jbe@121: #include <lua.h>
jbe@121: #include <lauxlib.h>
jbe@122: #include <stdlib.h>
jbe@121: #include <string.h>
jbe@121: 
jbe@130: #define JSON_UPVAL_NULLMARK  lua_upvalueindex(1)
jbe@130: #define JSON_UPVAL_SHADOWTBL lua_upvalueindex(2)
jbe@130: #define JSON_UPVAL_TYPES     lua_upvalueindex(3)
jbe@130: #define JSON_UPVAL_METATABLE lua_upvalueindex(4)
jbe@135: #define JSON_UPVAL_PAIRS_ITERFUNC  lua_upvalueindex(5)
jbe@135: #define JSON_UPVAL_IPAIRS_ITERFUNC lua_upvalueindex(6)
jbe@123: 
jbe@136: // marks a table as JSON object or JSON array:
jbe@136: // (returns its modified argument or a new table if argument is nil)
jbe@136: static int json_mark(lua_State *L, const char *marker) {
jbe@136:   // if argument is nil, then create new table:
jbe@136:   if (lua_isnoneornil(L, 1)) {
jbe@136:     lua_settop(L, 0);
jbe@136:     lua_newtable(L);
jbe@136:     // skip testing of existing shadow table:
jbe@136:     goto json_object_create_shadow_table;
jbe@136:   }
jbe@136:   lua_pushvalue(L, 1);
jbe@136:   lua_rawget(L, JSON_UPVAL_SHADOWTBL);
jbe@136:   if (lua_isnil(L, -1)) {
jbe@136:     json_object_create_shadow_table:
jbe@136:     // set shadow table:
jbe@136:     lua_pushvalue(L, 1);
jbe@136:     lua_newtable(L);
jbe@136:     lua_rawset(L, JSON_UPVAL_SHADOWTBL);
jbe@136:   }
jbe@136:   // set metatable:
jbe@136:   lua_pushvalue(L, JSON_UPVAL_METATABLE);
jbe@136:   lua_setmetatable(L, 1);
jbe@136:   // mark table as JSON object or as JSON array
jbe@136:   lua_pushvalue(L, 1);
jbe@136:   lua_pushstring(L, marker);
jbe@136:   lua_rawset(L, JSON_UPVAL_TYPES);
jbe@136:   return 1;
jbe@136: }
jbe@136: 
jbe@136: // marks a table as JSON object:
jbe@136: // (returns its modified argument or a new table if argument is nil)
jbe@136: static int json_object(lua_State *L) {
jbe@136:   return json_mark(L, "object");
jbe@136: }
jbe@136: 
jbe@136: // marks a table as JSON array:
jbe@136: // (returns its modified argument or a new table if argument is nil)
jbe@136: static int json_array(lua_State *L) {
jbe@136:   return json_mark(L, "array");
jbe@136: }
jbe@136: 
jbe@124: #define JSON_STATE_VALUE 0
jbe@124: #define JSON_STATE_OBJECT_KEY 1
jbe@124: #define JSON_STATE_OBJECT_KEY_TERMINATOR 2
jbe@124: #define JSON_STATE_OBJECT_VALUE 3
jbe@124: #define JSON_STATE_OBJECT_SEPARATOR 4
jbe@124: #define JSON_STATE_ARRAY_VALUE 5
jbe@124: #define JSON_STATE_ARRAY_SEPARATOR 6
jbe@124: #define JSON_STATE_END 7
jbe@121: 
jbe@136: // decodes a JSON document:
jbe@121: static int json_import(lua_State *L) {
jbe@136:   const char *str;   // string to parse
jbe@136:   size_t total;      // total length of string to parse
jbe@136:   size_t pos = 0;    // current position in string to parse
jbe@136:   size_t level = 0;  // nested levels of objects/arrays currently being processed
jbe@136:   int mode = JSON_STATE_VALUE;  // state of parser
jbe@136:   char c;              // variable to store a single character to be processed
jbe@136:   luaL_Buffer luabuf;  // Lua buffer to decode (possibly escaped) strings
jbe@136:   char *cbuf;          // C buffer to decode (possibly escaped) strings
jbe@136:   size_t writepos;     // write position of decoded strings in C buffer
jbe@136:   // require string as first argument:
jbe@136:   str = luaL_checklstring(L, 1, &total);
jbe@136:   // if string contains a NULL byte, this is a syntax error
