From d5090bb8f19f4b0fd868a5f9af367ebbb67b7f5a Mon Sep 17 00:00:00 2001
From: Mark Pulford <mark@kyne.com.au>
Date: Sat, 3 Mar 2012 10:48:09 +1030
Subject: Use Javascript compat values for Infinity/NaN

Use Javascript compatible values for Infinity/NaN when encoding invalid
numbers.
---
 dtoa.c         |  4 ++--
 lua_cjson.c    | 16 ++++++++++++----
 manual.txt     |  9 +++++----
 tests/test.lua | 12 +++++++-----
 4 files changed, 26 insertions(+), 15 deletions(-)

diff --git a/dtoa.c b/dtoa.c
index 520926c..56398ba 100644
--- a/dtoa.c
+++ b/dtoa.c
@@ -3748,9 +3748,9 @@ dtoa
 		*decpt = 9999;
 #ifdef IEEE_Arith
 		if (!word1(&u) && !(word0(&u) & 0xfffff))
-			return nrv_alloc("inf", rve, 8);
+			return nrv_alloc("Infinity", rve, 8);
 #endif
-		return nrv_alloc("nan", rve, 3);
+		return nrv_alloc("NaN", rve, 3);
 		}
 #endif
 #ifdef IBM
diff --git a/lua_cjson.c b/lua_cjson.c
index ca5b88d..c14a1c5 100644
--- a/lua_cjson.c
+++ b/lua_cjson.c
@@ -592,12 +592,20 @@ static void json_append_number(lua_State *l, json_config_t *cfg,
     if (cfg->encode_invalid_numbers == 0) {
         /* Prevent encoding invalid numbers */
         if (isinf(num) || isnan(num))
-            json_encode_exception(l, cfg, json, lindex, "must not be NaN or Inf");
+            json_encode_exception(l, cfg, json, lindex,
+                                  "must not be NaN or Infinity");
     } else if (cfg->encode_invalid_numbers == 1) {
-        /* Encode invalid numbers, but handle "nan" separately
-         * since some platforms may encode as "-nan". */
+        /* Encode NaN/Infinity separately to ensure Javascript compatible
+         * values are used. */
         if (isnan(num)) {
-            strbuf_append_mem(json, "nan", 3);
+            strbuf_append_mem(json, "NaN", 3);
+            return;
+        }
+        if (isinf(num)) {
+            if (num < 0)
+                strbuf_append_mem(json, "-Infinity", 9);
+            else
+                strbuf_append_mem(json, "Infinity", 8);
             return;
         }
     } else {
diff --git a/manual.txt b/manual.txt
index 3977f1f..a12e378 100644
--- a/manual.txt
+++ b/manual.txt
@@ -290,7 +290,7 @@ Lua CJSON may generate an error when trying to decode numbers not
 supported by the JSON specification. _Invalid numbers_ are defined as:
 
 - infinity
-- not-a-number (NaN)
+- NaN
 - hexadecimal
 
 Available settings:
@@ -438,12 +438,13 @@ Lua CJSON may generate an error when encoding floating point numbers not
 supported by the JSON specification (_invalid numbers_):
 
 - infinity
-- not-a-number (NaN)
+- NaN
 
 Available settings:
 
-+true+:: Allow _invalid numbers_ to be encoded. This will generate
-  non-standard JSON, but this output is supported by some libraries.
++true+:: Allow _invalid numbers_ to be encoded using the Javascript
+  compatible values +NaN+ and +Infinity+. This will generate
+  non-standard JSON, but these values are supported by some libraries.
 +"null"+:: Encode _invalid numbers_ as a JSON +null+ value. This allows
   infinity and NaN to be encoded into valid JSON.
 +false+:: Throw an error when attempting to encode _invalid numbers_.
diff --git a/tests/test.lua b/tests/test.lua
index 96a3201..b8fce84 100755
--- a/tests/test.lua
+++ b/tests/test.lua
@@ -261,10 +261,10 @@ local cjson_tests = {
       json.encode_invalid_numbers, { false }, true, { false } },
     { "Encode NaN [throw error]",
       json.encode, { NaN },
-      false, { "Cannot serialise number: must not be NaN or Inf" } },
+      false, { "Cannot serialise number: must not be NaN or Infinity" } },
     { "Encode Infinity [throw error]",
       json.encode, { Inf },
-      false, { "Cannot serialise number: must not be NaN or Inf" } },
+      false, { "Cannot serialise number: must not be NaN or Infinity" } },
     { "Set encode_invalid_numbers(\"null\")",
       json.encode_invalid_numbers, { "null" }, true, { "null" } },
     { "Encode NaN as null",
@@ -274,9 +274,11 @@ local cjson_tests = {
     { "Set encode_invalid_numbers(true)",
       json.encode_invalid_numbers, { true }, true, { true } },
     { "Encode NaN",
-      json.encode, { NaN }, true, { "nan" } },
-    { "Encode Infinity",
-      json.encode, { Inf }, true, { "inf" } },
+      json.encode, { NaN }, true, { "NaN" } },
+    { "Encode +Infinity",
+      json.encode, { Inf }, true, { "Infinity" } },
+    { "Encode -Infinity",
+      json.encode, { -Inf }, true, { "-Infinity" } },
     { 'Set encode_invalid_numbers("off")',
       json.encode_invalid_numbers, { "off" }, true, { false } },
 
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