Revert "Revert "Use native async/await support in pub.""

sdk/lib/_internal/pub/bin/async_compile.dart

-// Copyright (c) 2014, 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';
-
-import 'package:args/args.dart';
-import 'package:analyzer/src/services/formatter_impl.dart';
-import 'package:async_await/async_await.dart' as async_await;
-import 'package:stack_trace/stack_trace.dart';
-import 'package:path/path.dart' as p;
-
-/// The path to pub's root directory (sdk/lib/_internal/pub) in the Dart repo.
-///
-/// This assumes this script is itself being run from within the repo.
-final sourceDir = p.dirname(p.dirname(p.fromUri(Platform.script)));
-
-/// The [sourceDir] as a URL, for use in import strings.
-final sourceUrl = p.toUri(sourceDir).toString();
-
-/// The directory that compiler output should be written to.
-String generatedDir;
-
-/// `true` if any file failed to compile.
-bool hadFailure = false;
-
-bool verbose = false;
-
-/// Prefix for imports in pub that import dart2js libraries.
-final _compilerPattern = new RegExp(r"import '(\.\./)+compiler");
-
-/// Matches the Git commit hash of the compiler stored in the README.md file.
-///
-/// This is used both to find the current commit and replace it with the new
-/// one.
-final _commitPattern = new RegExp(r"[a-f0-9]{40}");
-
-/// The template for the README that's added to the generated source.
-///
-/// This is used to store the current commit of the async_await compiler.
-const _README = """
-Pub is currently dogfooding the new Dart async/await syntax. Since the Dart VM
-doesn't natively support it yet, we are using the [async-await][] compiler
-package.
-
-[async-await]: https://github.com/dart-lang/async_await
-
-We run that to compile pub-using-await from sdk/lib/_internal/pub down to
-vanilla Dart code which is what you see here. To interoperate more easily with
-the rest of the repositry, we check in that generated code.
-
-When bug #104 is fixed, we can remove this entirely.
-
-The code here was compiled using the async-await compiler at commit:
-
-    <<COMMIT>>
-
-(Note: this file is also parsed by a tool to update the above commit, so be
-careful not to reformat it.)
-""";
-
-/// This runs the async/await compiler on all of the pub source code.
-///
-/// It reads from the repo and writes the compiled output into the given build
-/// directory (using the same file names and relative layout). Does not
-/// compile files that haven't changed since the last time they were compiled.
-// TODO(rnystrom): Remove this when #104 is fixed.
-void main(List<String> arguments) {
-  var parser = new ArgParser(allowTrailingOptions: true);
-
-  parser.addFlag("verbose", callback: (value) => verbose = value);
-
-  var force = false;
-  parser.addFlag("force", callback: (value) => force = value);
-
-  var buildDir;
-  parser.addOption("snapshot-build-dir", callback: (value) => buildDir = value);
-
-  try {
-    var rest = parser.parse(arguments).rest;
-    if (rest.isEmpty) {
-      throw new FormatException('Missing generated directory.');
-    } else if (rest.length > 1) {
-      throw new FormatException(
-          'Unexpected arguments: ${rest.skip(1).join(" ")}.');
-    }
-
-    generatedDir = rest.first;
-  } on FormatException catch(ex) {
-    stderr.writeln(ex);
-    stderr.writeln();
-    stderr.writeln(
-        "Usage: dart async_compile.dart [--verbose] [--force] "
-        "[--snapshot-build-dir <dir>] <generated dir>");
-    exit(64);
-  }
-
-  // See what version (i.e. Git commit) of the async-await compiler we
-  // currently have. If this is different from the version that was used to
-  // compile the sources, recompile everything.
-  var currentCommit = _getCurrentCommit();
-
-  var readmePath = p.join(generatedDir, "README.md");
-  var lastCommit;
-  try {
-    var readme = new File(readmePath).readAsStringSync();
-    var match = _commitPattern.firstMatch(readme);
-    if (match == null) {
-      stderr.writeln("Could not find compiler commit hash in README.md.");
-      exit(1);
-    }
-
-    lastCommit = match[0];
-  } on IOException catch (error, stackTrace) {
-    if (verbose) {
-      stderr.writeln("Failed to load $readmePath: $error\n"
-          "${new Trace.from(stackTrace)}");
-    }
-  }
-
-  var numFiles = 0;
-  var numCompiled = 0;
-
-  // Compile any modified or missing files.
-  var sources = new Set();
-  for (var entry in new Directory(sourceDir).listSync(recursive: true)) {
-    if (p.extension(entry.path) != ".dart") continue;
-
-    numFiles++;
-    var relative = p.relative(entry.path, from: sourceDir);
-    sources.add(relative);
-
-    var sourceFile = entry as File;
-    var destPath = p.join(generatedDir, relative);
-    var destFile = new File(destPath);
-    if (force ||
-        currentCommit != lastCommit ||
-        !destFile.existsSync() ||
-        entry.lastModifiedSync().isAfter(destFile.lastModifiedSync())) {
-      _compile(sourceFile.path, sourceFile.readAsStringSync(), destPath);
-      numCompiled++;
-      if (verbose) print("Compiled $relative");
-    }
-  }
-
-  // Delete any previously compiled files whose source no longer exists.
