Mini Shell
# Copyright 2006 Google, Inc. All Rights Reserved.
# Licensed to PSF under a Contributor Agreement.
"""Refactoring framework.
Used as a main program, this can refactor any number of files and/or
recursively descend down directories. Imported as a module, this
provides infrastructure to write your own refactoring tool.
"""
__author__ = "Guido van Rossum <guido@python.org>"
# Python imports
import io
import os
import pkgutil
import sys
import logging
import operator
import collections
from itertools import chain
# Local imports
from .pgen2 import driver, tokenize, token
from .fixer_util import find_root
from . import pytree, pygram
from . import btm_matcher as bm
def get_all_fix_names(fixer_pkg, remove_prefix=True):
"""Return a sorted list of all available fix names in the given package."""
pkg = __import__(fixer_pkg, [], [], ["*"])
fix_names = []
for finder, name, ispkg in pkgutil.iter_modules(pkg.__path__):
if name.startswith("fix_"):
if remove_prefix:
name = name[4:]
fix_names.append(name)
return fix_names
class _EveryNode(Exception):
pass
def _get_head_types(pat):
""" Accepts a pytree Pattern Node and returns a set
of the pattern types which will match first. """
if isinstance(pat, (pytree.NodePattern, pytree.LeafPattern)):
# NodePatters must either have no type and no content
# or a type and content -- so they don't get any farther
# Always return leafs
if pat.type is None:
raise _EveryNode
return {pat.type}
if isinstance(pat, pytree.NegatedPattern):
if pat.content:
return _get_head_types(pat.content)
raise _EveryNode # Negated Patterns don't have a type
if isinstance(pat, pytree.WildcardPattern):
# Recurse on each node in content
r = set()
for p in pat.content:
for x in p:
r.update(_get_head_types(x))
return r
raise Exception("Oh no! I don't understand pattern %s" %(pat))
def _get_headnode_dict(fixer_list):
""" Accepts a list of fixers and returns a dictionary
of head node type --> fixer list. """
head_nodes = collections.defaultdict(list)
every = []
for fixer in fixer_list:
if fixer.pattern:
try:
heads = _get_head_types(fixer.pattern)
except _EveryNode:
every.append(fixer)
else:
for node_type in heads:
head_nodes[node_type].append(fixer)
else:
if fixer._accept_type is not None:
head_nodes[fixer._accept_type].append(fixer)
else:
every.append(fixer)
for node_type in chain(pygram.python_grammar.symbol2number.values(),
pygram.python_grammar.tokens):
head_nodes[node_type].extend(every)
return dict(head_nodes)
def get_fixers_from_package(pkg_name):
"""
Return the fully qualified names for fixers in the package pkg_name.
"""
return [pkg_name + "." + fix_name
for fix_name in get_all_fix_names(pkg_name, False)]
def _identity(obj):
return obj
def _detect_future_features(source):
have_docstring = False
gen = tokenize.generate_tokens(io.StringIO(source).readline)
def advance():
tok = next(gen)
return tok[0], tok[1]
ignore = frozenset({token.NEWLINE, tokenize.NL, token.COMMENT})
features = set()
try:
while True:
tp, value = advance()
if tp in ignore:
continue
elif tp == token.STRING:
if have_docstring:
break
have_docstring = True
elif tp == token.NAME and value == "from":
tp, value = advance()
if tp != token.NAME or value != "__future__":
break
tp, value = advance()
if tp != token.NAME or value != "import":
break
tp, value = advance()
if tp == token.OP and value == "(":
tp, value = advance()
while tp == token.NAME:
features.add(value)
tp, value = advance()
if tp != token.OP or value != ",":
break
tp, value = advance()
else:
break
except StopIteration:
pass
return frozenset(features)
class FixerError(Exception):
"""A fixer could not be loaded."""
class RefactoringTool(object):
_default_options = {"print_function" : False,
"exec_function": False,
"write_unchanged_files" : False}
CLASS_PREFIX = "Fix" # The prefix for fixer classes
FILE_PREFIX = "fix_" # The prefix for modules with a fixer within
def __init__(self, fixer_names, options=None, explicit=None):
"""Initializer.
