
        /// 
        /// Default constructor 
        ///  
        internal VarInfoMap() {
            m_map = new Dictionary(); 
        }

        /// 
        /// Create a new VarInfo for a structured type Var 
        /// 
        /// The structured type Var 
        /// "Mapped" type for v 
        /// List of vars corresponding to v
        /// Flattened Properties  
        /// Do the new vars include a var that represents a null sentinel either for this type or for any nested type
        /// the VarInfo
        internal VarInfo CreateStructuredVarInfo(Var v, md.RowType newType, List newVars, List newProperties, bool newVarsIncludeNullSentinelVar)
        { 
            VarInfo varInfo = new StructuredVarInfo(newType, newVars, newProperties, newVarsIncludeNullSentinelVar);
            m_map.Add(v, varInfo); 
            return varInfo; 
        }
 
        /// 
        /// Create a new VarInfo for a structured type Var where the newVars cannot include a null sentinel
        /// 
        /// The structured type Var 
        /// "Mapped" type for v
        /// List of vars corresponding to v 
        /// Flattened Properties  
        internal VarInfo CreateStructuredVarInfo(Var v, md.RowType newType, List newVars, List newProperties)
        { 
            return CreateStructuredVarInfo(v, newType, newVars, newProperties, false);
        }

        ///  
        /// Create a VarInfo for a collection typed Var
        ///  
        /// The collection-typed Var 
        /// the new Var
        /// the VarInfo 
        internal VarInfo CreateCollectionVarInfo(Var v, Var newVar) {
            VarInfo varInfo = new CollectionVarInfo(newVar);
            m_map.Add(v, varInfo);
            return varInfo; 
        }
 
        ///  
        /// Return the VarInfo for the specified var (if one exists, of course)
        ///  
        /// The Var
        /// the corresponding VarInfo
        /// 
        internal bool TryGetVarInfo(Var v, out VarInfo varInfo) { 
            return m_map.TryGetValue(v, out varInfo);
        } 
    } 

} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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VarInfo.cs source code in C# .NET

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