Initial API to build analysis contexts (replaces ContextLocator.locateContexts)

Change-Id: If00ce6321efb6ff4da96e654cfe2a0a8501bed95
Reviewed-on: https://dart-review.googlesource.com/50323
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>

pkg/analyzer/lib/dart/analysis/context_builder.dart

@@ -0,0 +1,42 @@
+// Copyright (c) 2018, the Dart project authors. Please see the AUTHORS file
+// 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/context/declared_variables.dart';
+import 'package:analyzer/dart/analysis/analysis_context.dart';
+import 'package:analyzer/dart/analysis/context_root.dart';
+import 'package:analyzer/file_system/file_system.dart';
+import 'package:analyzer/src/dart/analysis/context_builder.dart';
+import 'package:meta/meta.dart';
+
+/**
+ * A utility class used to build an analysis context based on a context root.
+ *
+ * Clients may not extend, implement or mix-in this class.
+ */
+abstract class ContextBuilder {
+  /**
+   * Initialize a newly created context builder. If a [resourceProvider] is
+   * given, then it will be used to access the file system, otherwise the
+   * default resource provider will be used.
+   */
+  factory ContextBuilder({ResourceProvider resourceProvider}) =
+      ContextBuilderImpl;
+
+  /**
+   * Return an analysis context corresponding to the given [contextRoot].
+   *
+   * If a set of [declaredVariables] is provided, the values will be used to map
+   * the the variable names found in `fromEnvironment` invocations to the
+   * constant value that will be returned. If none is given, then no variables
+   * will be defined.
+   *
+   * If an [sdkPath] is provided, and if it is a valid path to a directory
+   * containing a valid SDK, then the SDK in the referenced directory will be
+   * used when analyzing the code in the context.
+   */
+  AnalysisContext createContext(
+      {@required ContextRoot contextRoot,
+      DeclaredVariables declaredVariables,
+      String sdkPath});
+}

pkg/analyzer/lib/src/dart/analysis/context_builder.dart

@@ -0,0 +1,101 @@
+// Copyright (c) 2018, the Dart project authors. Please see the AUTHORS file
+// 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/context/context_root.dart' as old;
+import 'package:analyzer/context/declared_variables.dart';
+import 'package:analyzer/dart/analysis/analysis_context.dart';
+import 'package:analyzer/dart/analysis/context_builder.dart';
+import 'package:analyzer/dart/analysis/context_root.dart';
+import 'package:analyzer/file_system/file_system.dart';
+import 'package:analyzer/file_system/physical_file_system.dart';
+import 'package:analyzer/src/context/builder.dart' as old
+    show ContextBuilder, ContextBuilderOptions;
+import 'package:analyzer/src/dart/analysis/driver.dart'
+    show AnalysisDriver, AnalysisDriverScheduler;
+import 'package:analyzer/src/dart/analysis/driver_based_analysis_context.dart';
+import 'package:analyzer/src/dart/analysis/file_state.dart'
+    show FileContentOverlay;
+import 'package:analyzer/src/dart/sdk/sdk.dart';
+import 'package:analyzer/src/generated/sdk.dart' show DartSdkManager;
+import 'package:analyzer/src/generated/source.dart' show ContentCache;
+import 'package:front_end/src/base/performance_logger.dart' show PerformanceLog;
+import 'package:front_end/src/byte_store/byte_store.dart' show MemoryByteStore;
+import 'package:meta/meta.dart';
+
+/**
+ * An implementation of a context builder.
+ */
+class ContextBuilderImpl implements ContextBuilder {
+  /**
+   * The resource provider used to access the file system.
+   */
+  final ResourceProvider resourceProvider;
+
+  /**
+   * Initialize a newly created context builder. If a [resourceProvider] is
+   * given, then it will be used to access the file system, otherwise the
+   * default resource provider will be used.
+   */
+  ContextBuilderImpl({ResourceProvider resourceProvider})
+      : resourceProvider =
+            resourceProvider ?? PhysicalResourceProvider.INSTANCE;
+
+  /**
+   * Return the path to the default location of the SDK, or `null` if the sdk
+   * cannot be found.
+   */
+  String get _defaultSdkPath =>
+      FolderBasedDartSdk.defaultSdkDirectory(resourceProvider)?.path;
+
+  @override
+  AnalysisContext createContext(
+      {@required ContextRoot contextRoot,
+      DeclaredVariables declaredVariables,
+      String sdkPath}) {
+    PerformanceLog performanceLog = new PerformanceLog(new StringBuffer());
+    AnalysisDriverScheduler scheduler =
+        new AnalysisDriverScheduler(performanceLog);
+    sdkPath ??= _defaultSdkPath;
+    if (sdkPath == null) {
+      throw new ArgumentError('Cannot find path to the SDK');
+    }
+    DartSdkManager sdkManager = new DartSdkManager(sdkPath, true);
+    scheduler.start();
+
+    // TODO(brianwilkerson) Move the required implementation from the old
+    // ContextBuilder to this class and remove the old class.
+    old.ContextBuilderOptions options = new old.ContextBuilderOptions();
+    if (declaredVariables != null) {
+      options.declaredVariables = _toMap(declaredVariables);
+    }
+    options.defaultPackageFilePath = contextRoot.packagesFile?.path;
+
+    old.ContextBuilder builder = new old.ContextBuilder(
+        resourceProvider, sdkManager, new ContentCache(),
+        options: options);
+    builder.analysisDriverScheduler = scheduler;
+    builder.byteStore = new MemoryByteStore();
+    builder.fileContentOverlay = new FileContentOverlay();
+    builder.performanceLog = performanceLog;
+
+    old.ContextRoot oldContextRoot = new old.ContextRoot(
+        contextRoot.root.path, contextRoot.excludedPaths.toList());
+    AnalysisDriver driver = builder.buildDriver(oldContextRoot);
+    DriverBasedAnalysisContext context =
+        new DriverBasedAnalysisContext(resourceProvider, contextRoot, driver);
+    return context;
+  }
+
+  /**
+   * Convert the [declaredVariables] into a map for use with the old context
+   * builder.
+   */
+  Map<String, String> _toMap(DeclaredVariables declaredVariables) {
+    Map<String, String> map = <String, String>{};
+    for (String name in declaredVariables.variableNames) {
+      map[name] = declaredVariables.get(name);
+    }
+    return map;
+  }
+}

