py/builtinimport.c - lite/micropython - Linaro Git Browser

 /*
  * This file is part of the MicroPython project, http://micropython.org/
  *
  * The MIT License (MIT)
  *
  * Copyright (c) 2013, 2014 Damien P. George
  * Copyright (c) 2014 Paul Sokolovsky
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */

 #include <stdio.h>
 #include <string.h>
 #include <assert.h>

 #include "py/compile.h"
 #include "py/objmodule.h"
 #include "py/persistentcode.h"
 #include "py/runtime.h"
 #include "py/builtin.h"
 #include "py/frozenmod.h"

 #if MICROPY_DEBUG_VERBOSE // print debugging info
 #define DEBUG_PRINT (1)
 #define DEBUG_printf DEBUG_printf
 #else // don't print debugging info
 #define DEBUG_PRINT (0)
 #define DEBUG_printf(...) (void)0
 #endif

 #define PATH_SEP_CHAR '/'

 bool mp_obj_is_package(mp_obj_t module) {
     mp_obj_t dest[2];
     mp_load_method_maybe(module, MP_QSTR___path__, dest);
     return dest[0] != MP_OBJ_NULL;
 }

 // Stat either frozen or normal module by a given path
 // (whatever is available, if at all).
 STATIC mp_import_stat_t mp_import_stat_any(const char *path) {
     #if MICROPY_MODULE_FROZEN
     mp_import_stat_t st = mp_frozen_stat(path);
     if (st != MP_IMPORT_STAT_NO_EXIST) {
         return st;
     }
     #endif
     return mp_import_stat(path);
 }

 STATIC mp_import_stat_t stat_file_py_or_mpy(vstr_t *path) {
     mp_import_stat_t stat = mp_import_stat_any(vstr_null_terminated_str(path));
     if (stat == MP_IMPORT_STAT_FILE) {
         return stat;
     }

     #if MICROPY_PERSISTENT_CODE_LOAD
     vstr_ins_byte(path, path->len - 2, 'm');
     stat = mp_import_stat_any(vstr_null_terminated_str(path));
     if (stat == MP_IMPORT_STAT_FILE) {
         return stat;
     }
     #endif

     return MP_IMPORT_STAT_NO_EXIST;
 }

 STATIC mp_import_stat_t stat_dir_or_file(vstr_t *path) {
     mp_import_stat_t stat = mp_import_stat_any(vstr_null_terminated_str(path));
     DEBUG_printf("stat %s: %d\n", vstr_str(path), stat);
     if (stat == MP_IMPORT_STAT_DIR) {
         return stat;
     }

     // not a directory, add .py and try as a file
     vstr_add_str(path, ".py");
     return stat_file_py_or_mpy(path);
 }

 STATIC mp_import_stat_t find_file(const char *file_str, uint file_len, vstr_t *dest) {
 #if MICROPY_PY_SYS
     // extract the list of paths
     size_t path_num;
     mp_obj_t *path_items;
     mp_obj_list_get(mp_sys_path, &path_num, &path_items);

     if (path_num == 0) {
 #endif
         // mp_sys_path is empty, so just use the given file name
         vstr_add_strn(dest, file_str, file_len);
         return stat_dir_or_file(dest);
 #if MICROPY_PY_SYS
     } else {
         // go through each path looking for a directory or file
         for (size_t i = 0; i < path_num; i++) {
             vstr_reset(dest);
             size_t p_len;
             const char *p = mp_obj_str_get_data(path_items[i], &p_len);
             if (p_len > 0) {
                 vstr_add_strn(dest, p, p_len);
                 vstr_add_char(dest, PATH_SEP_CHAR);
             }
             vstr_add_strn(dest, file_str, file_len);
             mp_import_stat_t stat = stat_dir_or_file(dest);
             if (stat != MP_IMPORT_STAT_NO_EXIST) {
                 return stat;
             }
         }

         // could not find a directory or file
         return MP_IMPORT_STAT_NO_EXIST;
     }
 #endif
 }

 #if MICROPY_ENABLE_COMPILER
 STATIC void do_load_from_lexer(mp_obj_t module_obj, mp_lexer_t *lex) {
     #if MICROPY_PY___FILE__
     qstr source_name = lex->source_name;
     mp_store_attr(module_obj, MP_QSTR___file__, MP_OBJ_NEW_QSTR(source_name));
     #endif

     // parse, compile and execute the module in its context
     mp_obj_dict_t *mod_globals = mp_obj_module_get_globals(module_obj);
     mp_parse_compile_execute(lex, MP_PARSE_FILE_INPUT, mod_globals, mod_globals);
 }
 #endif

