HttpCacheParams.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / xsp / System / Web / HttpCacheParams.cs / 2 / HttpCacheParams.cs
                        

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

/* 
 * Cache Vary class.  Wraps Vary header 
 *
 * Copyright (c) 1998 Microsoft Corporation 
 */

namespace System.Web {
    using System.Text; 
    using System.Runtime.InteropServices;
    using System.Web.Util; 
    using System.Security.Permissions; 

 
    /// 
    ///    Indicates that a cache should contain multiple
    ///       representations for a particular Uri. This class is an encapsulation that
    ///       provides a rich, type-safe way to set the Vary header. 
    /// 
    [AspNetHostingPermission(SecurityAction.LinkDemand, Level=AspNetHostingPermissionLevel.Minimal)] 
    public sealed class HttpCacheVaryByParams { 
        HttpDictionary  _parameters;
        int             _ignoreParams; 
        bool            _isModified;
        bool            _paramsStar;

        internal HttpCacheVaryByParams() { 
            Reset();
        } 
 
        internal void Reset() {
            _isModified = false; 
            _paramsStar = false;
            _parameters = null;
            _ignoreParams = -1;
        } 

        /* 
         * Reset based on the cached vary headers. 
         */
        internal void ResetFromParams(String[] parameters) { 
            int i, n;

            Reset();
            if (parameters != null) { 
                _isModified = true;
                if (parameters[0].Length == 0) { 
                    Debug.Assert(parameters.Length == 1, "parameters.Length == 1"); 

                    IgnoreParams = true; 
                }
                else if (parameters[0].Equals("*")) {
                    Debug.Assert(parameters.Length == 1, "parameters.Length == 1");
 
                    _paramsStar = true;
                } 
                else { 
                    _parameters = new HttpDictionary();
                    for (i = 0, n = parameters.Length; i < n; i++) { 
                        _parameters.SetValue(parameters[i], parameters[i]);
                    }
                }
            } 
        }
 
        internal bool IsModified() { 
            return _isModified;
        } 

        internal bool AcceptsParams() {
            return _ignoreParams == 1 || _paramsStar || _parameters != null;
        } 

        internal String[] GetParams() { 
            String[]    s = null; 
            Object      item;
            int         i, j, c, n; 

            if (_ignoreParams == 1) {
                s =  new String[1] {String.Empty};
            } 
            else if (_paramsStar) {
                s =  new String[1] {"*"}; 
            } 
            else if (_parameters != null) {
                n = _parameters.Size; 
                c = 0;
                for (i = 0; i < n; i++) {
                    item = _parameters.GetValue(i);
                    if (item != null) { 
                        c++;
                    } 
                } 

                if (c > 0) { 
                    s = new string[c];
                    j = 0;
                    for (i = 0; i < n; i++) {
                        item = _parameters.GetValue(i); 
                        if (item != null) {
                            s[j] = (String) item; 
                            j++; 
                        }
                    } 

                    Debug.Assert(j == c, "j == c");
                }
            } 

            return s; 
        } 

        // 
        // Public methods and properties
        //

 
        /// 
        ///     Default property. 
        ///       Indexed property indicating that a cache should (or should not) vary according 
        ///       to a custom header.
        ///  
        public bool this[String header]
        {
            get {
                if (header == null) { 
                    throw new ArgumentNullException("header");
                } 
 
                if (header.Length == 0) {
                    return _ignoreParams == 1; 
                }
                else {
                    return _paramsStar ||
                           (_parameters != null && _parameters.GetValue(header) != null); 
                }
            } 
 
            set {
                if (header == null) { 
                    throw new ArgumentNullException("header");
                }

                if (header.Length == 0) { 
                    IgnoreParams = value;
                } 
                /* 
                 * Since adding a Vary parameter is more restrictive, we don't
                 * want components to be able to set a Vary parameter to false 
                 * if another component has set it to true.
                 */
                else if (value) {
                    _isModified = true; 
                    _ignoreParams = 0;
                    if (header.Equals("*")) { 
                        _paramsStar = true; 
                        _parameters = null;
                    } 
                    else {
                        // set value to header if true or null if false
                        if (!_paramsStar) {
                            if (_parameters == null) { 
                                _parameters = new HttpDictionary();
                            } 
 
                            _parameters.SetValue(header, header);
                        } 
                    }
                }
            }
        } 

 
        public bool IgnoreParams { 
            get {
                return _ignoreParams == 1; 
            }

            set {
                // Don't ignore if params have been added 
                if (_paramsStar || _parameters != null) {
                    return; 
                } 

                if (_ignoreParams == -1 || _ignoreParams == 1) { 
                    _ignoreParams = value ? 1 : 0;
                    _isModified = true;
                }
            } 
        }
 
        internal bool IsVaryByStar { 
            get {
                return _paramsStar; 
            }
        }
    }
}

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