packages/flutter_tools/lib/src/artifacts.dart - mirrors/flutter - Git at Google

 // Copyright 2017 The Chromium Authors. 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:meta/meta.dart';

 import 'base/context.dart';
 import 'base/file_system.dart';
 import 'base/platform.dart';
 import 'base/process_manager.dart';
 import 'base/utils.dart';
 import 'build_info.dart';
 import 'dart/sdk.dart';
 import 'globals.dart';

 enum Artifact {
   genSnapshot,
   flutterTester,
   snapshotDart,
   flutterFramework,
   flutterMacOSFramework,
   vmSnapshotData,
   isolateSnapshotData,
   platformKernelDill,
   platformLibrariesJson,
   flutterPatchedSdkPath,
   frontendServerSnapshotForEngineDartSdk,
   engineDartSdkPath,
   engineDartBinary,
   dart2jsSnapshot,
   dartdevcSnapshot,
   kernelWorkerSnapshot,
   flutterWebSdk,
 }

 String _artifactToFileName(Artifact artifact, [ TargetPlatform platform, BuildMode mode ]) {
   switch (artifact) {
     case Artifact.genSnapshot:
       return 'gen_snapshot';
     case Artifact.flutterTester:
       if (platform == TargetPlatform.windows_x64) {
         return 'flutter_tester.exe';
       }
       return 'flutter_tester';
     case Artifact.snapshotDart:
       return 'snapshot.dart';
     case Artifact.flutterFramework:
       return 'Flutter.framework';
     case Artifact.flutterMacOSFramework:
       return 'FlutterMacOS.framework';
     case Artifact.vmSnapshotData:
       return 'vm_isolate_snapshot.bin';
     case Artifact.isolateSnapshotData:
       return 'isolate_snapshot.bin';
     case Artifact.platformKernelDill:
       return 'platform_strong.dill';
     case Artifact.platformLibrariesJson:
       return 'libraries.json';
     case Artifact.flutterPatchedSdkPath:
       assert(false, 'No filename for sdk path, should not be invoked');
       return null;
     case Artifact.flutterWebSdk:
       assert(false, 'No filename for web sdk path, should not be invoked');
       return null;
     case Artifact.engineDartSdkPath:
       return 'dart-sdk';
     case Artifact.frontendServerSnapshotForEngineDartSdk:
       return 'frontend_server.dart.snapshot';
     case Artifact.engineDartBinary:
       return 'dart';
     case Artifact.dart2jsSnapshot:
       return 'dart2js.dart.snapshot';
     case Artifact.dartdevcSnapshot:
       return 'dartdevc.dart.snapshot';
     case Artifact.kernelWorkerSnapshot:
       return 'kernel_worker.dart.snapshot';
   }
   assert(false, 'Invalid artifact $artifact.');
   return null;
 }

 class EngineBuildPaths {
   const EngineBuildPaths({
     @required this.targetEngine,
     @required this.hostEngine,
   }) : assert(targetEngine != null),
        assert(hostEngine != null);

   final String targetEngine;
   final String hostEngine;
 }

 // Manages the engine artifacts of Flutter.
 abstract class Artifacts {
   static Artifacts get instance => context.get<Artifacts>();

   static LocalEngineArtifacts getLocalEngine(String engineSrcPath, EngineBuildPaths engineBuildPaths) {
     return LocalEngineArtifacts(engineSrcPath, engineBuildPaths.targetEngine, engineBuildPaths.hostEngine);
   }

   // Returns the requested [artifact] for the [platform] and [mode] combination.
   String getArtifactPath(Artifact artifact, { TargetPlatform platform, BuildMode mode });

   // Returns which set of engine artifacts is currently used for the [platform]
   // and [mode] combination.
   String getEngineType(TargetPlatform platform, [ BuildMode mode ]);
 }

 /// Manages the engine artifacts downloaded to the local cache.
 class CachedArtifacts extends Artifacts {