 #if MICROPY_PERSISTENT_CODE_LOAD || MICROPY_MODULE_FROZEN_MPY
 STATIC void do_execute_raw_code(mp_obj_t module_obj, mp_raw_code_t *raw_code) {
     #if MICROPY_PY___FILE__
     // TODO
     //qstr source_name = lex->source_name;
     //mp_store_attr(module_obj, MP_QSTR___file__, MP_OBJ_NEW_QSTR(source_name));
     #endif

     // execute the module in its context
     mp_obj_dict_t *mod_globals = mp_obj_module_get_globals(module_obj);

     // save context
     mp_obj_dict_t *volatile old_globals = mp_globals_get();
     mp_obj_dict_t *volatile old_locals = mp_locals_get();

     // set new context
     mp_globals_set(mod_globals);
     mp_locals_set(mod_globals);

     nlr_buf_t nlr;
     if (nlr_push(&nlr) == 0) {
         mp_obj_t module_fun = mp_make_function_from_raw_code(raw_code, MP_OBJ_NULL, MP_OBJ_NULL);
         mp_call_function_0(module_fun);

         // finish nlr block, restore context
         nlr_pop();
         mp_globals_set(old_globals);
         mp_locals_set(old_locals);
     } else {
         // exception; restore context and re-raise same exception
         mp_globals_set(old_globals);
         mp_locals_set(old_locals);
         nlr_jump(nlr.ret_val);
     }
 }
 #endif

 STATIC void do_load(mp_obj_t module_obj, vstr_t *file) {
     #if MICROPY_MODULE_FROZEN || MICROPY_PERSISTENT_CODE_LOAD || MICROPY_ENABLE_COMPILER
     char *file_str = vstr_null_terminated_str(file);
     #endif

     // If we support frozen modules (either as str or mpy) then try to find the
     // requested filename in the list of frozen module filenames.
     #if MICROPY_MODULE_FROZEN
     void *modref;
     int frozen_type = mp_find_frozen_module(file_str, file->len, &modref);
     #endif

     // If we support frozen str modules and the compiler is enabled, and we
     // found the filename in the list of frozen files, then load and execute it.
     #if MICROPY_MODULE_FROZEN_STR
     if (frozen_type == MP_FROZEN_STR) {
         do_load_from_lexer(module_obj, modref);
         return;
     }
     #endif

     // If we support frozen mpy modules and we found a corresponding file (and
     // its data) in the list of frozen files, execute it.
     #if MICROPY_MODULE_FROZEN_MPY
     if (frozen_type == MP_FROZEN_MPY) {
         do_execute_raw_code(module_obj, modref);
         return;
     }
     #endif

     // If we support loading .mpy files then check if the file extension is of
     // the correct format and, if so, load and execute the file.
     #if MICROPY_PERSISTENT_CODE_LOAD
     if (file_str[file->len - 3] == 'm') {
         mp_raw_code_t *raw_code = mp_raw_code_load_file(file_str);
         do_execute_raw_code(module_obj, raw_code);
         return;
     }
     #endif

     // If we can compile scripts then load the file and compile and execute it.
     #if MICROPY_ENABLE_COMPILER
     {
         mp_lexer_t *lex = mp_lexer_new_from_file(file_str);
         do_load_from_lexer(module_obj, lex);
         return;
     }
     #else

     // If we get here then the file was not frozen and we can't compile scripts.
     mp_raise_msg(&mp_type_ImportError, "script compilation not supported");
     #endif
 }

 STATIC void chop_component(const char *start, const char **end) {
     const char *p = *end;
     while (p > start) {
         if (*--p == '.') {
             *end = p;
             return;
         }
     }
     *end = p;
 }

 mp_obj_t mp_builtin___import__(size_t n_args, const mp_obj_t *args) {
 #if DEBUG_PRINT
     DEBUG_printf("__import__:\n");
     for (size_t i = 0; i < n_args; i++) {
         DEBUG_printf("  ");
         mp_obj_print(args[i], PRINT_REPR);
         DEBUG_printf("\n");
     }
 #endif

     mp_obj_t module_name = args[0];
     mp_obj_t fromtuple = mp_const_none;
     mp_int_t level = 0;
     if (n_args >= 4) {
         fromtuple = args[3];
         if (n_args >= 5) {
             level = MP_OBJ_SMALL_INT_VALUE(args[4]);
             if (level < 0) {
                 mp_raise_ValueError(NULL);
             }
         }
     }

     size_t mod_len;
     const char *mod_str = mp_obj_str_get_data(module_name, &mod_len);

