Make RTCStatsReport::ToString() return JSON-parseable string.

webrtc/stats/rtcstats.cc

 /*
  *  Copyright 2016 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #include "webrtc/api/stats/rtcstats.h"
 
+#include <iomanip>
 #include <sstream>
 
 #include "webrtc/rtc_base/stringencode.h"
 
 namespace webrtc {
 
 namespace {
 
-// Produces "{ a, b, c }". Works for non-vector |RTCStatsMemberInterface::Type|
+// Produces "[a,b,c]". Works for non-vector |RTCStatsMemberInterface::Type|
 // types.
 template<typename T>
 std::string VectorToString(const std::vector<T>& vector) {
   if (vector.empty())
-    return "{}";
+    return "[]";
   std::ostringstream oss;
-  oss << "{ " << rtc::ToString<T>(vector[0]);
+  oss << "[" << rtc::ToString<T>(vector[0]);
   for (size_t i = 1; i < vector.size(); ++i) {
-    oss << ", " << rtc::ToString<T>(vector[i]);
+    oss << "," << rtc::ToString<T>(vector[i]);
   }
-  oss << " }";
+  oss << "]";
   return oss.str();
 }
 
-// Produces "{ \"a\", \"b\", \"c\" }". Works for vectors of both const char* and
+// Produces "[\"a\",\"b\",\"c\"]". Works for vectors of both const char* and
 // std::string element types.
 template<typename T>
 std::string VectorOfStringsToString(const std::vector<T>& strings) {
   if (strings.empty())
-    return "{}";
+    return "[]";
   std::ostringstream oss;
-  oss << "{ \"" << rtc::ToString<T>(strings[0]) << '\"';
+  oss << "[\"" << rtc::ToString<T>(strings[0]) << '\"';
   for (size_t i = 1; i < strings.size(); ++i) {
-    oss << ", \"" << rtc::ToString<T>(strings[i]) << '\"';
+    oss << ",\"" << rtc::ToString<T>(strings[i]) << '\"';
   }
-  oss << " }";
+  oss << "]";
   return oss.str();
 }
 
+template <typename T>
+std::string ToStringAsDouble(const T value) {
+  // JSON represents numbers as floating point numbers with about 15 decimal
+  // digits of precision.
+  const int JSON_PRECISION = 16;
+  std::ostringstream oss;
+  oss << std::setprecision(JSON_PRECISION) << static_cast<double>(value);
+  return oss.str();
+}
+
+template <typename T>
+std::string VectorToStringAsDouble(const std::vector<T>& vector) {
+  if (vector.empty())
+    return "[]";
+  std::ostringstream oss;
+  oss << "[" << ToStringAsDouble<T>(vector[0]);
+  for (size_t i = 1; i < vector.size(); ++i) {
+    oss << "," << ToStringAsDouble<T>(vector[i]);
+  }
+  oss << "]";
+  return oss.str();
+}
+
 }  // namespace
 
 bool RTCStats::operator==(const RTCStats& other) const {
   if (type() != other.type() || id() != other.id())
     return false;
   std::vector<const RTCStatsMemberInterface*> members = Members();
   std::vector<const RTCStatsMemberInterface*> other_members = other.Members();
   RTC_DCHECK_EQ(members.size(), other_members.size());
   for (size_t i = 0; i < members.size(); ++i) {
     const RTCStatsMemberInterface* member = members[i];
     const RTCStatsMemberInterface* other_member = other_members[i];
     RTC_DCHECK_EQ(member->type(), other_member->type());
     RTC_DCHECK_EQ(member->name(), other_member->name());
     if (*member != *other_member)
       return false;
   }
   return true;
 }
 
 bool RTCStats::operator!=(const RTCStats& other) const {
   return !(*this == other);
 }
 