   @override
   String getArtifactPath(Artifact artifact, { TargetPlatform platform, BuildMode mode }) {
     platform ??= _currentHostPlatform;
     switch (platform) {
       case TargetPlatform.android_arm:
       case TargetPlatform.android_arm64:
       case TargetPlatform.android_x64:
       case TargetPlatform.android_x86:
         return _getAndroidArtifactPath(artifact, platform, mode);
       case TargetPlatform.ios:
         return _getIosArtifactPath(artifact, platform, mode);
       case TargetPlatform.darwin_x64:
       case TargetPlatform.linux_x64:
       case TargetPlatform.windows_x64:
       case TargetPlatform.fuchsia:
       case TargetPlatform.tester:
       case TargetPlatform.web_javascript:
         return _getHostArtifactPath(artifact, platform, mode);
     }
     assert(false, 'Invalid platform $platform.');
     return null;
   }

   @override
   String getEngineType(TargetPlatform platform, [ BuildMode mode ]) {
     return fs.path.basename(_getEngineArtifactsPath(platform, mode));
   }

   String _getAndroidArtifactPath(Artifact artifact, TargetPlatform platform, BuildMode mode) {
     final String engineDir = _getEngineArtifactsPath(platform, mode);
     switch (artifact) {
       case Artifact.frontendServerSnapshotForEngineDartSdk:
         assert(mode != BuildMode.debug, 'Artifact $artifact only available in non-debug mode.');
         return fs.path.join(engineDir, _artifactToFileName(artifact));
       case Artifact.genSnapshot:
         assert(mode != BuildMode.debug, 'Artifact $artifact only available in non-debug mode.');
         final String hostPlatform = getNameForHostPlatform(getCurrentHostPlatform());
         return fs.path.join(engineDir, hostPlatform, _artifactToFileName(artifact));
       default:
         assert(false, 'Artifact $artifact not available for platform $platform.');
         return null;
     }
   }

   String _getIosArtifactPath(Artifact artifact, TargetPlatform platform, BuildMode mode) {
     final String engineDir = _getEngineArtifactsPath(platform, mode);
     switch (artifact) {
       case Artifact.genSnapshot:
       case Artifact.snapshotDart:
       case Artifact.flutterFramework:
       case Artifact.frontendServerSnapshotForEngineDartSdk:
         return fs.path.join(engineDir, _artifactToFileName(artifact));
       default:
         assert(false, 'Artifact $artifact not available for platform $platform.');
         return null;
     }
   }

   String _getFlutterPatchedSdkPath(BuildMode mode) {
     final String engineArtifactsPath = cache.getArtifactDirectory('engine').path;
     return fs.path.join(engineArtifactsPath, 'common',
         mode == BuildMode.release ? 'flutter_patched_sdk_product' : 'flutter_patched_sdk');
   }

   String _getFlutterWebSdkPath() {
     return cache.getWebSdkDirectory().path;
   }

   String _getHostArtifactPath(Artifact artifact, TargetPlatform platform, BuildMode mode) {
     switch (artifact) {
       case Artifact.genSnapshot:
         // For script snapshots any gen_snapshot binary will do. Returning gen_snapshot for
         // android_arm in profile mode because it is available on all supported host platforms.
         return _getAndroidArtifactPath(artifact, TargetPlatform.android_arm, BuildMode.profile);
       case Artifact.flutterTester:
       case Artifact.vmSnapshotData:
       case Artifact.isolateSnapshotData:
       case Artifact.frontendServerSnapshotForEngineDartSdk:
         final String engineArtifactsPath = cache.getArtifactDirectory('engine').path;
         final String platformDirName = getNameForTargetPlatform(platform);
         return fs.path.join(engineArtifactsPath, platformDirName, _artifactToFileName(artifact, platform, mode));
       case Artifact.engineDartSdkPath:
         return dartSdkPath;
       case Artifact.engineDartBinary:
         return fs.path.join(dartSdkPath, 'bin', _artifactToFileName(artifact));
       case Artifact.platformKernelDill:
         return fs.path.join(_getFlutterPatchedSdkPath(mode), _artifactToFileName(artifact));
       case Artifact.platformLibrariesJson:
         return fs.path.join(_getFlutterPatchedSdkPath(mode), 'lib', _artifactToFileName(artifact));
       case Artifact.flutterPatchedSdkPath:
         return _getFlutterPatchedSdkPath(mode);
       case Artifact.flutterWebSdk:
         return _getFlutterWebSdkPath();
       case Artifact.dart2jsSnapshot:
         return fs.path.join(dartSdkPath, 'bin', 'snapshots', _artifactToFileName(artifact));
       case Artifact.dartdevcSnapshot:
         return fs.path.join(dartSdkPath, 'bin', 'snapshots', _artifactToFileName(artifact));
       case Artifact.kernelWorkerSnapshot:
         return fs.path.join(dartSdkPath, 'bin', 'snapshots', _artifactToFileName(artifact));
       case Artifact.flutterMacOSFramework:
         final String engineArtifactsPath = cache.getArtifactDirectory('engine').path;
         final String platformDirName = getNameForTargetPlatform(platform);
         return fs.path.join(engineArtifactsPath, platformDirName, _artifactToFileName(artifact, platform, mode));
       default:
         assert(false, 'Artifact $artifact not available for platform $platform.');
         return null;
     }
   }

