# HG changeset patch
# User jbe
# Date 1406862741 -7200
# Node ID 681367a16657f9492ea43466dab1c8cf1f105054
# Parent  e618ccd017a3217b343b332076fa228fd8c71eed
json.array and json.object functions create a new container rather than marking a table

diff -r e618ccd017a3 -r 681367a16657 libraries/json/json.c
--- a/libraries/json/json.c	Fri Aug 01 02:48:18 2014 +0200
+++ b/libraries/json/json.c	Fri Aug 01 05:12:21 2014 +0200
@@ -41,63 +41,67 @@
   return 1;
 }
 
-// marks a Lua table as JSON object or JSON array:
-// (returns its modified argument or a new table if argument is nil)
-static int json_mark(lua_State *L, JSON_REGPOINTER mt) {
-  // check if argument is nil
-  if (lua_isnoneornil(L, 1)) {
-    // create new table at stack position 1:
-    lua_settop(L, 0);
-    lua_newtable(L);
-    // create shadow table (leaving previously created table on stack position 1):
-    json_regfetch(L, shadowtbl);
-    lua_pushvalue(L, 1);
-    lua_newtable(L);
-    lua_rawset(L, -3);
-  } else {
-    // require argument to be a table:
-    luaL_checktype(L, 1, LUA_TTABLE);
-    // push shadow table on top of stack:
+#define json_convert_source_idx 1
+#define json_convert_iterator_idx 2
+#define json_convert_output_idx 3
+#define json_convert_shadow_idx 4
+
+// converts a Lua table to a  JSON object or JSON array:
+// (does never modify the argument, returns an empty object or array if argument is nil)
+static int json_convert(lua_State *L, int array) {
+  lua_settop(L, 1);
+  if (lua_isnoneornil(L, json_convert_source_idx)) {
     json_regfetch(L, shadowtbl);
-    lua_pushvalue(L, 1);
-    lua_rawget(L, -2);
-    // if shadow table does not exist:
-    if (lua_isnil(L, -1)) {
-      // create shadow table and leave it on top of stack:
-      lua_newtable(L);
-      lua_pushvalue(L, 1);
-      lua_pushvalue(L, -2);
-      lua_rawset(L, -5);
+    lua_newtable(L);
+    lua_pushvalue(L, -1);
+    lua_newtable(L);
+    lua_rawset(L, -4);
+  } else {
+    // push iterator function on stack position 2 if existent,
+    // else push null for normal tables:
+    if (lua_getmetatable(L, json_convert_source_idx)) {
+      lua_getfield(L, -1, array ? "__ipairs" : "__pairs");
+      if (lua_isnil(L, -1)) luaL_checktype(L, 1, LUA_TTABLE);
+      else if (lua_type(L, -1) != LUA_TFUNCTION)
+        return luaL_error(L, "%s metamethod is not a function", array ? "__ipairs" : "__pairs");
+      lua_replace(L, -2);
+    } else {
+      lua_pushnil(L);
     }
-    // move elements from original table to shadow table (that's expected on top of stack):
-    for(lua_pushnil(L); lua_next(L, 1); lua_pop(L, 1)) {
-      lua_pushvalue(L, -2);
-      lua_pushnil(L);
-      lua_rawset(L, 1);
-      lua_pushvalue(L, -2);
-      lua_pushvalue(L, -2);
-      lua_rawset(L, -5);
+    // create table on stack position 3:
+    lua_newtable(L);
+    // create shadow table on stack position 4:
+    json_regfetch(L, shadowtbl);
+    lua_newtable(L);
+    lua_pushvalue(L, json_convert_output_idx);
+    lua_pushvalue(L, -2);
+    lua_rawset(L, -4);
+    lua_replace(L, -2);
+    if (lua_isnil(L, json_convert_iterator_idx)) {
+      for (lua_pushnil(L); lua_next(L, json_convert_source_idx); lua_pop(L, 1)) {
+        lua_pushvalue(L, -2);
+        lua_pushvalue(L, -2);
+        lua_rawset(L, json_convert_shadow_idx);
+      }
+    } else {
+      return luaL_error(L, "Using %s metamethod not implemented yet", array ? "__ipairs" : "__pairs");
     }
+    lua_settop(L, json_convert_output_idx);
   }
-  // discard everything but table to return:
-  lua_settop(L, 1);
   // set metatable:
-  json_regfetchpointer(L, mt);
-  lua_setmetatable(L, 1);
+  if (array) json_regfetch(L, arraymt);
+  else json_regfetch(L, objectmt);
+  lua_setmetatable(L, -2);
   // return table:
   return 1;
 }
 
-// marks a table as JSON object:
-// (returns its modified argument or a new table if argument is nil)
 static int json_object(lua_State *L) {
-  return json_mark(L, json_regpointer(objectmt));
+  return json_convert(L, 0);
 }
 
-// marks a table as JSON array:
-// (returns its modified argument or a new table if argument is nil)
 static int json_array(lua_State *L) {
-  return json_mark(L, json_regpointer(arraymt));
+  return json_convert(L, 1);
 }
 
 // internal states of JSON parser: