StateBag.cs source code in C# .NET

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Code:

                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / xsp / System / Web / UI / StateBag.cs / 1 / StateBag.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

namespace System.Web.UI { 
    using System.Text; 
    using System.IO;
    using System.Collections; 
    using System.Collections.Specialized;
    using System.Reflection;
    using System.Web.Util;
    using System.Security.Permissions; 

    /* 
     * The StateBag class is a helper class used to manage state of properties. 
     * The class stores name/value pairs as string/object and tracks modifications of
     * properties after being 'marked'.  This class is used as the primary storage 
     * mechanism for all HtmlControls and WebControls.
     */

    ///  
    ///    Manages the state of Web Forms control properties. This
    ///       class stores attribute/value pairs as string/object and tracks changes to these 
    ///       attributes, which are treated as properties, after the Page.Init 
    ///       method is executed for a
    ///       page request.  
    ///    
    ///       Only values changed after Page.Init
    ///       has executed are persisted to the page's view state.
    ///     
    /// 
    [AspNetHostingPermission(SecurityAction.LinkDemand, Level=AspNetHostingPermissionLevel.Minimal)] 
    public sealed class StateBag : IStateManager, IDictionary { 
        private IDictionary bag;
        private bool        marked; 
        private bool        ignoreCase;

        /*
         * Constructs an StateBag 
         */
 
        ///  
        /// Initializes a new instance of the  class.
        ///  
        public StateBag() : this(false) {
        }

        /* 
         * Constructs an StateBag
         */ 
 
        /// 
        /// Initializes a new instance of the  class that allows stored state 
        ///    values to be case-insensitive.
        /// 
        public StateBag(bool ignoreCase) {
            marked = false; 
            this.ignoreCase = ignoreCase;
            bag = CreateBag(); 
        } 

 
        /*
         * Return count of number of StateItems in the bag.
         */
 
        /// 
        /// Indicates the number of items in the  object. This property is 
        ///    read-only. 
        /// 
        public int Count { 
            get {
                return bag.Count;
            }
        } 

        /* 
         * Returns a collection of keys. 
         */
 
        /// 
        /// Indicates a collection of keys representing the items in the  object.
        ///    This property is read-only.
        ///  
        public ICollection Keys {
            get { 
                return bag.Keys; 
            }
        } 

        /*
         * Returns a collection of values.
         */ 

        ///  
        /// Indicates a collection of view state values in the  object. 
        ///    This property is read-only.
        ///  
        public ICollection Values {
            get {
                return bag.Values;
            } 
        }
 
        /* 
         * Get or set value of a StateItem.
         * A set will automatically add a new StateItem for a 
         * key which is not already in the bag.  A set to null
         * will remove the item if set before mark, otherwise
         * a null set will be saved to allow tracking of state
         * removed after mark. 
         */
 
        ///  
        ///     Indicates the value of an item stored in the
        ///     
        ///    object. Setting this property with a key not already stored in the StateBag will
        ///    add an item to the bag. If you set this property to  before
        ///    the TrackState method is called on an item will remove it from the bag. Otherwise,
        ///    when you set this property to  
        ///    the key will be saved to allow tracking of the item's state.
        ///  
        public object this[string key] { 
            get {
                if (String.IsNullOrEmpty(key)) 
                    throw ExceptionUtil.ParameterNullOrEmpty("key");

                StateItem item = bag[key] as StateItem;
                if (item != null) 
                    return item.Value;
                return null; 
            } 
            set {
                Add(key,value); 
            }
        }

        /* 
         * Private implementation of IDictionary item accessor
         */ 
 
        /// 
        object IDictionary.this[object key] { 
            get { return this[(string) key]; }
            set { this[(string) key] = value; }
        }
 
        private IDictionary CreateBag() {
            return new HybridDictionary(ignoreCase); 
        } 

        /* 
         * Add a new StateItem or update an existing StateItem in the bag.
         */

        ///  
        ///    [To be supplied.]
        ///  
        public StateItem Add(string key,object value) { 

            if (String.IsNullOrEmpty(key)) 
                throw ExceptionUtil.ParameterNullOrEmpty("key");

            StateItem item = bag[key] as StateItem;
 
            if (item == null) {
                if (value != null || marked) { 
                    item = new StateItem(value); 
                    bag.Add(key,item);
                } 
            }
            else {
                if (value == null && !marked) {
                    bag.Remove(key); 
                }
                else { 
                    item.Value = value; 
                }
            } 
            if (item != null && marked) {
                item.IsDirty = true;
            }
            return item; 
        }
 
        /* 
         * Private implementation of IDictionary Add
         */ 

        /// 
        void IDictionary.Add(object key,object value) {
            Add((string) key, value); 
        }
 
        /* 
         * Clear all StateItems from the bag.
         */ 

        /// 
        /// Removes all controls from the  object.
        ///  
        public void Clear() {
            bag.Clear(); 
        } 

