finished (untested) sketch implementation

Author: Jonathon Belotti

src/extract_wheels.py

@@ -6,6 +6,7 @@
 
 
 from . import namespace_pkgs
+from . import purelib
 from .wheel import Wheel
 
 BUILD_TEMPLATE = """\
@@ -78,6 +79,7 @@ def extract_wheel(whl, directory, extras):
 
     whl.unzip(directory)
 
+    purelib.spread_purelib_into_root(directory)
     _setup_namespace_pkg_compatibility(directory)
 
     with open(os.path.join(directory, "BUILD"), "w") as f:

src/purelib.py

@@ -1,4 +1,21 @@
+import pathlib
+import shutil
+
+from . import wheel
+
 
 def spread_purelib_into_root(extracted_whl_directory: str) -> None:
-    pass
-    # Root-Is-Purelib: false
+    dist_info = wheel.get_dist_info(extracted_whl_directory)
+    wheel_metadata_file_path = pathlib.Path(dist_info, "WHEEL")
+    wheel_metadata_dict = wheel.parse_WHEEL_file(str(wheel_metadata_file_path))
+
+    if "Root-Is-Purelib" not in wheel_metadata_dict:
+        raise ValueError(f"Invalid WHEEL file '{wheel_metadata_file_path}'. Expected key 'Root-Is-Purelib'.")
+    root_is_purelib = wheel_metadata_dict["Root-Is-Purelib"]
+
+    if root_is_purelib.lower() == "true":
+        # The Python package code is in the root of the Wheel, so no need to 'spread' anything.
+        return
+
+    dot_data_dir = wheel.get_dot_data_directory(extracted_whl_directory)
+    shutil.move(dot_data_dir, extracted_whl_directory)

src/wheel.py

@@ -4,6 +4,8 @@
 import pkg_resources
 import glob
 
+from typing import Dict
+
 
 class Wheel(object):
     def __init__(self, path):
@@ -50,3 +52,29 @@ def get_dist_info(extracted_whl_directory):
     else:
         dist_info = dist_info_dirs[0]
     return dist_info
+
+
+def get_dot_data_directory(extracted_whl_directory):
+    # See: https://www.python.org/dev/peps/pep-0491/#the-data-directory
+    dot_data_dirs = glob.glob(os.path.join(extracted_whl_directory, "*.data"))
+    if not dot_data_dirs:
+        raise ValueError(f"No *.data directory found. {extracted_whl_directory} is not a valid Wheel.")
+    elif len(dot_data_dirs) > 1:
+        raise ValueError(f"Found more than 1 *.data directory. {extracted_whl_directory} is not a valid Wheel.")
+    else:
+        dot_data_dir = dot_data_dirs[0]
+    return dot_data_dir
+
+
+def parse_WHEEL_file(whl_file_path: str) -> Dict[str, str]:
+    contents = {}
+    with open(whl_file_path, "r") as f:
+        for line in f:
+            cleaned = line.strip()
+            try:
+                key, value = cleaned.split(":", maxsplit=1)
+                contents[key] = value.strip()
+            except ValueError:
+                raise RuntimeError(f"Encounted invalid line in WHEEL file: '{cleaned}'")
+    return contents
+