/usr/share/pyshared/logilab/astng/utils.py is in python-logilab-astng 0.23.0-1ubuntu1.
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# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
# copyright 2003-2010 Sylvain Thenault, all rights reserved.
# contact mailto:thenault@gmail.com
#
# This file is part of logilab-astng.
#
# logilab-astng is free software: you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by the
# Free Software Foundation, either version 2.1 of the License, or (at your
# option) any later version.
#
# logilab-astng is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
# for more details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with logilab-astng. If not, see <http://www.gnu.org/licenses/>.
"""this module contains some utilities to navigate in the tree or to
extract information from it
"""
__docformat__ = "restructuredtext en"
from logilab.astng.exceptions import ASTNGBuildingException
class ASTWalker:
"""a walker visiting a tree in preorder, calling on the handler:
* visit_<class name> on entering a node, where class name is the class of
the node in lower case
* leave_<class name> on leaving a node, where class name is the class of
the node in lower case
"""
def __init__(self, handler):
self.handler = handler
self._cache = {}
def walk(self, node, _done=None):
"""walk on the tree from <node>, getting callbacks from handler"""
if _done is None:
_done = set()
if node in _done:
raise AssertionError((id(node), node, node.parent))
_done.add(node)
self.visit(node)
for child_node in node.get_children():
self.handler.set_context(node, child_node)
assert child_node is not node
self.walk(child_node, _done)
self.leave(node)
assert node.parent is not node
def get_callbacks(self, node):
"""get callbacks from handler for the visited node"""
klass = node.__class__
methods = self._cache.get(klass)
if methods is None:
handler = self.handler
kid = klass.__name__.lower()
e_method = getattr(handler, 'visit_%s' % kid,
getattr(handler, 'visit_default', None))
l_method = getattr(handler, 'leave_%s' % kid,
getattr(handler, 'leave_default', None))
self._cache[klass] = (e_method, l_method)
else:
e_method, l_method = methods
return e_method, l_method
def visit(self, node):
"""walk on the tree from <node>, getting callbacks from handler"""
method = self.get_callbacks(node)[0]
if method is not None:
method(node)
def leave(self, node):
"""walk on the tree from <node>, getting callbacks from handler"""
method = self.get_callbacks(node)[1]
if method is not None:
method(node)
class LocalsVisitor(ASTWalker):
"""visit a project by traversing the locals dictionary"""
def __init__(self):
ASTWalker.__init__(self, self)
self._visited = {}
def visit(self, node):
"""launch the visit starting from the given node"""
if node in self._visited:
return
self._visited[node] = 1 # FIXME: use set ?
methods = self.get_callbacks(node)
if methods[0] is not None:
methods[0](node)
if 'locals' in node.__dict__: # skip Instance and other proxy
for name, local_node in node.items():
self.visit(local_node)
if methods[1] is not None:
return methods[1](node)
def _check_children(node):
"""a helper function to check children - parent relations"""
for child in node.get_children():
ok = False
if child is None:
print "Hm, child of %s is None" % node
continue
if not hasattr(child, 'parent'):
print " ERROR: %s has child %s %x with no parent" % (node, child, id(child))
elif not child.parent:
print " ERROR: %s has child %s %x with parent %r" % (node, child, id(child), child.parent)
elif child.parent is not node:
print " ERROR: %s %x has child %s %x with wrong parent %s" % (node,
id(node), child, id(child), child.parent)
else:
ok = True
if not ok:
print "lines;", node.lineno, child.lineno
print "of module", node.root(), node.root().name
raise ASTNGBuildingException
_check_children(child)
from _ast import PyCF_ONLY_AST
def parse(string):
return compile(string, "<string>", 'exec', PyCF_ONLY_AST)
class TreeTester(object):
'''A helper class to see _ast tree and compare with astng tree
indent: string for tree indent representation
lineno: bool to tell if we should print the line numbers
>>> tester = TreeTester('print')
>>> print tester.native_tree_repr()
<Module>
. body = [
. <Print>
. . nl = True
. ]
>>> print tester.astng_tree_repr()
Module()
body = [
Print()
dest =
values = [
]
]
'''
indent = '. '
lineno = False
def __init__(self, sourcecode):
self._string = ''
self.sourcecode = sourcecode
self._ast_node = None
self.build_ast()
def build_ast(self):
"""build the _ast tree from the source code"""
self._ast_node = parse(self.sourcecode)
def native_tree_repr(self, node=None, indent=''):
"""get a nice representation of the _ast tree"""
self._string = ''
if node is None:
node = self._ast_node
self._native_repr_tree(node, indent)
return self._string
def _native_repr_tree(self, node, indent, _done=None):
"""recursive method for the native tree representation"""
from _ast import Load as _Load, Store as _Store, Del as _Del
from _ast import AST as Node
if _done is None:
_done = set()
if node in _done:
self._string += '\nloop in tree: %r (%s)' % (node,
getattr(node, 'lineno', None))
return
_done.add(node)
self._string += '\n' + indent + '<%s>' % node.__class__.__name__
indent += self.indent
if not hasattr(node, '__dict__'):
self._string += '\n' + self.indent + " ** node has no __dict__ " + str(node)
return
node_dict = node.__dict__
if hasattr(node, '_attributes'):
for a in node._attributes:
attr = node_dict[a]
if attr is None:
continue
if a in ("lineno", "col_offset") and not self.lineno:
continue
self._string +='\n' + indent + a + " = " + repr(attr)
for field in node._fields or ():
attr = node_dict[field]
if attr is None:
continue
if isinstance(attr, list):
if not attr:
continue
self._string += '\n' + indent + field + ' = ['
for elt in attr:
self._native_repr_tree(elt, indent, _done)
self._string += '\n' + indent + ']'
continue
if isinstance(attr, (_Load, _Store, _Del)):
continue
if isinstance(attr, Node):
self._string += '\n' + indent + field + " = "
self._native_repr_tree(attr, indent, _done)
else:
self._string += '\n' + indent + field + " = " + repr(attr)
def build_astng_tree(self):
"""build astng tree from the _ast tree
"""
from logilab.astng.builder import ASTNGBuilder
tree = ASTNGBuilder().string_build(self.sourcecode)
return tree
def astng_tree_repr(self, ids=False):
"""build the astng tree and return a nice tree representation"""
mod = self.build_astng_tree()
return mod.repr_tree(ids)
__all__ = ('LocalsVisitor', 'ASTWalker',)
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