-  for (var entry in new Directory(generatedDir).listSync(recursive: true)) {
-    if (p.extension(entry.path) != ".dart") continue;
-
-    var relative = p.relative(entry.path, from: generatedDir);
-
-    if (!sources.contains(relative)) {
-      _deleteFile(entry.path);
-      if (verbose) print("Deleted  $relative");
-    }
-  }
-
-  // Update the README.
-  if (currentCommit != lastCommit) {
-    _writeFile(readmePath, _README.replaceAll("<<COMMIT>>", currentCommit));
-    if (verbose) print("Updated README.md");
-  }
-
-  if (numCompiled > 0 && buildDir != null) _generateSnapshot(buildDir);
-
-  if (verbose) print("Compiled $numCompiled out of $numFiles files");
-
-  if (hadFailure) exit(1);
-}
-
-String _getCurrentCommit() {
-  var command = "git";
-  var args = ["rev-parse", "HEAD"];
-
-  // Spawning a process on Windows will not look for the executable in the
-  // system path so spawn git through a shell to find it.
-  if (Platform.operatingSystem == "windows") {
-    command = "cmd";
-    args = ["/c", "git"]..addAll(args);
-  }
-
-  var result = Process.runSync(command, args, workingDirectory:
-      p.join(sourceDir, "../../../../third_party/pkg/async_await"));
-  if (result.exitCode != 0) {
-    stderr.writeln("Could not get Git revision of async_await compiler.");
-    exit(1);
-  }
-
-  return result.stdout.trim();
-}
-
-void _compile(String sourcePath, String source, String destPath) {
-  var destDir = new Directory(p.dirname(destPath));
-  destDir.createSync(recursive: true);
-
-  source = _translateAsyncAwait(sourcePath, source);
-  if (source != null) source = _fixDart2jsImports(sourcePath, source, destPath);
-
-  if (source == null) {
-    // If the async compile fails, delete the file so that we don't try to
-    // run the stale previous output and so that we try to recompile it later.
-    _deleteFile(destPath);
-  } else {
-    _writeFile(destPath, source);
-  }
-}
-
-/// Runs the async/await compiler on [source].
-///
-/// Returns the translated Dart code or `null` if the compiler failed.
-String _translateAsyncAwait(String sourcePath, String source) {
-  if (p.isWithin(p.join(sourceDir, "asset"), sourcePath)) {
-    // Don't run the async compiler on the special "asset" source files. These
-    // have preprocessor comments that get discarded by the compiler.
-    return source;
-  }
-
-  try {
-    source = async_await.compile(source);
-
-    // Reformat the result since the compiler ditches all whitespace.
-    // TODO(rnystrom): Remove when this is fixed:
-    // https://github.com/dart-lang/async_await/issues/12
-    var result = new CodeFormatter().format(CodeKind.COMPILATION_UNIT, source);
-    return result.source;
-  } catch (ex) {
-    stderr.writeln("Async compile failed on $sourcePath:\n$ex");
-    hadFailure = true;
-    return null;
-  }
-}
-
-/// Fix relative imports to dart2js libraries.
-///
-/// Pub imports dart2js using relative imports that reach outside of pub's
-/// source tree. Since the build directory is in a different location, we need
-/// to fix those to be valid relative imports from the build directory.
-String _fixDart2jsImports(String sourcePath, String source, String destPath) {
-  var compilerDir = p.url.join(sourceUrl, "../compiler");
-  var relative = p.url.relative(compilerDir,
-      from: p.url.dirname(p.toUri(destPath).toString()));
-  return source.replaceAll(_compilerPattern, "import '$relative");
-}
-
-/// Regenerate the pub snapshot from the async/await-compiled output. We do
-/// this here since the tests need it and it's faster than doing a full SDK
-/// build.
-void _generateSnapshot(String buildDir) {
-  buildDir = p.normalize(buildDir);
-  new Directory(buildDir).createSync(recursive: true);
-
-  var entrypoint = p.join(generatedDir, 'bin/pub.dart');
-  var packageRoot = p.join(buildDir, 'packages');
-  var snapshot = p.join(buildDir, 'dart-sdk/bin/snapshots/pub.dart.snapshot');
-
-  var result = Process.runSync(Platform.executable, [
-    "--package-root=$packageRoot",
-    "--snapshot=$snapshot",
-    entrypoint
-  ]);
-
-  if (result.exitCode != 0) {
-    stderr.writeln("Failed to generate snapshot:");
-    if (result.stderr.trim().isNotEmpty) stderr.writeln(result.stderr);
-    if (result.stdout.trim().isNotEmpty) stderr.writeln(result.stdout);
-    exit(result.exitCode);
-  }
-
-  if (verbose) print("Created pub snapshot");
-}
-
-/// Deletes the file at [path], ignoring any IO errors that occur.
-///
-/// This swallows errors to accommodate multiple compilers running concurrently.
-/// Since they will produce the same output anyway, a failure of one is fine.
-void _deleteFile(String path) {
-  try {
-    new File(path).deleteSync();
-  } on IOException catch (ex) {
-    // Do nothing.
-  }
-}
-
-/// Writes [contents] to [path], ignoring any IO errors that occur.
-///
-/// This swallows errors to accommodate multiple compilers running concurrently.
-/// Since they will produce the same output anyway, a failure of one is fine.
-void _writeFile(String path, String contents) {
-  try {
-    new File(path).writeAsStringSync(contents);
-  } on IOException catch (ex) {
-    // Do nothing.
-  }
-}