Args:
fixer_names: a list of fixers to import
options: a dict with configuration.
explicit: a list of fixers to run even if they are explicit.
"""
self.fixers = fixer_names
self.explicit = explicit or []
self.options = self._default_options.copy()
if options is not None:
self.options.update(options)
self.grammar = pygram.python_grammar.copy()
if self.options['print_function']:
del self.grammar.keywords["print"]
elif self.options['exec_function']:
del self.grammar.keywords["exec"]
# When this is True, the refactor*() methods will call write_file() for
# files processed even if they were not changed during refactoring. If
# and only if the refactor method's write parameter was True.
self.write_unchanged_files = self.options.get("write_unchanged_files")
self.errors = []
self.logger = logging.getLogger("RefactoringTool")
self.fixer_log = []
self.wrote = False
self.driver = driver.Driver(self.grammar,
convert=pytree.convert,
logger=self.logger)
self.pre_order, self.post_order = self.get_fixers()
self.files = [] # List of files that were or should be modified
self.BM = bm.BottomMatcher()
self.bmi_pre_order = [] # Bottom Matcher incompatible fixers
self.bmi_post_order = []
for fixer in chain(self.post_order, self.pre_order):
if fixer.BM_compatible:
self.BM.add_fixer(fixer)
# remove fixers that will be handled by the bottom-up
# matcher
elif fixer in self.pre_order:
self.bmi_pre_order.append(fixer)
elif fixer in self.post_order:
self.bmi_post_order.append(fixer)
self.bmi_pre_order_heads = _get_headnode_dict(self.bmi_pre_order)
self.bmi_post_order_heads = _get_headnode_dict(self.bmi_post_order)
def get_fixers(self):
"""Inspects the options to load the requested patterns and handlers.
Returns:
(pre_order, post_order), where pre_order is the list of fixers that
want a pre-order AST traversal, and post_order is the list that want
post-order traversal.
"""
pre_order_fixers = []
post_order_fixers = []
for fix_mod_path in self.fixers:
mod = __import__(fix_mod_path, {}, {}, ["*"])
fix_name = fix_mod_path.rsplit(".", 1)[-1]
if fix_name.startswith(self.FILE_PREFIX):
fix_name = fix_name[len(self.FILE_PREFIX):]
parts = fix_name.split("_")
class_name = self.CLASS_PREFIX + "".join([p.title() for p in parts])
try:
fix_class = getattr(mod, class_name)
except AttributeError:
raise FixerError("Can't find %s.%s" % (fix_name, class_name)) from None
fixer = fix_class(self.options, self.fixer_log)
if fixer.explicit and self.explicit is not True and \
fix_mod_path not in self.explicit:
self.log_message("Skipping optional fixer: %s", fix_name)
continue
self.log_debug("Adding transformation: %s", fix_name)
if fixer.order == "pre":
pre_order_fixers.append(fixer)
elif fixer.order == "post":
post_order_fixers.append(fixer)
else:
raise FixerError("Illegal fixer order: %r" % fixer.order)
key_func = operator.attrgetter("run_order")
pre_order_fixers.sort(key=key_func)
post_order_fixers.sort(key=key_func)
return (pre_order_fixers, post_order_fixers)
def log_error(self, msg, *args, **kwds):
"""Called when an error occurs."""
raise
def log_message(self, msg, *args):
"""Hook to log a message."""
if args:
msg = msg % args
self.logger.info(msg)
def log_debug(self, msg, *args):
if args:
msg = msg % args
self.logger.debug(msg)
def print_output(self, old_text, new_text, filename, equal):
"""Called with the old version, new version, and filename of a
refactored file."""
pass
def refactor(self, items, write=False, doctests_only=False):
"""Refactor a list of files and directories."""
for dir_or_file in items:
if os.path.isdir(dir_or_file):
self.refactor_dir(dir_or_file, write, doctests_only)
else:
self.refactor_file(dir_or_file, write, doctests_only)
def refactor_dir(self, dir_name, write=False, doctests_only=False):
"""Descends down a directory and refactor every Python file found.
Python files are assumed to have a .py extension.
Files and subdirectories starting with '.' are skipped.