-std::string RTCStats::ToString() const {
+std::string RTCStats::ToJson() const {
   std::ostringstream oss;
-  oss << type() << " {\n  id: \"" << id_ << "\"\n  timestamp: "
-      << timestamp_us_ << '\n';
+  oss << "{\"type\":\"" << type() << "\","
+      << "\"id\":\"" << id_ << "\","
+      << "\"timestamp\":" << timestamp_us_;
   for (const RTCStatsMemberInterface* member : Members()) {
-    oss << "  " << member->name() << ": ";
     if (member->is_defined()) {
+      oss << ",\"" << member->name() << "\":";
       if (member->is_string())
-        oss << '"' << member->ValueToString() << "\"\n";
+        oss << '"' << member->ValueToJson() << '"';
       else
-        oss << member->ValueToString() << '\n';
-    } else {
-      oss << "undefined\n";
+        oss << member->ValueToJson();
     }
   }
-  oss << '}';
+  oss << "}";
   return oss.str();
 }
 
 std::vector<const RTCStatsMemberInterface*> RTCStats::Members() const {
   return MembersOfThisObjectAndAncestors(0);
 }
 
 std::vector<const RTCStatsMemberInterface*>
 RTCStats::MembersOfThisObjectAndAncestors(
     size_t additional_capacity) const {
   std::vector<const RTCStatsMemberInterface*> members;
   members.reserve(additional_capacity);
   return members;
 }
 
-#define WEBRTC_DEFINE_RTCSTATSMEMBER(T, type, is_seq, is_str, to_str)          \
-  template<>                                                                   \
+#define WEBRTC_DEFINE_RTCSTATSMEMBER(T, type, is_seq, is_str, to_str, to_json) \
+  template <>                                                                  \
   const RTCStatsMemberInterface::Type RTCStatsMember<T>::kType =               \
       RTCStatsMemberInterface::type;                                           \
-  template<>                                                                   \
-  bool RTCStatsMember<T>::is_sequence() const { return is_seq; }               \
-  template<>                                                                   \
-  bool RTCStatsMember<T>::is_string() const { return is_str; }                 \
-  template<>                                                                   \
+  template <>                                                                  \
+  bool RTCStatsMember<T>::is_sequence() const {                                \
+    return is_seq;                                                             \
+  }                                                                            \
+  template <>                                                                  \
+  bool RTCStatsMember<T>::is_string() const {                                  \
+    return is_str;                                                             \
+  }                                                                            \
+  template <>                                                                  \
   std::string RTCStatsMember<T>::ValueToString() const {                       \
     RTC_DCHECK(is_defined_);                                                   \
     return to_str;                                                             \
+  }                                                                            \
+  template <>                                                                  \
+  std::string RTCStatsMember<T>::ValueToJson() const {                         \
+    RTC_DCHECK(is_defined_);                                                   \
+    return to_json;                                                            \
   }
 
