Add APIs to expose analyzer elements2 models. (dart-lang#735)

* publish_to: none

* Directives are not elements anymore, don't have annotations.

Author: scheglov

analysis_options.yaml

@@ -8,6 +8,7 @@ analyzer:
 
 linter:
   rules:
+    - analyzer_use_new_elements
     - avoid_bool_literals_in_conditional_expressions
     - avoid_classes_with_only_static_members
     - avoid_private_typedef_functions

example/lib/src/member_count_library_generator.dart

@@ -13,7 +13,7 @@ class MemberCountLibraryGenerator extends Generator {
     final topLevelVarCount = topLevelNumVariables(library).length;
 
     return '''
-// Source library: ${library.element.source.uri}
+// Source library: ${library.element2.uri}
 const topLevelNumVarCount = $topLevelVarCount;
 ''';
   }

example/lib/src/multiplier_generator.dart

@@ -2,21 +2,21 @@
 // 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 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/element2.dart';
 import 'package:build/build.dart';
 import 'package:source_gen/source_gen.dart';
 
 import '../annotations.dart';
 
 class MultiplierGenerator extends GeneratorForAnnotation<Multiplier> {
   @override
-  String generateForAnnotatedElement(
-    Element element,
+  String generateForAnnotatedElement2(
+    Element2 element,
     ConstantReader annotation,
     BuildStep buildStep,
   ) {
     final numValue = annotation.read('value').literalValue as num;
 
-    return 'num ${element.name}Multiplied() => ${element.name} * $numValue;';
+    return 'num ${element.name3}Multiplied() => ${element.name3} * $numValue;';
   }
 }

example/lib/src/property_product_generator.dart

@@ -11,7 +11,8 @@ class PropertyProductGenerator extends Generator {
   @override
   String generate(LibraryReader library, BuildStep buildStep) {
     final productNames = topLevelNumVariables(library)
-        .map((element) => element.name)
+        .map((element) => element.name3)
+        .nonNulls
         .join(' * ');
 
     return '''

example/lib/src/property_sum_generator.dart

@@ -11,7 +11,8 @@ class PropertySumGenerator extends Generator {
   @override
   String generate(LibraryReader library, BuildStep buildStep) {
     final sumNames = topLevelNumVariables(library)
-        .map((element) => element.name)
+        .map((element) => element.name3)
+        .nonNulls
         .join(' + ');
 
     return '''

example/lib/src/utils.dart

@@ -2,13 +2,13 @@
 // 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 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/element2.dart';
 import 'package:source_gen/source_gen.dart';
 
-/// Returns all [TopLevelVariableElement] members in [reader]'s library that
+/// Returns all [TopLevelVariableElement2] members in [reader]'s library that
 /// have a type of [num].
-Iterable<TopLevelVariableElement> topLevelNumVariables(LibraryReader reader) =>
-    reader.allElements.whereType<TopLevelVariableElement>().where(
+Iterable<TopLevelVariableElement2> topLevelNumVariables(LibraryReader reader) =>
+    reader.allElements2.whereType<TopLevelVariableElement2>().where(
           (element) =>
               element.type.isDartCoreNum ||
               element.type.isDartCoreInt ||

source_gen/lib/source_gen.dart

@@ -10,6 +10,6 @@ export 'src/generator.dart'
     show Generator, InvalidGenerationSource, InvalidGenerationSourceError;
 export 'src/generator_for_annotation.dart' show GeneratorForAnnotation;
 export 'src/library.dart' show AnnotatedElement, LibraryReader;
-export 'src/span_for_element.dart' show spanForElement;
+export 'src/span_for_element.dart' show spanForElement, spanForElement2;
 export 'src/type_checker.dart' show TypeChecker, UnresolvedAnnotationException;
 export 'src/utils.dart' show typeNameOf;

source_gen/lib/src/builder.dart

@@ -6,6 +6,9 @@ import 'dart:convert';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/element2.dart';
+// ignore: implementation_imports
+import 'package:analyzer/src/utilities/extensions/element.dart';
 import 'package:build/build.dart';
 import 'package:dart_style/dart_style.dart';
 import 'package:pub_semver/pub_semver.dart';
@@ -103,16 +106,17 @@ class _Builder extends Builder {
     }
 
     final lib = await buildStep.resolver
-        .libraryFor(buildStep.inputId, allowSyntaxErrors: allowSyntaxErrors);
+        .libraryFor2(buildStep.inputId, allowSyntaxErrors: allowSyntaxErrors);
     await _generateForLibrary(lib, buildStep);
   }
 
