pybricksdev.compile: fix parsing of imports

This fixes incorrectly including imports that are commented out or in
doc strings.

There is a standard Python module for discovering imports so we don't
have to come up with our own implementation.

This also removes support for relative imports since Python doesn't
support them outside of packages.

Author: dlech

demo/multidemo.py

@@ -1,7 +1,7 @@
 from pybricks.hubs import ThisHub
 from pybricks.parameters import Color
 from pybricks.tools import wait
-from .module2 import nice_color
+from module2 import nice_color
 
 hub = ThisHub()
 hub.light.on(Color.RED)

pybricksdev/compile.py

@@ -4,9 +4,7 @@
 import asyncio
 import logging
 import os
-import re
-
-from pathlib import Path
+from modulefinder import ModuleFinder
 from typing import List, Optional
 
 import mpy_cross_v5
@@ -114,61 +112,24 @@ async def compile_multi_file(path: str, abi: int):
         subprocess.CalledProcessError: if executing the ``mpy-cross` tool failed.
     """
 
-    # Make the build directory
-    make_build_dir()
+    # compile files using Python to find imports contained within the same directory as path
+    finder = ModuleFinder([os.path.dirname(path)])
+    finder.run_script(path)
 
-    # Directory where main and dependencies are located
-    source_dir = Path(path).parent
-
-    # Set of all dependencies
-    dependencies = set()
-    not_found = set()
-
-    # Find all dependencies recursively
-    def find_dependencies(module_name):
-        try:
-            path = source_dir / Path(*module_name.split(".")).with_suffix(".py")
-            with open(path) as source:
-                # Search non-recursively through current module
-                local_dependencies = set()
-                for line in source:
-                    # from my_module import thing1, thing2 ---> my_module
-                    if result := re.search("from (.*) import (.*)", line):
-                        local_dependencies.add(result.group(1))
-                    # import my_module ---> my_module
-                    elif result := re.search("import (.*)", line):
-                        local_dependencies.add(result.group(1))
-
-                # Add each file that wasn't already done, and find its
-                # dependencies.
-                for dep in local_dependencies.difference(dependencies):
-                    if dep not in dependencies:
-                        dependencies.add(dep)
-                        find_dependencies(dep)
-        # Some modules are stored on the hub so we can't find them here.
-        except FileNotFoundError:
-            not_found.add(module_name)
-
-    # Start searching from the top level.
-    main_module = Path(path).stem
-    find_dependencies(main_module)
-
-    # Subtract the (builtin or missing) modules we won't upload.
-    dependencies = dependencies.difference(not_found)
-
-    # Get the total tuple of main programs and module
-    modules = [main_module] + sorted(tuple(dependencies))
+    # we expect missing modules, namely builtin MicroPython packages like pybricks.*
+    logger.debug("missing modules: %r", finder.any_missing())
 
     # Get a data blob with all scripts.
-    blob = bytearray([])
-    for module in modules:
-        name = module.encode() + b"\x00"
-        mpy = await compile_file(
-            source_dir / Path(*module.split(".")).with_suffix(".py"), abi
-        )
-        size = len(mpy).to_bytes(4, "little")
-        blob += size + name + mpy
-    return blob
+    parts: List[bytes] = []
+
+    for name, module in finder.modules.items():
+        mpy = await compile_file(module.__file__, abi)
+
+        parts.append(len(mpy).to_bytes(4, "little"))
+        parts.append(name.encode() + b"\x00")
+        parts.append(mpy)
+
+    return b"".join(parts)
 
 
 def save_script(py_string):