MegaBites-AI/Windows-powershell

1// Copyright (c) Microsoft Corporation.2// Licensed under the MIT License.3 4using System;5using System.Collections;6using System.Collections.ObjectModel;7using System.Management.Automation;8using System.Management.Automation.Provider;9 10using Dbg = System.Management.Automation;11 12namespace Microsoft.PowerShell.Commands13{14    /// <summary>15    /// This provider is the data accessor for shell variables. It uses16    /// the HashtableProvider as the base class to get a hashtable as17    /// a data store.18    /// </summary>19    [CmdletProvider(VariableProvider.ProviderName, ProviderCapabilities.ShouldProcess)]20    [OutputType(typeof(PSVariable), ProviderCmdlet = ProviderCmdlet.SetItem)]21    [OutputType(typeof(PSVariable), ProviderCmdlet = ProviderCmdlet.RenameItem)]22    [OutputType(typeof(PSVariable), ProviderCmdlet = ProviderCmdlet.CopyItem)]23    [OutputType(typeof(PSVariable), ProviderCmdlet = ProviderCmdlet.GetItem)]24    [OutputType(typeof(PSVariable), ProviderCmdlet = ProviderCmdlet.NewItem)]25    public sealed class VariableProvider : SessionStateProviderBase26    {27        /// <summary>28        /// Gets the name of the provider.29        /// </summary>30        public const string ProviderName = "Variable";31 32        #region Constructor33 34        /// <summary>35        /// The constructor for the provider that exposes variables to the user36        /// as drives.37        /// </summary>38        public VariableProvider()39        {40        }41 42        #endregion Constructor43 44        #region DriveCmdletProvider overrides45 46        /// <summary>47        /// Initializes the variables drive.48        /// </summary>49        /// <returns>50        /// An array of a single PSDriveInfo object representing the variables drive.51        /// </returns>52        protected override Collection<PSDriveInfo> InitializeDefaultDrives()53        {54            string description = SessionStateStrings.VariableDriveDescription;55 56            PSDriveInfo variableDrive =57                new PSDriveInfo(58                    DriveNames.VariableDrive,59                    ProviderInfo,60                    string.Empty,61                    description,62                    null);63 64            Collection<PSDriveInfo> drives = new Collection<PSDriveInfo>();65            drives.Add(variableDrive);66            return drives;67        }68 69        #endregion DriveCmdletProvider overrides70 71        #region protected members72 73        /// <summary>74        /// Gets a variable from session state.75        /// </summary>76        /// <param name="name">77        /// The name of the variable to retrieve.78        /// </param>79        /// <returns>80        /// A PSVariable that represents the variable.81        /// </returns>82        internal override object GetSessionStateItem(string name)83        {84            Dbg.Diagnostics.Assert(85                !string.IsNullOrEmpty(name),86                "The caller should verify this parameter");87 88            return (PSVariable)SessionState.Internal.GetVariable(name, Context.Origin);89        }90 91        /// <summary>92        /// Sets the variable of the specified name to the specified value.93        /// </summary>94        /// <param name="name">95        /// The name of the variable to set.96        /// </param>97        /// <param name="value">98        /// The new value for the variable.99        /// </param>100        /// <param name="writeItem">101        /// If true, the item that was set should be written to WriteItemObject.102        /// </param>103        internal override void SetSessionStateItem(string name, object value, bool writeItem)104        {105            Dbg.Diagnostics.Assert(106                !string.IsNullOrEmpty(name),107                "The caller should verify this parameter");108 109            PSVariable variable = null;110 111            if (value != null)112            {113                variable = value as PSVariable;114                if (variable == null)115                {116                    variable = new PSVariable(name, value);117                }118                else119                {120                    // ensure the name matches121 122                    if (!string.Equals(name, variable.Name, StringComparison.OrdinalIgnoreCase))123                    {124                        PSVariable newVar = new PSVariable(name, variable.Value, variable.Options, variable.Attributes);125                        newVar.Description = variable.Description;126                        variable = newVar;127                    }128                }129            }130            else131            {132                variable = new PSVariable(name, null);133            }134 135            PSVariable item = SessionState.Internal.SetVariable(variable, Force, Context.Origin) as PSVariable;136 137            if (writeItem && item != null)138            {139                WriteItemObject(item, item.Name, false);140            }141        }142 143        /// <summary>144        /// Removes the specified variable from session state.145        /// </summary>146        /// <param name="name">147        /// The name of the variable to remove from session state.148        /// </param>149        internal override void RemoveSessionStateItem(string name)150        {151            Dbg.Diagnostics.Assert(152                !string.IsNullOrEmpty(name),153                "The caller should verify this parameter");154 155            SessionState.Internal.RemoveVariable(name, Force);156        }157 158        /// <summary>159        /// Gets a flattened view of the variables in session state.160        /// </summary>161        /// <returns>162        /// An IDictionary representing the flattened view of the variables in163        /// session state.164        /// </returns>165        internal override IDictionary GetSessionStateTable()166        {167            return (IDictionary)SessionState.Internal.GetVariableTable();168        }169 170        /// <summary>171        /// Gets the value of the item that is returned from GetItem by172        /// extracting the PSVariable value.173        /// </summary>174        /// <param name="item">175        /// The item to extract the value from.176        /// </param>177        /// <returns>178        /// The value of the specified item.179        /// </returns>180        internal override object GetValueOfItem(object item)181        {182            Dbg.Diagnostics.Assert(183                item != null,184                "Caller should verify the item parameter");185 186            // Call the base class to unwrap the DictionaryEntry187            // if necessary188 189            object value = base.GetValueOfItem(item);190 191            PSVariable var = item as PSVariable;192            if (var != null)193            {194                value = var.Value;195            }196 197            return value;198        }199 200        /// <summary>201        /// Determines if the item can be renamed. Derived classes that need202        /// to perform a check should override this method.203        /// </summary>204        /// <param name="item">205        /// The item to verify if it can be renamed.206        /// </param>207        /// <returns>208        /// true if the item can be renamed or false otherwise.209        /// </returns>210        internal override bool CanRenameItem(object item)211        {212            bool result = false;213 214            PSVariable variable = item as PSVariable;215            if (variable != null)216            {217                if ((variable.Options & ScopedItemOptions.Constant) != 0 ||218                    ((variable.Options & ScopedItemOptions.ReadOnly) != 0 && !Force))219                {220                    SessionStateUnauthorizedAccessException e =221                        new SessionStateUnauthorizedAccessException(222                            variable.Name,223                            SessionStateCategory.Variable,224                            "CannotRenameVariable",225                            SessionStateStrings.CannotRenameVariable);226 227                    throw e;228                }229 230                result = true;231            }232 233            return result;234        }235        #endregion protected members236 237    }238}239