Use same generator session in same build step

moor_generator/lib/src/analyzer/session.dart

@@ -3,6 +3,7 @@ import 'dart:async';
 import 'package:moor_generator/src/analyzer/runner/file_graph.dart';
 import 'package:moor_generator/src/analyzer/runner/task.dart';
 import 'package:moor_generator/src/backends/backend.dart';
+import 'package:moor_generator/src/backends/build/moor_builder.dart';
 import 'package:path/path.dart' as p;
 
 const _fileEndings = {
@@ -14,11 +15,12 @@ const _fileEndings = {
 class MoorSession {
   final FileGraph fileGraph = FileGraph();
   final Backend backend;
+  final MoorOptions options;
 
   final _completedTasks = StreamController<Task>.broadcast();
   final _changedFiles = StreamController<List<FoundFile>>.broadcast();
 
-  MoorSession(this.backend);
+  MoorSession(this.backend, {this.options = const MoorOptions()});
 
   /// Stream that emits a [Task] that has been completed.
   Stream<Task> get completedTasks => _completedTasks.stream;

moor_generator/lib/src/backends/backend.dart

@@ -1,20 +1,12 @@
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:logging/logging.dart';
-import 'package:moor_generator/src/analyzer/session.dart';
 
 /// A backend for the moor generator.
 ///
 /// Currently, we only have a backend based on the build package, but we can
 /// extend this to a backend for an analyzer plugin or a standalone tool.
 abstract class Backend {
-  MoorSession _session;
-  MoorSession get session => _session;
-
-  Backend() {
-    _session = MoorSession(this);
-  }
-
   /// Resolves an [import] statement from the context of a [base] uri. This
   /// should support both relative and `package:` imports.
   Uri resolve(Uri base, String import);

moor_generator/lib/src/backends/build/moor_builder.dart

@@ -1,5 +1,6 @@
 import 'package:build/build.dart';
 import 'package:moor_generator/src/analyzer/runner/results.dart';
+import 'package:moor_generator/src/analyzer/session.dart';
 import 'package:moor_generator/src/backends/build/build_backend.dart';
 import 'package:moor_generator/src/backends/build/generators/dao_generator.dart';
 import 'package:moor_generator/src/backends/build/generators/moor_generator.dart';
@@ -11,6 +12,9 @@ part 'options.dart';
 class MoorBuilder extends SharedPartBuilder {
   final MoorOptions options;
 
+  final BuildBackend _backend = BuildBackend();
+  final Expando<MoorSession> _sessions = Expando();
+
   MoorBuilder._(List<Generator> generators, String name, this.options)
       : super(generators, name);
 
@@ -33,10 +37,17 @@ class MoorBuilder extends SharedPartBuilder {
 
   Writer createWriter() => Writer(options);
 
+  MoorSession _getSession(BuildStep step) {
+    if (_sessions[step] != null) {
+      return _sessions[step];
+    } else {
+      return _sessions[step] = MoorSession(_backend, options: options);
+    }
+  }
+
   Future<ParsedDartFile> analyzeDartFile(BuildStep step) async {
-    final backend = BuildBackend();
+    final session = _getSession(step);
-    final backendTask = backend.createTask(step);
+    final backendTask = _backend.createTask(step);
-    final session = backend.session;
 
     final input = session.registerFile(step.inputId.uri);
     final task = session.startTask(backendTask);

moor_generator/lib/src/backends/plugin/backend/driver.dart

@@ -31,7 +31,7 @@ class MoorDriver implements AnalysisDriverGeneric {
       this.contentOverlay, this._resourceProvider) {
     _scheduler.add(this);
     final backend = PluginBackend(this);
-    session = backend.session;
+    session = MoorSession(backend);
 
     _fileChangeSubscription =
         session.changedFiles.listen(_tracker.notifyFilesChanged);

moor_generator/lib/src/model/specified_column.dart

@@ -2,6 +2,7 @@ import 'package:moor_generator/src/analyzer/sql_queries/meta/declarations.dart';
 import 'package:moor_generator/src/backends/build/moor_builder.dart';
 import 'package:moor_generator/src/model/used_type_converter.dart';
 
+/// The column types in sql.
 enum ColumnType { integer, text, boolean, datetime, blob, real }
 
 /// Name of a column. Contains additional info on whether the name was chosen

moor_generator/lib/src/writer/database_writer.dart

@@ -5,6 +5,8 @@ import 'package:moor_generator/src/writer/utils/memoized_getter.dart';
 import 'package:moor_generator/src/writer/writer.dart';
 import 'package:recase/recase.dart';
 
+/// Generates the Dart code put into a `.g.dart` file when running the
+/// generator.
 class DatabaseWriter {
   final SpecifiedDatabase db;
   final Scope scope;

moor_generator/lib/src/writer/writer.dart

@@ -17,6 +17,7 @@ class Writer {
     _root = Scope(parent: null, writer: this);
   }
 
+  /// Returns the code generated by this [Writer].
   String writeGenerated() => _leafNodes(_root).join();
 
   Iterable<StringBuffer> _leafNodes(Scope scope) sync* {

moor_generator/test/analyzer/cyclic_moor_dart_dependency.dart

@@ -30,7 +30,7 @@ CREATE TABLE bars (
 );
       ''',
     });
-    session = backend.session;
+    session = MoorSession(backend);
   });
 
   tearDownAll(() {

moor_generator/test/analyzer/integration_test.dart

@@ -66,7 +66,7 @@ class ProgrammingLanguages extends Table {
       ''',
       },
     );
-    session = backend.session;
+    session = MoorSession(backend);
   });
 
   tearDownAll(() {

moor_generator/test/analyzer/moor/cfe_test.dart

@@ -38,7 +38,7 @@ WITH alias(first, second) AS (SELECT * FROM foo) SELECT * FROM alias;
          ''',
       },
     );
-    session = backend.session;
+    session = MoorSession(backend);
   });
 
   setUp(() async {