-WEBRTC_DEFINE_RTCSTATSMEMBER(bool, kBool, false, false,
+WEBRTC_DEFINE_RTCSTATSMEMBER(bool,
+                             kBool,
+                             false,
+                             false,
+                             rtc::ToString(value_),
                              rtc::ToString(value_));
-WEBRTC_DEFINE_RTCSTATSMEMBER(int32_t, kInt32, false, false,
+WEBRTC_DEFINE_RTCSTATSMEMBER(int32_t,
+                             kInt32,
+                             false,
+                             false,
+                             rtc::ToString(value_),
                              rtc::ToString(value_));
-WEBRTC_DEFINE_RTCSTATSMEMBER(uint32_t, kUint32, false, false,
+WEBRTC_DEFINE_RTCSTATSMEMBER(uint32_t,
+                             kUint32,
+                             false,
+                             false,
+                             rtc::ToString(value_),
                              rtc::ToString(value_));
-WEBRTC_DEFINE_RTCSTATSMEMBER(int64_t, kInt64, false, false,
-                             rtc::ToString(value_));
-WEBRTC_DEFINE_RTCSTATSMEMBER(uint64_t, kUint64, false, false,
-                             rtc::ToString(value_));
-WEBRTC_DEFINE_RTCSTATSMEMBER(double, kDouble, false, false,
-                             rtc::ToString(value_));
-WEBRTC_DEFINE_RTCSTATSMEMBER(std::string, kString, false, true,
+WEBRTC_DEFINE_RTCSTATSMEMBER(int64_t,
+                             kInt64,
+                             false,
+                             false,
+                             rtc::ToString(value_),
+                             ToStringAsDouble(value_));
+WEBRTC_DEFINE_RTCSTATSMEMBER(uint64_t,
+                             kUint64,
+                             false,
+                             false,
+                             rtc::ToString(value_),
+                             ToStringAsDouble(value_));
+WEBRTC_DEFINE_RTCSTATSMEMBER(double,
+                             kDouble,
+                             false,
+                             false,
+                             rtc::ToString(value_),
+                             ToStringAsDouble(value_));
+WEBRTC_DEFINE_RTCSTATSMEMBER(std::string,
+                             kString,
+                             false,
+                             true,
+                             value_,
                              value_);
-WEBRTC_DEFINE_RTCSTATSMEMBER(
-    std::vector<bool>, kSequenceBool, true, false,
-    VectorToString(value_));
-WEBRTC_DEFINE_RTCSTATSMEMBER(
-    std::vector<int32_t>, kSequenceInt32, true, false,
-    VectorToString(value_));
-WEBRTC_DEFINE_RTCSTATSMEMBER(
-    std::vector<uint32_t>, kSequenceUint32, true, false,
-    VectorToString(value_));
-WEBRTC_DEFINE_RTCSTATSMEMBER(
-    std::vector<int64_t>, kSequenceInt64, true, false,
-    VectorToString(value_));
-WEBRTC_DEFINE_RTCSTATSMEMBER(
-    std::vector<uint64_t>, kSequenceUint64, true, false,
-    VectorToString(value_));
-WEBRTC_DEFINE_RTCSTATSMEMBER(
-    std::vector<double>, kSequenceDouble, true, false,
-    VectorToString(value_));
-WEBRTC_DEFINE_RTCSTATSMEMBER(
-    std::vector<std::string>, kSequenceString, true, false,
-    VectorOfStringsToString(value_));
+WEBRTC_DEFINE_RTCSTATSMEMBER(std::vector<bool>,
+                             kSequenceBool,
+                             true,
+                             false,
+                             VectorToString(value_),
+                             VectorToString(value_));
+WEBRTC_DEFINE_RTCSTATSMEMBER(std::vector<int32_t>,
+                             kSequenceInt32,
+                             true,
+                             false,
+                             VectorToString(value_),
+                             VectorToString(value_));
+WEBRTC_DEFINE_RTCSTATSMEMBER(std::vector<uint32_t>,
+                             kSequenceUint32,
+                             true,
+                             false,
+                             VectorToString(value_),
+                             VectorToString(value_));
+WEBRTC_DEFINE_RTCSTATSMEMBER(std::vector<int64_t>,
+                             kSequenceInt64,
+                             true,
+                             false,
+                             VectorToString(value_),
+                             VectorToStringAsDouble(value_));
+WEBRTC_DEFINE_RTCSTATSMEMBER(std::vector<uint64_t>,
+                             kSequenceUint64,
+                             true,
+                             false,
+                             VectorToString(value_),
+                             VectorToStringAsDouble(value_));
+WEBRTC_DEFINE_RTCSTATSMEMBER(std::vector<double>,
+                             kSequenceDouble,
+                             true,
+                             false,
+                             VectorToString(value_),
+                             VectorToStringAsDouble(value_));
+WEBRTC_DEFINE_RTCSTATSMEMBER(std::vector<std::string>,
+                             kSequenceString,
+                             true,
+                             false,
+                             VectorOfStringsToString(value_),
+                             VectorOfStringsToString(value_));
 
 }  // namespace webrtc