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 #ifndef TOOLS_BLINK_GC_PLUGIN_TRACING_STATUS_H_ 6 #define TOOLS_BLINK_GC_PLUGIN_TRACING_STATUS_H_ 7 8 // TracingStatus is a four-point value ordered by 9 // illegal < unneeded < unknown < needed 10 // 11 // It is used to categorize tracing of fields: 12 // 13 // * illegal field is invalid/illegal to trace. 14 // * unneeded field has type with no traceable fields of its own; 15 // it may have an empty trace() method. Not harmful 16 // to trace, but not needed. 17 // * unknown initial TracingStatus value. 18 // * needed field is a heap reference or an object containing 19 // traceable fields. 20 // 21 // Tracing status |illegal| is considered an error; treating |unneeded| also 22 // as an error would detect and report unnecessary tracing of objects that 23 // probably don't need to be on the Blink GC heap. However, template use 24 // and instantiation can leave us with classes that do have empty trace 25 // methods and no traceable fields -- reporting these as errors/warnings 26 // wouldn't work. Hence, only consider |illegal| as an error TracingStatus 27 // state. 28 class TracingStatus { 29 public: 30 static TracingStatus Illegal() { return kIllegal; } 31 static TracingStatus Unneeded() { return kUnneeded; } 32 static TracingStatus Unknown() { return kUnknown; } 33 static TracingStatus Needed() { return kNeeded; } 34 bool IsIllegal() const { return status_ == kIllegal; } 35 bool IsUnneeded() const { return status_ == kUnneeded; } 36 bool IsUnknown() const { return status_ == kUnknown; } 37 bool IsNeeded() const { return status_ == kNeeded; } 38 TracingStatus LUB(const TracingStatus& other) const { 39 return status_ > other.status_ ? status_ : other.status_; 40 } 41 bool operator==(const TracingStatus& other) const { 42 return status_ == other.status_; 43 } 44 private: 45 enum Status { kIllegal, kUnneeded, kUnknown, kNeeded }; 46 TracingStatus(Status status) : status_(status) {} 47 Status status_; 48 }; 49 50 #endif // TOOLS_BLINK_GC_PLUGIN_TRACING_STATUS_H_ 51
