Allow options for writing and parsing NaN/Infinity

This adds kWriteNanAndInfFlag to Writer to allow writing of nan,
inf and -inf doubles as "NaN", "Infinity" and "-Infinity",
respectively, and kParseNanAndInfFlag to Reader to allow parsing
of "NaN", "Inf", "Infinity", "-Inf" and "-Infinity". This is part
of issue #36, adding optional support for relaxed JSON syntax.

doc/dom.md

@@ -118,6 +118,7 @@ Parse flags                   | Meaning
 `kParseCommentsFlag`          | Allow one-line `// ...` and multi-line `/* ... */` comments (relaxed JSON syntax).
 `kParseNumbersAsStringsFlag`  | Parse numerical type values as strings.
 `kParseTrailingCommasFlag`    | Allow trailing commas at the end of objects and arrays (relaxed JSON syntax).
+`kParseNanAndInfFlag`         | Allow parsing `NaN`, `Inf`, `Infinity`, `-Inf` and `-Infinity` as `double` values (relaxed JSON syntax).
 
 By using a non-type template parameter, instead of a function parameter, C++ compiler can generate code which is optimized for specified combinations, improving speed, and reducing code size (if only using a single specialization). The downside is the flags needed to be determined in compile-time.
 

include/rapidjson/reader.h

@@ -23,6 +23,7 @@
 #include "internal/meta.h"
 #include "internal/stack.h"
 #include "internal/strtod.h"
+#include <limits>
 
 #if defined(RAPIDJSON_SIMD) && defined(_MSC_VER)
 #include <intrin.h>
@@ -150,6 +151,7 @@ enum ParseFlag {
     kParseCommentsFlag = 32,        //!< Allow one-line (//) and multi-line (/**/) comments.
     kParseNumbersAsStringsFlag = 64,    //!< Parse all numbers (ints/doubles) as strings.
     kParseTrailingCommasFlag = 128, //!< Allow trailing commas at the end of objects and arrays.
+    kParseNanAndInfFlag = 256,      //!< Allow parsing NaN, Inf, Infinity, -Inf and -Infinity as doubles.
     kParseDefaultFlags = RAPIDJSON_PARSE_DEFAULT_FLAGS  //!< Default parse flags. Can be customized by defining RAPIDJSON_PARSE_DEFAULT_FLAGS
 };
 
@@ -1137,6 +1139,8 @@ private:
                 (parseFlags & kParseInsituFlag) == 0> s(*this, copy.s);
 
         size_t startOffset = s.Tell();
+        double d = 0.0;
+        bool useNanOrInf = false;
 
         // Parse minus
         bool minus = Consume(s, '-');
@@ -1178,12 +1182,26 @@ private:
                     significandDigit++;
                 }
         }
+        // Parse NaN or Infinity here
+        else if ((parseFlags & kParseNanAndInfFlag) && RAPIDJSON_LIKELY((s.Peek() == 'I' || s.Peek() == 'N'))) {
+            useNanOrInf = true;
+            if (RAPIDJSON_LIKELY(Consume(s, 'N') && Consume(s, 'a') && Consume(s, 'N'))) {
+                d = std::numeric_limits<double>::quiet_NaN();
+            }
+            else if (RAPIDJSON_LIKELY(Consume(s, 'I') && Consume(s, 'n') && Consume(s, 'f'))) {
+                d = (minus ? -std::numeric_limits<double>::infinity() : std::numeric_limits<double>::infinity());
+                if (RAPIDJSON_UNLIKELY(s.Peek() == 'i' && !(Consume(s, 'i') && Consume(s, 'n')
+                                                            && Consume(s, 'i') && Consume(s, 't') && Consume(s, 'y'))))
+                    RAPIDJSON_PARSE_ERROR(kParseErrorValueInvalid, s.Tell());
+            }
+            else
+                RAPIDJSON_PARSE_ERROR(kParseErrorValueInvalid, s.Tell());
+        }
         else
             RAPIDJSON_PARSE_ERROR(kParseErrorValueInvalid, s.Tell());
 
