Change Generator to run on LibraryElement

CHANGELOG.md

@@ -1,6 +1,12 @@
 ## 0.7.0
 
 * **Breaking changes**
+  * `Generator.generate` now operates on a `LibraryElement` rather than being
+    called for every `Element` within a library. Generators can iterate over
+    elements using the `allElements` utility. `GeneratorForAnnotation` will
+    continue to call `generateForAnnotatedElement` repeatedly for each element.
+  * `GeneratorForAnnotation` passes in a `ConstantReader` for the annotation
+    instance rather than re-creating it using mirrors.
   * Removed `JsonSerializable` and related classes. These are moved to
     `package:json_serializable`.
   * Removed `lib/builder.dart`. Import through `source_gen.dart` instead.

lib/src/builder.dart

@@ -129,8 +129,6 @@ class GeneratorBuilder extends Builder {
       contentBuffer.writeln('');
       contentBuffer.writeln(_headerLine);
       contentBuffer.writeln('// Generator: ${output.generator}');
-      contentBuffer
-          .writeln('// Target: ${friendlyNameForElement(output.sourceMember)}');
       contentBuffer.writeln(_headerLine);
       contentBuffer.writeln('');
 
@@ -160,35 +158,20 @@ class GeneratorBuilder extends Builder {
   String toString() => 'GeneratorBuilder:$generators';
 }
 
-Stream<GeneratedOutput> _generate(LibraryElement unit,
+Stream<GeneratedOutput> _generate(LibraryElement library,
     List<Generator> generators, BuildStep buildStep) async* {
-  List<Element> elements;
-  try {
-    elements = allElements(unit).toList();
-  } catch (e) {
-    log.fine('Resolve error details:\n$e');
-    log.severe('Failed to resolve ${buildStep.inputId}.');
-    return;
-  }
-  for (var element in elements) {
-    yield* _processUnitMember(element, generators, buildStep);
-  }
-}
-
-Stream<GeneratedOutput> _processUnitMember(
-    Element element, List<Generator> generators, BuildStep buildStep) async* {
   for (var gen in generators) {
     try {
-      log.finer('Running $gen for $element');
-      var createdUnit = await gen.generate(element, buildStep);
+      log.finer('Running $gen for $library');
+      var createdUnit = await gen.generate(library, buildStep);
 
-      if (createdUnit != null) {
-        log.finest(() => 'Generated $createdUnit for $element');
-        yield new GeneratedOutput(element, gen, createdUnit);
+      if (createdUnit != null && createdUnit.isNotEmpty) {
+        log.finest(() => 'Generated $createdUnit for $library');
+        yield new GeneratedOutput(gen, createdUnit);
       }
     } catch (e, stack) {
-      log.severe('Error running $gen for $element.', e, stack);
-      yield new GeneratedOutput.fromError(element, gen, e, stack);
+      log.severe('Error running $gen for $library.', e, stack);
+      yield new GeneratedOutput.fromError(gen, e, stack);
     }
   }
 }

lib/src/generated_output.dart

@@ -2,29 +2,23 @@
 // 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.generated_output;
-
 import 'dart:convert';
 
-import 'package:analyzer/dart/element/element.dart';
-
 import 'generator.dart';
 
 class GeneratedOutput {
-  final Element sourceMember;
   final String output;
   final Generator generator;
   final error;
   final StackTrace stackTrace;
 
   bool get isError => error != null;
 
-  GeneratedOutput(this.sourceMember, this.generator, this.output)
+  GeneratedOutput(this.generator, this.output)
       : error = null,
         stackTrace = null;
 
-  GeneratedOutput.fromError(this.sourceMember, this.generator, Object error,
-      [this.stackTrace])
+  GeneratedOutput.fromError(this.generator, Object error, [this.stackTrace])
       : this.output = _outputFromError(error),
         this.error = error;
 }

lib/src/generator.dart

@@ -2,30 +2,24 @@
 // 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.generator;
-
 import 'dart:async';
 
 import 'package:analyzer/dart/element/element.dart';
 import 'package:build/build.dart';
 
-/// A simple API surface for emitting Dart source code from existing code.
+/// A tool to generate Dart code based on a Dart library source.
 ///
-/// Clients should _extend_ this class and _override_ [generate]:
-/// ```dart
-/// class MyGenerator extends Generator {
-///   Future<String> generate(Element element, BuildStep buildStep) async {
-///     // Return a string representing the code to emit.
-///   }
-/// }
-/// ```
+/// During a build [generate] is called once per input library.
 abstract class Generator {
   const Generator();
 
-  /// Override to return source code for a given [element].
+  /// Generates Dart code for an input Dart library.
   ///
-  /// May return `null` to signify "nothing to generate".
-  Future<String> generate(Element element, BuildStep buildStep) => null;
+  /// May create additional outputs through the `buildStep`, but the 'primary'
+  /// output is Dart code returned through the Future. If there is nothing to
+  /// generate for this library may return null, or a Future that resolves to
+  /// null or the empty string.
+  Future<String> generate(LibraryElement element, BuildStep buildStep) => null;
 
   @override
   String toString() => this.runtimeType.toString();