reinforce readToken function and add simple tests (#1012)

Author: dota17

src/lib_json/json_reader.cpp

@@ -1227,6 +1227,14 @@ bool OurReader::readToken(Token& token) {
       ok = features_.allowSpecialFloats_ && match("nfinity", 7);
     }
     break;
+  case '+':
+    if (readNumber(true)) {
+      token.type_ = tokenNumber;
+    } else {
+      token.type_ = tokenPosInf;
+      ok = features_.allowSpecialFloats_ && match("nfinity", 7);
+    }
+    break;
   case 't':
     token.type_ = tokenTrue;
     ok = match("rue", 3);

src/test_lib_json/main.cpp

@@ -2451,17 +2451,19 @@ JSONTEST_FIXTURE(CharReaderAllowSpecialFloatsTest, issue209) {
   Json::String errs;
   Json::CharReader* reader(b.newCharReader());
   {
-    char const doc[] = "{\"a\":NaN,\"b\":Infinity,\"c\":-Infinity}";
+    char const doc[] = "{\"a\":NaN,\"b\":Infinity,\"c\":-Infinity,\"d\":+Infinity}";
     bool ok = reader->parse(doc, doc + std::strlen(doc), &root, &errs);
     JSONTEST_ASSERT(ok);
     JSONTEST_ASSERT_STRING_EQUAL("", errs);
-    JSONTEST_ASSERT_EQUAL(3u, root.size());
+    JSONTEST_ASSERT_EQUAL(4u, root.size());
     double n = root["a"].asDouble();
     JSONTEST_ASSERT(std::isnan(n));
     JSONTEST_ASSERT_EQUAL(std::numeric_limits<double>::infinity(),
                           root.get("b", 0.0));
     JSONTEST_ASSERT_EQUAL(-std::numeric_limits<double>::infinity(),
                           root.get("c", 0.0));
+    JSONTEST_ASSERT_EQUAL(std::numeric_limits<double>::infinity(),
+                          root.get("d", 0.0));
   }
 
   struct TestData {
@@ -2485,7 +2487,8 @@ JSONTEST_FIXTURE(CharReaderAllowSpecialFloatsTest, issue209) {
       {__LINE__, false, "{\"a\":.Infinity}"}, //
       {__LINE__, false, "{\"a\":_Infinity}"}, //
       {__LINE__, false, "{\"a\":_nfinity}"},  //
-      {__LINE__, true, "{\"a\":-Infinity}"}   //
+      {__LINE__, true, "{\"a\":-Infinity}"},   //
+      {__LINE__, true, "{\"a\":+Infinity}"}   //
   };
   for (const auto& td : test_data) {
     bool ok = reader->parse(&*td.in.begin(), &*td.in.begin() + td.in.size(),
@@ -2499,7 +2502,7 @@ JSONTEST_FIXTURE(CharReaderAllowSpecialFloatsTest, issue209) {
   }
 
   {
-    char const doc[] = "{\"posInf\": Infinity, \"NegInf\": -Infinity}";
+    char const doc[] = "{\"posInf\": +Infinity, \"NegInf\": -Infinity}";
     bool ok = reader->parse(doc, doc + std::strlen(doc), &root, &errs);
     JSONTEST_ASSERT(ok);
     JSONTEST_ASSERT_STRING_EQUAL("", errs);