"""
py_ext = os.extsep + "py"
for dirpath, dirnames, filenames in os.walk(dir_name):
self.log_debug("Descending into %s", dirpath)
dirnames.sort()
filenames.sort()
for name in filenames:
if (not name.startswith(".") and
os.path.splitext(name)[1] == py_ext):
fullname = os.path.join(dirpath, name)
self.refactor_file(fullname, write, doctests_only)
# Modify dirnames in-place to remove subdirs with leading dots
dirnames[:] = [dn for dn in dirnames if not dn.startswith(".")]
def _read_python_source(self, filename):
"""
Do our best to decode a Python source file correctly.
"""
try:
f = open(filename, "rb")
except OSError as err:
self.log_error("Can't open %s: %s", filename, err)
return None, None
try:
encoding = tokenize.detect_encoding(f.readline)[0]
finally:
f.close()
with io.open(filename, "r", encoding=encoding, newline='') as f:
return f.read(), encoding
def refactor_file(self, filename, write=False, doctests_only=False):
"""Refactors a file."""
input, encoding = self._read_python_source(filename)
if input is None:
# Reading the file failed.
return
input += "\n" # Silence certain parse errors
if doctests_only:
self.log_debug("Refactoring doctests in %s", filename)
output = self.refactor_docstring(input, filename)
if self.write_unchanged_files or output != input:
self.processed_file(output, filename, input, write, encoding)
else:
self.log_debug("No doctest changes in %s", filename)
else:
tree = self.refactor_string(input, filename)
if self.write_unchanged_files or (tree and tree.was_changed):
# The [:-1] is to take off the \n we added earlier
self.processed_file(str(tree)[:-1], filename,
write=write, encoding=encoding)
else:
self.log_debug("No changes in %s", filename)
def refactor_string(self, data, name):
"""Refactor a given input string.
Args:
data: a string holding the code to be refactored.
name: a human-readable name for use in error/log messages.
Returns:
An AST corresponding to the refactored input stream; None if
there were errors during the parse.
"""
features = _detect_future_features(data)
if "print_function" in features:
self.driver.grammar = pygram.python_grammar_no_print_statement
try:
tree = self.driver.parse_string(data)
except Exception as err:
self.log_error("Can't parse %s: %s: %s",
name, err.__class__.__name__, err)
return
finally:
self.driver.grammar = self.grammar
tree.future_features = features
self.log_debug("Refactoring %s", name)
self.refactor_tree(tree, name)
return tree
def refactor_stdin(self, doctests_only=False):
input = sys.stdin.read()
if doctests_only:
self.log_debug("Refactoring doctests in stdin")
output = self.refactor_docstring(input, "<stdin>")
if self.write_unchanged_files or output != input:
self.processed_file(output, "<stdin>", input)
else:
self.log_debug("No doctest changes in stdin")
else:
tree = self.refactor_string(input, "<stdin>")
if self.write_unchanged_files or (tree and tree.was_changed):
self.processed_file(str(tree), "<stdin>", input)
else:
self.log_debug("No changes in stdin")
def refactor_tree(self, tree, name):
"""Refactors a parse tree (modifying the tree in place).
For compatible patterns the bottom matcher module is
used. Otherwise the tree is traversed node-to-node for
matches.
Args:
tree: a pytree.Node instance representing the root of the tree
to be refactored.
name: a human-readable name for this tree.
Returns:
True if the tree was modified, False otherwise.
