Floating-point NaN or Infinity values should be allowed as a feature open-source-parsers#209

Introduce 'allowSpecialFloats' for readers and 'useSpecialFloats' for writers, use consistent macro snprintf definition for writers and readers, provide new unit tests for open-source-parsers#209

Author: Dani-Hub

include/json/reader.h

@@ -321,6 +321,9 @@ class JSON_API CharReaderBuilder : public CharReader::Factory {
         the JSON value in the input string.
     - `"rejectDupKeys": false or true`
       - If true, `parse()` returns false when a key is duplicated within an object.
+    - `"allowSpecialFloats": false or true`
+      - If true, special float values (NaNs and infinities) are allowed 
+        and their values are lossfree restorable.
 
     You can examine 'settings_` yourself
     to see the defaults. You can also write and read them just like any

include/json/writer.h

@@ -99,6 +99,10 @@ class JSON_API StreamWriterBuilder : public StreamWriter::Factory {
         Strictly speaking, this is not valid JSON. But when the output is being
         fed to a browser's Javascript, it makes for smaller output and the
         browser can handle the output just fine.
+    - "useSpecialFloats": false or true
+      - If true, outputs non-finite floating point values in the following way:
+        NaN values as "NaN", positive infinity as "Infinity", and negative infinity
+        as "-Infinity".
 
     You can examine 'settings_` yourself
     to see the defaults. You can also write and read them just like any

src/lib_json/json_reader.cpp

@@ -17,10 +17,21 @@
 #include <sstream>
 #include <memory>
 #include <set>
+#include <limits>
 
-#if defined(_MSC_VER) && _MSC_VER < 1500 // VC++ 8.0 and below
+#if defined(_MSC_VER)
+#if !defined(WINCE) && defined(__STDC_SECURE_LIB__) && _MSC_VER >= 1500 // VC++ 9.0 and above 
+#define snprintf sprintf_s
+#elif _MSC_VER >= 1900 // VC++ 14.0 and above
+#define snprintf std::snprintf
+#else
 #define snprintf _snprintf
 #endif
+#elif defined(__ANDROID__)
+#define snprintf snprintf
+#elif __cplusplus >= 201103L
+#define snprintf std::snprintf
+#endif
 
 #if defined(_MSC_VER) && _MSC_VER >= 1400 // VC++ 8.0
 // Disable warning about strdup being deprecated.
@@ -795,15 +806,7 @@ std::string Reader::getLocationLineAndColumn(Location location) const {
   int line, column;
   getLocationLineAndColumn(location, line, column);
   char buffer[18 + 16 + 16 + 1];
-#if defined(_MSC_VER) && defined(__STDC_SECURE_LIB__)
-#if defined(WINCE)
-  _snprintf(buffer, sizeof(buffer), "Line %d, Column %d", line, column);
-#else
-  sprintf_s(buffer, sizeof(buffer), "Line %d, Column %d", line, column);
-#endif
-#else
   snprintf(buffer, sizeof(buffer), "Line %d, Column %d", line, column);
-#endif
   return buffer;
 }
 
@@ -894,6 +897,7 @@ class OurFeatures {
   bool allowSingleQuotes_;
   bool failIfExtra_;
   bool rejectDupKeys_;
+  bool allowSpecialFloats_;
   int stackLimit_;
 };  // OurFeatures
 
@@ -905,6 +909,7 @@ OurFeatures::OurFeatures()
     , allowDroppedNullPlaceholders_(false), allowNumericKeys_(false)
     , allowSingleQuotes_(false)
     , failIfExtra_(false)
+    , allowSpecialFloats_(false)
 {
 }
 
