cpython/Lib/lib2to3/refactor.py

585 lines
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Python
Executable File

#!/usr/bin/env python2.5
# 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 os
import sys
import difflib
import optparse
import logging
from collections import defaultdict
from itertools import chain
# Local imports
from .pgen2 import driver
from .pgen2 import tokenize
from . import pytree
from . import patcomp
from . import fixes
from . import pygram
def main(fixer_dir, args=None):
"""Main program.
Args:
fixer_dir: directory where fixer modules are located.
args: optional; a list of command line arguments. If omitted,
sys.argv[1:] is used.
Returns a suggested exit status (0, 1, 2).
"""
# Set up option parser
parser = optparse.OptionParser(usage="refactor.py [options] file|dir ...")
parser.add_option("-d", "--doctests_only", action="store_true",
help="Fix up doctests only")
parser.add_option("-f", "--fix", action="append", default=[],
help="Each FIX specifies a transformation; default all")
parser.add_option("-l", "--list-fixes", action="store_true",
help="List available transformations (fixes/fix_*.py)")
parser.add_option("-p", "--print-function", action="store_true",
help="Modify the grammar so that print() is a function")
parser.add_option("-v", "--verbose", action="store_true",
help="More verbose logging")
parser.add_option("-w", "--write", action="store_true",
help="Write back modified files")
# Parse command line arguments
options, args = parser.parse_args(args)
if options.list_fixes:
print "Available transformations for the -f/--fix option:"
for fixname in get_all_fix_names(fixer_dir):
print fixname
if not args:
return 0
if not args:
print >>sys.stderr, "At least one file or directory argument required."
print >>sys.stderr, "Use --help to show usage."
return 2
# Set up logging handler
if sys.version_info < (2, 4):
hdlr = logging.StreamHandler()
fmt = logging.Formatter('%(name)s: %(message)s')
hdlr.setFormatter(fmt)
logging.root.addHandler(hdlr)
else:
logging.basicConfig(format='%(name)s: %(message)s', level=logging.INFO)
# Initialize the refactoring tool
rt = RefactoringTool(fixer_dir, options)
# Refactor all files and directories passed as arguments
if not rt.errors:
rt.refactor_args(args)
rt.summarize()
# Return error status (0 if rt.errors is zero)
return int(bool(rt.errors))
def get_all_fix_names(fixer_dir):
"""Return a sorted list of all available fix names."""
fix_names = []
names = os.listdir(fixer_dir)
names.sort()
for name in names:
if name.startswith("fix_") and name.endswith(".py"):
fix_names.append(name[4:-3])
fix_names.sort()
return fix_names
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
return set([pat.type])
if isinstance(pat, pytree.NegatedPattern):
if pat.content:
return get_head_types(pat.content)
return set([None]) # 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 = defaultdict(list)
for fixer in fixer_list:
if not fixer.pattern:
head_nodes[None].append(fixer)
continue
for t in get_head_types(fixer.pattern):
head_nodes[t].append(fixer)
return head_nodes
class RefactoringTool(object):
def __init__(self, fixer_dir, options):
"""Initializer.
Args:
fixer_dir: directory in which to find fixer modules.
options: an optparse.Values instance.
"""
self.fixer_dir = fixer_dir
self.options = options
self.errors = []
self.logger = logging.getLogger("RefactoringTool")
self.fixer_log = []
if self.options.print_function:
del pygram.python_grammar.keywords["print"]
self.driver = driver.Driver(pygram.python_grammar,
convert=pytree.convert,
logger=self.logger)
self.pre_order, self.post_order = self.get_fixers()
self.pre_order = get_headnode_dict(self.pre_order)
self.post_order = get_headnode_dict(self.post_order)
self.files = [] # List of files that were or should be modified
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.
"""
fixer_pkg = self.fixer_dir.replace(os.path.sep, ".")
if os.path.altsep:
fixer_pkg = self.fixer_dir.replace(os.path.altsep, ".")
pre_order_fixers = []
post_order_fixers = []
fix_names = self.options.fix
if not fix_names or "all" in fix_names:
fix_names = get_all_fix_names(self.fixer_dir)
for fix_name in fix_names:
try:
mod = __import__(fixer_pkg + ".fix_" + fix_name, {}, {}, ["*"])
except ImportError:
self.log_error("Can't find transformation %s", fix_name)
continue
parts = fix_name.split("_")
class_name = "Fix" + "".join([p.title() for p in parts])
try:
fix_class = getattr(mod, class_name)
except AttributeError:
self.log_error("Can't find fixes.fix_%s.%s",
fix_name, class_name)
continue
try:
fixer = fix_class(self.options, self.fixer_log)
except Exception, err:
self.log_error("Can't instantiate fixes.fix_%s.%s()",
fix_name, class_name, exc_info=True)
continue
if fixer.explicit and fix_name not in self.options.fix:
self.log_message("Skipping implicit fixer: %s", fix_name)
continue
if self.options.verbose:
self.log_message("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 ValueError("Illegal fixer order: %r" % fixer.order)
pre_order_fixers.sort(key=lambda x: x.run_order)
post_order_fixers.sort(key=lambda x: x.run_order)
return (pre_order_fixers, post_order_fixers)
def log_error(self, msg, *args, **kwds):
"""Increments error count and log a message."""
