jbe@121: #include <lua.h>
jbe@121: #include <lauxlib.h>
jbe@122: #include <stdlib.h>
jbe@121: #include <string.h>
jbe@121: 
jbe@125: #define JSON_UPVAL_METATABLE lua_upvalueindex(1)
jbe@123: #define JSON_UPVAL_NULLS lua_upvalueindex(2)
jbe@125: #define JSON_UPVAL_ARYLEN lua_upvalueindex(3)
jbe@123: 
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@121: static int json_import(lua_State *L) {
jbe@121:   const char *str;
jbe@121:   size_t total;
jbe@121:   size_t pos = 0;
jbe@121:   size_t level = 0;
jbe@124:   int mode = JSON_STATE_VALUE;
jbe@121:   char c;
jbe@121:   luaL_Buffer luabuf;
jbe@121:   char *cbuf;
jbe@121:   size_t writepos;
jbe@121:   int aryidx;
jbe@121:   lua_settop(L, 1);
jbe@121:   str = lua_tostring(L, 1);
jbe@121:   total = strlen(str);
jbe@121: json_import_loop:
jbe@121:   while (c = str[pos], c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == '\f') pos++;
jbe@121:   switch (c) {
jbe@121:   case 0:
jbe@124:     if (mode == JSON_STATE_END) return 1;
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@121:   case '{':
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@121:     pos++;
jbe@125:     lua_newtable(L);  // the actual JSON object
jbe@125:     lua_pushvalue(L, JSON_UPVAL_METATABLE);
jbe@125:     lua_setmetatable(L, -2);
jbe@123:     lua_newtable(L);  // stores set of NULL values
jbe@123:     lua_pushvalue(L, -2);
jbe@123:     lua_pushvalue(L, -2);
jbe@123:     lua_rawset(L, JSON_UPVAL_NULLS);
jbe@124:     mode = JSON_STATE_OBJECT_KEY;
jbe@121:     level++;
jbe@121:     goto json_import_loop;
jbe@121:   case '[':
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@121:     pos++;
jbe@125:     lua_newtable(L);  // the actual JSON array
jbe@125:     lua_pushvalue(L, JSON_UPVAL_METATABLE);
jbe@125:     lua_setmetatable(L, -2);
jbe@123:     lua_newtable(L);  // stores set of NULL values
jbe@123:     lua_pushvalue(L, -2);
jbe@123:     lua_pushvalue(L, -2);
jbe@123:     lua_rawset(L, JSON_UPVAL_NULLS);
jbe@121:     lua_pushinteger(L, 0);  // length of array (since it may contain nil's)
jbe@124:     mode = JSON_STATE_ARRAY_VALUE;
jbe@121:     level++;
jbe@121:     goto json_import_loop;
jbe@121:   case '}':
jbe@124:     if (mode != JSON_STATE_OBJECT_KEY && mode != JSON_STATE_OBJECT_SEPARATOR)
jbe@121:       goto json_import_syntax_error;
jbe@121:     goto json_import_close;
jbe@121:   case ']':
jbe@124:     if (mode != JSON_STATE_ARRAY_VALUE && mode != JSON_STATE_ARRAY_SEPARATOR)
jbe@121:       goto json_import_syntax_error;
jbe@121:     lua_pushvalue(L, -2);  // use array table as key
jbe@121:     lua_insert(L, -2);  // use length of array as value
jbe@123:     lua_rawset(L, JSON_UPVAL_ARYLEN);  // store length in ephemeron table
jbe@121:     // leaves array table on top of stack
jbe@121:   json_import_close:
jbe@121:     pos++;
jbe@123:     lua_pop(L, 1);  // pop table that stores set of NULL values
jbe@121:     if (--level) {
jbe@121:       if (lua_type(L, -2) == LUA_TNUMBER) {
jbe@124:         mode = JSON_STATE_ARRAY_VALUE;
jbe@121:       } else {
jbe@124:         mode = JSON_STATE_OBJECT_VALUE;
jbe@121:       }
jbe@121:       goto json_import_process_value;
jbe@121:     } else {
jbe@124:       mode = JSON_STATE_END;
jbe@121:     }
jbe@121:     goto json_import_loop;
jbe@121:   case ':':
jbe@124:     if (mode != JSON_STATE_OBJECT_KEY_TERMINATOR)
jbe@121:       goto json_import_syntax_error;
jbe@121:     pos++;
jbe@124:     mode = JSON_STATE_OBJECT_VALUE;
jbe@121:     goto json_import_loop;
jbe@121:   case ',':
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@121:       goto json_import_syntax_error;
jbe@121:     }
jbe@121:     pos++;
jbe@121:     goto json_import_loop;
jbe@121:   case '"':
jbe@121:     cbuf = luaL_buffinitsize(L, &luabuf, total-pos);
jbe@121:     writepos = 0;
jbe@121:     pos++;
jbe@121:     while ((c = str[pos++]) != '"') {
jbe@121:       if (c == 0) {
jbe@121:         goto json_import_unexpected_eof;
jbe@121:       } else if (c < 32 || c == 127) {
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@121:         c = str[pos++];
jbe@121:         switch (c) {
jbe@121:         case 0:
jbe@121:           goto json_import_unexpected_eof;
jbe@121:         case '"':