@@ -950,6 +955,9 @@ class OurReader {
     tokenTrue,
     tokenFalse,
     tokenNull,
+    tokenNaN,
+    tokenPosInf,
+    tokenNegInf,
     tokenArraySeparator,
     tokenMemberSeparator,
     tokenComment,
@@ -980,7 +988,7 @@ class OurReader {
   bool readCppStyleComment();
   bool readString();
   bool readStringSingleQuote();
-  void readNumber();
+  bool readNumber();
   bool readValue();
   bool readObject(Token& token);
   bool readArray(Token& token);
@@ -1134,6 +1142,30 @@ bool OurReader::readValue() {
     currentValue().setOffsetLimit(token.end_ - begin_);
     }
     break;
+  case tokenNaN:
+    {
+    Value v(std::numeric_limits<double>::quiet_NaN());
+    currentValue().swapPayload(v);
+    currentValue().setOffsetStart(token.start_ - begin_);
+    currentValue().setOffsetLimit(token.end_ - begin_);
+    }
+    break;
+  case tokenPosInf:
+    {
+    Value v(std::numeric_limits<double>::infinity());
+    currentValue().swapPayload(v);
+    currentValue().setOffsetStart(token.start_ - begin_);
+    currentValue().setOffsetLimit(token.end_ - begin_);
+    }
+    break;
+  case tokenNegInf:
+    {
+    Value v(-std::numeric_limits<double>::infinity());
+    currentValue().swapPayload(v);
+    currentValue().setOffsetStart(token.start_ - begin_);
+    currentValue().setOffsetLimit(token.end_ - begin_);
+    }
+    break;
   case tokenArraySeparator:
   case tokenObjectEnd:
   case tokenArrayEnd:
@@ -1215,8 +1247,12 @@ bool OurReader::readToken(Token& token) {
   case '8':
   case '9':
   case '-':
-    token.type_ = tokenNumber;
-    readNumber();
+    if (readNumber()) {
+      token.type_ = tokenNumber;
+    } else {
+      token.type_ = tokenNegInf;
+      ok = features_.allowSpecialFloats_ && match("nfinity", 7);
+    }
     break;
   case 't':
     token.type_ = tokenTrue;
@@ -1230,6 +1266,22 @@ bool OurReader::readToken(Token& token) {
     token.type_ = tokenNull;
     ok = match("ull", 3);
     break;
+  case 'N':
+    if (features_.allowSpecialFloats_) {
+      token.type_ = tokenNaN;
+      ok = match("aN", 2);
+    } else {
+      ok = false;
+    }
+    break;
+  case 'I':
+    if (features_.allowSpecialFloats_) {
+      token.type_ = tokenPosInf;
+      ok = match("nfinity", 7);
+    } else {
+      ok = false;
+    }
+    break;
   case ',':
     token.type_ = tokenArraySeparator;
     break;
@@ -1330,8 +1382,12 @@ bool OurReader::readCppStyleComment() {
   return true;
 }
 
-void OurReader::readNumber() {
+bool OurReader::readNumber() {
   const char *p = current_;
+  if (p != end_ && *p == 'I') {
+    current_ = ++p;
+    return false;
+  }
   char c = '0'; // stopgap for already consumed character
   // integral part
   while (c >= '0' && c <= '9')
@@ -1350,6 +1406,7 @@ void OurReader::readNumber() {
     while (c >= '0' && c <= '9')
       c = (current_ = p) < end_ ? *p++ : 0;
   }
+  return true;
 }
 bool OurReader::readString() {
   Char c = 0;
@@ -1758,15 +1815,7 @@ std::string OurReader::getLocationLineAndColumn(Location location) const {
   int line, column;
   getLocationLineAndColumn(location, line, column);
   char buffer[18 + 16 + 16 + 1];
-#if defined(_MSC_VER) && defined(__STDC_SECURE_LIB__)
-#if defined(WINCE)
-  _snprintf(buffer, sizeof(buffer), "Line %d, Column %d", line, column);
-#else
-  sprintf_s(buffer, sizeof(buffer), "Line %d, Column %d", line, column);
-#endif
-#else
   snprintf(buffer, sizeof(buffer), "Line %d, Column %d", line, column);
-#endif
   return buffer;
 }
 
