Further improve json / lua serialization

third_party/double-conversion/wrapper.cc

@@ -18,6 +18,7 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/str/str.h"
 #include "third_party/double-conversion/double-conversion.h"
+#include "third_party/double-conversion/double-to-string.h"
 #include "third_party/double-conversion/wrapper.h"
 
 namespace double_conversion {
@@ -31,6 +32,16 @@ char* DoubleToEcmascript(char buf[128], double x) {
   return b.Finalize();
 }
 
+char* DoubleToLua(char buf[128], double x) {
+  static const DoubleToStringConverter kDoubleToLua(
+      DoubleToStringConverter::EMIT_TRAILING_DECIMAL_POINT |
+          DoubleToStringConverter::NO_TRAILING_ZERO,
+      "math.huge", "0/0", 'e', -6, 21, 6, 0);
+  StringBuilder b(buf, 128);
+  kDoubleToLua.ToShortest(x, &b);
+  return b.Finalize();
+}
+
 double StringToDouble(const char* s, size_t n, int* out_processed) {
   if (n == -1) n = strlen(s);
   int flags = StringToDoubleConverter::ALLOW_CASE_INSENSITIVITY |

third_party/double-conversion/wrapper.h

@@ -3,6 +3,7 @@
 #if !(__ASSEMBLER__ + __LINKER__ + 0)
 COSMOPOLITAN_C_START_
 
+char *DoubleToLua(char[128], double);
 char *DoubleToEcmascript(char[128], double);
 double StringToDouble(const char *, size_t, int *);
 

third_party/lua/luaencodejsondata.c

@@ -99,12 +99,17 @@ static int LuaEncodeJsonDataImpl(lua_State *L, char **buf, int level,
                 // json tables must be arrays or use string keys
                 goto OnError;
               }
-              RETURN_ON_ERROR(sli = AppendStrList(&sl));
-              RETURN_ON_ERROR(LuaEncodeJsonDataImpl(L, &sl.p[sli], level - 1,
-                                                    numformat, -2, visited));
-              RETURN_ON_ERROR(appendw(&sl.p[sli], ':'));
-              RETURN_ON_ERROR(LuaEncodeJsonDataImpl(L, &sl.p[sli], level - 1,
-                                                    numformat, -1, visited));
+              // the json parser inserts a `__json_object__` into empty
+              // objects, so we don't serialize `{}` as `[]` by mistake
+              // and as such, we should ignore it here, for readability
+              if (strcmp(luaL_checkstring(L, -2), "__json_object__")) {
+                RETURN_ON_ERROR(sli = AppendStrList(&sl));
+                RETURN_ON_ERROR(LuaEncodeJsonDataImpl(L, &sl.p[sli], level - 1,
+                                                      numformat, -2, visited));
+                RETURN_ON_ERROR(appendw(&sl.p[sli], ':'));
+                RETURN_ON_ERROR(LuaEncodeJsonDataImpl(L, &sl.p[sli], level - 1,
+                                                      numformat, -1, visited));
+              }
               lua_pop(L, 1);  // table/-2, key/-1
             }
             // stack: table/-1, as the key was popped by lua_next

third_party/lua/luaencodeluadata.c

@@ -25,6 +25,7 @@
 #include "libc/stdio/append.internal.h"
 #include "libc/stdio/strlist.internal.h"
 #include "libc/x/x.h"
+#include "third_party/double-conversion/wrapper.h"
 #include "third_party/lua/cosmo.h"
 #include "third_party/lua/lauxlib.h"
 #include "third_party/lua/lctype.h"
@@ -126,22 +127,8 @@ static int LuaEncodeLuaDataImpl(lua_State *L, char **buf, int level,
               appendd(buf, ibuf,
                       FormatFlex64(ibuf, luaL_checkinteger(L, idx), 2) - ibuf));
         } else {
-          // TODO(jart): replace this api
-          while (*numformat == '%' || *numformat == '.' ||
-                 isdigit(*numformat)) {
-            ++numformat;
-          }
-          switch (*numformat) {
-            case 'a':
-            case 'g':
-            case 'f':
-              fmt[4] = *numformat;
-              break;
-            default:
-              // prevent format string hacking
-              goto OnError;
-          }
-          RETURN_ON_ERROR(appendf(buf, fmt, lua_tonumber(L, idx)));
+          RETURN_ON_ERROR(
+              appends(buf, DoubleToLua(ibuf, lua_tonumber(L, idx))));
         }
         return 0;