     if (level != 0) {
         // What we want to do here is to take name of current module,
         // chop <level> trailing components, and concatenate with passed-in
         // module name, thus resolving relative import name into absolute.
         // This even appears to be correct per
         // http://legacy.python.org/dev/peps/pep-0328/#relative-imports-and-name
         // "Relative imports use a module's __name__ attribute to determine that
         // module's position in the package hierarchy."
         level--;
         mp_obj_t this_name_q = mp_obj_dict_get(MP_OBJ_FROM_PTR(mp_globals_get()), MP_OBJ_NEW_QSTR(MP_QSTR___name__));
         assert(this_name_q != MP_OBJ_NULL);
         #if MICROPY_CPYTHON_COMPAT
         if (MP_OBJ_QSTR_VALUE(this_name_q) == MP_QSTR___main__) {
             // This is a module run by -m command-line switch, get its real name from backup attribute
             this_name_q = mp_obj_dict_get(MP_OBJ_FROM_PTR(mp_globals_get()), MP_OBJ_NEW_QSTR(MP_QSTR___main__));
         }
         #endif
         mp_map_t *globals_map = &mp_globals_get()->map;
         mp_map_elem_t *elem = mp_map_lookup(globals_map, MP_OBJ_NEW_QSTR(MP_QSTR___path__), MP_MAP_LOOKUP);
         bool is_pkg = (elem != NULL);

 #if DEBUG_PRINT
         DEBUG_printf("Current module/package: ");
         mp_obj_print(this_name_q, PRINT_REPR);
         DEBUG_printf(", is_package: %d", is_pkg);
         DEBUG_printf("\n");
 #endif

         size_t this_name_l;
         const char *this_name = mp_obj_str_get_data(this_name_q, &this_name_l);

         const char *p = this_name + this_name_l;
         if (!is_pkg) {
             // We have module, but relative imports are anchored at package, so
             // go there.
             chop_component(this_name, &p);
         }

         while (level--) {
             chop_component(this_name, &p);
         }

         // We must have some component left over to import from
         if (p == this_name) {
             mp_raise_ValueError("cannot perform relative import");
         }

         uint new_mod_l = (mod_len == 0 ? (size_t)(p - this_name) : (size_t)(p - this_name) + 1 + mod_len);
         char *new_mod = mp_local_alloc(new_mod_l);
         memcpy(new_mod, this_name, p - this_name);
         if (mod_len != 0) {
             new_mod[p - this_name] = '.';
             memcpy(new_mod + (p - this_name) + 1, mod_str, mod_len);
         }

         qstr new_mod_q = qstr_from_strn(new_mod, new_mod_l);
         mp_local_free(new_mod);
         DEBUG_printf("Resolved base name for relative import: '%s'\n", qstr_str(new_mod_q));
         module_name = MP_OBJ_NEW_QSTR(new_mod_q);
         mod_str = qstr_str(new_mod_q);
         mod_len = new_mod_l;
     }

     // check if module already exists
     qstr module_name_qstr = mp_obj_str_get_qstr(module_name);
     mp_obj_t module_obj = mp_module_get(module_name_qstr);
     if (module_obj != MP_OBJ_NULL) {
         DEBUG_printf("Module already loaded\n");
         // If it's not a package, return module right away
         char *p = strchr(mod_str, '.');
         if (p == NULL) {
             return module_obj;
         }
         // If fromlist is not empty, return leaf module
         if (fromtuple != mp_const_none) {
             return module_obj;
         }
         // Otherwise, we need to return top-level package
         qstr pkg_name = qstr_from_strn(mod_str, p - mod_str);
         return mp_module_get(pkg_name);
     }
     DEBUG_printf("Module not yet loaded\n");

     uint last = 0;
     VSTR_FIXED(path, MICROPY_ALLOC_PATH_MAX)
     module_obj = MP_OBJ_NULL;
     mp_obj_t top_module_obj = MP_OBJ_NULL;
     mp_obj_t outer_module_obj = MP_OBJ_NULL;
     uint i;
     for (i = 1; i <= mod_len; i++) {
         if (i == mod_len || mod_str[i] == '.') {
             // create a qstr for the module name up to this depth
             qstr mod_name = qstr_from_strn(mod_str, i);
             DEBUG_printf("Processing module: %s\n", qstr_str(mod_name));
             DEBUG_printf("Previous path: =%.*s=\n", vstr_len(&path), vstr_str(&path));

             // find the file corresponding to the module name
             mp_import_stat_t stat;
             if (vstr_len(&path) == 0) {
                 // first module in the dotted-name; search for a directory or file
                 stat = find_file(mod_str, i, &path);
             } else {
                 // latter module in the dotted-name; append to path
                 vstr_add_char(&path, PATH_SEP_CHAR);
                 vstr_add_strn(&path, mod_str + last, i - last);
                 stat = stat_dir_or_file(&path);
             }
             DEBUG_printf("Current path: %.*s\n", vstr_len(&path), vstr_str(&path));

