Encode integer NOK scalars as floats

This commit outputs a trailing ".0" for scalars that are NOK but have
integer values (that do not require scientific notation).  Doing so
transmits what limited type information we can for consumption by more
strongly-typed languages.

There is one other significant behavior change to note: scalars resulting
from addition of numeric and non-numeric data wind up NOK (e.g. "42" +
"bar").

XS.xs

@@ -1177,6 +1177,7 @@ encode_sv (pTHX_ enc_t *enc, SV *sv)
   else if (SvNOKp (sv))
     {
       char *savecur, *saveend;
+      char inf_or_nan = 0;
       /* trust that perl will do the right thing w.r.t. JSON syntax. */
       need (aTHX_ enc, NV_DIG + 32);
       savecur = enc->cur;
@@ -1193,6 +1194,7 @@ encode_sv (pTHX_ enc_t *enc, SV *sv)
                || strEQ(enc->cur+1, STR_QNAN)
 #endif
                ))) {
+        inf_or_nan = 1;
         if (enc->json.infnan_mode == 0) {
           strncpy(enc->cur, "null\0", 5);
         }
@@ -1218,6 +1220,13 @@ encode_sv (pTHX_ enc_t *enc, SV *sv)
         *enc->cur = 0;
       }
       else {
+        double intpart;
+        if (!( inf_or_nan || modf(SvNVX(sv), &intpart) || SvIOK(sv)
+            || strchr(enc->cur,'e') || strchr(enc->cur,'E') ) )
+          {
+            char *tempend = enc->cur + strlen(enc->cur);
+            strncpy(tempend, ".0\0", 3);
+        }
         enc->cur += strlen (enc->cur);
       }
     }

t/03_types.t

@@ -1,4 +1,4 @@
-BEGIN { $| = 1; print "1..84\n"; }
+BEGIN { $| = 1; print "1..85\n"; }
 use utf8;
 use Cpanel::JSON::XS;
 
@@ -65,6 +65,8 @@ for $v (1, 2, 3, 5, -1, -2, -3, -4, 100, 1000, 10000, -999, -88, -7, 7, 88, 999,
    ok ($v == ((decode_json encode_json [$v])->[0]));
 }
 
+ok ('[1.0]' eq encode_json [1.0]);
+
 ok (30123 == ((decode_json encode_json [30123])->[0]));
 ok (32123 == ((decode_json encode_json [32123])->[0]));
 ok (32456 == ((decode_json encode_json [32456])->[0]));

t/117_numbers.t

@@ -57,4 +57,4 @@ is encode_json({test => [$num, $str]}), '{"test":[1,"0 but true"]}', 'int/string
 
 $str = 'bar';
 { no warnings "numeric"; $num = 23 + $str }
-is encode_json({test => [$num, $str]}), '{"test":[23,"bar"]}', , 'int/string dualvar';
+is encode_json({test => [$num, $str]}), '{"test":[23.0,"bar"]}', , 'int/string dualvar';

t/11_pc_expo.t

@@ -20,7 +20,7 @@ $js  = q|[-1.234e5]|;
 $obj = $pc->decode($js);
 is($obj->[0], -123400, 'digit -1.234e5');
 $js = $pc->encode($obj);
-is($js,'[-123400]', 'digit -1.234e5');
+is($js,'[-123400.0]', 'digit -1.234e5');
 
 $js  = q|[1.23E-4]|;
 $obj = $pc->decode($js);