"""
for fixer in chain(self.pre_order, self.post_order):
fixer.start_tree(tree, name)
#use traditional matching for the incompatible fixers
self.traverse_by(self.bmi_pre_order_heads, tree.pre_order())
self.traverse_by(self.bmi_post_order_heads, tree.post_order())
# obtain a set of candidate nodes
match_set = self.BM.run(tree.leaves())
while any(match_set.values()):
for fixer in self.BM.fixers:
if fixer in match_set and match_set[fixer]:
#sort by depth; apply fixers from bottom(of the AST) to top
match_set[fixer].sort(key=pytree.Base.depth, reverse=True)
if fixer.keep_line_order:
#some fixers(eg fix_imports) must be applied
#with the original file's line order
match_set[fixer].sort(key=pytree.Base.get_lineno)
for node in list(match_set[fixer]):
if node in match_set[fixer]:
match_set[fixer].remove(node)
try:
find_root(node)
except ValueError:
# this node has been cut off from a
# previous transformation ; skip
continue
if node.fixers_applied and fixer in node.fixers_applied:
# do not apply the same fixer again
continue
results = fixer.match(node)
if results:
new = fixer.transform(node, results)
if new is not None:
node.replace(new)
#new.fixers_applied.append(fixer)
for node in new.post_order():
# do not apply the fixer again to
# this or any subnode
if not node.fixers_applied:
node.fixers_applied = []
node.fixers_applied.append(fixer)
# update the original match set for
# the added code
new_matches = self.BM.run(new.leaves())
for fxr in new_matches:
if not fxr in match_set:
match_set[fxr]=[]
match_set[fxr].extend(new_matches[fxr])
for fixer in chain(self.pre_order, self.post_order):
fixer.finish_tree(tree, name)
return tree.was_changed
def traverse_by(self, fixers, traversal):
"""Traverse an AST, applying a set of fixers to each node.
This is a helper method for refactor_tree().
Args:
fixers: a list of fixer instances.
traversal: a generator that yields AST nodes.
Returns:
None
"""
if not fixers:
return
for node in traversal:
for fixer in fixers[node.type]:
results = fixer.match(node)
if results:
new = fixer.transform(node, results)
if new is not None:
node.replace(new)
node = new
def processed_file(self, new_text, filename, old_text=None, write=False,
encoding=None):
"""
Called when a file has been refactored and there may be changes.
"""
self.files.append(filename)
if old_text is None:
old_text = self._read_python_source(filename)[0]
if old_text is None:
return
equal = old_text == new_text
self.print_output(old_text, new_text, filename, equal)
if equal:
self.log_debug("No changes to %s", filename)
if not self.write_unchanged_files:
return
if write:
self.write_file(new_text, filename, old_text, encoding)
else:
self.log_debug("Not writing changes to %s", filename)
def write_file(self, new_text, filename, old_text, encoding=None):
"""Writes a string to a file.
It first shows a unified diff between the old text and the new text, and
then rewrites the file; the latter is only done if the write option is
set.
"""
try:
fp = io.open(filename, "w", encoding=encoding, newline='')
except OSError as err:
self.log_error("Can't create %s: %s", filename, err)
return
with fp:
try:
fp.write(new_text)
except OSError as err:
self.log_error("Can't write %s: %s", filename, err)
self.log_debug("Wrote changes to %s", filename)
self.wrote = True
PS1 = ">>> "
PS2 = "... "
def refactor_docstring(self, input, filename):
"""Refactors a docstring, looking for doctests.
This returns a modified version of the input string. It looks
for doctests, which start with a ">>>" prompt, and may be
continued with "..." prompts, as long as the "..." is indented
the same as the ">>>".
(Unfortunately we can't use the doctest module's parser,
since, like most parsers, it is not geared towards preserving
the original source.)
"""
result = []
block = None
block_lineno = None
indent = None
lineno = 0
for line in input.splitlines(keepends=True):
lineno += 1
if line.lstrip().startswith(self.PS1):
if block is not None:
result.extend(self.refactor_doctest(block, block_lineno,
indent, filename))
block_lineno = lineno
block = [line]
i = line.find(self.PS1)
indent = line[:i]
elif (indent is not None and
(line.startswith(indent + self.PS2) or
line == indent + self.PS2.rstrip() + "\n")):
block.append(line)
else:
if block is not None:
result.extend(self.refactor_doctest(block, block_lineno,
indent, filename))
block = None
indent = None
result.append(line)
if block is not None:
result.extend(self.refactor_doctest(block, block_lineno,
indent, filename))
return "".join(result)
def refactor_doctest(self, block, lineno, indent, filename):
"""Refactors one doctest.
A doctest is given as a block of lines, the first of which starts
with ">>>" (possibly indented), while the remaining lines start
with "..." (identically indented).