             if (stat == MP_IMPORT_STAT_NO_EXIST) {
                 #if MICROPY_MODULE_WEAK_LINKS
                 // check if there is a weak link to this module
                 if (i == mod_len) {
                     mp_map_elem_t *el = mp_map_lookup((mp_map_t*)&mp_builtin_module_weak_links_map, MP_OBJ_NEW_QSTR(mod_name), MP_MAP_LOOKUP);
                     if (el == NULL) {
                         goto no_exist;
                     }
                     // found weak linked module
                     module_obj = el->value;
                     if (MICROPY_MODULE_BUILTIN_INIT) {
                         // look for __init__ and call it if it exists
                         // Note: this code doesn't work fully correctly because it allows the
                         // __init__ function to be called twice if the module is imported by its
                         // non-weak-link name.  Also, this code is duplicated in objmodule.c.
                         mp_obj_t dest[2];
                         mp_load_method_maybe(el->value, MP_QSTR___init__, dest);
                         if (dest[0] != MP_OBJ_NULL) {
                             mp_call_method_n_kw(0, 0, dest);
                             // register module so __init__ is not called again
                             mp_module_register(mod_name, el->value);
                         }
                     }
                 } else {
                     no_exist:
                 #else
                 {
                 #endif
                     // couldn't find the file, so fail
                     if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
                         mp_raise_msg(&mp_type_ImportError, "module not found");
                     } else {
                         nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ImportError,
                             "no module named '%q'", mod_name));
                     }
                 }
             } else {
                 // found the file, so get the module
                 module_obj = mp_module_get(mod_name);
             }

             if (module_obj == MP_OBJ_NULL) {
                 // module not already loaded, so load it!

                 module_obj = mp_obj_new_module(mod_name);

                 // if args[3] (fromtuple) has magic value False, set up
                 // this module for command-line "-m" option (set module's
                 // name to __main__ instead of real name). Do this only
                 // for *modules* however - packages never have their names
                 // replaced, instead they're -m'ed using a special __main__
                 // submodule in them. (This all apparently is done to not
                 // touch package name itself, which is important for future
                 // imports).
                 if (i == mod_len && fromtuple == mp_const_false && stat != MP_IMPORT_STAT_DIR) {
                     mp_obj_module_t *o = MP_OBJ_TO_PTR(module_obj);
                     mp_obj_dict_store(MP_OBJ_FROM_PTR(o->globals), MP_OBJ_NEW_QSTR(MP_QSTR___name__), MP_OBJ_NEW_QSTR(MP_QSTR___main__));
                     #if MICROPY_CPYTHON_COMPAT
                     // Store module as "__main__" in the dictionary of loaded modules (returned by sys.modules).
                     mp_obj_dict_store(MP_OBJ_FROM_PTR(&MP_STATE_VM(mp_loaded_modules_dict)), MP_OBJ_NEW_QSTR(MP_QSTR___main__), module_obj);
                     // Store real name in "__main__" attribute. Chosen semi-randonly, to reuse existing qstr's.
                     mp_obj_dict_store(MP_OBJ_FROM_PTR(o->globals), MP_OBJ_NEW_QSTR(MP_QSTR___main__), MP_OBJ_NEW_QSTR(mod_name));
                     #endif
                 }

                 if (stat == MP_IMPORT_STAT_DIR) {
                     DEBUG_printf("%.*s is dir\n", vstr_len(&path), vstr_str(&path));
                     // https://docs.python.org/3/reference/import.html
                     // "Specifically, any module that contains a __path__ attribute is considered a package."
                     mp_store_attr(module_obj, MP_QSTR___path__, mp_obj_new_str(vstr_str(&path), vstr_len(&path)));
                     size_t orig_path_len = path.len;
                     vstr_add_char(&path, PATH_SEP_CHAR);
                     vstr_add_str(&path, "__init__.py");
                     if (stat_file_py_or_mpy(&path) != MP_IMPORT_STAT_FILE) {
                         //mp_warning("%s is imported as namespace package", vstr_str(&path));
                     } else {
                         do_load(module_obj, &path);
                     }
                     path.len = orig_path_len;
                 } else { // MP_IMPORT_STAT_FILE
                     do_load(module_obj, &path);
                     // This should be the last component in the import path.  If there are
                     // remaining components then it's an ImportError because the current path
                     // (the module that was just loaded) is not a package.  This will be caught
                     // on the next iteration because the file will not exist.
                 }
             }
             if (outer_module_obj != MP_OBJ_NULL) {
                 qstr s = qstr_from_strn(mod_str + last, i - last);
                 mp_store_attr(outer_module_obj, s, module_obj);
             }
             outer_module_obj = module_obj;
             if (top_module_obj == MP_OBJ_NULL) {
                 top_module_obj = module_obj;
             }
             last = i + 1;
         }
     }

