Add LimitedBinaryPrinter, tests and switch incremental generator to it.

pkg/front_end/lib/src/incremental/limited_ast_to_binary.dart

+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file

[ahe, 2017/05/22 09:27:05]

I think this file should be moved to package:kernel.

[scheglov, 2017/05/22 20:36:01]

I would not argue about.
But I'm very cautious about putting anything into package:kernel and causing "it
does not belong here" reaction from its authors.
OTOH, it is as well possible to get the opposite reaction.
So, I decided to be conservative and do as little changes to kernel as possible.
I would be happy to move it if this is OK with package:kernel authors.

+// 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 'package:kernel/ast.dart';
+import 'package:kernel/binary/ast_to_binary.dart';
+
+/// Writes libraries that satisfy the [predicate].
+///
+/// Only the referenced subset of canonical names is indexed and written,
+/// so we don't waste time indexing all libraries of a program, when only
+/// a tiny subset is used.
+class LimitedBinaryPrinter extends BinaryPrinter {
+  final LibraryFilter predicate;
+  ReferencesStringIndexer _stringIndexer;
+
+  LimitedBinaryPrinter(Sink<List<int>> sink, this.predicate) : super(sink);
+
+  @override
+  void addCanonicalNamesForLinkTable(List<CanonicalName> list) {
+    _stringIndexer.referencedNames.forEach((name) {
+      if (name.index != -1) return;
+      name.index = list.length;
+      list.add(name);
+    });
+  }
+
+  @override
+  void buildStringIndex(Program program) {
+    program.libraries.where(predicate).forEach((library) {
+      _stringIndexer.scanLibrary(library);
+    });
+    _stringIndexer.finish();
+  }
+
+  @override
+  StringIndexer createStringIndexer() {
+    assert(_stringIndexer == null, 'String indexer can be created only once.');
+    return _stringIndexer ??= new ReferencesStringIndexer();
+  }
+
+  @override
+  bool shouldWriteLibraryCanonicalNames(Library library) {
+    return predicate(library);
+  }
+
+  @override
+  void writeLibraries(Program program) {
+    var librariesToWrite = program.libraries.where(predicate).toList();
+    writeList(librariesToWrite, writeNode);
+  }
+
+  @override
+  void writeNode(Node node) {
+    if (node is Library && !predicate(node)) return;
+    node.accept(this);
+  }
+}
+
+/// Extension of [StringIndexer] that also indexes canonical names of
+/// referenced classes and members.
+class ReferencesStringIndexer extends StringIndexer {
+  final List<CanonicalName> referencedNames = <CanonicalName>[];
+
+  defaultMemberReference(Member node) {
+    _visitReferencedName(node.canonicalName);
+  }
+
+  visitClassReference(Class node) {
+    _visitReferencedName(node.canonicalName);
+  }
+
+  void _visitReferencedName(CanonicalName name) {

[ahe, 2017/05/22 09:27:05]

Rename to handleReferencedName or something as this isn't a visit method.

[scheglov, 2017/05/22 20:36:01]

Done.

+    if (name == null || name.parent == null) return;
+    _visitReferencedName(name.parent);
+    referencedNames.add(name);
+    name.index = -1;
+    put(name.name);
+  }
+}