Symbol.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / DataEntity / System / Data / SqlClient / SqlGen / Symbol.cs / 1305376 / Symbol.cs
                        

                        
                            //---------------------------------------------------------------------- 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// 
// @owner  [....]
// @backupOwner [....] 
//--------------------------------------------------------------------- 

using System; 
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Text; 
using System.Data.SqlClient;
using System.Data.Metadata.Edm; 
using System.Data.Common.CommandTrees; 

namespace System.Data.SqlClient.SqlGen 
{
    /// 
    /// 
    /// This class represents an extent/nested select statement, 
    /// or a column.
    /// 
    /// The important fields are Name, Type and NewName. 
    /// NewName starts off the same as Name, and is then modified as necessary.
    /// 
    ///
    /// The rest are used by special symbols.
    /// e.g. NeedsRenaming is used by columns to indicate that a new name must
    /// be picked for the column in the second phase of translation. 
    ///
    /// IsUnnest is used by symbols for a collection expression used as a from clause. 
    /// This allows  to add the column list 
    /// after the alias.
    /// 
    /// 
    internal class Symbol : ISqlFragment
    {
        ///  
        /// Used to track the columns originating from this Symbol when it is used
        /// in as a from extent in a SqlSelectStatement with a Join or as a From Extent 
        /// in a Join Symbol. 
        /// 
        private Dictionary columns; 
        internal Dictionary Columns
        {
            get
            { 
                if (null == columns)
                { 
                    columns = new Dictionary(StringComparer.OrdinalIgnoreCase); 
                }
                return columns; 
            }
        }

        ///  
        /// Used to track the output columns of a SqlSelectStatement it represents
        ///  
        private Dictionary outputColumns; 
        internal Dictionary OutputColumns
        { 
            get
            {
                if (null == outputColumns)
                { 
                    outputColumns = new Dictionary(StringComparer.OrdinalIgnoreCase);
                } 
                return outputColumns; 
            }
        } 

        private bool needsRenaming;
        internal bool NeedsRenaming
        { 
            get { return needsRenaming; }
            set { needsRenaming = value; } 
        } 

        private bool outputColumnsRenamed; 
        internal bool OutputColumnsRenamed
        {
            get { return outputColumnsRenamed; }
            set { outputColumnsRenamed = value; } 
        }
 
        private string name; 
        public string Name
        { 
            get { return name; }
        }

        private string newName; 
        public string NewName
        { 
            get { return newName; } 
            set { newName = value; }
        } 

        private TypeUsage type;
        internal TypeUsage Type
        { 
            get { return type; }
            set { type = value; } 
        } 

        public Symbol(string name, TypeUsage type) 
        {
            this.name = name;
            this.newName = name;
            this.Type = type; 
        }
 
        ///  
        /// Use this constructor if the symbol represents a SqlStatement for which the output columns need to be tracked.
        ///  
        /// 
        /// 
        /// 
        ///  
        public Symbol(string name, TypeUsage type, Dictionary outputColumns, bool outputColumnsRenamed)
        { 
            this.name = name; 
            this.newName = name;
            this.Type = type; 
            this.outputColumns = outputColumns;
            this.OutputColumnsRenamed = outputColumnsRenamed;
        }
 
        #region ISqlFragment Members
 
        ///  
        /// Write this symbol out as a string for sql.  This is just
        /// the new name of the symbol (which could be the same as the old name). 
        ///
        /// We rename columns here if necessary.
        /// 
        ///  
        /// 
        public void WriteSql(SqlWriter writer, SqlGenerator sqlGenerator) 
        { 
            if (this.NeedsRenaming)
            { 
                int i;

                if (sqlGenerator.AllColumnNames.TryGetValue(this.NewName, out i))
                { 
                    string newNameCandidate;
                    do 
                    { 
                        ++i;
                        newNameCandidate = this.NewName + i.ToString(System.Globalization.CultureInfo.InvariantCulture); 
                    } while (sqlGenerator.AllColumnNames.ContainsKey(newNameCandidate));

                    sqlGenerator.AllColumnNames[this.NewName] = i;
 
                    this.NewName = newNameCandidate;
                } 
 
                // Add this column name to list of known names so that there are no subsequent
                // collisions 
                sqlGenerator.AllColumnNames[this.NewName] = 0;

                // Prevent it from being renamed repeatedly.
                this.NeedsRenaming = false; 
            }
            writer.Write(SqlGenerator.QuoteIdentifier(this.NewName)); 
        } 

        #endregion 
    }
}

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

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