   Future<void> _generateForLibrary(
-    LibraryElement library,
+    LibraryElement2 library2,
     BuildStep buildStep,
   ) async {
+    final library = library2.asElement;
     final generatedOutputs =
-        await _generate(library, _generators, buildStep).toList();
+        await _generate(library2, _generators, buildStep).toList();
 
     // Don't output useless files.
     //
@@ -353,11 +357,11 @@ class LibraryBuilder extends _Builder {
 }
 
 Stream<GeneratedOutput> _generate(
-  LibraryElement library,
+  LibraryElement2 library2,
   List<Generator> generators,
   BuildStep buildStep,
 ) async* {
-  final libraryReader = LibraryReader(library);
+  final libraryReader = LibraryReader.v2(library2);
   for (var i = 0; i < generators.length; i++) {
     final gen = generators[i];
     var msg = 'Running $gen';

source_gen/lib/src/generator.dart

@@ -6,6 +6,9 @@ import 'dart:async';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/element2.dart';
+// ignore: implementation_imports
+import 'package:analyzer/src/utilities/extensions/element.dart';
 import 'package:build/build.dart';
 
 import 'library.dart';
@@ -49,7 +52,7 @@ class InvalidGenerationSource implements Exception {
   ///
   /// May be `null` if the error had no associated element, or if the location
   /// was passed with [node].
-  final Element? element;
+  final Element2? element2;
 
   /// The AST Node associated with this error.
   ///
@@ -60,9 +63,18 @@ class InvalidGenerationSource implements Exception {
   InvalidGenerationSource(
     this.message, {
     this.todo = '',
-    this.element,
+    Element? element,
     this.node,
-  });
+  }) : element2 = element?.asElement2;
+
+  InvalidGenerationSource.v2(
+    this.message, {
+    this.todo = '',
+    Element2? element,
+    this.node,
+  }) : element2 = element;
+
+  Element? get element => element2?.asElement;
 
   @override
   String toString() {

source_gen/lib/src/generator_for_annotation.dart

@@ -5,6 +5,7 @@
 import 'dart:async';
 
 import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/element2.dart';
 import 'package:build/build.dart';
 
 import 'constants/reader.dart';
@@ -58,11 +59,16 @@ abstract class GeneratorForAnnotation<T> extends Generator {
       typeChecker,
       throwOnUnresolved: throwOnUnresolved,
     )) {
-      final generatedValue = generateForAnnotatedElement(
+      var generatedValue = generateForAnnotatedElement(
         annotatedElement.element,
         annotatedElement.annotation,
         buildStep,
       );
+      generatedValue ??= generateForAnnotatedElement2(
+        annotatedElement.element2,
+        annotatedElement.annotation,
+        buildStep,
+      );
       await for (var value in normalizeGeneratorOutput(generatedValue)) {
         assert(value.length == value.trim().length);
         values.add(value);
@@ -93,5 +99,28 @@ abstract class GeneratorForAnnotation<T> extends Generator {
     Element element,
     ConstantReader annotation,
     BuildStep buildStep,
-  );
+  ) {}
+
+  /// Implement to return source code to generate for [element].
+  ///
+  /// This method is invoked based on finding elements annotated with an
+  /// instance of [T]. The [annotation] is provided as a [ConstantReader].
+  ///
+  /// Supported return values include a single [String] or multiple [String]
+  /// instances within an [Iterable] or [Stream]. It is also valid to return a
+  /// [Future] of [String], [Iterable], or [Stream]. When multiple values are
+  /// returned through an iterable or stream they will be deduplicated.
+  /// Typically each value will be an independent unit of code and the
+  /// deduplication prevents re-defining the same member multiple times. For
+  /// example if multiple annotated elements may need a specific utility method
+  /// available it can be output for each one, and the single deduplicated
+  /// definition can be shared.
+  ///
+  /// Implementations should return `null` when no content is generated. Empty
+  /// or whitespace-only [String] instances are also ignored.
+  dynamic generateForAnnotatedElement2(
+    Element2 element,
+    ConstantReader annotation,
+    BuildStep buildStep,
+  ) {}
 }