   String _getEngineArtifactsPath(TargetPlatform platform, [ BuildMode mode ]) {
     final String engineDir = cache.getArtifactDirectory('engine').path;
     final String platformName = getNameForTargetPlatform(platform);
     switch (platform) {
       case TargetPlatform.linux_x64:
       case TargetPlatform.darwin_x64:
       case TargetPlatform.windows_x64:
       case TargetPlatform.fuchsia:
       case TargetPlatform.tester:
       case TargetPlatform.web_javascript:
         assert(mode == null, 'Platform $platform does not support different build modes.');
         return fs.path.join(engineDir, platformName);
       case TargetPlatform.ios:
       case TargetPlatform.android_arm:
       case TargetPlatform.android_arm64:
       case TargetPlatform.android_x64:
       case TargetPlatform.android_x86:
         assert(mode != null, 'Need to specify a build mode for platform $platform.');
         final String suffix = mode != BuildMode.debug ? '-${snakeCase(getModeName(mode), '-')}' : '';
         return fs.path.join(engineDir, platformName + suffix);
     }
     assert(false, 'Invalid platform $platform.');
     return null;
   }

   TargetPlatform get _currentHostPlatform {
     if (platform.isMacOS)
       return TargetPlatform.darwin_x64;
     if (platform.isLinux)
       return TargetPlatform.linux_x64;
     if (platform.isWindows)
       return TargetPlatform.windows_x64;
     throw UnimplementedError('Host OS not supported.');
   }
 }

 /// Manages the artifacts of a locally built engine.
 class LocalEngineArtifacts extends Artifacts {
   LocalEngineArtifacts(this._engineSrcPath, this.engineOutPath, this._hostEngineOutPath);

   final String _engineSrcPath;
   final String engineOutPath; // TODO(goderbauer): This should be private.
   String _hostEngineOutPath;

   @override
   String getArtifactPath(Artifact artifact, { TargetPlatform platform, BuildMode mode }) {
     switch (artifact) {
       case Artifact.snapshotDart:
         return fs.path.join(_engineSrcPath, 'flutter', 'lib', 'snapshot', _artifactToFileName(artifact));
       case Artifact.genSnapshot:
         return _genSnapshotPath();
       case Artifact.flutterTester:
         return _flutterTesterPath(platform);
       case Artifact.isolateSnapshotData:
       case Artifact.vmSnapshotData:
         return fs.path.join(engineOutPath, 'gen', 'flutter', 'lib', 'snapshot', _artifactToFileName(artifact));
       case Artifact.platformKernelDill:
         return fs.path.join(_getFlutterPatchedSdkPath(mode), _artifactToFileName(artifact));
       case Artifact.platformLibrariesJson:
         return fs.path.join(_getFlutterPatchedSdkPath(mode), 'lib', _artifactToFileName(artifact));
       case Artifact.flutterFramework:
         return fs.path.join(engineOutPath, _artifactToFileName(artifact));
       case Artifact.flutterMacOSFramework:
         return fs.path.join(engineOutPath, _artifactToFileName(artifact));
       case Artifact.flutterPatchedSdkPath:
         // When using local engine always use [BuildMode.debug] regardless of
         // what was specified in [mode] argument because local engine will
         // have only one flutter_patched_sdk in standard location, that
         // is happen to be what debug(non-release) mode is using.
         return _getFlutterPatchedSdkPath(BuildMode.debug);
       case Artifact.flutterWebSdk:
         return _getFlutterWebSdkPath();
       case Artifact.frontendServerSnapshotForEngineDartSdk:
         return fs.path.join(_hostEngineOutPath, 'gen', _artifactToFileName(artifact));
       case Artifact.engineDartSdkPath:
         return fs.path.join(_hostEngineOutPath, 'dart-sdk');
       case Artifact.engineDartBinary:
         return fs.path.join(_hostEngineOutPath, 'dart-sdk', 'bin', _artifactToFileName(artifact));
       case Artifact.dart2jsSnapshot:
         return fs.path.join(_hostEngineOutPath, 'dart-sdk', 'bin', 'snapshots', _artifactToFileName(artifact));
       case Artifact.dartdevcSnapshot:
         return fs.path.join(dartSdkPath, 'bin', 'snapshots', _artifactToFileName(artifact));
       case Artifact.kernelWorkerSnapshot:
         return fs.path.join(_hostEngineOutPath, 'dart-sdk', 'bin', 'snapshots', _artifactToFileName(artifact));
     }
     assert(false, 'Invalid artifact $artifact.');
     return null;
   }

