Generate with LibraryReader over LibraryElement (#239)

Similar to ConstantReader this will make it easier to use new utility
methods as we add them.

- Make `_element` public so that clients can still access the
  `LibraryElement` when needed.
- Change the `generate` method signature and all implementations.
- Wrap the argument in `builder.dart`.

Author: natebosch

CHANGELOG.md

@@ -1,9 +1,9 @@
 ## 0.7.0
 
 * **Breaking changes**
-  * `Generator.generate` now operates on a `LibraryElement` rather than being
+  * `Generator.generate` now operates on a `LibraryReader` rather than being
     called for every `Element` within a library. Generators can iterate over
-    elements using the `allElements` utility. `GeneratorForAnnotation` will
+    elements using `LibraryReader.allElements`. `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.
@@ -15,6 +15,7 @@
   * Removed `OutputFormatter` typedef.
 * Add `LibraryReader.allElements` - a utility to iterate across all `Element`
   instances contained in Dart library.
+* Add `LibraryReader.element` to get back to the `LibraryElement` instance.
 
 ## 0.6.1+1
 

lib/src/builder.dart

@@ -10,6 +10,7 @@ import 'package:dart_style/dart_style.dart';
 
 import 'generated_output.dart';
 import 'generator.dart';
+import 'library.dart';
 import 'utils.dart';
 
 typedef String _OutputFormatter(String code);
@@ -195,10 +196,11 @@ class LibraryBuilder extends _Builder {
 
 Stream<GeneratedOutput> _generate(LibraryElement library,
     List<Generator> generators, BuildStep buildStep) async* {
+  var libraryReader = new LibraryReader(library);
   for (var gen in generators) {
     try {
       log.finer('Running $gen for $library');
-      var createdUnit = await gen.generate(library, buildStep);
+      var createdUnit = await gen.generate(libraryReader, buildStep);
 
       if (createdUnit != null && createdUnit.isNotEmpty) {
         log.finest(() => 'Generated $createdUnit for $library');

lib/src/generator.dart

@@ -4,9 +4,10 @@
 
 import 'dart:async';
 
-import 'package:analyzer/dart/element/element.dart';
 import 'package:build/build.dart';
 
+import 'library.dart';
+
 /// A tool to generate Dart code based on a Dart library source.
 ///
 /// During a build [generate] is called once per input library.
@@ -19,7 +20,7 @@ abstract class Generator {
   /// 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;
+  Future<String> generate(LibraryReader library, BuildStep buildStep) => null;
 
   @override
   String toString() => this.runtimeType.toString();

lib/src/generator_for_annotation.dart

@@ -35,9 +35,8 @@ abstract class GeneratorForAnnotation<T> extends Generator {
   TypeChecker get typeChecker => new TypeChecker.fromRuntime(T);
 
   @override
-  Future<String> generate(LibraryElement library, BuildStep buildStep) async {
-    var elements = new LibraryReader(library)
-        .allElements
+  Future<String> generate(LibraryReader library, BuildStep buildStep) async {
+    var elements = library.allElements
         .map((e) => new _AnnotatedElement(e, typeChecker.firstAnnotationOf(e)))
         .where((e) => e.annotation != null);
     var allOutput = await Future.wait(elements.map((e) =>

lib/src/library.dart

@@ -10,27 +10,27 @@ import 'package:analyzer/src/dart/resolver/scope.dart';
 
 /// A high-level wrapper API with common functionality for [LibraryElement].
 class LibraryReader {
-  final LibraryElement _element;
+  final LibraryElement element;
 
   Namespace _namespaceCache;
 
-  LibraryReader(this._element);
+  LibraryReader(this.element);
 
   Namespace get _namespace => _namespaceCache ??=
-      new NamespaceBuilder().createExportNamespaceForLibrary(_element);
+      new NamespaceBuilder().createExportNamespaceForLibrary(element);
 
   /// Returns a top-level [ClassElement] publicly visible in by [name].
   ///
   /// Unlike [LibraryElement.getType], this also correctly traverses identifiers
   /// that are accessible via one or more `export` directives.
   ClassElement findType(String name) =>
-      _element.getType(name) ?? _namespace.get(name) as ClassElement;
+      element.getType(name) ?? _namespace.get(name) as ClassElement;
 
-  /// Returns all of the declarations in this library, including the
-  /// [LibraryElement] as the first item.
+  /// All of the declarations in this library, including the [LibraryElement] as
+  /// the first item.
   Iterable<Element> get allElements sync* {
-    yield _element;
-    for (var cu in _element.units) {
+    yield element;
+    for (var cu in element.units) {
       for (var compUnitMember in cu.unit.declarations) {
         yield* _getElements(compUnitMember);
       }

test/builder_test.dart

@@ -5,7 +5,6 @@
 @TestOn('vm')
 import 'dart:async';
 
-import 'package:analyzer/dart/element/element.dart';
 import 'package:build_test/build_test.dart';
 import 'package:source_gen/source_gen.dart';
 import 'package:test/test.dart';
@@ -175,12 +174,12 @@ Map<String, String> _createPackageStub(String pkgName,
 /// Doesn't generate output for any element
 class _NoOpGenerator extends Generator {
   const _NoOpGenerator();
-  Future<String> generate(LibraryElement element, _) => null;
+  Future<String> generate(LibraryReader library, _) => null;
 }
 
 class _BadOutputGenerator extends Generator {
   const _BadOutputGenerator();
-  Future<String> generate(LibraryElement element, _) async => 'not valid code!';
+  Future<String> generate(LibraryReader library, _) async => 'not valid code!';
 }
 
 const pkgName = 'pkg';

test/src/comment_generator.dart

@@ -14,15 +14,14 @@ class CommentGenerator extends Generator {
   const CommentGenerator({this.forClasses: true, this.forLibrary: false});
 
   @override
-  Future<String> generate(LibraryElement library, _) async {
+  Future<String> generate(LibraryReader library, _) async {
     var output = new StringBuffer();
     if (forLibrary) {
-      output.writeln('// Code for "$library"');
+      output.writeln('// Code for "${library.element}"');
     }
     if (forClasses) {
-      for (var classElement in new LibraryReader(library)
-          .allElements
-          .where((e) => e is ClassElement)) {
+      for (var classElement
+          in library.allElements.where((e) => e is ClassElement)) {
         if (classElement.displayName.contains('GoodError')) {
           throw new InvalidGenerationSourceError(
               "Don't use classes with the word 'Error' in the name",

test/src/unformatted_code_generator.dart

@@ -4,15 +4,14 @@
 
 import 'dart:async';
 
-import 'package:analyzer/dart/element/element.dart';
 import 'package:source_gen/source_gen.dart';
 
 /// Generates a single-line of unformatted code.
 class UnformattedCodeGenerator extends Generator {
   const UnformattedCodeGenerator();
 
   @override
-  Future<String> generate(LibraryElement element, _) async => unformattedCode;
+  Future<String> generate(LibraryReader library, _) async => unformattedCode;
 
   static const formattedCode = '''
 void hello() => print('hello');