pkg/analyzer/test/src/dart/analysis/context_builder_test.dart

@@ -0,0 +1,91 @@
+// Copyright (c) 2018, the Dart project authors. Please see the AUTHORS file
+// 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 'dart:io' as io;
+
+import 'package:analyzer/context/declared_variables.dart';
+import 'package:analyzer/dart/analysis/analysis_context.dart';
+import 'package:analyzer/dart/analysis/context_root.dart';
+import 'package:analyzer/file_system/file_system.dart';
+import 'package:analyzer/src/dart/analysis/context_builder.dart';
+import 'package:analyzer/src/dart/analysis/context_root.dart';
+import 'package:analyzer/src/dart/analysis/driver_based_analysis_context.dart';
+import 'package:analyzer/src/test_utilities/resource_provider_mixin.dart';
+import 'package:test/test.dart';
+import 'package:test_reflective_loader/test_reflective_loader.dart';
+
+import '../../context/mock_sdk.dart';
+
+main() {
+  defineReflectiveSuite(() {
+    defineReflectiveTests(ContextBuilderImplTest);
+  });
+}
+
+@reflectiveTest
+class ContextBuilderImplTest extends Object with ResourceProviderMixin {
+  ContextBuilderImpl contextBuilder;
+  ContextRoot contextRoot;
+
+  void assertEquals(DeclaredVariables actual, DeclaredVariables expected) {
+    Iterable<String> actualNames = actual.variableNames;
+    Iterable<String> expectedNames = expected.variableNames;
+    expect(actualNames, expectedNames);
+    for (String name in expectedNames) {
+      expect(actual.get(name), expected.get(name));
+    }
+  }
+
+  void setUp() {
+    resourceProvider.newFolder(resourceProvider.pathContext.dirname(
+        resourceProvider.pathContext.dirname(io.Platform.resolvedExecutable)));
+    contextBuilder = new ContextBuilderImpl(resourceProvider: resourceProvider);
+    String path = resourceProvider.convertPath('/temp/root');
+    Folder folder = resourceProvider.newFolder(path);
+    contextRoot = new ContextRootImpl(resourceProvider, folder);
+  }
+
+  test_createContext_declaredVariables() {
+    DeclaredVariables declaredVariables = new DeclaredVariables();
+    declaredVariables.define('foo', 'true');
+    DriverBasedAnalysisContext context = contextBuilder.createContext(
+        contextRoot: contextRoot, declaredVariables: declaredVariables);
+    expect(context.analysisOptions, isNotNull);
+    expect(context.contextRoot, contextRoot);
+    assertEquals(context.driver.declaredVariables, declaredVariables);
+  }
+
+  test_createContext_declaredVariables_sdkPath() {
+    DeclaredVariables declaredVariables = new DeclaredVariables();
+    declaredVariables.define('bar', 'true');
+    MockSdk sdk = new MockSdk(resourceProvider: resourceProvider);
+    DriverBasedAnalysisContext context = contextBuilder.createContext(
+        contextRoot: contextRoot,
+        declaredVariables: declaredVariables,
+        sdkPath: sdkRoot);
+    expect(context.analysisOptions, isNotNull);
+    expect(context.contextRoot, contextRoot);
+    assertEquals(context.driver.declaredVariables, declaredVariables);
+    expect(context.driver.sourceFactory.dartSdk.mapDartUri('dart:core'),
+        sdk.mapDartUri('dart:core'));
+  }
+
+  test_createContext_defaults() {
+    AnalysisContext context =
+        contextBuilder.createContext(contextRoot: contextRoot);
+    expect(context.analysisOptions, isNotNull);
+    expect(context.contextRoot, contextRoot);
+  }
+
+  test_createContext_sdkPath() {
+    String sdkPath = resourceProvider.convertPath('/path/to/sdk');
+    resourceProvider.newFolder(sdkPath);
+    AnalysisContext context = contextBuilder.createContext(
+        contextRoot: contextRoot, sdkPath: sdkPath);
+    expect(context.analysisOptions, isNotNull);
+    expect(context.contextRoot, contextRoot);
+    // TODO(brianwilkerson) We don't currently have a way to test whether the
+    // sdkPath is being handled correctly.
+  }
+}

pkg/analyzer/test/src/dart/analysis/test_all.dart

@@ -4,6 +4,7 @@
 
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
+import 'context_builder_test.dart' as context_builder_test;
 import 'context_locator_test.dart' as context_locator_test;
 import 'context_root_test.dart' as context_root_test;
 import 'defined_names_test.dart' as defined_names_test;
@@ -21,6 +22,7 @@ import 'session_test.dart' as session_test;
 
 main() {
   defineReflectiveSuite(() {
+    context_builder_test.main();
     context_locator_test.main();
     context_root_test.main();
     defined_names_test.main();