jbe@136:   if (strlen(str) != total) goto json_import_syntax_error;
jbe@136:   // main loop of parser:
jbe@136:   json_import_loop:
jbe@136:   // skip whitespace and store next character in variable 'c':
jbe@121:   while (c = str[pos], c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == '\f') pos++;
jbe@136:   // switch statement to handle certain (single) characters:
jbe@121:   switch (c) {
jbe@136:   // handle end of JSON document:
jbe@121:   case 0:
jbe@136:     // if end of JSON document was expected, then return top element of stack as result:
jbe@124:     if (mode == JSON_STATE_END) return 1;
jbe@136:     // otherwise, the JSON document was malformed:
jbe@121:     json_import_unexpected_eof:
jbe@121:     lua_pushnil(L);
jbe@121:     if (level == 0) lua_pushliteral(L, "Empty string");
jbe@121:     else lua_pushliteral(L, "Unexpected end of JSON document");
jbe@121:     return 2;
jbe@136:   // new JSON object:
jbe@121:   case '{':
jbe@136:     // if a JSON object is not expected here, then return an error:
jbe@124:     if (mode != JSON_STATE_VALUE && mode != JSON_STATE_OBJECT_VALUE && mode != JSON_STATE_ARRAY_VALUE)
jbe@121:       goto json_import_syntax_error;
jbe@136:     // consume input character:
jbe@121:     pos++;
jbe@136:     // create JSON object on stack:
jbe@136:     lua_newtable(L);
jbe@136:     // set metatable of JSON object:
jbe@125:     lua_pushvalue(L, JSON_UPVAL_METATABLE);
jbe@125:     lua_setmetatable(L, -2);
jbe@136:     // mark JSON object as JSON object (as opposed to JSON array):
jbe@127:     lua_pushvalue(L, -1);
jbe@127:     lua_pushliteral(L, "object");
jbe@127:     lua_rawset(L, JSON_UPVAL_TYPES);
jbe@136:     // create internal shadow table on stack:
jbe@136:     lua_newtable(L);
jbe@136:     // register internal shadow table:
jbe@123:     lua_pushvalue(L, -2);
jbe@123:     lua_pushvalue(L, -2);
jbe@130:     lua_rawset(L, JSON_UPVAL_SHADOWTBL);
jbe@136:     // increment level:
jbe@121:     level++;
jbe@136:     // expect object key (or end of object) and continue with loop:
jbe@136:     mode = JSON_STATE_OBJECT_KEY;
jbe@121:     goto json_import_loop;
jbe@136:   // new JSON array:
jbe@121:   case '[':
jbe@136:     // if a JSON array is not expected here, then return an error:
jbe@124:     if (mode != JSON_STATE_VALUE && mode != JSON_STATE_OBJECT_VALUE && mode != JSON_STATE_ARRAY_VALUE)
jbe@121:       goto json_import_syntax_error;
jbe@136:     // consume input character:
jbe@121:     pos++;
jbe@136:     // create JSON array on stack:
jbe@136:     lua_newtable(L);
jbe@136:     // set metatable of JSON array:
jbe@125:     lua_pushvalue(L, JSON_UPVAL_METATABLE);
jbe@125:     lua_setmetatable(L, -2);
jbe@136:     // mark JSON array as JSON array (as opposed to JSON object):
jbe@127:     lua_pushvalue(L, -1);
jbe@127:     lua_pushliteral(L, "array");
jbe@127:     lua_rawset(L, JSON_UPVAL_TYPES);
jbe@136:     // create internal shadow table on stack:
jbe@136:     lua_newtable(L);
jbe@136:     // register internal shadow table:
jbe@123:     lua_pushvalue(L, -2);
jbe@123:     lua_pushvalue(L, -2);
jbe@130:     lua_rawset(L, JSON_UPVAL_SHADOWTBL);
jbe@136:     // increment level:
jbe@121:     level++;
jbe@136:     // expect array value (or end of array) and continue with loop:
jbe@136:     mode = JSON_STATE_ARRAY_VALUE;
