T4ParameterValues Support

T4.Build/.gitignore

@@ -0,0 +1,2 @@
+# Ignore any immediate `tools` directories, as they are likely someone building and testing locally from another project
+/tools/*

T4.Build/BuildTemplateGenerator.cs

@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.CodeDom.Compiler;
 using System.IO;
+using System.Text;
 using Mono.TextTemplating;
 
 namespace T4.Build
@@ -11,13 +12,20 @@ class BuildTemplateGenerator : TemplateGenerator
  List<string> includedFiles = new List<string>();
  string lockPath;
  ParsedTemplate parsedTemplate;
+ readonly Func<string, string> preprocessor = null;
 
  public BuildTemplateGenerator(string template)
  {
  TemplateFile = template;
  Engine.UseInProcessCompiler();
  }
 
+ public BuildTemplateGenerator(string template, Func<string, string> preprocessor)
+ : this(template)
+ {
+ this.preprocessor = preprocessor;
+ }
+
  public string[] IncludedFiles
  {
  get
@@ -98,24 +106,64 @@ public bool ProcessTemplate(bool skipUpToDate, out bool skipped)
  {
  skipped = false;
 
- if (string.IsNullOrEmpty(OutputFile))
+ var outputFile = OutputFile;
+ if (string.IsNullOrWhiteSpace(outputFile))
+ {
  return false;
+ }
 
  if (skipUpToDate)
  {
  var templateInfo = new FileInfo(TemplateFile);
- var outputInfo = new FileInfo(OutputFile);
+ var outputInfo = new FileInfo(outputFile);
  if (outputInfo.Exists
- && templateInfo.LastWriteTime.Ticks < outputInfo.LastWriteTime.Ticks
-&& includedFiles.TrueForAll(x => (new FileInfo(x)).LastWriteTime.Ticks < outputInfo.LastWriteTime.Ticks)
+  && templateInfo.LastWriteTime.Ticks < outputInfo.LastWriteTime.Ticks
+ && includedFiles.TrueForAll(x => (new FileInfo(x)).LastWriteTime.Ticks < outputInfo.LastWriteTime.Ticks)
  )
  {
  skipped = true;
  return true;
  }
  }
- return ProcessTemplate(TemplateFile, OutputFile);
+
+ string content;
+ try
+ {
+ content = File.ReadAllText(TemplateFile);
+ }
+ catch (IOException ex)
+ {
+ Errors.Clear();
+ AddError($"Could not read input file '{TemplateFile}':\n{ex}");
+ return false;
+ }
+
+ if (!(preprocessor is null))
+ {
+ content = preprocessor(content);
+ }
+ ProcessTemplate(TemplateFile, content, ref outputFile, out var output);
+
+ try
+ {
+ if (!Errors.HasErrors)
+ {
+ File.WriteAllText(outputFile, output, new UTF8Encoding(encoderShouldEmitUTF8Identifier: false));
+ }
+ }
+ catch (IOException ex)
+ {
+ AddError($"Could not write output file '{outputFile}':\n{ex}");
+ }
+
+ return !Errors.HasErrors;
  }
 
+ CompilerError AddError(string error)
+ {
+ var err = new CompilerError { ErrorText = error };
+ Errors.Add(err);
+ return err;
+ }
  }
 }

T4.Build/Program.cs

@@ -2,6 +2,7 @@
 using System.CodeDom.Compiler;
 using System.Collections;
 using System.Collections.Concurrent;
+using System.Collections.Generic;
 using System.CommandLine;
 using System.CommandLine.Invocation;
 using System.Diagnostics;
@@ -30,7 +31,12 @@ static int Main(string[] args)
  transformCommand.Add(skipOption);
  var parallelOption = new Option<bool>(new[] { "--parallel", "-p" }, "Transform templates in parallel");
  transformCommand.Add(parallelOption);
- transformCommand.Handler = CommandHandler.Create<FileInfo[], int, bool, bool>(Transform);
+ var variableOptions = new Option<string[]>(new[] { "--variable", "-v" }, "T4ParameterValues variable to replace within the template; syntax is \"Include=Value\"")
+ {
+ AllowMultipleArgumentsPerToken = false,
+ };
+ transformCommand.Add(variableOptions);
+ transformCommand.Handler = CommandHandler.Create<FileInfo[], int, bool, bool, string[]>(Transform);
  rootCommand.Add(transformCommand);
 
  var cleanCommand = new Command("clean", "List the output files");
@@ -41,7 +47,7 @@ static int Main(string[] args)
  return rootCommand.InvokeAsync(args).Result;
  }
 
- static int Transform(FileInfo[] templates, int lockTimeout, bool skipUpToDate, bool parallel)
+ static int Transform(FileInfo[] templates, int lockTimeout, bool skipUpToDate, bool parallel, string[] variable)
  {
  using (var locker = new Lock($"Global\\T4.Build.transform.{ComputeHash(templates)}.lock", lockTimeout))
  {
@@ -50,12 +56,13 @@ static int Transform(FileInfo[] templates, int lockTimeout, bool skipUpToDate, b
  var didSomeWork = false;
  var stopwatch = new Stopwatch();
 
