File watching compiler.

dart/pkg/dart2js_incremental/lib/compiler.dart

+// Copyright (c) 2015, 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 'dart:async' show
+    StreamSubscription,
+    EventSink,
+    Future;
+
+import 'package:dart2js_incremental/dart2js_incremental.dart' show
+    IncrementalCompilationFailed,
+    IncrementalCompiler;
+
+import 'package:compiler/src/source_file_provider.dart' show
+    FormattingDiagnosticHandler;
+
+import 'watcher.dart';
+
+main(List<String> arguments) async {
+  Uri originalInput = Uri.base.resolve(arguments.first);
+  var watcher = new Watcher();
+
+  Uri libraryRoot = Uri.base.resolve('sdk/');
+  Uri packageRoot = Uri.base.resolve('packages/');
+
+  FormattingDiagnosticHandler diagnosticHandler =
+      new FormattingDiagnosticHandler();
+
+  OutputProvider outputProvider = new OutputProvider();
+
+  void resilientDiagnosticHandler(
+      Uri uri, int begin, int end, String message, kind) {
+    try {
+      diagnosticHandler(uri, begin, end, message, kind);
+    } catch (e) {
+      String name = diagnosticHandler.provider.relativizeUri(uri);
+      print('$name@$begin+${end - begin}: [$kind] $message}');
+    }
+  }
+
+  Future/*<String | List<int>>*/ inputProvider(Uri uri) {

[kasperl, 2015/01/20 10:23:00]

I probably wouldn't bother with the fancy "type in comments" here since you're
just wrapping the provider method from diagnosticHandler.

[ahe, 2015/01/20 10:45:52]

Done.

+    if (uri.scheme == "file") {
+      watcher.watchFile(uri);
+    }
+    return diagnosticHandler.provider(uri);
+  }
+
+  while (true) {
+    IncrementalCompiler compiler = new IncrementalCompiler(
+        libraryRoot: libraryRoot,
+        packageRoot: packageRoot,
+        inputProvider: inputProvider,
+        diagnosticHandler: resilientDiagnosticHandler,
+        outputProvider: outputProvider);
+
+    if (!await compiler.compile(originalInput)) {
+      print("Compilation failed");
+    } else {
+      print('// Compiled JavaScript:');
+      print(outputProvider['.js']);
+    }
+

[kasperl, 2015/01/20 10:23:00]

Only one newline.

[ahe, 2015/01/20 10:45:52]

Done.

+
+    int updateCount = 1;

[kasperl, 2015/01/20 10:23:00]

0 and then use prefix ++?

[ahe, 2015/01/20 10:45:52]

Done.

+    while (await watcher.hasChanges()) {
+      try {
+        Map<Uri, Uri> changes = watcher.readChanges();
+
+        Stopwatch sw = new Stopwatch()..start();
+        await compiler.compileUpdates(changes);
+
+        String updates = '${compiler.allUpdates()}';
+
+        sw.stop();
+        print('// Patch after ${updateCount++} updates,');
+        print('// computed in ${sw.elapsedMicroseconds/1000000} seconds:');
+        print(updates);
+      } on IncrementalCompilationFailed catch (error) {
+        print("Incremental compilation failed due to:\n${error.reason}");
+        break;
+      }
+    }
+  }
+}
+
+/// Output provider which collect output in [output].

[kasperl, 2015/01/20 10:23:00]

collect -> collects

[ahe, 2015/01/20 10:45:52]

Done.

+class OutputProvider {
+  final Map<String, String> output = new Map<String, String>();
+
+  EventSink<String> call(String name, String extension) {
+    return new StringEventSink((String data) {
+      output['$name.$extension'] = data;
+    });
+  }
+
+  String operator[] (String key) => output[key];

[kasperl, 2015/01/20 10:23:00]

I'd remove the space between [] and (.

[ahe, 2015/01/20 10:45:52]

Done.

+}
+
+/// Helper class to collect sources.
+class StringEventSink implements EventSink<String> {
+  List<String> data = <String>[];
+
+  final Function onClose;
+
+  StringEventSink(this.onClose);
+
+  void add(String event) {
+    if (data == null) throw 'StringEventSink is closed.';
+    data.add(event);
+  }
+
+  void addError(errorEvent, [StackTrace stackTrace]) {
+    throw 'addError($errorEvent, $stackTrace)';
+  }
+
+  void close() {
+    if (data != null) {
+      onClose(data.join());
+      data = null;
+    }
+  }
+}