     // If fromlist is not empty, return leaf module
     if (fromtuple != mp_const_none) {
         return module_obj;
     }
     // Otherwise, we need to return top-level package
     return top_module_obj;
 }
 MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_builtin___import___obj, 1, 5, mp_builtin___import__);
	/*
	* This file is part of the MicroPython project, http://micropython.org/
	*
	* The MIT License (MIT)
	*
	* Copyright (c) 2013, 2014 Damien P. George
	* Copyright (c) 2014 Paul Sokolovsky
	*
	* Permission is hereby granted, free of charge, to any person obtaining a copy
	* of this software and associated documentation files (the "Software"), to deal
	* in the Software without restriction, including without limitation the rights
	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	* copies of the Software, and to permit persons to whom the Software is
	* furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	* THE SOFTWARE.
	*/

	#include <stdio.h>
	#include <string.h>
	#include <assert.h>

	#include "py/compile.h"
	#include "py/objmodule.h"
	#include "py/persistentcode.h"
	#include "py/runtime.h"
	#include "py/builtin.h"
	#include "py/frozenmod.h"

	#if MICROPY_DEBUG_VERBOSE // print debugging info
	#define DEBUG_PRINT (1)
	#define DEBUG_printf DEBUG_printf
	#else // don't print debugging info
	#define DEBUG_PRINT (0)
	#define DEBUG_printf(...) (void)0
	#endif

	#define PATH_SEP_CHAR '/'

	bool mp_obj_is_package(mp_obj_t module) {
	mp_obj_t dest[2];
	mp_load_method_maybe(module, MP_QSTR___path__, dest);
	return dest[0] != MP_OBJ_NULL;
	}

	// Stat either frozen or normal module by a given path
	// (whatever is available, if at all).
	STATIC mp_import_stat_t mp_import_stat_any(const char *path) {
	#if MICROPY_MODULE_FROZEN
	mp_import_stat_t st = mp_frozen_stat(path);
	if (st != MP_IMPORT_STAT_NO_EXIST) {
	return st;
	}
	#endif
	return mp_import_stat(path);
	}

	STATIC mp_import_stat_t stat_file_py_or_mpy(vstr_t *path) {
	mp_import_stat_t stat = mp_import_stat_any(vstr_null_terminated_str(path));
	if (stat == MP_IMPORT_STAT_FILE) {
	return stat;
	}

	#if MICROPY_PERSISTENT_CODE_LOAD
	vstr_ins_byte(path, path->len - 2, 'm');
	stat = mp_import_stat_any(vstr_null_terminated_str(path));
	if (stat == MP_IMPORT_STAT_FILE) {
	return stat;
	}
	#endif

	return MP_IMPORT_STAT_NO_EXIST;
	}

	STATIC mp_import_stat_t stat_dir_or_file(vstr_t *path) {
	mp_import_stat_t stat = mp_import_stat_any(vstr_null_terminated_str(path));
	DEBUG_printf("stat %s: %d\n", vstr_str(path), stat);
	if (stat == MP_IMPORT_STAT_DIR) {
	return stat;
	}

	// not a directory, add .py and try as a file
	vstr_add_str(path, ".py");
	return stat_file_py_or_mpy(path);
	}

	STATIC mp_import_stat_t find_file(const char file_str, uint file_len, vstr_t dest) {
	#if MICROPY_PY_SYS
	// extract the list of paths
	size_t path_num;
	mp_obj_t *path_items;
	mp_obj_list_get(mp_sys_path, &path_num, &path_items);

	if (path_num == 0) {
	#endif
	// mp_sys_path is empty, so just use the given file name
	vstr_add_strn(dest, file_str, file_len);
	return stat_dir_or_file(dest);
	#if MICROPY_PY_SYS
	} else {
	// go through each path looking for a directory or file
	for (size_t i = 0; i < path_num; i++) {
	vstr_reset(dest);
	size_t p_len;
	const char *p = mp_obj_str_get_data(path_items[i], &p_len);
	if (p_len > 0) {
	vstr_add_strn(dest, p, p_len);
	vstr_add_char(dest, PATH_SEP_CHAR);
	}
	vstr_add_strn(dest, file_str, file_len);
	mp_import_stat_t stat = stat_dir_or_file(dest);
	if (stat != MP_IMPORT_STAT_NO_EXIST) {
	return stat;
	}
	}

	// could not find a directory or file
	return MP_IMPORT_STAT_NO_EXIST;
	}
	#endif
	}

	#if MICROPY_ENABLE_COMPILER
	STATIC void do_load_from_lexer(mp_obj_t module_obj, mp_lexer_t *lex) {
	#if MICROPY_PY___FILE__
	qstr source_name = lex->source_name;
	mp_store_attr(module_obj, MP_QSTR___file__, MP_OBJ_NEW_QSTR(source_name));
	#endif

	// parse, compile and execute the module in its context
	mp_obj_dict_t *mod_globals = mp_obj_module_get_globals(module_obj);
	mp_parse_compile_execute(lex, MP_PARSE_FILE_INPUT, mod_globals, mod_globals);
	}
	#endif