jbe@121:     goto json_import_loop;
jbe@136:   // end of JSON object:
jbe@121:   case '}':
jbe@136:     // if end of JSON object is not expected here, then return an error:
jbe@124:     if (mode != JSON_STATE_OBJECT_KEY && mode != JSON_STATE_OBJECT_SEPARATOR)
jbe@121:       goto json_import_syntax_error;
jbe@136:     // jump to common code for end of JSON object and JSON array:
jbe@121:     goto json_import_close;
jbe@136:   // end of JSON array:
jbe@121:   case ']':
jbe@136:     // if end of JSON array is not expected here, then return an error:
jbe@124:     if (mode != JSON_STATE_ARRAY_VALUE && mode != JSON_STATE_ARRAY_SEPARATOR)
jbe@121:       goto json_import_syntax_error;
jbe@136:     // continue with common code for end of JSON object and JSON array:
jbe@136:   // common code for end of JSON object or JSON array:
jbe@121:   json_import_close:
jbe@136:     // consume input character:
jbe@121:     pos++;
jbe@136:     // pop shadow table:
jbe@136:     lua_pop(L, 1);
jbe@136:     // check if nested:
jbe@121:     if (--level) {
jbe@136:       // if nested, then check if outer(!) structure is an array or object:
jbe@136:       lua_pushvalue(L, c == '}' ? -4 : -3);
jbe@136:       lua_rawget(L, JSON_UPVAL_TYPES);
jbe@136:       if (lua_tostring(L, -1)[0] == 'a') {
jbe@136:         // select array value processing:
jbe@124:         mode = JSON_STATE_ARRAY_VALUE;
jbe@121:       } else {
jbe@136:         // select object value processing:
jbe@124:         mode = JSON_STATE_OBJECT_VALUE;
jbe@121:       }
jbe@136:       // pop JSON type from stack (from rawget JSON_UPVAL_TYPES):
jbe@136:       lua_pop(L, 1);
jbe@136:       // store value in outer structure:
jbe@121:       goto json_import_process_value;
jbe@121:     }
jbe@136:     // if not nested, then expect end of JSON document and continue with loop:
jbe@136:     mode = JSON_STATE_END;
jbe@121:     goto json_import_loop;
jbe@136:   // key terminator:
jbe@121:   case ':':
jbe@136:     // if key terminator is not expected here, then return an error:
jbe@124:     if (mode != JSON_STATE_OBJECT_KEY_TERMINATOR)
jbe@121:       goto json_import_syntax_error;
jbe@136:     // consume input character:
jbe@121:     pos++;
jbe@136:     // set state of parser and continue with loop:
jbe@124:     mode = JSON_STATE_OBJECT_VALUE;
jbe@121:     goto json_import_loop;
jbe@136:   // value terminator (NOTE: trailing comma at end of value or key-value list is tolerated by this parser)
jbe@121:   case ',':
jbe@136:     // change parser state accordingly:
jbe@124:     if (mode == JSON_STATE_OBJECT_SEPARATOR) {
jbe@124:       mode = JSON_STATE_OBJECT_KEY;
jbe@124:     } else if (mode == JSON_STATE_ARRAY_SEPARATOR) {
jbe@124:       mode = JSON_STATE_ARRAY_VALUE;
jbe@121:     } else {
jbe@136:        // if value terminator is not expected here, then return an error:
jbe@136:        goto json_import_syntax_error;
jbe@121:     }
jbe@136:     // consume input character:
jbe@121:     pos++;
jbe@136:     // continue with loop:
jbe@121:     goto json_import_loop;
jbe@136:   // string literal:
jbe@121:   case '"':
jbe@136:     // prepare buffer to decode string (with maximum possible length) and set write position to zero:
jbe@121:     cbuf = luaL_buffinitsize(L, &luabuf, total-pos);
jbe@121:     writepos = 0;