   @override
   String getEngineType(TargetPlatform platform, [ BuildMode mode ]) {
     return fs.path.basename(engineOutPath);
   }

   String _getFlutterPatchedSdkPath(BuildMode buildMode) {
     return fs.path.join(engineOutPath,
         buildMode == BuildMode.release ? 'flutter_patched_sdk_product' : 'flutter_patched_sdk');
   }

   String _getFlutterWebSdkPath() {
     return fs.path.join(engineOutPath, 'flutter_web_sdk');
   }

   String _genSnapshotPath() {
     const List<String> clangDirs = <String>['.', 'clang_x86', 'clang_x64', 'clang_i386'];
     final String genSnapshotName = _artifactToFileName(Artifact.genSnapshot);
     for (String clangDir in clangDirs) {
       final String genSnapshotPath = fs.path.join(engineOutPath, clangDir, genSnapshotName);
       if (processManager.canRun(genSnapshotPath))
         return genSnapshotPath;
     }
     throw Exception('Unable to find $genSnapshotName');
   }

   String _flutterTesterPath(TargetPlatform platform) {
     if (getCurrentHostPlatform() == HostPlatform.linux_x64) {
       return fs.path.join(engineOutPath, _artifactToFileName(Artifact.flutterTester));
     } else if (getCurrentHostPlatform() == HostPlatform.darwin_x64) {
       return fs.path.join(engineOutPath, 'flutter_tester');
     } else if (getCurrentHostPlatform() == HostPlatform.windows_x64) {
       return fs.path.join(engineOutPath, 'flutter_tester.exe');
     }
     throw Exception('Unsupported platform $platform.');
   }
 }

 /// An implementation of [Artifacts] that provides individual overrides.
 ///
 /// If an artifact is not provided, the lookup delegates to the parent.
 class OverrideArtifacts implements Artifacts {
   /// Creates a new [OverrideArtifacts].
   ///
   /// [parent] must be provided.
   OverrideArtifacts({
     @required this.parent,
     this.frontendServer,
     this.engineDartBinary,
     this.platformKernelDill,
     this.flutterPatchedSdk,
   }) : assert(parent != null);

   final Artifacts parent;
   final File frontendServer;
   final File engineDartBinary;
   final File platformKernelDill;
   final File flutterPatchedSdk;

   @override
   String getArtifactPath(Artifact artifact, { TargetPlatform platform, BuildMode mode }) {
     if (artifact == Artifact.frontendServerSnapshotForEngineDartSdk && frontendServer != null) {
       return frontendServer.path;
     }
     if (artifact == Artifact.engineDartBinary && engineDartBinary != null) {
       return engineDartBinary.path;
     }
     if (artifact == Artifact.platformKernelDill && platformKernelDill != null) {
       return platformKernelDill.path;
     }
     if (artifact == Artifact.flutterPatchedSdkPath && flutterPatchedSdk != null) {
       return flutterPatchedSdk.path;
     }
     return parent.getArtifactPath(artifact, platform: platform, mode: mode);
   }