	#if MICROPY_PERSISTENT_CODE_LOAD \|\| MICROPY_MODULE_FROZEN_MPY
	STATIC void do_execute_raw_code(mp_obj_t module_obj, mp_raw_code_t *raw_code) {
	#if MICROPY_PY___FILE__
	// TODO
	//qstr source_name = lex->source_name;
	//mp_store_attr(module_obj, MP_QSTR___file__, MP_OBJ_NEW_QSTR(source_name));
	#endif

	// execute the module in its context
	mp_obj_dict_t *mod_globals = mp_obj_module_get_globals(module_obj);

	// save context
	mp_obj_dict_t *volatile old_globals = mp_globals_get();
	mp_obj_dict_t *volatile old_locals = mp_locals_get();

	// set new context
	mp_globals_set(mod_globals);
	mp_locals_set(mod_globals);

	nlr_buf_t nlr;
	if (nlr_push(&nlr) == 0) {
	mp_obj_t module_fun = mp_make_function_from_raw_code(raw_code, MP_OBJ_NULL, MP_OBJ_NULL);
	mp_call_function_0(module_fun);

	// finish nlr block, restore context
	nlr_pop();
	mp_globals_set(old_globals);
	mp_locals_set(old_locals);
	} else {
	// exception; restore context and re-raise same exception
	mp_globals_set(old_globals);
	mp_locals_set(old_locals);
	nlr_jump(nlr.ret_val);
	}
	}
	#endif

	STATIC void do_load(mp_obj_t module_obj, vstr_t *file) {
	#if MICROPY_MODULE_FROZEN \|\| MICROPY_PERSISTENT_CODE_LOAD \|\| MICROPY_ENABLE_COMPILER
	char *file_str = vstr_null_terminated_str(file);
	#endif

	// If we support frozen modules (either as str or mpy) then try to find the
	// requested filename in the list of frozen module filenames.
	#if MICROPY_MODULE_FROZEN
	void *modref;
	int frozen_type = mp_find_frozen_module(file_str, file->len, &modref);
	#endif

	// If we support frozen str modules and the compiler is enabled, and we
	// found the filename in the list of frozen files, then load and execute it.
	#if MICROPY_MODULE_FROZEN_STR
	if (frozen_type == MP_FROZEN_STR) {
	do_load_from_lexer(module_obj, modref);
	return;
	}
	#endif

	// If we support frozen mpy modules and we found a corresponding file (and
	// its data) in the list of frozen files, execute it.
	#if MICROPY_MODULE_FROZEN_MPY
	if (frozen_type == MP_FROZEN_MPY) {
	do_execute_raw_code(module_obj, modref);
	return;
	}
	#endif

	// If we support loading .mpy files then check if the file extension is of
	// the correct format and, if so, load and execute the file.
	#if MICROPY_PERSISTENT_CODE_LOAD
	if (file_str[file->len - 3] == 'm') {
	mp_raw_code_t *raw_code = mp_raw_code_load_file(file_str);
	do_execute_raw_code(module_obj, raw_code);
	return;
	}
	#endif

	// If we can compile scripts then load the file and compile and execute it.
	#if MICROPY_ENABLE_COMPILER
	{
	mp_lexer_t *lex = mp_lexer_new_from_file(file_str);
	do_load_from_lexer(module_obj, lex);
	return;
	}
	#else

	// If we get here then the file was not frozen and we can't compile scripts.
	mp_raise_msg(&mp_type_ImportError, "script compilation not supported");
	#endif
	}

	STATIC void chop_component(const char start, const char *end) {
	const char p = end;
	while (p > start) {
	if (*--p == '.') {
	*end = p;
	return;
	}
	}
	*end = p;
	}

	mp_obj_t mp_builtin___import__(size_t n_args, const mp_obj_t *args) {
	#if DEBUG_PRINT
	DEBUG_printf("__import__:\n");
	for (size_t i = 0; i < n_args; i++) {
	DEBUG_printf(" ");
	mp_obj_print(args[i], PRINT_REPR);
	DEBUG_printf("\n");
	}
	#endif

	mp_obj_t module_name = args[0];
	mp_obj_t fromtuple = mp_const_none;
	mp_int_t level = 0;
	if (n_args >= 4) {
	fromtuple = args[3];
	if (n_args >= 5) {
	level = MP_OBJ_SMALL_INT_VALUE(args[4]);
	if (level < 0) {
	mp_raise_ValueError(NULL);
	}
	}
	}

	size_t mod_len;
	const char *mod_str = mp_obj_str_get_data(module_name, &mod_len);