+ var t4ParameterValues = ProcessT4ParameterValues(variable);
  stopwatch.Start();
  Parallel.ForEach(templates,
  new ParallelOptions { MaxDegreeOfParallelism = parallel ? -1 : 1 },
  t =>
  {
- var generator = new BuildTemplateGenerator(t.ToString());
+ var generator = new BuildTemplateGenerator(t.ToString(), templateContent => PreprocessTemplate(templateContent, t4ParameterValues));
  try
  {
  bool skipped;
@@ -175,6 +182,42 @@ static void LogErrors(CompilerErrorCollection errors)
 
  Console.ForegroundColor = oldColor;
  }
+
+ static IReadOnlyDictionary<string, string> ProcessT4ParameterValues(string[] variableSets)
+ {
+ if (variableSets?.Any() != true)
+ {
+ return null;
+ }
+
+ var t4ParameterValues = new Dictionary<string, string>(variableSets.Length);
+ foreach (var variableSet in variableSets)
+ {
+ var pair = variableSet.Split('=', 2, StringSplitOptions.None);
+ t4ParameterValues.Add($"$({pair[0]})", pair[1]);
+ }
+
+ return t4ParameterValues;
+ }
+
+ static string PreprocessTemplate(string templateContent, IReadOnlyDictionary<string, string> t4ParameterValues)
+ {
+ if (string.IsNullOrWhiteSpace(templateContent) || t4ParameterValues?.Keys.Any() != true)
+ {
+ return templateContent;
+ }
+
+ var replacementBuilder = (StringBuilder)null;
+ foreach (var t4ParameterValuesPair in t4ParameterValues)
+ {
+ if (replacementBuilder is null && templateContent.IndexOf(t4ParameterValuesPair.Key) > -1)
+ {
+ replacementBuilder = new StringBuilder(templateContent);
+ }
+ replacementBuilder?.Replace(t4ParameterValuesPair.Key, t4ParameterValuesPair.Value);
+ }
+
+ return replacementBuilder is null ? templateContent : replacementBuilder.ToString();
+ }
  }
 }
-

T4.Build/build/common.targets

@@ -22,7 +22,7 @@
 
  <Target Name="TextTemplateCreateTransformList">
  <ItemGroup>
- <T4Build_TransformFiles Include="@(None)" Condition=" '%(None.Generator)' == 'TextTemplatingFileGenerator' " />
+ <T4Build_TransformFiles Include="@(Compile);@(None);@(Content);@(EmbeddedResource)" Condition=" '%(*.Generator)' == 'TextTemplatingFileGenerator' " />
  <T4Build_TransformFiles Include="@(TextTemplateTransformFiles)" />
  </ItemGroup>
  <ItemGroup Condition=" '$(TextTemplateTransformAll)' == 'true' ">
@@ -31,10 +31,24 @@
  </ItemGroup>
  </Target>
 
- <Target Name="TextTemplateTransform" DependsOnTargets="TextTemplateCreateTransformList">
+ <Target Name="TextTemplateCreateParameterValueList" Inputs="@(T4ParameterValues)" Outputs="%(T4ParameterValues.Identity)">
+ <PropertyGroup>
+ <T4Build_ParameterIdentity>%(T4ParameterValues.Identity)</T4Build_ParameterIdentity>
+ <T4Build_ParameterValue>%(T4ParameterValues.Value)</T4Build_ParameterValue>
+ </PropertyGroup>
+ <PropertyGroup>
+ <T4Build_ParameterValue>$(T4Build_ParameterValue.Replace('"', '""'))</T4Build_ParameterValue>
+ </PropertyGroup>
+ <ItemGroup>
+ <T4Build_ParameterValueList Include="--variable &quot;$(T4Build_ParameterIdentity)=$(T4Build_ParameterValue)&quot;" Condition="!$([System.String]::IsNullOrWhiteSpace('$(T4Build_ParameterIdentity)'))" />
+ </ItemGroup>
+ </Target>
+
+ <Target Name="TextTemplateTransform" DependsOnTargets="TextTemplateCreateTransformList;TextTemplateCreateParameterValueList">
  <ItemGroup>
  <T4Build_TransformOptions Include="--skip-up-to-date" Condition=" '$(TextTemplateTransformSkipUpToDate)' == 'true' " />
  <T4Build_TransformOptions Include="--parallel" Condition=" '$(TextTemplateTransformParallel)' == 'true' " />
+ <T4Build_TransformOptions Include="@(T4Build_ParameterValueList, ' ')" />
  </ItemGroup>
  <Exec Command="$(T4Build_Command) transform @(T4Build_TransformOptions, ' ') @(T4Build_TransformFiles, ' ')" Condition=" '@(T4Build_TransformFiles)' != '' " ConsoleToMSBuild="true" StandardOutputImportance="normal">
  <Output TaskParameter="ConsoleOutput" ItemName="T4Build_GeneratedFiles" />