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//------------------------------------------------------------------------------
// <copyright file="HttpCacheVary.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
/*
* 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;
/// <devdoc>
/// <para>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.</para>
/// </devdoc>
public sealed class HttpCacheVaryByHeaders {
bool _isModified;
bool _varyStar;
HttpDictionary _headers;
public HttpCacheVaryByHeaders() {
Reset();
}
internal void Reset() {
_isModified = false;
_varyStar = false;
_headers = null;
}
/// <summary>
/// Set the Headers in Cache Vary
/// </summary>
/// <param name="headers"></param>
public void SetHeaders(string[] headers) {
int i, n;
if (headers == null) {
_isModified = false;
_varyStar = false;
_headers = null;
}
else {
_isModified = true;
if (headers[0].Equals("*")) {
Debug.Assert(headers.Length == 1, "headers.Length == 1");
_varyStar = true;
_headers = null;
}
else {
_varyStar = false;
_headers = new HttpDictionary();
for (i = 0, n = headers.Length; i < n; i++) {
_headers.SetValue(headers[i], headers[i]);
}
}
}
}
internal bool IsModified() {
return _isModified;
}
/*
* Construct header value string
*/
internal String ToHeaderString() {
StringBuilder s;
Object item;
int i, n;
if (_varyStar) {
return "*";
}
else if (_headers != null) {
s = new StringBuilder();
for (i = 0, n = _headers.Size; i < n; i++) {
item = _headers.GetValue(i);
if (item != null) {
HttpCachePolicy.AppendValueToHeader(s, (String)item);
}
}
if (s.Length > 0)
return s.ToString();
}
return null;
}
/// <summary>
/// Get the Headers in Cache Vary
/// </summary>
/// <returns></returns>
public string[] GetHeaders() {
string[] s = null;
Object item;
int i, j, c, n;
if (_varyStar) {
return new string[1] {"*"};
}
else if (_headers != null) {
n = _headers.Size;
c = 0;
for (i = 0; i < n; i++) {
item = _headers.GetValue(i);
if (item != null) {
c++;
}
}
if (c > 0) {
s = new string[c];
j = 0;
for (i = 0; i < n; i++) {
item = _headers.GetValue(i);
if (item != null) {
s[j] = (string) item;
j++;
}
}
Debug.Assert(j == c, "j == c");
}
}
return s;
}
//
// Public methods and properties
//
/// <devdoc>
/// <para>Sets the "Vary: *" header and causes all other Vary:
/// header information to be dropped.</para>
/// </devdoc>
public void VaryByUnspecifiedParameters() {
_isModified = true;
_varyStar = true;
_headers = null;
}
internal bool GetVaryByUnspecifiedParameters() {
return _varyStar;
}
/*
* Vary by accept types
*/
/// <devdoc>
/// <para>Retrieves or assigns a value indicating whether the cache should vary by Accept types. This causes the
/// Vary: header to include an Accept field.</para>
/// </devdoc>
public bool AcceptTypes {
get {
return this["Accept"];
}
set {
_isModified = true;
this["Accept"] = value;
}
}
/*
* Vary by accept language
*/
/// <devdoc>
/// <para> Retrieves or assigns a Boolean value indicating whether
/// the cache should vary by user language.</para>
/// </devdoc>
public bool UserLanguage {
get {
return this["Accept-Language"];
}
set {
_isModified = true;
this["Accept-Language"] = value;
}
}
/*
* Vary by user agent
*/
/// <devdoc>
/// <para> Retrieves or assigns a Boolean value indicating whether
/// the cache should vary by user agent.</para>
/// </devdoc>
public bool UserAgent {
get {
return this["User-Agent"];
}
set {
_isModified = true;
this["User-Agent"] = value;
}
}
/*
* Vary by charset
*/
/// <devdoc>
/// <para> Retrieves or assigns a value indicating whether the
/// cache should vary by browser character set.</para>
/// </devdoc>
public bool UserCharSet {
get {
return this["Accept-Charset"];
}
set {
_isModified = true;
this["Accept-Charset"] = value;
}
}
/*
* Vary by a given header
*/
/// <devdoc>
/// <para> Default property.
/// Indexed property indicating that a cache should (or should not) vary according
/// to a custom header.</para>
/// </devdoc>
public bool this[String header]
{
get {
if (header == null) {
throw new ArgumentNullException("header");
}
if (header.Equals("*")) {
return _varyStar;
}
else {
return (_headers != null && _headers.GetValue(header) != null);
}
}
set {
if (header == null) {
throw new ArgumentNullException("header");
}
/*
* Since adding a Vary header is more restrictive, we don't
* want components to be able to set a Vary header to false
* if another component has set it to true.
*/
if (value == false) {
return;
}
_isModified = true;
if (header.Equals("*")) {
VaryByUnspecifiedParameters();
}
else {
// set value to header if true or null if false
if (!_varyStar) {
if (_headers == null) {
_headers = new HttpDictionary();
}
_headers.SetValue(header, header);
}
}
}
}
}
}
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