        /* 
         * Get an enumerator for the StateItems.
         */

        ///  
        ///    Returns an enumerator that iterates over the key/value pairs stored in
        ///       the . 
        ///  
        public IDictionaryEnumerator GetEnumerator() {
            return bag.GetEnumerator(); 
        }

        /*
         * Return the dirty flag of the state item. 
         * Returns false if there is not an item for given key.
         */ 
 
        /// 
        /// Checks an item stored in the  to see if it has been 
        ///    modified.
        /// 
        public bool IsItemDirty(string key) {
            StateItem item = bag[key] as StateItem; 
            if (item != null)
                return item.IsDirty; 
 
            return false;
        } 

        /*
         * Return true if 'marked' and state changes are being tracked.
         */ 

        ///  
        ///    Determines if state changes in the StateBag object's store are being tracked. 
        /// 
        internal bool IsTrackingViewState { 
            get {
                return marked;
            }
        } 

        /* 
         * Restore state that was previously saved via SaveViewState. 
         */
 
        /// 
        ///    Loads the specified previously saved state information
        /// 
        internal void LoadViewState(object state) { 
            if (state != null) {
                ArrayList data = (ArrayList)state; 
 
                for (int i = 0; i < data.Count; i += 2) {
#if OBJECTSTATEFORMATTER 
                    string key = ((IndexedString)data[i]).Value;
#else
                    string key = (string)data[i];
#endif 
                    object value = data[i + 1];
 
                    Add(key, value); 
                }
            } 
        }

        /*
         * Start tracking state changes after "mark". 
         */
 
        ///  
        ///    Initiates the tracking of state changes for items stored in the
        ///     object. 
        /// 
        internal void TrackViewState() {
            marked = true;
        } 

        /* 
         * Remove a StateItem from the bag altogether regardless of marked. 
         * Used internally by controls.
         */ 

        /// 
        /// Removes the specified item from the  object.
        ///  
        public void Remove(string key) {
            bag.Remove(key); 
        } 

        /* 
         * Private implementation of IDictionary Remove
         */

        ///  
        void IDictionary.Remove(object key) {
            Remove((string) key); 
        } 

 
        /*
         * Return object containing state that has been modified since "mark".
         * Returns null if there is no modified state.
         */ 

        ///  
        ///    Returns an object that contains all state changes for items stored in the 
        ///     object.
        ///  
        internal object SaveViewState() {
            ArrayList data = null;

            // 

            if (bag.Count != 0) { 
                IDictionaryEnumerator e = bag.GetEnumerator(); 
                while (e.MoveNext()) {
                    StateItem item = (StateItem)(e.Value); 
                    if (item.IsDirty) {
                        if (data == null) {
                            data = new ArrayList();
                        } 
#if OBJECTSTATEFORMATTER
                        data.Add(new IndexedString((string)e.Key)); 
#else 
                        data.Add(e.Key);
#endif 
                        data.Add(item.Value);
                    }
                }
            } 

            return data; 
        } 

 
        /// 
        /// Sets the dirty state of all item values currently in the StateBag.
        /// 
        public void SetDirty(bool dirty) { 
            if (bag.Count != 0) {
                foreach (StateItem item in bag.Values) { 
                    item.IsDirty = dirty; 
                }
            } 
        }

        /*
         * Internal method for setting dirty flag on a state item. 
         * Used internallly to prevent state management of certain properties.
         */ 
 
        /// 
        ///  
        /// 
        public void SetItemDirty(string key,bool dirty) {
            StateItem item = bag[key] as StateItem;
            if (item != null) { 
                item.IsDirty = dirty;
            } 
        } 

        ///  
        bool IDictionary.IsFixedSize {
            get { return false; }
        }
 

        ///  
        bool IDictionary.IsReadOnly { 
            get { return false; }
        } 


        /// 
        bool ICollection.IsSynchronized { 
            get { return false;}
        } 
 

        ///  
        object ICollection.SyncRoot {
            get {return this; }
        }
 

        ///  
        bool IDictionary.Contains(object key) { 
            return bag.Contains((string) key);
        } 


        /// 
        IEnumerator IEnumerable.GetEnumerator() { 
            return ((IDictionary)this).GetEnumerator();
        } 
 

        ///  
        void ICollection.CopyTo(Array array, int index) {
            Values.CopyTo(array, index);
        }
 

        /* 
         * Return true if tracking state changes. 
         * Method of private interface, IStateManager.
         */ 

        /// 
        bool IStateManager.IsTrackingViewState {
            get { 
                return IsTrackingViewState;
            } 
        } 

        /* 
         * Load previously saved state.
         * Method of private interface, IStateManager.
         */
 
        /// 
        void IStateManager.LoadViewState(object state) { 
            LoadViewState(state); 
        }
 
        /*
         * Start tracking state changes.
         * Method of private interface, IStateManager.
         */ 

        ///  
        void IStateManager.TrackViewState() { 
            TrackViewState();
        } 

        /*
         * Return object containing state changes.
         * Method of private interface, IStateManager. 
         */
 
        ///  
        object IStateManager.SaveViewState() {
            return SaveViewState(); 
        }
    }
}

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