Initial commit

venv/lib/python3.8/site-packages/astroid/transforms.py

@@ -0,0 +1,90 @@
+# Copyright (c) 2015-2016, 2018 Claudiu Popa <pcmanticore@gmail.com>
+# Copyright (c) 2016 Ceridwen <ceridwenv@gmail.com>
+# Copyright (c) 2018 Nick Drozd <nicholasdrozd@gmail.com>
+
+# Licensed under the LGPL: https://www.gnu.org/licenses/old-licenses/lgpl-2.1.en.html
+# For details: https://github.com/PyCQA/astroid/blob/master/COPYING.LESSER
+
+
+import collections
+from functools import lru_cache
+
+
+class TransformVisitor:
+    """A visitor for handling transforms.
+
+    The standard approach of using it is to call
+    :meth:`~visit` with an *astroid* module and the class
+    will take care of the rest, walking the tree and running the
+    transforms for each encountered node.
+    """
+
+    TRANSFORM_MAX_CACHE_SIZE = 10000
+
+    def __init__(self):
+        self.transforms = collections.defaultdict(list)
+
+    @lru_cache(maxsize=TRANSFORM_MAX_CACHE_SIZE)
+    def _transform(self, node):
+        """Call matching transforms for the given node if any and return the
+        transformed node.
+        """
+        cls = node.__class__
+        if cls not in self.transforms:
+            # no transform registered for this class of node
+            return node
+
+        transforms = self.transforms[cls]
+        for transform_func, predicate in transforms:
+            if predicate is None or predicate(node):
+                ret = transform_func(node)
+                # if the transformation function returns something, it's
+                # expected to be a replacement for the node
+                if ret is not None:
+                    node = ret
+                if ret.__class__ != cls:
+                    # Can no longer apply the rest of the transforms.
+                    break
+        return node
+
+    def _visit(self, node):
+        if hasattr(node, "_astroid_fields"):
+            for name in node._astroid_fields:
+                value = getattr(node, name)
+                visited = self._visit_generic(value)
+                if visited != value:
+                    setattr(node, name, visited)
+        return self._transform(node)
+
+    def _visit_generic(self, node):
+        if isinstance(node, list):
+            return [self._visit_generic(child) for child in node]
+        if isinstance(node, tuple):
+            return tuple(self._visit_generic(child) for child in node)
+        if not node or isinstance(node, str):
+            return node
+
+        return self._visit(node)
+
+    def register_transform(self, node_class, transform, predicate=None):
+        """Register `transform(node)` function to be applied on the given
+        astroid's `node_class` if `predicate` is None or returns true
+        when called with the node as argument.
+
+        The transform function may return a value which is then used to
+        substitute the original node in the tree.
+        """
+        self.transforms[node_class].append((transform, predicate))
+
+    def unregister_transform(self, node_class, transform, predicate=None):
+        """Unregister the given transform."""
+        self.transforms[node_class].remove((transform, predicate))
+
+    def visit(self, module):
+        """Walk the given astroid *tree* and transform each encountered node
+
+        Only the nodes which have transforms registered will actually
+        be replaced or changed.
+        """
+        module.body = [self._visit(child) for child in module.body]
+        return self._transform(module)