         // Parse 64bit int
         bool useDouble = false;
-        double d = 0.0;
         if (use64bit) {
             if (minus)
                 while (RAPIDJSON_LIKELY(s.Peek() >= '0' && s.Peek() <= '9')) {
@@ -1346,6 +1364,9 @@ private:
 
                cont = handler.Double(minus ? -d : d);
            }
+           else if (useNanOrInf) {
+               cont = handler.Double(d);
+           }
            else {
                if (use64bit) {
                    if (minus)

include/rapidjson/writer.h

@@ -62,6 +62,7 @@ RAPIDJSON_NAMESPACE_BEGIN
 enum WriteFlag {
     kWriteNoFlags = 0,              //!< No flags are set.
     kWriteValidateEncodingFlag = 1, //!< Validate encoding of JSON strings.
+    kWriteNanAndInfFlag = 2,        //!< Allow writing of Inf, -Inf and NaN.
     kWriteDefaultFlags = RAPIDJSON_WRITE_DEFAULT_FLAGS  //!< Default write flags. Can be customized by defining RAPIDJSON_WRITE_DEFAULT_FLAGS
 };
 
@@ -319,9 +320,25 @@ protected:
     }
 
     bool WriteDouble(double d) {
-        if (internal::Double(d).IsNanOrInf())
-            return false;
-        
+        if (internal::Double(d).IsNanOrInf()) {
+            if (!(writeFlags & kWriteNanAndInfFlag))
+                return false;
+            if (internal::Double(d).IsNan()) {
+                PutReserve(*os_, 3);
+                PutUnsafe(*os_, 'N'); PutUnsafe(*os_, 'a'); PutUnsafe(*os_, 'N');
+                return true;
+            }
+            if (internal::Double(d).Sign()) {
+                PutReserve(*os_, 9);
+                PutUnsafe(*os_, '-');
+            }
+            else
+                PutReserve(*os_, 8);
+            PutUnsafe(*os_, 'I'); PutUnsafe(*os_, 'n'); PutUnsafe(*os_, 'f');
+            PutUnsafe(*os_, 'i'); PutUnsafe(*os_, 'n'); PutUnsafe(*os_, 'i'); PutUnsafe(*os_, 't'); PutUnsafe(*os_, 'y');
+            return true;
+        }
+
         char buffer[25];
         char* end = internal::dtoa(d, buffer, maxDecimalPlaces_);
         PutReserve(*os_, static_cast<size_t>(end - buffer));
@@ -489,8 +506,25 @@ inline bool Writer<StringBuffer>::WriteUint64(uint64_t u) {
 
 template<>
 inline bool Writer<StringBuffer>::WriteDouble(double d) {
-    if (internal::Double(d).IsNanOrInf())
-        return false;
+    if (internal::Double(d).IsNanOrInf()) {
+        // Note: This code path can only be reached if (RAPIDJSON_WRITE_DEFAULT_FLAGS & kWriteNanAndInfFlag).
+        if (!(kWriteDefaultFlags & kWriteNanAndInfFlag))
+            return false;
+        if (internal::Double(d).IsNan()) {
+            PutReserve(*os_, 3);
+            PutUnsafe(*os_, 'N'); PutUnsafe(*os_, 'a'); PutUnsafe(*os_, 'N');
+            return true;
+        }
+        if (internal::Double(d).Sign()) {
+            PutReserve(*os_, 9);
+            PutUnsafe(*os_, '-');
+        }
+        else
+            PutReserve(*os_, 8);
+        PutUnsafe(*os_, 'I'); PutUnsafe(*os_, 'n'); PutUnsafe(*os_, 'f');
+        PutUnsafe(*os_, 'i'); PutUnsafe(*os_, 'n'); PutUnsafe(*os_, 'i'); PutUnsafe(*os_, 't'); PutUnsafe(*os_, 'y');
+        return true;
+    }
     
     char *buffer = os_->Push(25);
     char* end = internal::dtoa(d, buffer, maxDecimalPlaces_);

test/unittest/readertest.cpp

@@ -19,6 +19,8 @@
 #include "rapidjson/internal/itoa.h"
 #include "rapidjson/memorystream.h"
 
+#include <limits>
+
 using namespace rapidjson;
 
 #ifdef __GNUC__
@@ -1774,6 +1776,69 @@ TEST(Reader, TrailingCommaHandlerTerminationIterative) {
     TestTrailingCommaHandlerTermination<kParseIterativeFlag>();
 }
 
