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

pkg/front_end/lib/kernel_generator.dart

 // Copyright (c) 2016, 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;
 
+import 'compiler_options.dart';
 import 'dart:async' show Future;
 import 'dart:async';
-
+import 'package:front_end/src/base/processed_options.dart';
+import 'src/fasta/dill/dill_target.dart' show DillTarget;
+import 'src/fasta/errors.dart' show InputError;
+import 'src/fasta/kernel/kernel_target.dart' show KernelTarget;
 import 'package:kernel/kernel.dart' show Program;
-
-import 'compiler_options.dart';
-import 'src/base/processed_options.dart';
-import 'src/kernel_generator_impl.dart';
+import 'package:kernel/target/targets.dart' show TargetFlags;
+import 'package:kernel/target/vm_fasta.dart' show VmFastaTarget;
+import 'src/fasta/ticker.dart' show Ticker;
+import 'src/fasta/translate_uri.dart' show TranslateUri;
+import 'src/simple_error.dart';
 
 /// Generates a kernel representation of the program whose main library is in
 /// the given [source].
 ///
 /// Intended for whole program (non-modular) compilation.
 ///
 /// Given the Uri of a file containing a program's `main` method, this function
 /// follows `import`, `export`, and `part` declarations to discover the whole
 /// program, and converts the result to Dart Kernel format.
 ///
 /// If `compileSdk` in [options] is true, the generated program will include
 /// code for the SDK.
 ///
-/// If summaries are provided in [options], the compiler will use them instead
-/// of compiling the libraries contained in those summaries. This is useful, for
-/// example, when compiling for platforms that already embed those sources (like
-/// the sdk in the standalone VM).
-///
-/// The input [source] is expected to be a script with a main method, otherwise
-/// an error is reported.
-// TODO(sigmund): rename to kernelForScript?
+/// If summaries are provided in [options], they will be used to speed up
+/// the process. If in addition `compileSdk` is false, then the resulting
+/// program will not contain the sdk contents. This is useful when building apps
+/// for platforms that already embed the sdk (e.g. the VM), so there is no need
+/// to spend time and space rebuilding it.
 Future<Program> kernelForProgram(Uri source, CompilerOptions options) async {
-  var pOptions = new ProcessedOptions(options, false, [source]);
-  var program = (await generateKernel(pOptions))?.program;
-  if (program == null) return null;
-
-  if (program.mainMethod == null) {
-    pOptions.reportError("No 'main' method found.");
+  var fs = options.fileSystem;
+  report(String msg) {
+    options.onError(new SimpleError(msg));
     return null;
   }
 
-  return program;
+  if (!await fs.entityForUri(source).exists()) {
+    return report("Entry-point file not found: $source");
+  }
+
+  var pOptions = new ProcessedOptions(options);
+
+  if (!await pOptions.validateOptions()) return null;
+
+  try {
+    TranslateUri uriTranslator = await pOptions.getUriTranslator();
+
+    var dillTarget = new DillTarget(new Ticker(isVerbose: false), uriTranslator,
+        new VmFastaTarget(new TargetFlags(strongMode: options.strongMode)));
+    var summary = await pOptions.sdkSummaryProgram;
+    if (summary != null) {
+      dillTarget.loader.appendLibraries(summary);
+    }
+
+    var kernelTarget =
+        new KernelTarget(options.fileSystem, dillTarget, uriTranslator);
+    kernelTarget.read(source);
+
+    await dillTarget.buildOutlines();
+    await kernelTarget.buildOutlines();
+    Program program = await kernelTarget.buildProgram(trimDependencies: true);
+
+    if (kernelTarget.errors.isNotEmpty) {
+      kernelTarget.errors.forEach(report);
+      return null;
+    }
+
+    if (program.mainMethod == null) {
+      return report("No 'main' method found.");
+    }
+
+    if (!options.compileSdk) {
+      // TODO(sigmund): ensure that the result is not including
+      // sources for the sdk, only external references.
+    }
+    return program;
+  } on InputError catch (e) {
+    options.onError(new SimpleError(e.format()));
+    return null;
+  }
 }
 