   @override
   String getEngineType(TargetPlatform platform, [ BuildMode mode ]) => parent.getEngineType(platform, mode);
 }
	// Copyright 2017 The Chromium Authors. 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:meta/meta.dart';

	import 'base/context.dart';
	import 'base/file_system.dart';
	import 'base/platform.dart';
	import 'base/process_manager.dart';
	import 'base/utils.dart';
	import 'build_info.dart';
	import 'dart/sdk.dart';
	import 'globals.dart';

	enum Artifact {
	genSnapshot,
	flutterTester,
	snapshotDart,
	flutterFramework,
	flutterMacOSFramework,
	vmSnapshotData,
	isolateSnapshotData,
	platformKernelDill,
	platformLibrariesJson,
	flutterPatchedSdkPath,
	frontendServerSnapshotForEngineDartSdk,
	engineDartSdkPath,
	engineDartBinary,
	dart2jsSnapshot,
	dartdevcSnapshot,
	kernelWorkerSnapshot,
	flutterWebSdk,
	}

	String _artifactToFileName(Artifact artifact, [ TargetPlatform platform, BuildMode mode ]) {
	switch (artifact) {
	case Artifact.genSnapshot:
	return 'gen_snapshot';
	case Artifact.flutterTester:
	if (platform == TargetPlatform.windows_x64) {
	return 'flutter_tester.exe';
	}
	return 'flutter_tester';
	case Artifact.snapshotDart:
	return 'snapshot.dart';
	case Artifact.flutterFramework:
	return 'Flutter.framework';
	case Artifact.flutterMacOSFramework:
	return 'FlutterMacOS.framework';
	case Artifact.vmSnapshotData:
	return 'vm_isolate_snapshot.bin';
	case Artifact.isolateSnapshotData:
	return 'isolate_snapshot.bin';
	case Artifact.platformKernelDill:
	return 'platform_strong.dill';
	case Artifact.platformLibrariesJson:
	return 'libraries.json';
	case Artifact.flutterPatchedSdkPath:
	assert(false, 'No filename for sdk path, should not be invoked');
	return null;
	case Artifact.flutterWebSdk:
	assert(false, 'No filename for web sdk path, should not be invoked');
	return null;
	case Artifact.engineDartSdkPath:
	return 'dart-sdk';
	case Artifact.frontendServerSnapshotForEngineDartSdk:
	return 'frontend_server.dart.snapshot';
	case Artifact.engineDartBinary:
	return 'dart';
	case Artifact.dart2jsSnapshot:
	return 'dart2js.dart.snapshot';
	case Artifact.dartdevcSnapshot:
	return 'dartdevc.dart.snapshot';
	case Artifact.kernelWorkerSnapshot:
	return 'kernel_worker.dart.snapshot';
	}
	assert(false, 'Invalid artifact $artifact.');
	return null;
	}

	class EngineBuildPaths {
	const EngineBuildPaths({
	@required this.targetEngine,
	@required this.hostEngine,
	}) : assert(targetEngine != null),
	assert(hostEngine != null);

	final String targetEngine;
	final String hostEngine;
	}

	// Manages the engine artifacts of Flutter.
	abstract class Artifacts {
	static Artifacts get instance => context.get<Artifacts>();

	static LocalEngineArtifacts getLocalEngine(String engineSrcPath, EngineBuildPaths engineBuildPaths) {
	return LocalEngineArtifacts(engineSrcPath, engineBuildPaths.targetEngine, engineBuildPaths.hostEngine);
	}

	// Returns the requested [artifact] for the [platform] and [mode] combination.
	String getArtifactPath(Artifact artifact, { TargetPlatform platform, BuildMode mode });

	// Returns which set of engine artifacts is currently used for the [platform]
	// and [mode] combination.
	String getEngineType(TargetPlatform platform, [ BuildMode mode ]);
	}

	/// Manages the engine artifacts downloaded to the local cache.
	class CachedArtifacts extends Artifacts {