@@ -1880,6 +1929,7 @@ CharReader* CharReaderBuilder::newCharReader() const
   features.stackLimit_ = settings_["stackLimit"].asInt();
   features.failIfExtra_ = settings_["failIfExtra"].asBool();
   features.rejectDupKeys_ = settings_["rejectDupKeys"].asBool();
+  features.allowSpecialFloats_ = settings_["allowSpecialFloats"].asBool();
   return new OurCharReader(collectComments, features);
 }
 static void getValidReaderKeys(std::set<std::string>* valid_keys)
@@ -1894,6 +1944,7 @@ static void getValidReaderKeys(std::set<std::string>* valid_keys)
   valid_keys->insert("stackLimit");
   valid_keys->insert("failIfExtra");
   valid_keys->insert("rejectDupKeys");
+  valid_keys->insert("allowSpecialFloats");
 }
 bool CharReaderBuilder::validate(Json::Value* invalid) const
 {
@@ -1927,6 +1978,7 @@ void CharReaderBuilder::strictMode(Json::Value* settings)
   (*settings)["allowSingleQuotes"] = false;
   (*settings)["failIfExtra"] = true;
   (*settings)["rejectDupKeys"] = true;
+  (*settings)["allowSpecialFloats"] = false;
 //! [CharReaderBuilderStrictMode]
 }
 // static
@@ -1942,6 +1994,7 @@ void CharReaderBuilder::setDefaults(Json::Value* settings)
   (*settings)["stackLimit"] = 1000;
   (*settings)["failIfExtra"] = false;
   (*settings)["rejectDupKeys"] = false;
+  (*settings)["allowSpecialFloats"] = false;
 //! [CharReaderBuilderDefaults]
 }
 

src/lib_json/json_writer.cpp

@@ -27,8 +27,14 @@
 #define isfinite std::isfinite
 #endif
 
-#if defined(_MSC_VER) && _MSC_VER < 1500 // VC++ 8.0 and below
+#if defined(_MSC_VER)
+#if !defined(WINCE) && defined(__STDC_SECURE_LIB__) && _MSC_VER >= 1500 // VC++ 9.0 and above 
+#define snprintf sprintf_s
+#elif _MSC_VER >= 1900 // VC++ 14.0 and above
+#define snprintf std::snprintf
+#else
 #define snprintf _snprintf
+#endif
 #elif defined(__ANDROID__)
 #define snprintf snprintf
 #elif __cplusplus >= 201103L
@@ -108,43 +114,35 @@ std::string valueToString(UInt value) {
 
 #endif // # if defined(JSON_HAS_INT64)
 
-std::string valueToString(double value) {
+std::string valueToString(double value, bool useSpecialFloats) {
   // Allocate a buffer that is more than large enough to store the 16 digits of
   // precision requested below.
   char buffer[32];
   int len = -1;
 
-// Print into the buffer. We need not request the alternative representation
-// that always has a decimal point because JSON doesn't distingish the
-// concepts of reals and integers.
-#if defined(_MSC_VER) && defined(__STDC_SECURE_LIB__) // Use secure version with
-                                                      // visual studio 2005 to
-                                                      // avoid warning.
-#if defined(WINCE)
-  len = _snprintf(buffer, sizeof(buffer), "%.17g", value);
-#else
-  len = sprintf_s(buffer, sizeof(buffer), "%.17g", value);
-#endif
-#else
+  // Print into the buffer. We need not request the alternative representation
+  // that always has a decimal point because JSON doesn't distingish the
+  // concepts of reals and integers.
   if (isfinite(value)) {
     len = snprintf(buffer, sizeof(buffer), "%.17g", value);
   } else {
     // IEEE standard states that NaN values will not compare to themselves
     if (value != value) {
-      len = snprintf(buffer, sizeof(buffer), "null");
+      len = snprintf(buffer, sizeof(buffer), useSpecialFloats ? "NaN" : "null");
     } else if (value < 0) {
-      len = snprintf(buffer, sizeof(buffer), "-1e+9999");
+      len = snprintf(buffer, sizeof(buffer), useSpecialFloats ? "-Infinity" : "-1e+9999");
     } else {
-      len = snprintf(buffer, sizeof(buffer), "1e+9999");
+      len = snprintf(buffer, sizeof(buffer), useSpecialFloats ? "Infinity" : "1e+9999");
     }
     // For those, we do not need to call fixNumLoc, but it is fast.
   }
-#endif
   assert(len >= 0);
   fixNumericLocale(buffer, buffer + len);
   return buffer;
 }
 
