Regenerate pub sources.

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

Index: sdk/lib/_internal/pub_generated/bin/async_compile.dart
diff --git a/sdk/lib/_internal/pub_generated/bin/async_compile.dart b/sdk/lib/_internal/pub_generated/bin/async_compile.dart
index 15acba1ca63cf33ba2b775d4a33e75aa5bc150ba..a029c521294cef1603afbae148655e364cf1c8c6 100644
--- a/sdk/lib/_internal/pub_generated/bin/async_compile.dart
+++ b/sdk/lib/_internal/pub_generated/bin/async_compile.dart
@@ -1,21 +1,55 @@
+// 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: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.
 final generatedDir = p.join(p.dirname(sourceDir), 'pub_generated');
+
+/// `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}");
+
+/// 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;
+
   try {
     var rest = parser.parse(arguments).rest;
     if (rest.isEmpty) {
@@ -24,6 +58,7 @@ void main(List<String> arguments) {
       throw new FormatException(
           'Unexpected arguments: ${rest.skip(1).join(" ")}.');
     }
+
     buildDir = rest.first;
   } on FormatException catch (ex) {
     stderr.writeln(ex);
@@ -32,7 +67,12 @@ void main(List<String> arguments) {
         "Usage: dart async_compile.dart [--verbose] [--force] <build 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;
   var readme = new File(readmePath).readAsStringSync();
@@ -41,15 +81,21 @@ void main(List<String> arguments) {
     stderr.writeln("Could not find compiler commit hash in README.md.");
     exit(1);
   }
+
   lastCommit = match[0];
+
   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);
@@ -62,30 +108,44 @@ void main(List<String> arguments) {
       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) {
     readme = readme.replaceAll(_commitPattern, currentCommit);
     _writeFile(readmePath, readme);
     if (verbose) print("Updated README.md");
   }
+
   if (numCompiled > 0) _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,
@@ -94,25 +154,42 @@ String _getCurrentCommit() {
     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) {
@@ -121,35 +198,63 @@ String _translateAsyncAwait(String sourcePath, String source) {
     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);
+
   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) {}
+  } 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) {}
+  } on IOException catch (ex) {
+    // Do nothing.
+  }
 }