💥 implemented new handling of NaN and INF #70 #329 #388

- If an overflow occurs during parsing a number from a JSON text, an
exception (std::out_of_range for the moment, to be replaced by a
user-defined exception #244) is thrown so that the overflow is detected
early and roundtripping is guaranteed.
- NaN and INF floating-point values can be stored in a JSON value and
are not replaced by null. That is, the basic_json class behaves like
double in this regard (no exception occurs). However, NaN and INF are
serialized to “null”.
- Adjusted test cases appropriately.

test/src/unit-class_parser.cpp

@@ -272,7 +272,9 @@ TEST_CASE("parser class")
 
             SECTION("overflow")
             {
-                CHECK(json::parser("1.18973e+4932").parse() == json());
+                // overflows during parsing yield an exception
+                CHECK_THROWS_AS(json::parser("1.18973e+4932").parse() == json(), std::out_of_range);
+                CHECK_THROWS_WITH(json::parser("1.18973e+4932").parse() == json(), "number overflow: 1.18973e+4932");
             }
 
             SECTION("invalid numbers")