	if (level != 0) {
	// What we want to do here is to take name of current module,
	// chop <level> trailing components, and concatenate with passed-in
	// module name, thus resolving relative import name into absolute.
	// This even appears to be correct per
	// http://legacy.python.org/dev/peps/pep-0328/#relative-imports-and-name
	// "Relative imports use a module's __name__ attribute to determine that
	// module's position in the package hierarchy."
	level--;
	mp_obj_t this_name_q = mp_obj_dict_get(MP_OBJ_FROM_PTR(mp_globals_get()), MP_OBJ_NEW_QSTR(MP_QSTR___name__));
	assert(this_name_q != MP_OBJ_NULL);
	#if MICROPY_CPYTHON_COMPAT
	if (MP_OBJ_QSTR_VALUE(this_name_q) == MP_QSTR___main__) {
	// This is a module run by -m command-line switch, get its real name from backup attribute
	this_name_q = mp_obj_dict_get(MP_OBJ_FROM_PTR(mp_globals_get()), MP_OBJ_NEW_QSTR(MP_QSTR___main__));
	}
	#endif
	mp_map_t *globals_map = &mp_globals_get()->map;
	mp_map_elem_t *elem = mp_map_lookup(globals_map, MP_OBJ_NEW_QSTR(MP_QSTR___path__), MP_MAP_LOOKUP);
	bool is_pkg = (elem != NULL);

	#if DEBUG_PRINT
	DEBUG_printf("Current module/package: ");
	mp_obj_print(this_name_q, PRINT_REPR);
	DEBUG_printf(", is_package: %d", is_pkg);
	DEBUG_printf("\n");
	#endif

	size_t this_name_l;
	const char *this_name = mp_obj_str_get_data(this_name_q, &this_name_l);

	const char *p = this_name + this_name_l;
	if (!is_pkg) {
	// We have module, but relative imports are anchored at package, so
	// go there.
	chop_component(this_name, &p);
	}

	while (level--) {
	chop_component(this_name, &p);
	}

	// We must have some component left over to import from
	if (p == this_name) {
	mp_raise_ValueError("cannot perform relative import");
	}

	uint new_mod_l = (mod_len == 0 ? (size_t)(p - this_name) : (size_t)(p - this_name) + 1 + mod_len);
	char *new_mod = mp_local_alloc(new_mod_l);
	memcpy(new_mod, this_name, p - this_name);
	if (mod_len != 0) {
	new_mod[p - this_name] = '.';
	memcpy(new_mod + (p - this_name) + 1, mod_str, mod_len);
	}

	qstr new_mod_q = qstr_from_strn(new_mod, new_mod_l);
	mp_local_free(new_mod);
	DEBUG_printf("Resolved base name for relative import: '%s'\n", qstr_str(new_mod_q));
	module_name = MP_OBJ_NEW_QSTR(new_mod_q);
	mod_str = qstr_str(new_mod_q);
	mod_len = new_mod_l;
	}

	// check if module already exists
	qstr module_name_qstr = mp_obj_str_get_qstr(module_name);
	mp_obj_t module_obj = mp_module_get(module_name_qstr);
	if (module_obj != MP_OBJ_NULL) {
	DEBUG_printf("Module already loaded\n");
	// If it's not a package, return module right away
	char *p = strchr(mod_str, '.');
	if (p == NULL) {
	return module_obj;
	}
	// If fromlist is not empty, return leaf module
	if (fromtuple != mp_const_none) {
	return module_obj;
	}
	// Otherwise, we need to return top-level package
	qstr pkg_name = qstr_from_strn(mod_str, p - mod_str);
	return mp_module_get(pkg_name);
	}
	DEBUG_printf("Module not yet loaded\n");

	uint last = 0;
	VSTR_FIXED(path, MICROPY_ALLOC_PATH_MAX)
	module_obj = MP_OBJ_NULL;
	mp_obj_t top_module_obj = MP_OBJ_NULL;
	mp_obj_t outer_module_obj = MP_OBJ_NULL;
	uint i;
	for (i = 1; i <= mod_len; i++) {
	if (i == mod_len \|\| mod_str[i] == '.') {
	// create a qstr for the module name up to this depth
	qstr mod_name = qstr_from_strn(mod_str, i);
	DEBUG_printf("Processing module: %s\n", qstr_str(mod_name));
	DEBUG_printf("Previous path: =%.*s=\n", vstr_len(&path), vstr_str(&path));

