chromium之pickle

pickle谷歌翻译成泡菜

醉了，看一下头文件的说明

// This class provides facilities for basic binary value packing and unpacking.

献丑一下翻译一下：此类提供基本的二进制打包、解包的功能。

看一下头文件提供的函数

class Pickle {
 public:
  virtual ~Pickle();

  // Initialize a Pickle object using the default header size.
  Pickle();

  // Initialize a Pickle object with the specified header size in bytes, which
  // must be greater-than-or-equal-to sizeof(Pickle::Header).  The header size
  // will be rounded up to ensure that the header size is 32bit-aligned.
  explicit Pickle(int header_size);

  // Initializes a Pickle from a const block of data.  The data is not copied;
  // instead the data is merely referenced by this Pickle.  Only const methods
  // should be used on the Pickle when initialized this way.  The header
  // padding size is deduced from the data length.
  Pickle(const char* data, int data_len);

  // Initializes a Pickle as a deep copy of another Pickle.
  Pickle(const Pickle& other);

  // Performs a deep copy.
  Pickle& operator=(const Pickle& other);

  // Returns the size of the Pickle's data.
  int size() const { return static_cast<int>(header_size_ +
                                             header_->payload_size); }

  // Returns the data for this Pickle.
  const void* data() const { return header_; }

  // Methods for reading the payload of the Pickle.  To read from the start of
  // the Pickle, initialize *iter to NULL.  If successful, these methods return
  // true.  Otherwise, false is returned to indicate that the result could not
  // be extracted.
  bool ReadBool(void** iter, bool* result) const;
  bool ReadInt(void** iter, int* result) const;
  bool ReadLong(void** iter, long* result) const;
  bool ReadSize(void** iter, size_t* result) const;
  bool ReadUInt32(void** iter, uint32* result) const;
  bool ReadInt64(void** iter, int64* result) const;
  bool ReadIntPtr(void** iter, intptr_t* result) const;
  bool ReadString(void** iter, std::string* result) const;
  bool ReadWString(void** iter, std::wstring* result) const;
  bool ReadString16(void** iter, string16* result) const;
  bool ReadData(void** iter, const char** data, int* length) const;
  bool ReadBytes(void** iter, const char** data, int length) const;

  // Safer version of ReadInt() checks for the result not being negative.
  // Use it for reading the object sizes.
  bool ReadLength(void** iter, int* result) const;

  // Methods for adding to the payload of the Pickle.  These values are
  // appended to the end of the Pickle's payload.  When reading values from a
  // Pickle, it is important to read them in the order in which they were added
  // to the Pickle.
  bool WriteBool(bool value) {
    return WriteInt(value ? 1 : 0);
  }
  bool WriteInt(int value) {
    return WriteBytes(&value, sizeof(value));
  }
  bool WriteLong(long value) {
    return WriteBytes(&value, sizeof(value));
  }
  bool WriteSize(size_t value) {
    return WriteBytes(&value, sizeof(value));
  }
  bool WriteUInt32(uint32 value) {
    return WriteBytes(&value, sizeof(value));
  }
  bool WriteInt64(int64 value) {
    return WriteBytes(&value, sizeof(value));
  }
  bool WriteIntPtr(intptr_t value) {
    return WriteBytes(&value, sizeof(value));
  }
  bool WriteString(const std::string& value);
  bool WriteWString(const std::wstring& value);
  bool WriteString16(const string16& value);
  bool WriteData(const char* data, int length);
  bool WriteBytes(const void* data, int data_len);

  // .....
}；

再瞄一下测试用例，这样这个类是干嘛的，就心里有数了

const int testint = 2093847192;
const std::string teststr("Hello world");  // note non-aligned string length
const std::wstring testwstr(L"Hello, world");
const char testdata[] = "AAA\0BBB\0";
const int testdatalen = arraysize(testdata) - 1;
const bool testbool1 = false;
const bool testbool2 = true;

// checks that the result
void VerifyResult(const Pickle& pickle) {
  void* iter = NULL;

  int outint;
  EXPECT_TRUE(pickle.ReadInt(&iter, &outint));
  EXPECT_EQ(testint, outint);

  std::string outstr;
  EXPECT_TRUE(pickle.ReadString(&iter, &outstr));
  EXPECT_EQ(teststr, outstr);

  std::wstring outwstr;
  EXPECT_TRUE(pickle.ReadWString(&iter, &outwstr));
  EXPECT_EQ(testwstr, outwstr);

  bool outbool;
  EXPECT_TRUE(pickle.ReadBool(&iter, &outbool));
  EXPECT_EQ(testbool1, outbool);
  EXPECT_TRUE(pickle.ReadBool(&iter, &outbool));
  EXPECT_EQ(testbool2, outbool);

  const char* outdata;
  int outdatalen;
  EXPECT_TRUE(pickle.ReadData(&iter, &outdata, &outdatalen));
  EXPECT_EQ(testdatalen, outdatalen);
  EXPECT_EQ(memcmp(testdata, outdata, outdatalen), 0);

  EXPECT_TRUE(pickle.ReadData(&iter, &outdata, &outdatalen));
  EXPECT_EQ(testdatalen, outdatalen);
  EXPECT_EQ(memcmp(testdata, outdata, outdatalen), 0);

  // reads past the end should fail
  EXPECT_FALSE(pickle.ReadInt(&iter, &outint));
}

}  // namespace

TEST(PickleTest, EncodeDecode) {
  Pickle pickle;

  EXPECT_TRUE(pickle.WriteInt(testint));
  EXPECT_TRUE(pickle.WriteString(teststr));
  EXPECT_TRUE(pickle.WriteWString(testwstr));
  EXPECT_TRUE(pickle.WriteBool(testbool1));
  EXPECT_TRUE(pickle.WriteBool(testbool2));
  EXPECT_TRUE(pickle.WriteData(testdata, testdatalen));

  // Over allocate BeginWriteData so we can test TrimWriteData.
  char* dest = pickle.BeginWriteData(testdatalen + 100);
  EXPECT_TRUE(dest);
  memcpy(dest, testdata, testdatalen);

  pickle.TrimWriteData(testdatalen);

  VerifyResult(pickle);

  // test copy constructor
  Pickle pickle2(pickle);
  VerifyResult(pickle2);

  // test operator=
  Pickle pickle3;
  pickle3 = pickle;
  VerifyResult(pickle3);
}