File: XamlTaskFactory\XamlTaskFactory.cs
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Project: ..\..\..\src\Tasks\Microsoft.Build.Tasks.csproj (Microsoft.Build.Tasks.Core)
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System;
using System.Collections.Generic;
using Microsoft.Build.Framework;
using Microsoft.Build.Shared;
using Microsoft.Build.Utilities;
 
#nullable disable
 
namespace Microsoft.Build.Tasks
{
#if FEATURE_XAMLTASKFACTORY

    using System.CodeDom;
    using System.CodeDom.Compiler;
    using System.IO;
    using System.Reflection;
    using System.Text;
    using System.Threading;
    using Microsoft.Build.Tasks.Xaml;
 
    /// <summary>
    /// The task factory provider for XAML tasks.
    /// </summary>
    public class XamlTaskFactory : ITaskFactory
    {
        /// <summary>
        /// The namespace we put the task in.
        /// </summary>
        private const string XamlTaskNamespace = "XamlTaskNamespace";
 
        /// <summary>
        /// The compiled task assembly.
        /// </summary>
        private Assembly _taskAssembly;
 
        /// <summary>
        /// The task type.
        /// </summary>
        private Type _taskType;
 
        /// <summary>
        /// The name of the task pulled from the XAML.
        /// </summary>
        public string TaskName { get; private set; }
 
        /// <summary>
        /// The namespace of the task pulled from the XAML.
        /// </summary>
        public string TaskNamespace { get; private set; }
 
        /// <summary>
        /// The contents of the UsingTask body.
        /// </summary>
        public string TaskElementContents { get; private set; }
 
        /// <summary>
        /// The name of this factory. This factory name will be used in error messages. For example
        /// Task "Mytask" failed to load from "FactoryName".
        /// </summary>
        public string FactoryName { get; } = "XamlTaskFactory";
 
        /// <summary>
        /// The task type object.
        /// </summary>
        public Type TaskType
        {
            get
            {
                if (_taskType == null)
                {
                    _taskType = _taskAssembly.GetType(String.Concat(XamlTaskNamespace, ".", TaskName), true);
                }
 
                return _taskType;
            }
        }
 
        /// <summary>
        /// MSBuild engine will call this to initialize the factory. This should initialize the factory enough so that the factory can be asked
        ///  whether or not task names can be created by the factory.
        /// </summary>
        public bool Initialize(string taskName, IDictionary<string, TaskPropertyInfo> taskParameters, string taskElementContents, IBuildEngine taskFactoryLoggingHost)
        {
            ErrorUtilities.VerifyThrowArgumentNull(taskName);
            ErrorUtilities.VerifyThrowArgumentNull(taskParameters);
 
            var log = new TaskLoggingHelper(taskFactoryLoggingHost, taskName)
            {
                TaskResources = AssemblyResources.PrimaryResources,
                HelpKeywordPrefix = "MSBuild."
            };
 
            if (taskElementContents == null)
            {
                log.LogErrorWithCodeFromResources("Xaml.MissingTaskBody");
                return false;
            }
 
            TaskElementContents = taskElementContents.Trim();
 
            // Attempt to load the task
            TaskParser parser = new TaskParser();
 
            bool parseSuccessful = parser.Parse(TaskElementContents, taskName);
 
            TaskName = parser.GeneratedTaskName;
            TaskNamespace = parser.Namespace;
            var generator = new TaskGenerator(parser);
 
            CodeCompileUnit dom = generator.GenerateCode();
 
            // MSBuildToolsDirectoryRoot is the canonical location for MSBuild dll's.
            string pathToMSBuildBinaries = BuildEnvironmentHelper.Instance.MSBuildToolsDirectoryRoot;
 
            // create the code generator options
            // Since we are running msbuild 12.0 these had better load.
            var compilerParameters = new CompilerParameters(
                [
                    "System.dll",
                    Path.Combine(pathToMSBuildBinaries, "Microsoft.Build.Framework.dll"),
                    Path.Combine(pathToMSBuildBinaries, "Microsoft.Build.Utilities.Core.dll"),
                    Path.Combine(pathToMSBuildBinaries, "Microsoft.Build.Tasks.Core.dll")
                ])
            {
                GenerateInMemory = true,
                TreatWarningsAsErrors = false
            };
 
