# HG changeset patch
# User Chris Jerdonek <chris.jerdonek@gmail.com>
# Date 1387750226 28800
# Node ID 761f2929a6ad28db8e3c4d1f3d074c544be1c8b4
# Parent  59198508b0bdbc3b2a945051475cd70c70c8ee7d
import-checker: refactor sys.path prefix check (issue4129)

This patch refactors the logic in contrib/import-checker.py responsible for
checking the beginnings of the paths in sys.path.  In particular, it adds a
variable that defines the set of allowed prefixes.

The primary purpose of this change is to make it easier to add more allowed
prefixes.  This will be useful in resolving issue4129, which involves making
the function list_stdlib_modules() work when run from a virtualenv.

diff -r 59198508b0bd -r 761f2929a6ad contrib/import-checker.py
--- a/contrib/import-checker.py	Tue Dec 24 17:44:23 2013 -0500
+++ b/contrib/import-checker.py	Sun Dec 22 14:10:26 2013 -0800
@@ -48,11 +48,14 @@
     for m in 'ctypes', 'email':
         yield m
     yield 'builtins' # python3 only
+    stdlib_prefixes = set([sys.prefix, sys.exec_prefix])
     for libpath in sys.path:
-        # We want to walk everything in sys.path that starts with
-        # either sys.prefix or sys.exec_prefix.
-        if not (libpath.startswith(sys.prefix)
-                or libpath.startswith(sys.exec_prefix)):
+        # We want to walk everything in sys.path that starts with something
+        # in stdlib_prefixes.
+        for prefix in stdlib_prefixes:
+            if libpath.startswith(prefix):
+                break
+        else:
             continue
         if 'site-packages' in libpath:
             continue