+TEST(Reader, ParseNanAndInfinity) {
+#define TEST_NAN_INF(str, x) \
+    { \
+        { \
+            StringStream s(str); \
+            ParseDoubleHandler h; \
+            Reader reader; \
+            ASSERT_EQ(kParseErrorNone, reader.Parse<kParseNanAndInfFlag>(s, h).Code()); \
+            EXPECT_EQ(1u, h.step_); \
+            internal::Double e(x), a(h.actual_); \
+            EXPECT_EQ(e.IsNan(), a.IsNan()); \
+            EXPECT_EQ(e.IsInf(), a.IsInf()); \
+            if (!e.IsNan()) \
+                EXPECT_EQ(e.Sign(), a.Sign()); \
+        } \
+        { \
+            const char* json = "{ \"naninfdouble\": " str " } "; \
+            StringStream s(json); \
+            NumbersAsStringsHandler h(str); \
+            Reader reader; \
+            EXPECT_TRUE(reader.Parse<kParseNumbersAsStringsFlag|kParseNanAndInfFlag>(s, h)); \
+        } \
+        { \
+            char* json = StrDup("{ \"naninfdouble\": " str " } "); \
+            InsituStringStream s(json); \
+            NumbersAsStringsHandler h(str); \
+            Reader reader; \
+            EXPECT_TRUE(reader.Parse<kParseInsituFlag|kParseNumbersAsStringsFlag|kParseNanAndInfFlag>(s, h)); \
+            free(json); \
+        } \
+    }
+#define TEST_NAN_INF_ERROR(errorCode, str, errorOffset) \
+    { \
+        int streamPos = errorOffset; \
+        char buffer[1001]; \
+        strncpy(buffer, str, 1000); \
+        InsituStringStream s(buffer); \
+        BaseReaderHandler<> h; \
+        Reader reader; \
+        EXPECT_FALSE(reader.Parse<kParseNanAndInfFlag>(s, h)); \
+        EXPECT_EQ(errorCode, reader.GetParseErrorCode());\
+        EXPECT_EQ(errorOffset, reader.GetErrorOffset());\
+        EXPECT_EQ(streamPos, s.Tell());\
+    }
+
+    double nan = std::numeric_limits<double>::quiet_NaN();
+    double inf = std::numeric_limits<double>::infinity();
+
+    TEST_NAN_INF("NaN", nan);
+    TEST_NAN_INF("-NaN", nan);
+    TEST_NAN_INF("Inf", inf);
+    TEST_NAN_INF("Infinity", inf);
+    TEST_NAN_INF("-Inf", -inf);
+    TEST_NAN_INF("-Infinity", -inf);
+    TEST_NAN_INF_ERROR(kParseErrorValueInvalid, "nan", 1);
+    TEST_NAN_INF_ERROR(kParseErrorValueInvalid, "-nan", 1);
+    TEST_NAN_INF_ERROR(kParseErrorValueInvalid, "NAN", 1);
+    TEST_NAN_INF_ERROR(kParseErrorValueInvalid, "-Infinty", 6);
+
+#undef TEST_NAN_INF_ERROR
+#undef TEST_NAN_INF
+}
+
 #ifdef __GNUC__
 RAPIDJSON_DIAG_POP
 #endif

test/unittest/writertest.cpp

@@ -446,9 +446,15 @@ TEST(Writer, NaN) {
     double nan = zero / zero;
     EXPECT_TRUE(internal::Double(nan).IsNan());
     StringBuffer buffer;
-    Writer<StringBuffer> writer(buffer);
-    EXPECT_FALSE(writer.Double(nan));
-
+    {
+        Writer<StringBuffer> writer(buffer);
+        EXPECT_FALSE(writer.Double(nan));
+    }
+    {
+        Writer<StringBuffer, UTF8<>, UTF8<>, CrtAllocator, kWriteNanAndInfFlag> writer(buffer);
+        EXPECT_TRUE(writer.Double(nan));
+        EXPECT_STREQ("NaN", buffer.GetString());
+    }
     GenericStringBuffer<UTF16<> > buffer2;
     Writer<GenericStringBuffer<UTF16<> > > writer2(buffer2);
     EXPECT_FALSE(writer2.Double(nan));
@@ -460,12 +466,21 @@ TEST(Writer, Inf) {
     StringBuffer buffer;
     {
         Writer<StringBuffer> writer(buffer);
-        EXPECT_FALSE(writer.Double(inf));        
+        EXPECT_FALSE(writer.Double(inf));
     }
     {
         Writer<StringBuffer> writer(buffer);
         EXPECT_FALSE(writer.Double(-inf));
     }
+    {
+        Writer<StringBuffer, UTF8<>, UTF8<>, CrtAllocator, kWriteNanAndInfFlag> writer(buffer);
+        EXPECT_TRUE(writer.Double(inf));
+    }
+    {
+        Writer<StringBuffer, UTF8<>, UTF8<>, CrtAllocator, kWriteNanAndInfFlag> writer(buffer);
+        EXPECT_TRUE(writer.Double(-inf));
+    }
+    EXPECT_STREQ("Infinity-Infinity", buffer.GetString());
 }
 
 TEST(Writer, RawValue) {