Migrate to the build package instead of custom build scripts

Author: jakemac53

.gitignore

@@ -1,5 +1,5 @@
-.buildlog
-pubspec.lock
-packages
-.pub
+.dart_tool
 .packages
+.pub
+packages
+pubspec.lock

CHANGELOG.md

@@ -1,3 +1,23 @@
+## 0.5.0
+
+* **Breaking**: Switch to the `build` package for running `Generator`s. This
+  means that the top level `build` and `generate` functions are no longer
+  available, and have been replaced by the top level `build`, `watch`, and
+  `serve` functions from the `build` package, and the `GeneratorBuilder` class.
+  See `tool/build.dart`, `tool/watch.dart`, and `tool/phases.dart` for usage.
+
+  * Note that the `build` package is experimental, and likely to change.
+
+* **Breaking**: The build package provides an abstraction for reading/writing
+  files via the `BuildStep` class, and that is now also provided to
+  `Generator#generate` and `GeneratorForAnnotation#generateForAnnotatedElement`
+  as a second argument.
+
+* There is no longer a need to specify the files related to an individual
+  generator via `AssociatedFileSet`. Simply use the `BuildStep` instance to read
+  and write files and the `build` package will track any files you read in and
+  run incremental rebuilds as necessary.
+
 ## 0.4.8
 
 * Added support for `Symbol` and `Type` in annotations.
@@ -18,7 +38,7 @@
 
 ## 0.4.6
 
-* `JsonSerializable`: Added `JsonKey` annotation. 
+* `JsonSerializable`: Added `JsonKey` annotation.
 
 * Improved output of generation errors and stack traces.
 

build.dart

@@ -1,20 +1,10 @@
 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
-
 library source_gen.build_file;
 
-import 'package:source_gen/generators/json_literal_generator.dart' as literal;
-import 'package:source_gen/generators/json_serializable_generator.dart' as json;
-import 'package:source_gen/source_gen.dart';
+import 'tool/build.dart' as build;
 
-main(List<String> args) async {
-  var msg = await build(args, const [
-    const json.JsonSerializableGenerator(),
-    const literal.JsonLiteralGenerator()
-  ], librarySearchPaths: [
-    'example',
-    'test/test_files/json_test_example.dart'
-  ]);
-  print(msg);
+main() async {
+  build.main();
 }

example/example.g.dart

@@ -0,0 +1,5 @@
+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+export 'src/builder.dart';

lib/builder.dart

@@ -6,45 +6,28 @@ library source_gen.example.json_literal_generator;
 
 import 'dart:async';
 import 'dart:convert';
-import 'dart:io';
 
 import 'package:analyzer/src/generated/element.dart';
-import 'package:analyzer/src/generated/source_io.dart';
+import 'package:build/build.dart';
 import 'package:path/path.dart' as p;
 import 'package:source_gen/source_gen.dart';
 
 import 'json_literal.dart';
 
 class JsonLiteralGenerator extends GeneratorForAnnotation<JsonLiteral> {
-  @override
-  final AssociatedFileSet associatedFileSet;
-
-  /// If [associatedFileSet] is not set, the default value of
-  /// [AssociatedFileSet.sameDirectory] is used.
-  const JsonLiteralGenerator(
-      {AssociatedFileSet associatedFileSet: AssociatedFileSet.sameDirectory})
-      : this.associatedFileSet = associatedFileSet;
+  const JsonLiteralGenerator();
 
   @override
   Future<String> generateForAnnotatedElement(
-      Element element, JsonLiteral annotation) async {
+      Element element, JsonLiteral annotation, BuildStep buildStep) async {
     if (p.isAbsolute(annotation.path)) {
       throw 'must be relative path to the source file';
     }
 
-    var source = element.source as FileBasedSource;
-    var sourcePath = source.file.getAbsolutePath();
-
-    var sourcePathDir = p.dirname(sourcePath);
-
-    var filePath = p.join(sourcePathDir, annotation.path);
-
-    if (!await FileSystemEntity.isFile(filePath)) {
-      throw 'Not a file! - $filePath';
-    }
-
-    var file = new File(filePath);
-    var content = await JSON.decode(await file.readAsString());
+    var sourcePathDir = p.dirname(buildStep.input.id.path);
+    var fileId = new AssetId(
+        buildStep.input.id.package, p.join(sourcePathDir, annotation.path));
+    var content = JSON.decode(await buildStep.readAsString(fileId));
 
     var thing = JSON.encode(content);
 

lib/generators/json_literal_generator.dart

@@ -21,7 +21,7 @@ class JsonSerializableGenerator
 
   @override
   Future<String> generateForAnnotatedElement(
-      Element element, JsonSerializable annotation) async {
+      Element element, JsonSerializable annotation, _) async {
     if (element is! ClassElement) {
       var friendlyName = friendlyNameForElement(element);
       throw new InvalidGenerationSourceError(

lib/generators/json_serializable_generator.dart

@@ -1,7 +1,6 @@
 library source_gen;
 