	@override
	String getArtifactPath(Artifact artifact, { TargetPlatform platform, BuildMode mode }) {
	platform ??= _currentHostPlatform;
	switch (platform) {
	case TargetPlatform.android_arm:
	case TargetPlatform.android_arm64:
	case TargetPlatform.android_x64:
	case TargetPlatform.android_x86:
	return _getAndroidArtifactPath(artifact, platform, mode);
	case TargetPlatform.ios:
	return _getIosArtifactPath(artifact, platform, mode);
	case TargetPlatform.darwin_x64:
	case TargetPlatform.linux_x64:
	case TargetPlatform.windows_x64:
	case TargetPlatform.fuchsia:
	case TargetPlatform.tester:
	case TargetPlatform.web_javascript:
	return _getHostArtifactPath(artifact, platform, mode);
	}
	assert(false, 'Invalid platform $platform.');
	return null;
	}

	@override
	String getEngineType(TargetPlatform platform, [ BuildMode mode ]) {
	return fs.path.basename(_getEngineArtifactsPath(platform, mode));
	}

	String _getAndroidArtifactPath(Artifact artifact, TargetPlatform platform, BuildMode mode) {
	final String engineDir = _getEngineArtifactsPath(platform, mode);
	switch (artifact) {
	case Artifact.frontendServerSnapshotForEngineDartSdk:
	assert(mode != BuildMode.debug, 'Artifact $artifact only available in non-debug mode.');
	return fs.path.join(engineDir, _artifactToFileName(artifact));
	case Artifact.genSnapshot:
	assert(mode != BuildMode.debug, 'Artifact $artifact only available in non-debug mode.');
	final String hostPlatform = getNameForHostPlatform(getCurrentHostPlatform());
	return fs.path.join(engineDir, hostPlatform, _artifactToFileName(artifact));
	default:
	assert(false, 'Artifact $artifact not available for platform $platform.');
	return null;
	}
	}

	String _getIosArtifactPath(Artifact artifact, TargetPlatform platform, BuildMode mode) {
	final String engineDir = _getEngineArtifactsPath(platform, mode);
	switch (artifact) {
	case Artifact.genSnapshot:
	case Artifact.snapshotDart:
	case Artifact.flutterFramework:
	case Artifact.frontendServerSnapshotForEngineDartSdk:
	return fs.path.join(engineDir, _artifactToFileName(artifact));
	default:
	assert(false, 'Artifact $artifact not available for platform $platform.');
	return null;
	}
	}

	String _getFlutterPatchedSdkPath(BuildMode mode) {
	final String engineArtifactsPath = cache.getArtifactDirectory('engine').path;
	return fs.path.join(engineArtifactsPath, 'common',
	mode == BuildMode.release ? 'flutter_patched_sdk_product' : 'flutter_patched_sdk');
	}

	String _getFlutterWebSdkPath() {
	return cache.getWebSdkDirectory().path;
	}

	String _getHostArtifactPath(Artifact artifact, TargetPlatform platform, BuildMode mode) {
	switch (artifact) {
	case Artifact.genSnapshot:
	// For script snapshots any gen_snapshot binary will do. Returning gen_snapshot for
	// android_arm in profile mode because it is available on all supported host platforms.
	return _getAndroidArtifactPath(artifact, TargetPlatform.android_arm, BuildMode.profile);
	case Artifact.flutterTester:
	case Artifact.vmSnapshotData:
	case Artifact.isolateSnapshotData:
	case Artifact.frontendServerSnapshotForEngineDartSdk:
	final String engineArtifactsPath = cache.getArtifactDirectory('engine').path;
	final String platformDirName = getNameForTargetPlatform(platform);
	return fs.path.join(engineArtifactsPath, platformDirName, _artifactToFileName(artifact, platform, mode));
	case Artifact.engineDartSdkPath:
	return dartSdkPath;
	case Artifact.engineDartBinary:
	return fs.path.join(dartSdkPath, 'bin', _artifactToFileName(artifact));
	case Artifact.platformKernelDill:
	return fs.path.join(_getFlutterPatchedSdkPath(mode), _artifactToFileName(artifact));
	case Artifact.platformLibrariesJson:
	return fs.path.join(_getFlutterPatchedSdkPath(mode), 'lib', _artifactToFileName(artifact));
	case Artifact.flutterPatchedSdkPath:
	return _getFlutterPatchedSdkPath(mode);
	case Artifact.flutterWebSdk:
	return _getFlutterWebSdkPath();
	case Artifact.dart2jsSnapshot:
	return fs.path.join(dartSdkPath, 'bin', 'snapshots', _artifactToFileName(artifact));
	case Artifact.dartdevcSnapshot:
	return fs.path.join(dartSdkPath, 'bin', 'snapshots', _artifactToFileName(artifact));
	case Artifact.kernelWorkerSnapshot:
	return fs.path.join(dartSdkPath, 'bin', 'snapshots', _artifactToFileName(artifact));
	case Artifact.flutterMacOSFramework:
	final String engineArtifactsPath = cache.getArtifactDirectory('engine').path;
	final String platformDirName = getNameForTargetPlatform(platform);
	return fs.path.join(engineArtifactsPath, platformDirName, _artifactToFileName(artifact, platform, mode));
	default:
	assert(false, 'Artifact $artifact not available for platform $platform.');
	return null;
	}
	}

