Python: Copy Python extractor to codeql repo

python/extractor/semmle/thrift/__init__.py

@@ -0,0 +1,34 @@
+import os.path
+
+from .parse import Parser
+from .emit import Emitter
+
+class Extractor(object):
+
+    def __init__(self, trap_folder, src_archive=None):
+        self.parser = Parser()
+        self.emitter = Emitter(trap_folder)
+        self.src_archive = src_archive
+
+    def _walk(self, path):
+        for dirpath, _, filenames in os.walk(path):
+            for filename in filenames:
+                if filename.endswith(".thrift"):
+                    yield os.path.join(dirpath, filename)
+
+    def extract_files(self, files):
+        for file in files:
+            self.extract_file(file)
+
+    def extract_folder(self, path):
+        for file in self._walk(path):
+            self.extract_file(file)
+
+    def extract_file(self, file):
+        with open(file, "rb") as fd:
+            bytes_source = fd.read()
+        src = bytes_source.decode('utf-8')
+        tree = self.parser.parse(src)
+        self.emitter.emit(file, tree)
+        if self.src_archive:
+            self.src_archive.write(file, bytes_source)