blob: 0c0a5a8d66f34c801ed99e55a31e66dfb04e0a31 [file] [log] [blame]
// Copyright (c) 2017, 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.
part of dart._vmservice;
/// Set like contains which automatically generated String ids for its items
class NamedLookup<E extends Object> extends Object with IterableMixin<E> {
final IdGenerator _generator;
final _elements = <String, E>{};
final _ids = <E, String>{};
NamedLookup({String prologue = ''})
: _generator = IdGenerator(prologue: prologue);
void add(E e) {
final id = _generator.newId();
_elements[id] = e;
_ids[e] = id;
}
void remove(E e) {
final id = _ids.remove(e)!;
_elements.remove(id);
_generator.release(id);
}
E operator [](String id) => _elements[id]!;
String keyOf(E e) => _ids[e]!;
Iterator<E> get iterator => _ids.keys.iterator;
}
/// Generator for unique ids which recycles expired ones
class IdGenerator {
/// Fixed initial part of the id
final String prologue;
// Ids in use
final _used = <String>{};
/// Ids that has been released (use these before generate new ones)
final _free = <String>{};
/// Next id to generate if no one can be recycled (first use _free);
int _next = 0;
IdGenerator({this.prologue = ''});
/// Returns a new Id (possibly recycled)
String newId() {
var id;
if (_free.isEmpty) {
id = prologue + (_next++).toString();
} else {
id = _free.first;
}
_free.remove(id);
_used.add(id);
return id;
}
/// Releases the id and mark it for recycle
void release(String id) {
if (_used.remove(id)) {
_free.add(id);
}
}
}