ContentPlaceHolder.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 / UI / WebControls / ContentPlaceHolder.cs / 1 / ContentPlaceHolder.cs
                        

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

namespace System.Web.UI.WebControls { 
 
    using System;
    using System.Collections; 
    using System.ComponentModel;
    using System.Security.Permissions;
    using System.Web.UI;
    using System.Web.Util; 

    internal class ContentPlaceHolderBuilder : ControlBuilder { 
 
        private string _contentPlaceHolderID;
        private string _templateName; 

        internal string Name { get { return _templateName; } }

        public override void Init(TemplateParser parser, ControlBuilder parentBuilder, 
                                  Type type, string tagName, string ID, IDictionary attribs) {
 
            // Copy the ID so that it will be available when BuildObject is called 
            _contentPlaceHolderID = ID;
 
            if (parser.FInDesigner) {
                // shortcut for designer
                base.Init(parser, parentBuilder, type, tagName, ID, attribs);
                return; 
            }
 
            if (String.IsNullOrEmpty(ID)) { 
                throw new HttpException(SR.GetString(SR.Control_Missing_Attribute, "ID", type.Name));
            } 

            _templateName = ID;

            MasterPageParser masterPageParser = parser as MasterPageParser; 
            if (masterPageParser == null) {
                throw new HttpException(SR.GetString(SR.ContentPlaceHolder_only_in_master)); 
            } 

 			base.Init(parser, parentBuilder, type, tagName, ID, attribs); 

            if (masterPageParser.PlaceHolderList.Contains(Name))
                throw new HttpException(SR.GetString(SR.ContentPlaceHolder_duplicate_contentPlaceHolderID, Name));
 
            masterPageParser.PlaceHolderList.Add(Name);
        } 
 
        public override object BuildObject() {
            MasterPage masterPage = TemplateControl as MasterPage; 

            Debug.Assert(masterPage != null || InDesigner);

            // Instantiate the ContentPlaceHolder 
            ContentPlaceHolder cph = (ContentPlaceHolder) base.BuildObject();
 
            // If the page is providing content, instantiate it in the holder 
            if (PageProvidesMatchingContent(masterPage)) {
                ITemplate tpl = ((System.Web.UI.ITemplate)(masterPage.ContentTemplates[_contentPlaceHolderID])); 

                HttpContext context = HttpContext.Current;

                // Remember the old TemplateControl 
                TemplateControl oldControl = context.TemplateControl;
 
                // Storing the  template control into the context 
                // since each thread needs to set it differently.
                context.TemplateControl = masterPage._ownerControl; 

                try {
                    // Instantiate the template using the correct TemplateControl
                    tpl.InstantiateIn(cph); 
                }
                finally { 
                    // Revert back to the old templateControl 
                    context.TemplateControl = oldControl;
                } 
            }

            return cph;
        } 

        internal override void BuildChildren(object parentObj) { 
 
            MasterPage masterPage = TemplateControl as MasterPage;
 
            // If the page is providing content, don't call the base, which would
            // instantiate the default content (which we don't want)
            if (PageProvidesMatchingContent(masterPage))
                return; 

            base.BuildChildren(parentObj); 
        } 

        private bool PageProvidesMatchingContent(MasterPage masterPage) { 

            if (masterPage != null && masterPage.ContentTemplates != null
                        && masterPage.ContentTemplates.Contains(_contentPlaceHolderID)) {
                return true; 
            }
 
            return false; 
        }
    } 

    // Factory used to efficiently create builder instances
    internal class ContentPlaceHolderBuilderFactory: IWebObjectFactory {
        object IWebObjectFactory.CreateInstance() { 
            return new ContentPlaceHolderBuilder();
        } 
    } 

 
    [AspNetHostingPermission(SecurityAction.LinkDemand, Level=AspNetHostingPermissionLevel.Minimal)]
    [AspNetHostingPermission(SecurityAction.InheritanceDemand, Level=AspNetHostingPermissionLevel.Minimal)]
    [ControlBuilderAttribute(typeof(ContentPlaceHolderBuilder))]
    [Designer("System.Web.UI.Design.WebControls.ContentPlaceHolderDesigner, " + AssemblyRef.SystemDesign)] 
    [ToolboxItemFilter("System.Web.UI")]
    [ToolboxItemFilter("Microsoft.VisualStudio.Web.WebForms.MasterPageWebFormDesigner", ToolboxItemFilterType.Require)] 
    [ToolboxData("<{0}:ContentPlaceHolder runat=\"server\">")] 

    public class ContentPlaceHolder : Control, INonBindingContainer { 
    }
}

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