Squash one-use inference utility functions to help reduce recursion errors

Author: brycepg

astroid/context.py

@@ -105,17 +105,6 @@ def clone(self):
         clone.extra_context = self.extra_context
         return clone
 
-    def cache_generator(self, key, generator):
-        """Cache result of generator into dictionary
-
-        Used to cache inference results"""
-        results = []
-        for result in generator:
-            results.append(result)
-            yield result
-
-        self.inferred[key] = tuple(results)
-
     @contextlib.contextmanager
     def restore_path(self):
         path = set(self.path)

astroid/node_classes.py

@@ -354,19 +354,37 @@ def infer(self, context=None, **kwargs):
             # explicit_inference is not bound, give it self explicitly
             try:
                 # pylint: disable=not-callable
-                return self._explicit_inference(self, context, **kwargs)
+                yield from self._explicit_inference(self, context, **kwargs)
+                return
             except exceptions.UseInferenceDefault:
                 pass
 
         if not context:
-            return self._infer(context, **kwargs)
+            yield from self._infer(context, **kwargs)
+            return
 
         key = (self, context.lookupname, context.callcontext, context.boundnode)
         if key in context.inferred:
-            return iter(context.inferred[key])
+            yield from context.inferred[key]
+            return
+
+        generator = self._infer(context, **kwargs)
+        results = []
+
+        # Limit inference amount to help with performance issues with
+        # exponentially exploding possible results.
+        limit = MANAGER.max_inferable_values
+        for i, result in enumerate(generator):
+            if i >= limit:
+                yield util.Uninferable
+                break
+            results.append(result)
+            yield result
 
-        gen = context.cache_generator(key, self._infer(context, **kwargs))
-        return util.limit_inference(gen, MANAGER.max_inferable_values)
+        # Cache generated results for subsequent inferences of the
+        # same node using the same context
+        context.inferred[key] = tuple(results)
+        return
 
     def _repr_name(self):
         """Get a name for nice representation.

astroid/util.py

@@ -7,7 +7,6 @@
 # For details: https://github.com/PyCQA/astroid/blob/master/COPYING.LESSER
 
 import warnings
-from itertools import islice
 
 import importlib
 import lazy_object_proxy
@@ -139,26 +138,3 @@ def proxy_alias(alias_name, node_type):
         },
     )
     return proxy(lambda: node_type)
-
-
-def limit_inference(iterator, size):
-    """Limit inference amount.
-
-    Limit inference amount to help with performance issues with
-    exponentially exploding possible results.
-
-    :param iterator: Inference generator to limit
-    :type iterator: Iterator(NodeNG)
-
-    :param size: Maximum mount of nodes yielded plus an
-        Uninferable at the end if limit reached
-    :type size: int
-
-    :yields: A possibly modified generator
-    :rtype param: Iterable
-    """
-    yield from islice(iterator, size)
-    has_more = next(iterator, False)
-    if has_more is not False:
-        yield Uninferable
-        return

tests/unittest_inference.py

@@ -428,7 +428,7 @@ def test_del1(self):
             del undefined_attr
         """
         delete = extract_node(code, __name__)
-        self.assertRaises(InferenceError, delete.infer)
+        self.assertRaises(InferenceError, next, delete.infer())
 
     def test_del2(self):
         code = """