CPLAT-5152: Optimize builder's use of asset reads to avoid unnecessary rebuilds

build.yaml

@@ -23,6 +23,7 @@ targets:
           exclude:
             # This tests un-built behavior, and therefore should not be built
             - "test/over_react/component_declaration/builder_helpers_test.dart"
+
       over_react|overReactBuilder:
         enabled: false
 
@@ -37,13 +38,9 @@ targets:
             - "web/**"
           exclude:
             - "lib/src/builder/**"
+
       build_web_compilers|entrypoint:
         generate_for:
-          include:
-            - "example/**"
-            - "lib/*.dart"
-            - "test/*.dart"
-            - "web/*.dart"
-          exclude:
-            - "lib/src/builder/**"
-
+          - "example/**.dart"
+          - "test/*.browser_test.dart"
+          - "web/*.dart"

lib/src/builder/builder.dart

@@ -1,8 +1,144 @@
+import 'dart:async';
+
+import 'package:analyzer/analyzer.dart';
 import 'package:build/build.dart';
-import 'package:source_gen/source_gen.dart';
+import 'package:dart_style/dart_style.dart';
+import 'package:over_react/src/builder/generation/declaration_parsing.dart';
+import 'package:over_react/src/builder/generation/impl_generation.dart';
+import 'package:path/path.dart' as p;
+import 'package:source_span/source_span.dart';
 
 import './util.dart';
-import './generator.dart';
 
-Builder overReactBuilder(BuilderOptions options) =>
-    new PartBuilder([new OverReactGenerator()], outputExtension);
+Builder overReactBuilder(BuilderOptions options) => new OverReactBuilder();
+
+class OverReactBuilder extends Builder {
+  static final _headerLine = '// '.padRight(77, '*');
+
+  static final _formatter = new DartFormatter();
+
+  static final RegExp _overReactPartDirective = new RegExp(
+    r'''['"].*\.over_react\.g\.dart['"]''',
+  );
+
+  static bool _mightContainDeclarations(String source) {
+    return ParsedDeclarations.key_any_annotation.hasMatch(source) ||
+      _overReactPartDirective.hasMatch(source);
+  }
+
+  @override
+  FutureOr<void> build(BuildStep buildStep) async {
+    final source = await buildStep.readAsString(buildStep.inputId);
+    if (!_mightContainDeclarations(source)) {
+      return;
+    }
+
+    CompilationUnit libraryUnit;
+    try {
+      libraryUnit = parseCompilationUnit(
+        source,
+        name: buildStep.inputId.path,
+        suppressErrors: false,
+        parseFunctionBodies: true);
+    } catch (error, stackTrace) {
+      log.severe('There was an error parsing the compilation unit for file: ${buildStep.inputId}');
+      log.fine(error);
+      log.fine(stackTrace);
+      return;
+    }
+
+    if (isPart(libraryUnit)) {
+      return;
+    }
+
+    final librarySourceFile = new SourceFile.fromString(
+      source,
+      url: idToPackageUri(buildStep.inputId));
+    final libraryDeclarations = new ParsedDeclarations(
+      libraryUnit,
+      librarySourceFile,
+      log);
+    if (libraryDeclarations.hasErrors) {
+      log.severe('There was an error parsing the file declarations for file: ${buildStep.inputId}');
+      return;
+    }
+
+    final outputs = <String>[];
+    final libraryGenerator = new ImplGenerator(log, librarySourceFile)
+      ..generate(libraryDeclarations);
+    outputs.add(libraryGenerator.outputContentsBuffer.toString());
+
+    final parts = libraryUnit.directives
+      .whereType<PartDirective>()
+      // Ignore `.over_react.g.dart` parts - that's what we're generating.
+      .where((part) => !part.uri.stringValue.endsWith(outputExtension));
+
+    for (final part in parts) {
+      final partId = new AssetId.resolve(
+        part.uri.stringValue,
+        from: buildStep.inputId);
+      final partSource = await buildStep.readAsString(partId);
+      final partSourceFile = new SourceFile.fromString(
+        partSource,
+        url: idToPackageUri(partId));
+      CompilationUnit partUnit;
+      try {
+        partUnit = parseCompilationUnit(
+          partSource,
+          name: partId.path,
+          suppressErrors: false,
+          parseFunctionBodies: true);
+      } catch (error, stackTrace) {
+        log.severe('There was an error parsing the compilation unit for file: $partId');
+        log.fine(error);
+        log.fine(stackTrace);
+        return;
+      }
+      final partDeclarations = new ParsedDeclarations(partUnit, partSourceFile, log);
+      if (partDeclarations.hasErrors) {
+        log.severe('There was an error parsing the file declarations for file: ${buildStep.inputId}');
+        return;
+      }
+      final partGenerator = new ImplGenerator(log, partSourceFile)
+        ..generate(partDeclarations);
+      outputs.add(partGenerator.outputContentsBuffer.toString());
+    }
+
+    final nonEmptyOutputs = outputs
+      .map((s) => s.trim())
+      .where((s) => s.isNotEmpty);
+    if (nonEmptyOutputs.isEmpty) {
+      return;
+    }
+
+    await _writePart(buildStep, nonEmptyOutputs);
+  }
+
+  FutureOr<void> _writePart(BuildStep buildStep, Iterable<String> outputs) async {
+    final outputId = buildStep.inputId.changeExtension(outputExtension);
+    final partOf = "'${p.basename(buildStep.inputId.uri.toString())}'";
+
+    final buffer = new StringBuffer()
+      ..writeln('// GENERATED CODE - DO NOT MODIFY BY HAND')
+      ..writeln()
+      ..writeln('part of $partOf;')
+      ..writeln()
+      ..writeln(_headerLine)
+      ..writeln('// OverReactGenerator')
+      ..writeln(_headerLine);
+
+    for (final item in outputs) {
+      buffer
+        ..writeln()
+        ..writeln(item);
+    }
+
+    final output = _formatter.format(buffer.toString());
+    await buildStep.writeAsString(outputId, output);
+  }
+
+  @override
+  Map<String, List<String>> get buildExtensions => {
+    '.dart': [outputExtension],
+  };
+}

lib/src/builder/util.dart

@@ -1,6 +1,6 @@
 import 'dart:mirrors';
 
-import 'package:analyzer/analyzer.dart';
+import 'package:analyzer/dart/ast/ast.dart';
 import 'package:path/path.dart' as p;
 import 'package:build/build.dart' show AssetId;
 import 'package:source_span/source_span.dart';
@@ -28,6 +28,10 @@ Uri idToPackageUri(AssetId id) {
       path: p.url.join(id.package, id.path.replaceFirst('lib/', '')));
 }
 
+/// Returns true if the given compilation unit is a part file.
+bool isPart(CompilationUnit unit) =>
+    unit.directives.any((directive) => directive is PartOfDirective);
+
 /// Returns a string representing a [TypeParameterList], but type bounds removed.
 ///
 /// Example:

pubspec.yaml

@@ -14,12 +14,12 @@ dependencies:
   build: ^1.0.0
   built_redux: ^7.4.2
   built_value: ^5.4.4
+  dart_style: '>=0.1.7 <2.0.0'
   js: ^0.6.1+1
   logging: ">=0.11.3+2 <1.0.0"
   meta: ^1.1.6
   path: ^1.5.1
   react: ^4.6.0
-  source_gen: ^0.9.0
   source_span: ^1.4.1
   transformer_utils: ^0.2.0
   w_common: ^1.13.0