1// Copyright 2014 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5// NeedsTracing is a three-point value ordered by unneeded < unknown < needed.
6// Unneeded means that the point definitively does not need to be traced.
7
8#ifndef TOOLS_BLINK_GC_PLUGIN_NEEDS_TRACING_H_
9#define TOOLS_BLINK_GC_PLUGIN_NEEDS_TRACING_H_
10
11class NeedsTracing {
12 public:
13  static NeedsTracing Unneeded() { return kUnneeded; }
14  static NeedsTracing Unknown() { return kUnknown; }
15  static NeedsTracing Needed() { return kNeeded; }
16  bool IsUnneeded() { return value_ == kUnneeded; }
17  bool IsUnknown() { return value_ == kUnknown; }
18  bool IsNeeded() { return value_ == kNeeded; }
19  NeedsTracing LUB(const NeedsTracing& other) {
20    return value_ > other.value_ ? value_ : other.value_;
21  }
22  bool operator==(const NeedsTracing& other) {
23    return value_ == other.value_;
24  }
25 private:
26  enum Value { kUnneeded, kUnknown, kNeeded };
27  NeedsTracing(Value value) : value_(value) {}
28  Value value_;
29};
30
31#endif // TOOLS_BLINK_GC_PLUGIN_NEEDS_TRACING_H_
32