-export 'src/build.dart';
-export 'src/generate.dart';
+export 'src/builder.dart';
 export 'src/results.dart';
 export 'src/generator.dart';
 export 'src/generator_for_annotation.dart';

lib/source_gen.dart

@@ -0,0 +1,128 @@
+// Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+import 'dart:async';
+
+import 'package:analyzer/src/generated/element.dart';
+import 'package:build/build.dart';
+import 'package:dart_style/src/dart_formatter.dart';
+
+import 'generated_output.dart';
+import 'generator.dart';
+import 'utils.dart';
+
+class GeneratorBuilder extends Builder {
+  final List<Generator> generators;
+  final bool omitGenerateTimestamp;
+  final String generatedExtension;
+
+  GeneratorBuilder(this.generators,
+      {this.omitGenerateTimestamp: false, this.generatedExtension: '.g.dart'}) {
+    // TODO: validate that generatedExtension starts with a `.'
+    //       not null, empty, etc
+  }
+
+  @override
+  Future build(BuildStep buildStep) async {
+    var id = buildStep.input.id;
+    var resolver = await buildStep.resolve(id, resolveAllConstants: false);
+    var lib = resolver.getLibrary(id);
+    await _generateForLibrary(lib, !omitGenerateTimestamp, buildStep);
+    resolver.release();
+  }
+
+  @override
+  List<AssetId> declareOutputs(AssetId input) {
+    if (input.extension != '.dart') return const [];
+    return [_generatedFile(input)];
+  }
+
+  AssetId _generatedFile(AssetId input) =>
+      input.changeExtension(generatedExtension);
+
+  Future _generateForLibrary(LibraryElement library, bool includeTimestamp,
+      BuildStep buildStep) async {
+    buildStep.logger.fine('Running $generators for ${buildStep.input.id}');
+    var generatedOutputs =
+        await _generate(library, generators, buildStep).toList();
+
+    // Don't outputs useless files.
+    if (generatedOutputs.isEmpty) return;
+
+    var contentBuffer = new StringBuffer();
+
+    contentBuffer.writeln('part of ${library.name};');
+    contentBuffer.writeln();
+
+    for (GeneratedOutput output in generatedOutputs) {
+      contentBuffer.writeln('');
+      contentBuffer.writeln(_headerLine);
+      contentBuffer.writeln('// Generator: ${output.generator}');
+      contentBuffer
+          .writeln('// Target: ${friendlyNameForElement(output.sourceMember)}');
+      contentBuffer.writeln(_headerLine);
+      contentBuffer.writeln('');
+
+      contentBuffer.writeln(output.output);
+    }
+
+    var genPartContent = contentBuffer.toString();
+
+    var formatter = new DartFormatter();
+    try {
+      genPartContent = formatter.format(genPartContent);
+    } catch (e, stack) {
+      buildStep.logger.severe(
+          """Error formatting the generated source code.
+This may indicate an issue in the generated code or in the formatter.
+Please check the generated code and file an issue on source_gen
+if approppriate.""",
+          e,
+          stack);
+    }
+
+    var outputId = _generatedFile(buildStep.input.id);
+    var output =
+        new Asset(outputId, '${_getHeader(includeTimestamp)}$genPartContent');
+    buildStep.writeAsString(output);
+  }
+
+  String _getHeader(bool includeTimestamp) {
+    var buffer = new StringBuffer('// GENERATED CODE - DO NOT MODIFY BY HAND');
+    buffer.writeln();
+
+    if (includeTimestamp) {
+      buffer.writeln("// ${new DateTime.now().toUtc().toIso8601String()}");
+    }
+
+    buffer.writeln();
+    return buffer.toString();
+  }
+}
+
+Stream<GeneratedOutput> _generate(LibraryElement unit,
+    List<Generator> generators, BuildStep buildStep) async* {
+  for (var element in getElementsFromLibraryElement(unit)) {
+    yield* _processUnitMember(element, generators, buildStep);
+  }
+}
+
+Stream<GeneratedOutput> _processUnitMember(
+    Element element, List<Generator> generators, BuildStep buildStep) async* {
+  for (var gen in generators) {
+    try {
+      buildStep.logger.finer('Running $gen for $element');
+      var createdUnit = await gen.generate(element, buildStep);
+
+      if (createdUnit != null) {
+        buildStep.logger.finest(() => 'Generated $createdUnit for $element');
+        yield new GeneratedOutput(element, gen, createdUnit);
+      }
+    } catch (e, stack) {
+      buildStep.logger.severe('Error running $gen for $element.', e, stack);
+      yield new GeneratedOutput.fromError(element, gen, e, stack);
+    }
+  }
+}
+
+final _headerLine = '// '.padRight(77, '*');