-/// Generates a kernel representation for a build unit containing [sources].
+/// Generates a kernel representation for a build unit.
 ///
-/// A build unit is a collection of libraries that are compiled together.
-/// Libraries in the build unit may depend on each other and may have
-/// dependencies to libraries in other build units. Unlinke library
-/// dependencies, build unit dependencies must be acyclic.
+/// Intended for modular compilation.
 ///
-/// This API is intended for modular compilation. Dependencies to other build
-/// units are specified using [CompilerOptions.inputSummaries].
+/// The build unit by default contains only the source files in [sources]
+/// (including library and part files), but if
+/// [CompilerOptions.chaseDependencies] is true, it may include some additional
+/// source files.  All of the library files are transformed into Dart Kernel
+/// Library objects.
 ///
 /// By default, the compilation process is hermetic, meaning that the only files
 /// which will be read are those listed in [sources],
 /// [CompilerOptions.inputSummaries], and [CompilerOptions.sdkSummary].  If a
 /// source file attempts to refer to a file which is not obtainable from these
 /// URIs, that will result in an error, even if the file exists on the
 /// filesystem.
 ///
 /// When [CompilerOptions.chaseDependencies] is true, this default behavior
 /// changes, and any dependency of [sources] that is not listed in
 /// [CompilerOptions.inputSummaries] and [CompilerOptions.sdkSummary] is treated
 /// as an additional source file for the build unit.
 ///
 /// Any `part` declarations found in [sources] must refer to part files which
 /// are also listed in the build unit sources, otherwise an error results.  (It
 /// is not permitted to refer to a part file declared in another build unit).
 ///
-/// The return value is a [Program] object with no main method set. The
-/// [Program] includes external libraries for those libraries loaded through
-/// summaries.
+/// The return value is a [Program] object with no main method set.
+/// TODO(paulberry): would it be better to define a data type in kernel to
+/// represent a bundle of all the libraries in a given build unit?
+///
+/// TODO(paulberry): does additional information need to be output to allow the
+/// caller to match up referenced elements to the summary files they were
+/// obtained from?
 Future<Program> kernelForBuildUnit(
     List<Uri> sources, CompilerOptions options) async {
-  return (await generateKernel(new ProcessedOptions(options, true, sources)))
-      ?.program;
+  var fs = options.fileSystem;
+  report(String msg) {
+    options.onError(new SimpleError(msg));
+    return null;
+  }
+
+  if (!options.chaseDependencies) {
+    // TODO(sigmund): add support, most likely we can do so by adding a wrapper
+    // on top of filesystem that restricts reads to a set of known files.
+    report("hermetic mode (chaseDependencies = false) is not implemented");
+    return null;
+  }
+
+  for (var source in sources) {
+    if (!await fs.entityForUri(source).exists()) {
+      return report("Entry-point file not found: $source");
+    }
+  }
+
+  var pOptions = new ProcessedOptions(options);
+
+  if (!await pOptions.validateOptions()) return null;
+
+  try {
+    TranslateUri uriTranslator = await pOptions.getUriTranslator();
+
+    var dillTarget = new DillTarget(new Ticker(isVerbose: false), uriTranslator,
+        new VmFastaTarget(new TargetFlags(strongMode: options.strongMode)));
+    var summary = await pOptions.sdkSummaryProgram;
+    if (summary != null) {
+      dillTarget.loader.appendLibraries(summary);
+    }
+
+    // TODO(sigmund): this is likely not going to work if done naively: if
+    // summaries contain external references we need to ensure they are loaded
+    // in a specific order.
+    for (var inputSummary in await pOptions.inputSummariesPrograms) {
+      dillTarget.loader.appendLibraries(inputSummary);
+    }
+
+    await dillTarget.buildOutlines();
+
+    var kernelTarget =
+        new KernelTarget(options.fileSystem, dillTarget, uriTranslator);
+    sources.forEach(kernelTarget.read);
+    await kernelTarget.buildOutlines();
+
+    Program program = await kernelTarget.buildProgram(trimDependencies: true);
+
+    if (kernelTarget.errors.isNotEmpty) {
+      kernelTarget.errors.forEach(report);
+      return null;
+    }
+
+    return program;
+  } on InputError catch (e) {
+    options.onError(new SimpleError(e.format()));
+    return null;
+  }
 }