jbe@136:     // consume quote character:
jbe@121:     pos++;
jbe@136:     // read next character until encountering end quote:
jbe@121:     while ((c = str[pos++]) != '"') {
jbe@121:       if (c == 0) {
jbe@136:         // handle unexpected end-of-string:
jbe@121:         goto json_import_unexpected_eof;
jbe@121:       } else if (c < 32 || c == 127) {
jbe@136:         // do not allow ASCII control characters:
jbe@136:         // NOTE: illegal UTF-8 sequences and extended control characters are not sanitized
jbe@136:         //       by this parser to allow different encodings than Unicode
jbe@121:         lua_pushnil(L);
jbe@121:         lua_pushliteral(L, "Unexpected control character in JSON string");
jbe@121:         return 2;
jbe@121:       } else if (c == '\\') {
jbe@136:         // read next char after backslash escape:
jbe@121:         c = str[pos++];
jbe@121:         switch (c) {
jbe@136:         // unexpected end-of-string:
jbe@121:         case 0:
jbe@121:           goto json_import_unexpected_eof;
jbe@136:         // unescaping of quotation mark, slash, and backslash:
jbe@121:         case '"':
jbe@121:         case '/':
jbe@121:         case '\\':
jbe@121:           cbuf[writepos++] = c;
jbe@121:           break;
jbe@136:         // unescaping of backspace:
jbe@121:         case 'b':
jbe@121:           cbuf[writepos++] = '\b';
jbe@121:           break;
jbe@136:         // unescaping of form-feed:
jbe@121:         case 'f':
jbe@121:           cbuf[writepos++] = '\f';
jbe@121:           break;
jbe@136:         // unescaping of new-line:
jbe@121:         case 'n':
jbe@121:           cbuf[writepos++] = '\n';
jbe@121:           break;
jbe@136:         // unescaping of carriage-return:
jbe@121:         case 'r':
jbe@121:           cbuf[writepos++] = '\r';
jbe@121:           break;
jbe@136:         // unescaping of tabulator:
jbe@121:         case 't':
jbe@121:           cbuf[writepos++] = '\t';
jbe@121:           break;
jbe@136:         // unescaping of UTF-16 characters
jbe@121:         case 'u':
jbe@121:           lua_pushnil(L);
jbe@121:           lua_pushliteral(L, "JSON unicode escape sequences are not implemented yet");  // TODO
jbe@121:           return 2;
jbe@136:         // unexpected escape sequence:
jbe@121:         default:
jbe@121:           lua_pushnil(L);
jbe@121:           lua_pushliteral(L, "Unexpected string escape sequence in JSON document");
jbe@121:           return 2;
jbe@121:         }
jbe@121:       } else {
jbe@136:         // normal character:
jbe@121:         cbuf[writepos++] = c;
jbe@121:       }
jbe@121:     }
jbe@136:     // process buffer to Lua string:
jbe@121:     luaL_pushresultsize(&luabuf, writepos);
jbe@136:     // continue with processing of decoded string:
jbe@121:     goto json_import_process_value;
jbe@121:   }
jbe@136:   // process values whose type is is not deducible from a single character:
jbe@136:   if ((c >= '0' && c <= '9') || c == '-' || c == '+') {
jbe@136:     // numbers:
jbe@122:     char *endptr;
jbe@122:     double numval;
jbe@122:     numval = strtod(str+pos, &endptr);
jbe@122:     if (endptr == str+pos) goto json_import_syntax_error;
jbe@122:     pos += endptr - (str+pos);
jbe@122:     lua_pushnumber(L, numval);
jbe@122:   } else if (!strncmp(str+pos, "true", 4)) {
jbe@136:     // consume 4 input characters for "true":
