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# Copyright (c) 2015-2016 Cara Vinson <ceridwenv@gmail.com>
# Copyright (c) 2015-2016 Claudiu Popa <pcmanticore@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
"""Various context related utilities, including inference and call contexts."""
import contextlib
import copy
import pprint
class InferenceContext(object):
"""Provide context for inference
Store already inferred nodes to save time
Account for already visited nodes to infinite stop infinite recursion
"""
__slots__ = ('path', 'lookupname', 'callcontext', 'boundnode', 'inferred')
def __init__(self, path=None, inferred=None):
self.path = path or set()
"""Path of visited nodes and their lookupname
:type: set(tuple(NodeNG, optional(str)))"""
self.lookupname = None
self.callcontext = None
self.boundnode = None
self.inferred = inferred or {}
"""
:type: dict(seq, seq)
Inferred node contexts to their mapped results
Currently the key is (node, lookupname, callcontext, boundnode)
and the value is tuple of the inferred results
"""
def push(self, node):
"""Push node into inference path
:return: True if node is already in context path else False
:rtype: bool
Allows one to see if the given node has already
been looked at for this inference context"""
name = self.lookupname
if (node, name) in self.path:
return True
self.path.add((node, name))
return False
def clone(self):
"""Clone inference path
For example, each side of a binary operation (BinOp)
starts with the same context but diverge as each side is inferred
so the InferenceContext will need be cloned"""
# XXX copy lookupname/callcontext ?
clone = InferenceContext(copy.copy(self.path), inferred=self.inferred)
clone.callcontext = self.callcontext
clone.boundnode = self.boundnode
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)
return
@contextlib.contextmanager
def restore_path(self):
path = set(self.path)
yield
self.path = path
def __str__(self):
state = ('%s=%s' % (field, pprint.pformat(getattr(self, field),
width=80 - len(field)))
for field in self.__slots__)
return '%s(%s)' % (type(self).__name__, ',\n '.join(state))
class CallContext(object):
"""Holds information for a call site."""
__slots__ = ('args', 'keywords')
def __init__(self, args, keywords=None):
self.args = args
if keywords:
keywords = [(arg.arg, arg.value) for arg in keywords]
else:
keywords = []
self.keywords = keywords
def copy_context(context):
if context is not None:
return context.clone()
return InferenceContext()
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