+std::string valueToString(double value) { return valueToString(value, false); }
+
 std::string valueToString(bool value) { return value ? "true" : "false"; }
 
 std::string valueToQuotedString(const char* value) {
@@ -816,7 +814,8 @@ struct BuiltStyledStreamWriter : public StreamWriter
       CommentStyle::Enum cs,
       std::string const& colonSymbol,
       std::string const& nullSymbol,
-      std::string const& endingLineFeedSymbol);
+      std::string const& endingLineFeedSymbol,
+      bool useSpecialFloats);
   virtual int write(Value const& root, std::ostream* sout);
 private:
   void writeValue(Value const& value);
@@ -843,13 +842,15 @@ struct BuiltStyledStreamWriter : public StreamWriter
   std::string endingLineFeedSymbol_;
   bool addChildValues_ : 1;
   bool indented_ : 1;
+  bool useSpecialFloats_ : 1;
 };
 BuiltStyledStreamWriter::BuiltStyledStreamWriter(
       std::string const& indentation,
       CommentStyle::Enum cs,
       std::string const& colonSymbol,
       std::string const& nullSymbol,
-      std::string const& endingLineFeedSymbol)
+      std::string const& endingLineFeedSymbol,
+      bool useSpecialFloats)
   : rightMargin_(74)
   , indentation_(indentation)
   , cs_(cs)
@@ -858,6 +859,7 @@ BuiltStyledStreamWriter::BuiltStyledStreamWriter(
   , endingLineFeedSymbol_(endingLineFeedSymbol)
   , addChildValues_(false)
   , indented_(false)
+  , useSpecialFloats_(useSpecialFloats)
 {
 }
 int BuiltStyledStreamWriter::write(Value const& root, std::ostream* sout)
@@ -887,7 +889,7 @@ void BuiltStyledStreamWriter::writeValue(Value const& value) {
     pushValue(valueToString(value.asLargestUInt()));
     break;
   case realValue:
-    pushValue(valueToString(value.asDouble()));
+    pushValue(valueToString(value.asDouble(), useSpecialFloats_));
     break;
   case stringValue:
   {
@@ -1102,6 +1104,7 @@ StreamWriter* StreamWriterBuilder::newStreamWriter() const
   std::string cs_str = settings_["commentStyle"].asString();
   bool eyc = settings_["enableYAMLCompatibility"].asBool();
   bool dnp = settings_["dropNullPlaceholders"].asBool();
+  bool usf = settings_["useSpecialFloats"].asBool(); 
   CommentStyle::Enum cs = CommentStyle::All;
   if (cs_str == "All") {
     cs = CommentStyle::All;
@@ -1123,7 +1126,7 @@ StreamWriter* StreamWriterBuilder::newStreamWriter() const
   std::string endingLineFeedSymbol = "";
   return new BuiltStyledStreamWriter(
       indentation, cs,
-      colonSymbol, nullSymbol, endingLineFeedSymbol);
+      colonSymbol, nullSymbol, endingLineFeedSymbol, usf);
 }
 static void getValidWriterKeys(std::set<std::string>* valid_keys)
 {
@@ -1132,6 +1135,7 @@ static void getValidWriterKeys(std::set<std::string>* valid_keys)
   valid_keys->insert("commentStyle");
   valid_keys->insert("enableYAMLCompatibility");
   valid_keys->insert("dropNullPlaceholders");
+  valid_keys->insert("useSpecialFloats");
 }
 bool StreamWriterBuilder::validate(Json::Value* invalid) const
 {
@@ -1162,6 +1166,7 @@ void StreamWriterBuilder::setDefaults(Json::Value* settings)
   (*settings)["indentation"] = "\t";
   (*settings)["enableYAMLCompatibility"] = false;
   (*settings)["dropNullPlaceholders"] = false;
+  (*settings)["useSpecialFloats"] = false;
   //! [StreamWriterBuilderDefaults]
 }