jbe@121:     pos += 4;
jbe@136:     // put Lua true value on stack:
jbe@136:     lua_pushboolean(L, 1);
jbe@121:   } else if (!strncmp(str+pos, "false", 5)) {
jbe@136:     // consume 5 input characters for "false":
jbe@121:     pos += 5;
jbe@136:     // put Lua false value on stack:
jbe@136:     lua_pushboolean(L, 0);
jbe@121:   } else if (!strncmp(str+pos, "null", 4)) {
jbe@136:     // consume 4 input characters for "null":
jbe@136:     pos += 4;
jbe@136:     // put special null-marker on stack:
jbe@130:     lua_pushvalue(L, JSON_UPVAL_NULLMARK);
jbe@121:   } else {
jbe@136:     // all other cases are a syntax error:
jbe@121:     goto json_import_syntax_error;
jbe@121:   }
jbe@136:   // process a decoded value or key value pair (expected on top of Lua stack):
jbe@136:   json_import_process_value:
jbe@121:   switch (mode) {
jbe@136:   // an object key has been read:
jbe@124:   case JSON_STATE_OBJECT_KEY:
jbe@136:     // if an object key is not a string, then this is a syntax error:
jbe@121:     if (lua_type(L, -1) != LUA_TSTRING) goto json_import_syntax_error;
jbe@136:     // expect key terminator and continue with loop:
jbe@124:     mode = JSON_STATE_OBJECT_KEY_TERMINATOR;
jbe@121:     goto json_import_loop;
jbe@136:   // a key value pair has been read:
jbe@124:   case JSON_STATE_OBJECT_VALUE:
jbe@136:     // store key value pair in outer shadow table:
jbe@130:     lua_rawset(L, -3);
jbe@136:     // expect value terminator (or end of object) and continue with loop:
jbe@124:     mode = JSON_STATE_OBJECT_SEPARATOR;
jbe@121:     goto json_import_loop;
jbe@136:   // an array value has been read:
jbe@124:   case JSON_STATE_ARRAY_VALUE:
jbe@136:     // store value in outer shadow table:
jbe@136:     lua_rawseti(L, -2, lua_rawlen(L, -2) + 1);
jbe@136:     // expect value terminator (or end of object) and continue with loop:
jbe@124:     mode = JSON_STATE_ARRAY_SEPARATOR;
jbe@121:     goto json_import_loop;
jbe@136:   // a single value has been read:
jbe@124:   case JSON_STATE_VALUE:
jbe@136:     // leave value on top of stack, expect end of JSON document, and continue with loop:
jbe@124:     mode = JSON_STATE_END;
jbe@121:     goto json_import_loop;
jbe@121:   }
jbe@136:   // syntax error handling (only reachable by goto statement):
jbe@136:   json_import_syntax_error:
jbe@121:   lua_pushnil(L);
jbe@121:   lua_pushliteral(L, "Syntax error in JSON document");
jbe@121:   return 2;
jbe@121: }
jbe@121: 
jbe@130: #define JSON_PATH_GET 1
jbe@130: #define JSON_PATH_TYPE 2
jbe@130: #define JSON_PATH_ISNULL 3
jbe@130: 
jbe@136: // gets a value, its type, or information 
jbe@130: static int json_path(lua_State *L, int mode) {
jbe@130:   int argc;
jbe@130:   int idx = 2;
jbe@130:   argc = lua_gettop(L);
jbe@126:   lua_pushvalue(L, 1);
jbe@130:   while (idx <= argc) {
jbe@132:     if (lua_isnil(L, -1)) {
jbe@132:       if (mode == JSON_PATH_ISNULL) lua_pushboolean(L, 0);
jbe@132:       return 1;
jbe@132:     }
jbe@130:     lua_pushvalue(L, -1);
jbe@130:     lua_rawget(L, JSON_UPVAL_SHADOWTBL);
jbe@126:     if (lua_isnil(L, -1)) {
jbe@126:       lua_pop(L, 1);
jbe@130:       if (lua_type(L, -1) == LUA_TTABLE) {
jbe@130:         lua_pushvalue(L, idx++);
jbe@130:         lua_gettable(L, -2);
jbe@130:       } else {
jbe@130:         lua_pushnil(L);
jbe@130:       }
