Allow dartk to print out binary Kernel IR results to stdout if requested.

pkg/kernel/lib/kernel.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.
 
 /// Conventions for paths:
 ///
 /// - Use the [Uri] class for paths that may have the `file`, `dart` or
 ///   `package` scheme.  Never use [Uri] for relative paths.
 /// - Use [String]s for all filenames and paths that have no scheme prefix.
 /// - Never translate a `dart:` or `package:` URI into a `file:` URI, instead
@@ skipping 11 matching lines @@
 
 export 'ast.dart';
 
 Program loadProgramFromBinary(String path, [Program program]) {
   program ??= new Program();
   new BinaryBuilder(new File(path).readAsBytesSync()).readProgram(program);
   return program;
 }
 
 Future writeProgramToBinary(Program program, String path) {
-  var sink = new File(path).openWrite();
+  var sink;
+  if (path == 'null' || path == 'stdout') {
+    sink = new _ByteBuffer();

[asgerf, 2017/03/31 08:40:16]

Is the wrapper necessary?  Could you try this instead?

var sink = stdout.nonBlocking
new BinaryPrinter(sink).writeProgramFile(program)
return sink.flush()

(i.e with stdout.nonBlocking as the sink, but without closing it)

[Emily Fortuna, 2017/03/31 17:46:55]

Ah, that's MUCH better. I didn't know about that. Thanks!

+  } else {
+    sink = new File(path).openWrite();
+  }
+
   var future;
   try {
     new BinaryPrinter(sink).writeProgramFile(program);
   } finally {
     future = sink.close();
   }
+
+  if (sink is _ByteBuffer) print(sink.takeBytes());

[asgerf, 2017/03/31 08:40:16]

Calling toString on a List<int> normally emits something of form [1, 2, 3, ...].
Is this the intention? I think it would make more sense to print the actual byte
stream.

(With the change I suggested above we will not need the print)

[Emily Fortuna, 2017/03/31 17:46:56]

touche. No I hadn't actually tested consuming this input, so I bet I was about
to run into this problem.

   return future;
 }
 
 void writeLibraryToText(Library library, {String path}) {
   StringBuffer buffer = new StringBuffer();
   new Printer(buffer).writeLibraryFile(library);
   if (path == null) {
     print(buffer);
   } else {
     new File(path).writeAsStringSync('$buffer');
   }
 }
 
 void writeProgramToText(Program program,
     {String path, bool showExternal: false, bool showOffsets: false}) {
   StringBuffer buffer = new StringBuffer();
   new Printer(buffer, showExternal: showExternal, showOffsets: showOffsets)
       .writeProgramFile(program);
   if (path == null) {
     print(buffer);
   } else {
     new File(path).writeAsStringSync('$buffer');
   }
 }
+
+/// Silly wrapper around BytesBuilder that conforms to the Sink interface.

[Johnni Winther, 2017/03/31 06:38:35]

'Silly' -> 'Simple'

[Emily Fortuna, 2017/03/31 17:46:56]

Acknowledged.

+class _ByteBuffer implements Sink<List<int>> {
+  BytesBuilder _builder;
+  bool _open;
+
+  _ByteBuffer()
+      : _open = true,
+        _builder = new BytesBuilder();

[asgerf, 2017/03/31 08:40:16]

You can pass `copy: false` to the BytesBuilder here.

[Emily Fortuna, 2017/03/31 17:46:56]

No longer needed once I took this out.

+
+  void add(List<int> data) {
+    if (_open) {
+      _builder.add(data);
+    }
+  }
+
+  void close() {
+    _open = false;
+  }
+
+  List<int> takeBytes() => _builder.takeBytes();
+}