            // create the code provider
            using var codegenerator = CodeDomProvider.CreateProvider("cs");
            CompilerResults results;
            bool debugXamlTask = Environment.GetEnvironmentVariable("MSBUILDWRITEXAMLTASK") == "1";
            if (debugXamlTask)
            {
                using (var outputWriter = new StreamWriter(taskName + "_XamlTask.cs"))
                {
                    var options = new CodeGeneratorOptions
                    {
                        BlankLinesBetweenMembers = true,
                        BracingStyle = "C"
                    };
 
                    codegenerator.GenerateCodeFromCompileUnit(dom, outputWriter, options);
                }
 
                results = codegenerator.CompileAssemblyFromFile(compilerParameters, taskName + "_XamlTask.cs");
            }
            else
            {
                results = codegenerator.CompileAssemblyFromDom(compilerParameters, dom);
            }
 
            try
            {
                _taskAssembly = results.CompiledAssembly;
            }
            catch (FileNotFoundException)
            {
                // This occurs if there is a failure to compile the assembly.  We just pass through because we will take care of the failure below.
            }
 
            if (_taskAssembly == null)
            {
                var errorList = new StringBuilder();
                errorList.AppendLine();
                foreach (CompilerError error in results.Errors)
                {
                    if (error.IsWarning)
                    {
                        continue;
                    }
 
                    if (debugXamlTask)
                    {
                        errorList.AppendFormat(Thread.CurrentThread.CurrentUICulture, "({0},{1}) {2}", error.Line, error.Column, error.ErrorText).AppendLine();
                    }
                    else
                    {
                        errorList.AppendLine(error.ErrorText);
                    }
                }
 
                log.LogErrorWithCodeFromResources("Xaml.TaskCreationFailed", errorList.ToString());
            }
 
            return !log.HasLoggedErrors;
        }
 
        /// <summary>
        /// Create an instance of the task to be used.
        /// </summary>
        /// <param name="taskFactoryLoggingHost">The task factory logging host will log messages in the context of the task.</param>
        public ITask CreateTask(IBuildEngine taskFactoryLoggingHost)
        {
            string fullTaskName = String.Concat(TaskNamespace, ".", TaskName);
            return (ITask)_taskAssembly.CreateInstance(fullTaskName);
        }
 
        /// <summary>
        /// Cleans up any context or state that may have been built up for a given task.
        /// </summary>
        /// <param name="task">The task to clean up.</param>
        /// <remarks>
        /// For many factories, this method is a no-op.  But some factories may have built up
        /// an AppDomain as part of an individual task instance, and this is their opportunity
        /// to shutdown the AppDomain.
        /// </remarks>
        public void CleanupTask(ITask task)
        {
            ErrorUtilities.VerifyThrowArgumentNull(task);
        }
 
        /// <summary>
        /// Get a list of parameters for the task.
        /// </summary>
        public TaskPropertyInfo[] GetTaskParameters()
        {
            PropertyInfo[] infos = TaskType.GetProperties(BindingFlags.Instance | BindingFlags.Public);
            var propertyInfos = new TaskPropertyInfo[infos.Length];
            for (int i = 0; i < infos.Length; i++)
            {
                propertyInfos[i] = new TaskPropertyInfo(
                    infos[i].Name,
                    infos[i].PropertyType,
                    infos[i].GetCustomAttributes(typeof(OutputAttribute), false).Length > 0,
                    infos[i].GetCustomAttributes(typeof(RequiredAttribute), false).Length > 0);
            }
 
            return propertyInfos;
        }
    }
#else
    /// <summary>
    /// The task factory provider for XAML tasks.
    /// </summary>
    /// <remarks>Xaml is not supported on .NET Core so this task factory simply logs an error that it isn't supported.
    /// If we don't compile this class, then the user will get an error that the class doesn't exist which is a bad experience.</remarks>
    [Obsolete("The XamlTaskFactory is not supported on .NET Core.  This class is included so that users receive run-time errors and should not be used for any other purpose.", error: true)]
    public sealed class XamlTaskFactory : ITaskFactory
    {
        public string FactoryName => "XamlTaskFactory";
 
        public Type TaskType { get; } = null;
 
        public bool Initialize(string taskName, IDictionary<string, TaskPropertyInfo> parameterGroup, string taskBody, IBuildEngine taskFactoryLoggingHost)
        {
            TaskLoggingHelper log = new TaskLoggingHelper(taskFactoryLoggingHost, taskName)
            {
                TaskResources = AssemblyResources.PrimaryResources,
                HelpKeywordPrefix = "MSBuild."
            };
 
            log.LogErrorWithCodeFromResources("TaskFactoryNotSupportedFailure", nameof(XamlTaskFactory));
 
            return false;
        }
 
        public TaskPropertyInfo[] GetTaskParameters()
        {
            throw new NotSupportedException();
        }
 
        public ITask CreateTask(IBuildEngine taskFactoryLoggingHost)
        {
            throw new NotSupportedException();
        }
 
        public void CleanupTask(ITask task)
        {
            throw new NotSupportedException();
        }
    }
#endif
}