Function ParseFlagValue

test/common/gtest/gtest.cpp:6593–6619

Parses a string as a command line flag. The string should have the format "--flag=value". When def_optional is true, the "=value" part can be omitted. Returns the value of the flag, or NULL if the parsing failed.

//
// Returns the value of the flag, or NULL if the parsing failed.
const char* ParseFlagValue(const char* str,
                           const char* flag,
                           bool def_optional) {
  // str and flag must not be NULL.
  if (str == NULL || flag == NULL) return NULL;

  // The flag must start with "--" followed by GTEST_FLAG_PREFIX_.
  const std::string flag_str = std::string("--") + GTEST_FLAG_PREFIX_ + flag;
  const size_t flag_len = flag_str.length();
  if (strncmp(str, flag_str.c_str(), flag_len) != 0) return NULL;

  // Skips the flag name.
  const char* flag_end = str + flag_len;

  // When def_optional is true, it's OK to not have a "=value" part.
  if (def_optional && (flag_end[0] == '\0')) {
    return flag_end;
  }

  // If def_optional is true and there are more characters after the
  // flag name, or if def_optional is false, there must be a '=' after
  // the flag name.
  if (flag_end[0] != '=') return NULL;

  // Returns the string after "=".
  return flag_end + 1;
}

// Parses a string for a bool flag, in the form of either
// "--flag=value" or "--flag".