jbe@130:     } else {
jbe@130:       lua_replace(L, -2);
jbe@130:       lua_pushvalue(L, idx++);
jbe@130:       lua_rawget(L, -2);
jbe@126:     }
jbe@130:     lua_replace(L, -2);
jbe@126:   }
jbe@130:   switch (mode) {
jbe@130:   case JSON_PATH_GET:
jbe@130:     if (lua_rawequal(L, -1, JSON_UPVAL_NULLMARK)) lua_pushnil(L);
jbe@130:     return 1;
jbe@130:   case JSON_PATH_TYPE:
jbe@130:     if (lua_rawequal(L, -1, JSON_UPVAL_NULLMARK)) {
jbe@130:       lua_pushliteral(L, "null");
jbe@130:       return 1;
jbe@126:     }
jbe@130:     lua_pushvalue(L, -1);
jbe@130:     lua_rawget(L, JSON_UPVAL_TYPES);
jbe@130:     if (lua_isnil(L, -1)) lua_pushstring(L, lua_typename(L, lua_type(L, -2)));
jbe@130:     return 1;
jbe@130:   case JSON_PATH_ISNULL:
jbe@130:     lua_pushboolean(L, lua_rawequal(L, -1, JSON_UPVAL_NULLMARK));
jbe@130:     return 1;
jbe@126:   }
jbe@130:   return 0;
jbe@130: }
jbe@130: 
jbe@130: static int json_get(lua_State *L) {
jbe@130:   return json_path(L, JSON_PATH_GET);
jbe@130: }
jbe@130: 
jbe@130: static int json_type(lua_State *L) {
jbe@130:   return json_path(L, JSON_PATH_TYPE);
jbe@130: }
jbe@130: 
jbe@130: static int json_isnull(lua_State *L) {
jbe@130:   return json_path(L, JSON_PATH_ISNULL);
jbe@130: }
jbe@130: 
jbe@131: static int json_setnull(lua_State *L) {
jbe@131:   lua_settop(L, 2);
jbe@131:   lua_pushvalue(L, JSON_UPVAL_METATABLE);
jbe@131:   lua_setmetatable(L, 1);
jbe@131:   lua_pushvalue(L, 1);
jbe@131:   lua_rawget(L, JSON_UPVAL_SHADOWTBL);
jbe@131:   if (lua_isnil(L, -1)) {
jbe@131:     lua_newtable(L);
jbe@131:     lua_pushvalue(L, 1);
jbe@131:     lua_pushvalue(L, -2);
jbe@131:     lua_rawset(L, JSON_UPVAL_SHADOWTBL);
jbe@131:   }
jbe@131:   lua_pushvalue(L, 2);
jbe@131:   lua_pushvalue(L, JSON_UPVAL_NULLMARK);
jbe@131:   lua_rawset(L, -3);
jbe@131:   return 0;
jbe@131: }
jbe@131: 
jbe@130: static int json_len(lua_State *L) {
jbe@130:   lua_settop(L, 1);
jbe@130:   lua_pushvalue(L, 1);
jbe@130:   lua_rawget(L, JSON_UPVAL_SHADOWTBL);
jbe@130:   if (lua_isnil(L, -1)) lua_pop(L, 1);
jbe@130:   lua_pushinteger(L, lua_rawlen(L, -1));
jbe@123:   return 1;
jbe@123: }
jbe@123: 
jbe@130: static int json_index(lua_State *L) {
jbe@130:   lua_settop(L, 2);
jbe@130:   lua_pushvalue(L, 1);
jbe@130:   lua_rawget(L, JSON_UPVAL_SHADOWTBL);
jbe@130:   if (lua_isnil(L, -1)) return 1;
jbe@130:   lua_pushvalue(L, 2);
jbe@130:   lua_rawget(L, -2);
jbe@130:   if (lua_rawequal(L, -1, JSON_UPVAL_NULLMARK)) lua_pushnil(L);
jbe@127:   return 1;
jbe@127: }
jbe@127: 
jbe@130: static int json_newindex(lua_State *L) {
jbe@130:   lua_settop(L, 3);
jbe@123:   lua_pushvalue(L, 1);
jbe@130:   lua_rawget(L, JSON_UPVAL_SHADOWTBL);
jbe@130:   if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@130:   lua_replace(L, 1);
jbe@130:   lua_rawset(L, 1);
jbe@121:   return 1;
jbe@121: }
jbe@121: 
jbe@135: static int json_pairs_iterfunc(lua_State *L) {
jbe@135:   lua_settop(L, 2);
jbe@135:   lua_pushvalue(L, 1);
jbe@135:   lua_rawget(L, JSON_UPVAL_SHADOWTBL);
jbe@135:   if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@135:   lua_pushvalue(L, 2);
jbe@135:   if (!lua_next(L, -2)) return 0;
jbe@135:   if (lua_rawequal(L, -1, JSON_UPVAL_NULLMARK)) {
jbe@135:     lua_pop(L, 1);
jbe@135:     lua_pushnil(L);
jbe@135:   }
jbe@135:   return 2;
jbe@135: }
jbe@135: 