jbe@121:         case '/':
jbe@121:         case '\\':
jbe@121:           cbuf[writepos++] = c;
jbe@121:           break;
jbe@121:         case 'b':
jbe@121:           cbuf[writepos++] = '\b';
jbe@121:           break;
jbe@121:         case 'f':
jbe@121:           cbuf[writepos++] = '\f';
jbe@121:           break;
jbe@121:         case 'n':
jbe@121:           cbuf[writepos++] = '\n';
jbe@121:           break;
jbe@121:         case 'r':
jbe@121:           cbuf[writepos++] = '\r';
jbe@121:           break;
jbe@121:         case 't':
jbe@121:           cbuf[writepos++] = '\t';
jbe@121:           break;
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@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@121:         cbuf[writepos++] = c;
jbe@121:       }
jbe@121:     }
jbe@121:     if (!c) goto json_import_unexpected_eof;
jbe@121:     luaL_pushresultsize(&luabuf, writepos);
jbe@121:     goto json_import_process_value;
jbe@121:   }
jbe@122:   if (c == '-' || (c >= '0' && c <= '9')) {
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@121:     lua_pushboolean(L, 1);
jbe@121:     pos += 4;
jbe@121:   } else if (!strncmp(str+pos, "false", 5)) {
jbe@121:     lua_pushboolean(L, 0);
jbe@121:     pos += 5;
jbe@121:   } else if (!strncmp(str+pos, "null", 4)) {
jbe@121:     lua_pushnil(L);
jbe@121:     pos += 4;
jbe@121:   } else {
jbe@121:     goto json_import_syntax_error;
jbe@121:   }
jbe@121: json_import_process_value:
jbe@121:   switch (mode) {
jbe@124:   case JSON_STATE_OBJECT_KEY:
jbe@121:     if (lua_type(L, -1) != LUA_TSTRING) goto json_import_syntax_error;
jbe@124:     mode = JSON_STATE_OBJECT_KEY_TERMINATOR;
jbe@121:     goto json_import_loop;
jbe@124:   case JSON_STATE_OBJECT_VALUE:
jbe@123:     if (lua_isnil(L, -1)) {
jbe@123:       lua_pushvalue(L, -2);
jbe@123:       lua_pushboolean(L, 1);
jbe@123:       lua_rawset(L, -5);
jbe@123:     }
jbe@123:     lua_rawset(L, -4);
jbe@124:     mode = JSON_STATE_OBJECT_SEPARATOR;
jbe@121:     goto json_import_loop;
jbe@124:   case JSON_STATE_ARRAY_VALUE:
jbe@121:     aryidx = lua_tointeger(L, -2) + 1;
jbe@123:     if (lua_isnil(L, -1)) {
jbe@123:       lua_pushinteger(L, aryidx);
jbe@123:       lua_pushboolean(L, 1);
jbe@123:       lua_rawset(L, -5);
jbe@123:     }
jbe@123:     lua_rawseti(L, -4, aryidx);
jbe@121:     lua_pop(L, 1);
jbe@121:     lua_pushinteger(L, aryidx);
jbe@124:     mode = JSON_STATE_ARRAY_SEPARATOR;
jbe@121:     goto json_import_loop;
jbe@124:   case JSON_STATE_VALUE:
jbe@124:     mode = JSON_STATE_END;
jbe@121:     goto json_import_loop;
jbe@121:   }
jbe@121: 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@121: static int json_arylen(lua_State *L) {
jbe@121:   lua_settop(L, 1);
jbe@123:   lua_rawget(L, JSON_UPVAL_ARYLEN);
jbe@123:   return 1;
jbe@123: }
jbe@123: 
jbe@123: static int json_isnull(lua_State *L) {
jbe@123:   lua_pushvalue(L, 1);
jbe@123:   lua_rawget(L, JSON_UPVAL_NULLS);
jbe@123:   if (lua_isnil(L, -1)) goto json_isnull_false;
jbe@123:   lua_pushvalue(L, 2);
jbe@123:   lua_rawget(L, -2);
jbe@123:   if (!lua_isnil(L, -1)) return 1;
jbe@123: json_isnull_false:
jbe@123:   lua_pushboolean(L, 0);
jbe@121:   return 1;
jbe@121: }
jbe@121: 
jbe@121: static const struct luaL_Reg json_module_functions[] = {
jbe@121:   {"import", json_import},
jbe@121:   {"arylen", json_arylen},
jbe@123:   {"isnull", json_isnull},
jbe@121:   {NULL, NULL}
jbe@121: };
jbe@121: 
jbe@121: int luaopen_json(lua_State *L) {
jbe@121:   lua_newtable(L);  // library table
jbe@125:   lua_newtable(L);  // metatable for JSON objects and JSON arrays
jbe@125:   lua_pushvalue(L, -1);
jbe@125:   lua_setfield(L, -3, "metatable");
jbe@125:   lua_newtable(L);  // ephemeron table to store a set of keys associated with JSON-null values
jbe@121:   lua_newtable(L);  // ephemeron table to store the length of arrays (that may contain nil's)
jbe@121:   lua_newtable(L);  // meta table for ephemeron table
jbe@121:   lua_pushliteral(L, "__mode");
jbe@121:   lua_pushliteral(L, "k");
jbe@121:   lua_rawset(L, -3);
jbe@123:   lua_pushvalue(L, -1);
jbe@123:   lua_setmetatable(L, -3);
jbe@121:   lua_setmetatable(L, -2);
jbe@125:   luaL_setfuncs(L, json_module_functions, 3);
jbe@121:   return 1;
jbe@121: }