Reapply "Tweak public APIs and use them in patch_sdk, dart2js, and kernel-service.""

pkg/front_end/lib/src/kernel_generator_impl.dart

Index: pkg/front_end/lib/src/kernel_generator_impl.dart
diff --git a/pkg/front_end/lib/src/kernel_generator_impl.dart b/pkg/front_end/lib/src/kernel_generator_impl.dart
new file mode 100644
index 0000000000000000000000000000000000000000..3a36278fb46ec5cde3145c95157769e510ff86c0
--- /dev/null
+++ b/pkg/front_end/lib/src/kernel_generator_impl.dart
@@ -0,0 +1,171 @@
+// Copyright (c) 2017, 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.
+
+/// Defines the front-end API for converting source code to Dart Kernel objects.
+library front_end.kernel_generator_impl;
+
+import 'dart:async' show Future;
+import 'dart:async';
+
+import 'package:kernel/kernel.dart' show Program, CanonicalName;
+
+import 'base/processed_options.dart';
+import 'fasta/dill/dill_target.dart' show DillTarget;
+import 'fasta/errors.dart' show InputError, reportCrash;
+import 'fasta/kernel/kernel_outline_shaker.dart';
+import 'fasta/kernel/kernel_target.dart' show KernelTarget;
+import 'fasta/kernel/verifier.dart';
+import 'fasta/kernel/utils.dart';
+import 'fasta/compiler_command_line.dart';
+import 'fasta/translate_uri.dart' show TranslateUri;
+
+/// Implementation for the `package:front_end/kernel_generator.dart` and
+/// `package:front_end/summary_generator.dart` APIs.
+Future<CompilerResult> generateKernel(ProcessedOptions options,
+    {bool buildSummary: false,
+    bool buildProgram: true,
+    bool trimDependencies: false}) async {
+  // TODO(sigmund): Replace CompilerCommandLine and instead simply use a
+  // CompilerContext that directly uses the ProcessedOptions throught the
+  // system.
+  return await CompilerCommandLine.withGlobalOptions("", [""], (context) async {
+    context.options.options['--target'] = options.target;
+    context.options.options['--strong-mode'] = options.strongMode;
+    context.options.options['--verbose'] = options.verbose;
+
+    return await generateKernelInternal(options,
+        buildSummary: buildSummary,
+        buildProgram: buildProgram,
+        trimDependencies: trimDependencies);
+  });
+}
+
+Future<CompilerResult> generateKernelInternal(ProcessedOptions options,
+    {bool buildSummary: false,
+    bool buildProgram: true,
+    bool trimDependencies: false}) async {
+  var fs = options.fileSystem;
+  if (!await options.validateOptions()) return null;
+  options.ticker.logMs("Validated arguments");
+
+  try {
+    TranslateUri uriTranslator = await options.getUriTranslator();
+
+    var dillTarget =
+        new DillTarget(options.ticker, uriTranslator, options.target);
+
+    CanonicalName nameRoot = new CanonicalName.root();
+    Set<Uri> externalLibs(Program program) {
+      return program.libraries
+          .where((lib) => lib.isExternal)
+          .map((lib) => lib.importUri)
+          .toSet();
+    }
+
+    var sdkSummary = await options.loadSdkSummary(nameRoot);
+    if (sdkSummary != null) {
+      var excluded = externalLibs(sdkSummary);
+      dillTarget.loader
+          .appendLibraries(sdkSummary, (uri) => !excluded.contains(uri));
+    }
+
+    // TODO(sigmund): provide better error reporting if input summaries or
+    // linked dependencies were listed out of order (or provide mechanism to
+    // sort them).
+    for (var inputSummary in await options.loadInputSummaries(nameRoot)) {
+      var excluded = externalLibs(inputSummary);
+      dillTarget.loader
+          .appendLibraries(inputSummary, (uri) => !excluded.contains(uri));
+    }
+
+    // All summaries are considered external and shouldn't include source-info.
+    dillTarget.loader.libraries.forEach((lib) => lib.isExternal = true);
+
+    // Linked dependencies are meant to be part of the program so they are not
+    // marked external.
+    for (var dependency in await options.loadLinkDependencies(nameRoot)) {
+      var excluded = externalLibs(dependency);
+      dillTarget.loader
+          .appendLibraries(dependency, (uri) => !excluded.contains(uri));
+    }
+
+    await dillTarget.buildOutlines();
+
+    var kernelTarget = new KernelTarget(fs, dillTarget, uriTranslator);
+    options.inputs.forEach(kernelTarget.read);
+    Program summaryProgram =
+        await kernelTarget.buildOutlines(nameRoot: nameRoot);
+    List<int> summary = null;
+    if (buildSummary) {
+      if (trimDependencies) {
+        // TODO(sigmund): see if it is worth supporting this. Note: trimming the
+        // program is destructive, so if we are emitting summaries and the
+        // program in a single API call, we would need to clone the program here
+        // to avoid deleting pieces that are needed by kernelTarget.buildProgram
+        // below.
+        assert(!buildProgram);
+        var excluded =
+            dillTarget.loader.libraries.map((lib) => lib.importUri).toSet();
+        trimProgram(summaryProgram, (uri) => !excluded.contains(uri));
+      }
+      if (options.verify) {
+        verifyProgram(summaryProgram).forEach((e) => options.reportError('$e'));
+      }
+      if (options.debugDump) {
+        printProgramText(summaryProgram,
+            libraryFilter: kernelTarget.isSourceLibrary);
+      }
+      if (kernelTarget.errors.isEmpty) {
+        summary = serializeProgram(summaryProgram, excludeUriToSource: true);
+      }
+      options.ticker.logMs("Generated outline");
+    }
+
+    Program program;
+    if (buildProgram && kernelTarget.errors.isEmpty) {
+      program = await kernelTarget.buildProgram(verify: options.verify);
+      if (trimDependencies) {
+        var excluded =
+            dillTarget.loader.libraries.map((lib) => lib.importUri).toSet();
+        trimProgram(program, (uri) => !excluded.contains(uri));
+      }
+      if (options.debugDump) {
+        printProgramText(program, libraryFilter: kernelTarget.isSourceLibrary);
+      }
+      options.ticker.logMs("Generated program");
+    }
+
+    if (kernelTarget.errors.isNotEmpty) {
+      kernelTarget.errors.forEach(options.reportError);
+      return null;
+    }
+
+    return new CompilerResult(
+        summary: summary,
+        program: program,
+        deps: kernelTarget.loader.getDependencies());
+  } on InputError catch (e) {
+    options.reportError(e.format());
+    return null;
+  } catch (e, t) {
+    return reportCrash(e, t);
+  }
+}
+
+/// Result object of [generateKernel].
+class CompilerResult {
+  /// The generated summary bytes, if it was requested.
+  final List<int> summary;
+
+  /// The generated program, if it was requested.
+  final Program program;
+
+  /// Dependencies traversed by the compiler. Used only for generating
+  /// dependency .GN files in the dart-sdk build system.
+  /// Note this might be removed when we switch to compute depencencies without
+  /// using the compiler itself.
+  final List<Uri> deps;
+
+  CompilerResult({this.summary, this.program, this.deps});
+}