	String _getEngineArtifactsPath(TargetPlatform platform, [ BuildMode mode ]) {
	final String engineDir = cache.getArtifactDirectory('engine').path;
	final String platformName = getNameForTargetPlatform(platform);
	switch (platform) {
	case TargetPlatform.linux_x64:
	case TargetPlatform.darwin_x64:
	case TargetPlatform.windows_x64:
	case TargetPlatform.fuchsia:
	case TargetPlatform.tester:
	case TargetPlatform.web_javascript:
	assert(mode == null, 'Platform $platform does not support different build modes.');
	return fs.path.join(engineDir, platformName);
	case TargetPlatform.ios:
	case TargetPlatform.android_arm:
	case TargetPlatform.android_arm64:
	case TargetPlatform.android_x64:
	case TargetPlatform.android_x86:
	assert(mode != null, 'Need to specify a build mode for platform $platform.');
	final String suffix = mode != BuildMode.debug ? '-${snakeCase(getModeName(mode), '-')}' : '';
	return fs.path.join(engineDir, platformName + suffix);
	}
	assert(false, 'Invalid platform $platform.');
	return null;
	}

	TargetPlatform get _currentHostPlatform {
	if (platform.isMacOS)
	return TargetPlatform.darwin_x64;
	if (platform.isLinux)
	return TargetPlatform.linux_x64;
	if (platform.isWindows)
	return TargetPlatform.windows_x64;
	throw UnimplementedError('Host OS not supported.');
	}
	}

	/// Manages the artifacts of a locally built engine.
	class LocalEngineArtifacts extends Artifacts {
	LocalEngineArtifacts(this._engineSrcPath, this.engineOutPath, this._hostEngineOutPath);

	final String _engineSrcPath;
	final String engineOutPath; // TODO(goderbauer): This should be private.
	String _hostEngineOutPath;

	@override
	String getArtifactPath(Artifact artifact, { TargetPlatform platform, BuildMode mode }) {
	switch (artifact) {
	case Artifact.snapshotDart:
	return fs.path.join(_engineSrcPath, 'flutter', 'lib', 'snapshot', _artifactToFileName(artifact));
	case Artifact.genSnapshot:
	return _genSnapshotPath();
	case Artifact.flutterTester:
	return _flutterTesterPath(platform);
	case Artifact.isolateSnapshotData:
	case Artifact.vmSnapshotData:
	return fs.path.join(engineOutPath, 'gen', 'flutter', 'lib', 'snapshot', _artifactToFileName(artifact));
	case Artifact.platformKernelDill:
	return fs.path.join(_getFlutterPatchedSdkPath(mode), _artifactToFileName(artifact));
	case Artifact.platformLibrariesJson:
	return fs.path.join(_getFlutterPatchedSdkPath(mode), 'lib', _artifactToFileName(artifact));
	case Artifact.flutterFramework:
	return fs.path.join(engineOutPath, _artifactToFileName(artifact));
	case Artifact.flutterMacOSFramework:
	return fs.path.join(engineOutPath, _artifactToFileName(artifact));
	case Artifact.flutterPatchedSdkPath:
	// When using local engine always use [BuildMode.debug] regardless of
	// what was specified in [mode] argument because local engine will
	// have only one flutter_patched_sdk in standard location, that
	// is happen to be what debug(non-release) mode is using.
	return _getFlutterPatchedSdkPath(BuildMode.debug);
	case Artifact.flutterWebSdk:
	return _getFlutterWebSdkPath();
	case Artifact.frontendServerSnapshotForEngineDartSdk:
	return fs.path.join(_hostEngineOutPath, 'gen', _artifactToFileName(artifact));
	case Artifact.engineDartSdkPath:
	return fs.path.join(_hostEngineOutPath, 'dart-sdk');
	case Artifact.engineDartBinary:
	return fs.path.join(_hostEngineOutPath, 'dart-sdk', 'bin', _artifactToFileName(artifact));
	case Artifact.dart2jsSnapshot:
	return fs.path.join(_hostEngineOutPath, 'dart-sdk', 'bin', 'snapshots', _artifactToFileName(artifact));
	case Artifact.dartdevcSnapshot:
	return fs.path.join(dartSdkPath, 'bin', 'snapshots', _artifactToFileName(artifact));
	case Artifact.kernelWorkerSnapshot:
	return fs.path.join(_hostEngineOutPath, 'dart-sdk', 'bin', 'snapshots', _artifactToFileName(artifact));
	}
	assert(false, 'Invalid artifact $artifact.');
	return null;
	}