	// find the file corresponding to the module name
	mp_import_stat_t stat;
	if (vstr_len(&path) == 0) {
	// first module in the dotted-name; search for a directory or file
	stat = find_file(mod_str, i, &path);
	} else {
	// latter module in the dotted-name; append to path
	vstr_add_char(&path, PATH_SEP_CHAR);
	vstr_add_strn(&path, mod_str + last, i - last);
	stat = stat_dir_or_file(&path);
	}
	DEBUG_printf("Current path: %.*s\n", vstr_len(&path), vstr_str(&path));

	if (stat == MP_IMPORT_STAT_NO_EXIST) {
	#if MICROPY_MODULE_WEAK_LINKS
	// check if there is a weak link to this module
	if (i == mod_len) {
	mp_map_elem_t el = mp_map_lookup((mp_map_t)&mp_builtin_module_weak_links_map, MP_OBJ_NEW_QSTR(mod_name), MP_MAP_LOOKUP);
	if (el == NULL) {
	goto no_exist;
	}
	// found weak linked module
	module_obj = el->value;
	if (MICROPY_MODULE_BUILTIN_INIT) {
	// look for __init__ and call it if it exists
	// Note: this code doesn't work fully correctly because it allows the
	// __init__ function to be called twice if the module is imported by its
	// non-weak-link name. Also, this code is duplicated in objmodule.c.
	mp_obj_t dest[2];
	mp_load_method_maybe(el->value, MP_QSTR___init__, dest);
	if (dest[0] != MP_OBJ_NULL) {
	mp_call_method_n_kw(0, 0, dest);
	// register module so __init__ is not called again
	mp_module_register(mod_name, el->value);
	}
	}
	} else {
	no_exist:
	#else
	{
	#endif
	// couldn't find the file, so fail
	if (MICROPY_ERROR_REPORTING == MICROPY_ERROR_REPORTING_TERSE) {
	mp_raise_msg(&mp_type_ImportError, "module not found");
	} else {
	nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ImportError,
	"no module named '%q'", mod_name));
	}
	}
	} else {
	// found the file, so get the module
	module_obj = mp_module_get(mod_name);
	}

	if (module_obj == MP_OBJ_NULL) {
	// module not already loaded, so load it!

	module_obj = mp_obj_new_module(mod_name);

	// if args[3] (fromtuple) has magic value False, set up
	// this module for command-line "-m" option (set module's
	// name to __main__ instead of real name). Do this only
	// for modules however - packages never have their names
	// replaced, instead they're -m'ed using a special __main__
	// submodule in them. (This all apparently is done to not
	// touch package name itself, which is important for future
	// imports).
	if (i == mod_len && fromtuple == mp_const_false && stat != MP_IMPORT_STAT_DIR) {
	mp_obj_module_t *o = MP_OBJ_TO_PTR(module_obj);
	mp_obj_dict_store(MP_OBJ_FROM_PTR(o->globals), MP_OBJ_NEW_QSTR(MP_QSTR___name__), MP_OBJ_NEW_QSTR(MP_QSTR___main__));
	#if MICROPY_CPYTHON_COMPAT
	// Store module as "__main__" in the dictionary of loaded modules (returned by sys.modules).
	mp_obj_dict_store(MP_OBJ_FROM_PTR(&MP_STATE_VM(mp_loaded_modules_dict)), MP_OBJ_NEW_QSTR(MP_QSTR___main__), module_obj);
	// Store real name in "__main__" attribute. Chosen semi-randonly, to reuse existing qstr's.
	mp_obj_dict_store(MP_OBJ_FROM_PTR(o->globals), MP_OBJ_NEW_QSTR(MP_QSTR___main__), MP_OBJ_NEW_QSTR(mod_name));
	#endif
	}

	if (stat == MP_IMPORT_STAT_DIR) {
	DEBUG_printf("%.*s is dir\n", vstr_len(&path), vstr_str(&path));
	// https://docs.python.org/3/reference/import.html
	// "Specifically, any module that contains a __path__ attribute is considered a package."
	mp_store_attr(module_obj, MP_QSTR___path__, mp_obj_new_str(vstr_str(&path), vstr_len(&path)));
	size_t orig_path_len = path.len;
	vstr_add_char(&path, PATH_SEP_CHAR);
	vstr_add_str(&path, "__init__.py");
	if (stat_file_py_or_mpy(&path) != MP_IMPORT_STAT_FILE) {
	//mp_warning("%s is imported as namespace package", vstr_str(&path));
	} else {
	do_load(module_obj, &path);
	}
	path.len = orig_path_len;
	} else { // MP_IMPORT_STAT_FILE
	do_load(module_obj, &path);
	// This should be the last component in the import path. If there are
	// remaining components then it's an ImportError because the current path
	// (the module that was just loaded) is not a package. This will be caught
	// on the next iteration because the file will not exist.
	}
	}
	if (outer_module_obj != MP_OBJ_NULL) {
	qstr s = qstr_from_strn(mod_str + last, i - last);
	mp_store_attr(outer_module_obj, s, module_obj);
	}
	outer_module_obj = module_obj;
	if (top_module_obj == MP_OBJ_NULL) {
	top_module_obj = module_obj;
	}
	last = i + 1;
	}
	}

	// If fromlist is not empty, return leaf module
	if (fromtuple != mp_const_none) {
	return module_obj;
	}
	// Otherwise, we need to return top-level package
	return top_module_obj;
	}
	MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_builtin___import___obj, 1, 5, mp_builtin___import__);