Python: Copy Python extractor to codeql repo

python/extractor/semmle/path_rename.py

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+import os
+import semmle.projectlayout as projectlayout
+from semmle.util import SemmleError
+
+__all__ = "renamer_from_options_and_env"
+
+def _realpath(path):
+    try:
+        return os.path.realpath(path)
+    except IOError:
+        return os.path.abspath(path)
+
+def renamer_from_options_and_env(options, logger):
+    'Returns a renamer function which takes a path and returns the nominal path'
+    preserve_symlinks = os.environ.get('SEMMLE_PRESERVE_SYMLINKS', "")
+    if options.no_symlinks or preserve_symlinks.lower() == "true":
+        pre_rename = os.path.abspath
+    else:
+        pre_rename = _realpath
+
+    if options.renamer:
+        try:
+            module = __import__(options.renamer, fromlist=['get_renamer'])
+            rename = module.get_renamer()
+        except (AttributeError, ImportError):
+            raise SemmleError("Cannot get renamer from module " + options.renamer)
+    else:
+        path_transformer = os.environ.get("SEMMLE_PATH_TRANSFORMER", None)
+        if path_transformer:
+            logger.info("Using path transformer '%s'", path_transformer)
+            rename = projectlayout.get_renamer(path_transformer)
+        else:
+            rename = lambda path : path
+
+    if os.name == "nt":
+        def post_rename(path):
+            if path[1] == ':':
+                path = path[0].upper() + path[1:]
+            return path
+    else:
+        post_rename = lambda path : path
+
+    renamer = lambda path : post_rename(rename(pre_rename(path)))
+    return renamer