[njs] Fixed toString() for -0.

[Dmitry Volyntsev]

details:   http://hg.nginx.org/njs/rev/7ce43874f706
branches:  
changeset: 585:7ce43874f706
user:      Dmitry Volyntsev <xeioex at nginx.com>
date:      Mon Aug 27 16:06:33 2018 +0300
description:
Fixed toString() for -0.

diffstat:

 njs/njs_vm.c             |  12 +++++++++++-
 njs/njs_vm.h             |   1 +
 njs/test/njs_unit_test.c |   6 ++++++
 nxt/nxt_dtoa.c           |  12 ++++++------
 4 files changed, 24 insertions(+), 7 deletions(-)

diffs (91 lines):

diff -r b15051895c8e -r 7ce43874f706 njs/njs_vm.c
--- a/njs/njs_vm.c	Mon Aug 27 14:59:59 2018 +0300
+++ b/njs/njs_vm.c	Mon Aug 27 16:06:33 2018 +0300
@@ -88,6 +88,7 @@ const njs_value_t  njs_string_boolean = 
 const njs_value_t  njs_string_false =       njs_string("false");
 const njs_value_t  njs_string_true =        njs_string("true");
 const njs_value_t  njs_string_number =      njs_string("number");
+const njs_value_t  njs_string_minus_zero =  njs_string("-0");
 const njs_value_t  njs_string_minus_infinity =
                                             njs_string("-Infinity");
 const njs_value_t  njs_string_plus_infinity =
@@ -3310,7 +3311,16 @@ again:
             }
         }
 
-        ret = njs_primitive_value_to_string(vm, &value, &value);
+        if (nxt_slow_path((value.type == NJS_NUMBER
+                            && value.data.u.number == 0
+                            && signbit(value.data.u.number))))
+        {
+            value = njs_string_minus_zero;
+            ret = NXT_OK;
+
+        } else {
+            ret = njs_primitive_value_to_string(vm, &value, &value);
+        }
 
         if (nxt_fast_path(ret == NXT_OK)) {
             size = value.short_string.size;
diff -r b15051895c8e -r 7ce43874f706 njs/njs_vm.h
--- a/njs/njs_vm.h	Mon Aug 27 14:59:59 2018 +0300
+++ b/njs/njs_vm.h	Mon Aug 27 16:06:33 2018 +0300
@@ -1269,6 +1269,7 @@ extern const njs_value_t  njs_string_nul
 extern const njs_value_t  njs_string_false;
 extern const njs_value_t  njs_string_true;
 extern const njs_value_t  njs_string_native;
+extern const njs_value_t  njs_string_minus_zero;
 extern const njs_value_t  njs_string_minus_infinity;
 extern const njs_value_t  njs_string_plus_infinity;
 extern const njs_value_t  njs_string_nan;
diff -r b15051895c8e -r 7ce43874f706 njs/test/njs_unit_test.c
--- a/njs/test/njs_unit_test.c	Mon Aug 27 14:59:59 2018 +0300
+++ b/njs/test/njs_unit_test.c	Mon Aug 27 16:06:33 2018 +0300
@@ -420,6 +420,9 @@ static njs_unit_test_t  njs_test[] =
     { nxt_string("1 + 1 + '2' + 1 + 1"),
       nxt_string("2211") },
 
+    { nxt_string("'gg' + -0"),
+      nxt_string("gg0") },
+
     { nxt_string("1.2 - '5.7'"),
       nxt_string("-4.5") },
 
@@ -8976,6 +8979,9 @@ static njs_unit_test_t  njs_test[] =
     { nxt_string("JSON.stringify(123)"),
       nxt_string("123") },
 
+    { nxt_string("JSON.stringify(-0)"),
+      nxt_string("0") },
+
     { nxt_string("JSON.stringify(0.00000123)"),
       nxt_string("0.00000123") },
 
diff -r b15051895c8e -r 7ce43874f706 nxt/nxt_dtoa.c
--- a/nxt/nxt_dtoa.c	Mon Aug 27 14:59:59 2018 +0300
+++ b/nxt/nxt_dtoa.c	Mon Aug 27 16:06:33 2018 +0300
@@ -346,18 +346,18 @@ nxt_dtoa(double value, char *start)
     minus = 0;
     p = start;
 
+    if (value == 0) {
+        *p++ = '0';
+
+        return (p - start);
+    }
+
     if (signbit(value)) {
         *p++ = '-';
         value = -value;
         minus = 1;
     }
 
-    if (value == 0) {
-        *p++ = '0';
-
-        return (p - start);
-    }
-
     length = nxt_grisu2(value, p, &dec_exp);
 
     length = nxt_prettify(p, length, dec_exp);