jbe@135: static int json_pairs(lua_State *L) {
jbe@135:   lua_pushvalue(L, JSON_UPVAL_PAIRS_ITERFUNC);
jbe@135:   lua_pushvalue(L, 1);
jbe@135:   lua_pushnil(L);
jbe@135:   return 3;
jbe@135: }
jbe@135: 
jbe@134: static int json_ipairs_iterfunc(lua_State *L) {
jbe@134:   int idx;
jbe@134:   lua_settop(L, 2);
jbe@134:   idx = lua_tointeger(L, 2) + 1;
jbe@134:   lua_pushvalue(L, 1);
jbe@134:   lua_rawget(L, JSON_UPVAL_SHADOWTBL);
jbe@134:   if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@134:   lua_rawgeti(L, -1, idx);
jbe@134:   if (lua_isnil(L, -1)) return 0;
jbe@134:   lua_pushinteger(L, idx);
jbe@134:   if (lua_rawequal(L, -2, JSON_UPVAL_NULLMARK)) lua_pushnil(L);
jbe@134:   else lua_pushvalue(L, -2);
jbe@134:   return 2;
jbe@134: }
jbe@134: 
jbe@134: static int json_ipairs(lua_State *L) {
jbe@134:   lua_pushvalue(L, JSON_UPVAL_IPAIRS_ITERFUNC);
jbe@134:   lua_pushvalue(L, 1);
jbe@134:   lua_pushinteger(L, 0);
jbe@134:   return 3;
jbe@134: }
jbe@134: 
jbe@121: static const struct luaL_Reg json_module_functions[] = {
jbe@133:   {"object", json_object},
jbe@133:   {"array", json_array},
jbe@121:   {"import", json_import},
jbe@130:   {"get", json_get},
jbe@127:   {"type", json_type},
jbe@123:   {"isnull", json_isnull},
jbe@131:   {"setnull", json_setnull},
jbe@121:   {NULL, NULL}
jbe@121: };
jbe@121: 
jbe@126: static const struct luaL_Reg json_metatable_functions[] = {
jbe@130:   {"__len", json_len},
jbe@130:   {"__index", json_index},
jbe@130:   {"__newindex", json_newindex},
jbe@135:   {"__pairs", json_pairs},
jbe@134:   {"__ipairs", json_ipairs},
jbe@126:   {NULL, NULL}
jbe@126: };
jbe@126: 
jbe@121: int luaopen_json(lua_State *L) {
jbe@126:   lua_settop(L, 0);
jbe@126:   lua_newtable(L);  // 1: library table on stack position
jbe@130:   lua_newtable(L);  // 2: table used as JSON NULL value in internal shadow tables
jbe@130:   lua_newtable(L);  // 3: ephemeron table to store shadow tables for each JSON object/array to allow NULL values returned as nil
jbe@130:   lua_newtable(L);  // 4: ephemeron table to store the type of the JSON object/array
jbe@130:   lua_newtable(L);  // 5: metatable for ephemeron tables
jbe@121:   lua_pushliteral(L, "__mode");
jbe@121:   lua_pushliteral(L, "k");
jbe@130:   lua_rawset(L, 5);
jbe@130:   lua_pushvalue(L, 5);  // 6: cloned metatable reference
jbe@127:   lua_setmetatable(L, 3);
jbe@130:   lua_setmetatable(L, 4);
jbe@130:   lua_newtable(L);  // 5: metatable for JSON objects and JSON arrays
jbe@126:   lua_pushvalue(L, 2);
jbe@126:   lua_pushvalue(L, 3);
jbe@127:   lua_pushvalue(L, 4);
jbe@130:   lua_pushvalue(L, 5);
jbe@135:   lua_pushcclosure(L, json_pairs_iterfunc, 4);  // 6: iteration function for pairs
jbe@135:   lua_pushvalue(L, 2);
jbe@135:   lua_pushvalue(L, 3);
jbe@135:   lua_pushvalue(L, 4);
jbe@135:   lua_pushvalue(L, 5);
jbe@135:   lua_pushcclosure(L, json_ipairs_iterfunc, 4);  // 7: iteration function for ipairs
jbe@134:   lua_pushvalue(L, 5);
jbe@134:   lua_pushvalue(L, 2);
jbe@134:   lua_pushvalue(L, 3);
jbe@134:   lua_pushvalue(L, 4);
jbe@134:   lua_pushvalue(L, 5);
jbe@134:   lua_pushvalue(L, 6);
jbe@135:   lua_pushvalue(L, 7);
jbe@135:   luaL_setfuncs(L, json_metatable_functions, 6);
jbe@135:   lua_setfield(L, 1, "metatable");
jbe@135:   luaL_setfuncs(L, json_module_functions, 6);
jbe@121:   return 1;
jbe@121: }