"""
try:
tree = self.parse_block(block, lineno, indent)
except Exception as err:
if self.logger.isEnabledFor(logging.DEBUG):
for line in block:
self.log_debug("Source: %s", line.rstrip("\n"))
self.log_error("Can't parse docstring in %s line %s: %s: %s",
filename, lineno, err.__class__.__name__, err)
return block
if self.refactor_tree(tree, filename):
new = str(tree).splitlines(keepends=True)
# Undo the adjustment of the line numbers in wrap_toks() below.
clipped, new = new[:lineno-1], new[lineno-1:]
assert clipped == ["\n"] * (lineno-1), clipped
if not new[-1].endswith("\n"):
new[-1] += "\n"
block = [indent + self.PS1 + new.pop(0)]
if new:
block += [indent + self.PS2 + line for line in new]
return block
def summarize(self):
if self.wrote:
were = "were"
else:
were = "need to be"
if not self.files:
self.log_message("No files %s modified.", were)
else:
self.log_message("Files that %s modified:", were)
for file in self.files:
self.log_message(file)
if self.fixer_log:
self.log_message("Warnings/messages while refactoring:")
for message in self.fixer_log:
self.log_message(message)
if self.errors:
if len(self.errors) == 1:
self.log_message("There was 1 error:")
else:
self.log_message("There were %d errors:", len(self.errors))
for msg, args, kwds in self.errors:
self.log_message(msg, *args, **kwds)
def parse_block(self, block, lineno, indent):
"""Parses a block into a tree.
This is necessary to get correct line number / offset information
in the parser diagnostics and embedded into the parse tree.
"""
tree = self.driver.parse_tokens(self.wrap_toks(block, lineno, indent))
tree.future_features = frozenset()
return tree
def wrap_toks(self, block, lineno, indent):
"""Wraps a tokenize stream to systematically modify start/end."""
tokens = tokenize.generate_tokens(self.gen_lines(block, indent).__next__)
for type, value, (line0, col0), (line1, col1), line_text in tokens:
line0 += lineno - 1
line1 += lineno - 1
# Don't bother updating the columns; this is too complicated
# since line_text would also have to be updated and it would
# still break for tokens spanning lines. Let the user guess
# that the column numbers for doctests are relative to the
# end of the prompt string (PS1 or PS2).
yield type, value, (line0, col0), (line1, col1), line_text
def gen_lines(self, block, indent):
"""Generates lines as expected by tokenize from a list of lines.
This strips the first len(indent + self.PS1) characters off each line.
"""
prefix1 = indent + self.PS1
prefix2 = indent + self.PS2
prefix = prefix1
for line in block:
if line.startswith(prefix):
yield line[len(prefix):]
elif line == prefix.rstrip() + "\n":
yield "\n"
else:
raise AssertionError("line=%r, prefix=%r" % (line, prefix))
prefix = prefix2
while True:
yield ""
class MultiprocessingUnsupported(Exception):
pass
class MultiprocessRefactoringTool(RefactoringTool):
def __init__(self, *args, **kwargs):
super(MultiprocessRefactoringTool, self).__init__(*args, **kwargs)
self.queue = None
self.output_lock = None
def refactor(self, items, write=False, doctests_only=False,
num_processes=1):
if num_processes == 1:
return super(MultiprocessRefactoringTool, self).refactor(
items, write, doctests_only)
try:
import multiprocessing
except ImportError:
raise MultiprocessingUnsupported
if self.queue is not None:
raise RuntimeError("already doing multiple processes")
self.queue = multiprocessing.JoinableQueue()
self.output_lock = multiprocessing.Lock()
processes = [multiprocessing.Process(target=self._child)
for i in range(num_processes)]
try:
for p in processes:
p.start()
super(MultiprocessRefactoringTool, self).refactor(items, write,
doctests_only)
finally:
self.queue.join()
for i in range(num_processes):
self.queue.put(None)
for p in processes:
if p.is_alive():
p.join()
self.queue = None
def _child(self):
task = self.queue.get()
while task is not None:
args, kwargs = task
try:
super(MultiprocessRefactoringTool, self).refactor_file(
*args, **kwargs)
finally:
self.queue.task_done()
task = self.queue.get()
def refactor_file(self, *args, **kwargs):
if self.queue is not None:
self.queue.put((args, kwargs))
else:
return super(MultiprocessRefactoringTool, self).refactor_file(
*args, **kwargs)
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