MegaBites-AI/Windows-powershell

1// Copyright (c) Microsoft Corporation.2// Licensed under the MIT License.3 4using System;5using System.Text;6using System.Transactions;7 8namespace Microsoft.PowerShell.Commands.Management9{10    /// <summary>11    /// Represents a string that can be used in transactions.12    /// </summary>13    public class TransactedString : IEnlistmentNotification14    {15        private StringBuilder _value;16        private StringBuilder _temporaryValue;17        private Transaction _enlistedTransaction = null;18 19        /// <summary>20        /// Constructor for the TransactedString class.21        /// </summary>22        public TransactedString() : this(string.Empty)23        {24        }25 26        /// <summary>27        /// Constructor for the TransactedString class.28        /// </summary>29        /// <param name="value">30        /// The initial value of the transacted string.31        /// </param>32        public TransactedString(string value)33        {34            _value = new StringBuilder(value);35            _temporaryValue = null;36        }37 38        /// <summary>39        /// Make the transacted changes permanent.40        /// </summary>41        void IEnlistmentNotification.Commit(Enlistment enlistment)42        {43            _value = new StringBuilder(_temporaryValue.ToString());44            _temporaryValue = null;45            _enlistedTransaction = null;46            enlistment.Done();47        }48 49        /// <summary>50        /// Discard the transacted changes.51        /// </summary>52        void IEnlistmentNotification.Rollback(Enlistment enlistment)53        {54            _temporaryValue = null;55            _enlistedTransaction = null;56            enlistment.Done();57        }58 59        /// <summary>60        /// Discard the transacted changes.61        /// </summary>62        void IEnlistmentNotification.InDoubt(Enlistment enlistment)63        {64            enlistment.Done();65        }66 67        void IEnlistmentNotification.Prepare(PreparingEnlistment preparingEnlistment)68        {69            preparingEnlistment.Prepared();70        }71 72        /// <summary>73        /// Append text to the transacted string.74        /// </summary>75        /// <param name="text">76        /// The text to append.77        /// </param>78        public void Append(string text)79        {80            ValidateTransactionOrEnlist();81 82            if (_enlistedTransaction != null)83            {84                _temporaryValue.Append(text);85            }86            else87            {88                _value.Append(text);89            }90        }91 92        /// <summary>93        /// Remove text from the transacted string.94        /// </summary>95        /// <param name="startIndex">96        /// The position in the string from which to start removing.97        /// </param>98        /// <param name="length">99        /// The length of text to remove.100        /// </param>101        public void Remove(int startIndex, int length)102        {103            ValidateTransactionOrEnlist();104 105            if (_enlistedTransaction != null)106            {107                _temporaryValue.Remove(startIndex, length);108            }109            else110            {111                _value.Remove(startIndex, length);112            }113        }114 115        /// <summary>116        /// Gets the length of the transacted string. If this is117        /// called within the transaction, it returns the length of118        /// the transacted value. Otherwise, it returns the length of119        /// the original value.120        /// </summary>121        public int Length122        {123            get124            {125                // If we're not in a transaction, or we are in a different transaction than the one we126                // enlisted to, return the publicly visible state.127                if (128                    (Transaction.Current == null) ||129                    (_enlistedTransaction != Transaction.Current))130                {131                    return _value.Length;132                }133                else134                {135                    return _temporaryValue.Length;136                }137            }138        }139 140        /// <summary>141        /// Gets the System.String that represents the transacted142        /// transacted string. If this is called within the143        /// transaction, it returns the transacted value.144        /// Otherwise, it returns the original value.145        /// </summary>146        public override string ToString()147        {148            // If we're not in a transaction, or we are in a different transaction than the one we149            // enlisted to, return the publicly visible state.150            if (151               (Transaction.Current == null) ||152               (_enlistedTransaction != Transaction.Current))153            {154                return _value.ToString();155            }156            else157            {158                return _temporaryValue.ToString();159            }160        }161 162        private void ValidateTransactionOrEnlist()163        {164            // We're in a transaction165            if (Transaction.Current != null)166            {167                // We haven't yet been called inside of a transaction. So enlist168                // in the transaction, and store our save point169                if (_enlistedTransaction == null)170                {171                    Transaction.Current.EnlistVolatile(this, EnlistmentOptions.None);172                    _enlistedTransaction = Transaction.Current;173 174                    _temporaryValue = new StringBuilder(_value.ToString());175                }176                // We're already enlisted in a transaction177                else178                {179                    // And we're in that transaction180                    if (Transaction.Current != _enlistedTransaction)181                    {182                        throw new InvalidOperationException("Cannot modify string. It has been modified by another transaction.");183                    }184                }185            }186            // We're not in a transaction187            else188            {189                // If we're not subscribed to a transaction, modify the underlying value190                if (_enlistedTransaction != null)191                {192                    throw new InvalidOperationException("Cannot modify string. It has been modified by another transaction.");193                }194            }195        }196    }197}198