Initial reorg.

This is largely the same as #305, but updated for the current tree.

crates/misc/py/python/wasmtime/__init__.py

@@ -0,0 +1,49 @@
+from .lib_wasmtime import imported_modules, instantiate
+import sys
+import os.path
+
+from importlib import import_module
+from importlib.abc import Loader, MetaPathFinder
+from importlib.util import spec_from_file_location
+
+# Mostly copied from
+# https://stackoverflow.com/questions/43571737/how-to-implement-an-import-hook-that-can-modify-the-source-code-on-the-fly-using
+class MyMetaFinder(MetaPathFinder):
+    def find_spec(self, fullname, path, target=None):
+        if path is None or path == "":
+            path = [os.getcwd()] # top level import --
+            path.extend(sys.path)
+        if "." in fullname:
+            *parents, name = fullname.split(".")
+        else:
+            name = fullname
+        for entry in path:
+            filename = os.path.join(entry, name + ".wasm")
+            if not os.path.exists(filename):
+                continue
+
+            return spec_from_file_location(fullname, filename, loader=MyLoader(filename))
+        return None
+
+class MyLoader(Loader):
+    def __init__(self, filename):
+        self.filename = filename
+
+    def create_module(self, spec):
+        return None # use default module creation semantics
+
+    def exec_module(self, module):
+        with open(self.filename, "rb") as f:
+            data = f.read()
+
+        imports = {}
+        for module_name, fields in imported_modules(data).items():
+            imports[module_name] = {}
+            imported_module = import_module(module_name)
+            for field_name in fields:
+                imports[module_name][field_name] = imported_module.__dict__[field_name]
+
+        res = instantiate(data, imports)
+        module.__dict__.update(res.instance.exports)
+
+sys.meta_path.insert(0, MyMetaFinder())