# HG changeset patch
# User jbe
# Date 1406464680 -7200
# Node ID 83aced09adc793540d98ffc42e54350f9546cd7e
# Parent  bccaa05aada7e40577d5fb02ffacb37881fe74b5
New function json.type(...)

diff -r bccaa05aada7 -r 83aced09adc7 libraries/json/json.c
--- a/libraries/json/json.c	Sun Jul 27 03:54:39 2014 +0200
+++ b/libraries/json/json.c	Sun Jul 27 14:38:00 2014 +0200
@@ -3,8 +3,9 @@
 #include <stdlib.h>
 #include <string.h>
 
-#define JSON_UPVAL_NULLS lua_upvalueindex(1)
-#define JSON_UPVAL_METATABLE lua_upvalueindex(2)
+#define JSON_UPVAL_TYPES lua_upvalueindex(1)
+#define JSON_UPVAL_NULLS lua_upvalueindex(2)
+#define JSON_UPVAL_METATABLE lua_upvalueindex(3)
 
 #define JSON_STATE_VALUE 0
 #define JSON_STATE_OBJECT_KEY 1
@@ -46,6 +47,9 @@
     lua_newtable(L);  // the actual JSON object
     lua_pushvalue(L, JSON_UPVAL_METATABLE);
     lua_setmetatable(L, -2);
+    lua_pushvalue(L, -1);
+    lua_pushliteral(L, "object");
+    lua_rawset(L, JSON_UPVAL_TYPES);
     lua_newtable(L);  // stores set of NULL values
     lua_pushvalue(L, -2);
     lua_pushvalue(L, -2);
@@ -60,6 +64,9 @@
     lua_newtable(L);  // the actual JSON array
     lua_pushvalue(L, JSON_UPVAL_METATABLE);
     lua_setmetatable(L, -2);
+    lua_pushvalue(L, -1);
+    lua_pushliteral(L, "array");
+    lua_rawset(L, JSON_UPVAL_TYPES);
     lua_newtable(L);  // stores set of NULL values
     lua_pushvalue(L, -2);
     lua_pushvalue(L, -2);
@@ -218,18 +225,16 @@
 static int json_arylen(lua_State *L) {
   int lower, middle;
   int upper = 1;
-  // TODO: check input for valid array!
   lua_settop(L, 1);
   lua_pushvalue(L, 1);
   lua_rawget(L, JSON_UPVAL_NULLS);
-  if (lua_isnil(L, -1)) goto json_arylen_default;
+  if (lua_isnil(L, 2)) goto json_arylen_default;
   lua_pushnil(L);
-  if (!lua_next(L, -2)) goto json_arylen_default;
-  lua_pop(L, 2);
+  if (!lua_next(L, 2)) goto json_arylen_default;
+  lua_settop(L, 2);
   while (1) {
     lua_rawgeti(L, 1, upper);
     if (lua_isnil(L, -1)) {
-      // TODO: require metatable set?
       lua_pop(L, 1);
       lua_pushinteger(L, upper);
       lua_rawget(L, 2);
@@ -245,7 +250,6 @@
     middle = (lower + upper) / 2;
     lua_rawgeti(L, 1, middle);
     if (lua_isnil(L, -1)) {
-      // TODO: require metatable set?
       lua_pop(L, 1);
       lua_pushinteger(L, middle);
       lua_rawget(L, 2);
@@ -261,8 +265,16 @@
   return 1;
 }
 
+static int json_type(lua_State *L) {
+  lua_settop(L, 1);
+  lua_rawget(L, JSON_UPVAL_TYPES);
+  return 1;
+}
+
 static int json_isnull(lua_State *L) {
-  // TODO: require metatable set?
+  lua_settop(L, 2);
+  lua_getmetatable(L, 1);
+  if (!lua_rawequal(L, -1, JSON_UPVAL_METATABLE)) goto json_isnull_false;
   lua_pushvalue(L, 1);
   lua_rawget(L, JSON_UPVAL_NULLS);
   if (lua_isnil(L, -1)) goto json_isnull_false;
@@ -276,7 +288,7 @@
 
 static const struct luaL_Reg json_module_functions[] = {
   {"import", json_import},
-  {"arylen", json_arylen},
+  {"type", json_type},
   {"isnull", json_isnull},
   {NULL, NULL}
 };
@@ -289,18 +301,22 @@
 int luaopen_json(lua_State *L) {
   lua_settop(L, 0);
   lua_newtable(L);  // 1: library table on stack position
-  lua_newtable(L);  // 2: ephemeron table to store a set of keys associated with JSON-null values
-  lua_newtable(L);  // 3: meta table for ephemeron table
+  lua_newtable(L);  // 2: ephemeron table to store the type of the JSON object/array
+  lua_newtable(L);  // 3: ephemeron table to store a set of keys associated with JSON-null values
+  lua_newtable(L);  // 4: metatable for ephemeron tables
   lua_pushliteral(L, "__mode");
   lua_pushliteral(L, "k");
-  lua_rawset(L, 3);
+  lua_rawset(L, 4);
+  lua_pushvalue(L, 4);  // 5: cloned metatable reference
   lua_setmetatable(L, 2);
-  lua_newtable(L);  // 3: metatable for JSON objects and JSON arrays
-  lua_pushvalue(L, 3);
+  lua_setmetatable(L, 3);
+  lua_newtable(L);  // 4: metatable for JSON objects and JSON arrays
+  lua_pushvalue(L, 4);
   lua_setfield(L, 1, "metatable");
   lua_pushvalue(L, 2);
   lua_pushvalue(L, 3);
-  luaL_setfuncs(L, json_metatable_functions, 2);
-  luaL_setfuncs(L, json_module_functions, 2);
+  lua_pushvalue(L, 4);
+  luaL_setfuncs(L, json_metatable_functions, 3);
+  luaL_setfuncs(L, json_module_functions, 3);
   return 1;
 }