	@override
	String getEngineType(TargetPlatform platform, [ BuildMode mode ]) {
	return fs.path.basename(engineOutPath);
	}

	String _getFlutterPatchedSdkPath(BuildMode buildMode) {
	return fs.path.join(engineOutPath,
	buildMode == BuildMode.release ? 'flutter_patched_sdk_product' : 'flutter_patched_sdk');
	}

	String _getFlutterWebSdkPath() {
	return fs.path.join(engineOutPath, 'flutter_web_sdk');
	}

	String _genSnapshotPath() {
	const List<String> clangDirs = <String>['.', 'clang_x86', 'clang_x64', 'clang_i386'];
	final String genSnapshotName = _artifactToFileName(Artifact.genSnapshot);
	for (String clangDir in clangDirs) {
	final String genSnapshotPath = fs.path.join(engineOutPath, clangDir, genSnapshotName);
	if (processManager.canRun(genSnapshotPath))
	return genSnapshotPath;
	}
	throw Exception('Unable to find $genSnapshotName');
	}

	String _flutterTesterPath(TargetPlatform platform) {
	if (getCurrentHostPlatform() == HostPlatform.linux_x64) {
	return fs.path.join(engineOutPath, _artifactToFileName(Artifact.flutterTester));
	} else if (getCurrentHostPlatform() == HostPlatform.darwin_x64) {
	return fs.path.join(engineOutPath, 'flutter_tester');
	} else if (getCurrentHostPlatform() == HostPlatform.windows_x64) {
	return fs.path.join(engineOutPath, 'flutter_tester.exe');
	}
	throw Exception('Unsupported platform $platform.');
	}
	}

	/// An implementation of [Artifacts] that provides individual overrides.
	///
	/// If an artifact is not provided, the lookup delegates to the parent.
	class OverrideArtifacts implements Artifacts {
	/// Creates a new [OverrideArtifacts].
	///
	/// [parent] must be provided.
	OverrideArtifacts({
	@required this.parent,
	this.frontendServer,
	this.engineDartBinary,
	this.platformKernelDill,
	this.flutterPatchedSdk,
	}) : assert(parent != null);

	final Artifacts parent;
	final File frontendServer;
	final File engineDartBinary;
	final File platformKernelDill;
	final File flutterPatchedSdk;

	@override
	String getArtifactPath(Artifact artifact, { TargetPlatform platform, BuildMode mode }) {
	if (artifact == Artifact.frontendServerSnapshotForEngineDartSdk && frontendServer != null) {
	return frontendServer.path;
	}
	if (artifact == Artifact.engineDartBinary && engineDartBinary != null) {
	return engineDartBinary.path;
	}
	if (artifact == Artifact.platformKernelDill && platformKernelDill != null) {
	return platformKernelDill.path;
	}
	if (artifact == Artifact.flutterPatchedSdkPath && flutterPatchedSdk != null) {
	return flutterPatchedSdk.path;
	}
	return parent.getArtifactPath(artifact, platform: platform, mode: mode);
	}

	@override
	String getEngineType(TargetPlatform platform, [ BuildMode mode ]) => parent.getEngineType(platform, mode);
	}