self.errors.append((msg, args, kwds))
self.logger.error(msg, *args, **kwds)
def log_message(self, msg, *args):
"""Hook to log a message."""
if args:
msg = msg % args
self.logger.info(msg)
def refactor_args(self, args):
"""Refactors files and directories from an argument list."""
for arg in args:
if arg == "-":
self.refactor_stdin()
elif os.path.isdir(arg):
self.refactor_dir(arg)
else:
self.refactor_file(arg)
def refactor_dir(self, arg):
"""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.
"""
for dirpath, dirnames, filenames in os.walk(arg):
if self.options.verbose:
self.log_message("Descending into %s", dirpath)
dirnames.sort()
filenames.sort()
for name in filenames:
if not name.startswith(".") and name.endswith("py"):
fullname = os.path.join(dirpath, name)
self.refactor_file(fullname)
# Modify dirnames in-place to remove subdirs with leading dots
dirnames[:] = [dn for dn in dirnames if not dn.startswith(".")]
def refactor_file(self, filename):
"""Refactors a file."""
try:
f = open(filename)
except IOError, err:
self.log_error("Can't open %s: %s", filename, err)
return
try:
input = f.read() + "\n" # Silence certain parse errors
finally:
f.close()
if self.options.doctests_only:
if self.options.verbose:
self.log_message("Refactoring doctests in %s", filename)
output = self.refactor_docstring(input, filename)
if output != input:
self.write_file(output, filename, input)
elif self.options.verbose:
self.log_message("No doctest changes in %s", filename)
else:
tree = self.refactor_string(input, filename)
if tree and tree.was_changed:
# The [:-1] is to take off the \n we added earlier
self.write_file(str(tree)[:-1], filename)
elif self.options.verbose:
self.log_message("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.
"""
try:
tree = self.driver.parse_string(data,1)
except Exception, err:
self.log_error("Can't parse %s: %s: %s",
name, err.__class__.__name__, err)
return
if self.options.verbose:
self.log_message("Refactoring %s", name)
self.refactor_tree(tree, name)
return tree
def refactor_stdin(self):
if self.options.write:
self.log_error("Can't write changes back to stdin")
return
input = sys.stdin.read()
if self.options.doctests_only:
if self.options.verbose:
self.log_message("Refactoring doctests in stdin")
output = self.refactor_docstring(input, "<stdin>")
if output != input:
self.write_file(output, "<stdin>", input)
elif self.options.verbose:
self.log_message("No doctest changes in stdin")
else:
tree = self.refactor_string(input, "<stdin>")
if tree and tree.was_changed:
self.write_file(str(tree), "<stdin>", input)
elif self.options.verbose:
self.log_message("No changes in stdin")
def refactor_tree(self, tree, name):
"""Refactors a parse tree (modifying the tree in place).
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.
"""
# Two calls to chain are required because pre_order.values()
# will be a list of lists of fixers:
# [[<fixer ...>, <fixer ...>], [<fixer ...>]]
all_fixers = chain(chain(*self.pre_order.values()),\
chain(*self.post_order.values()))
for fixer in all_fixers:
fixer.start_tree(tree, name)
self.traverse_by(self.pre_order, tree.pre_order())
self.traverse_by(self.post_order, tree.post_order())
for fixer in all_fixers:
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] + fixers[None]:
results = fixer.match(node)
if results:
new = fixer.transform(node, results)
if new is not None and (new != node or
str(new) != str(node)):
node.replace(new)
node = new
def write_file(self, new_text, filename, old_text=None):
"""Writes a string to a file.
If there are no changes, this is a no-op.
Otherwise, 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.
"""
self.files.append(filename)
if old_text is None:
try:
f = open(filename, "r")
except IOError, err:
self.log_error("Can't read %s: %s", filename, err)
return
try:
old_text = f.read()
finally:
f.close()
if old_text == new_text:
if self.options.verbose:
self.log_message("No changes to %s", filename)
return
diff_texts(old_text, new_text, filename)
if not self.options.write:
if self.options.verbose:
self.log_message("Not writing changes to %s", filename)
return
backup = filename + ".bak"
if os.path.lexists(backup):
try:
os.remove(backup)
except os.error, err:
self.log_message("Can't remove backup %s", backup)
try:
os.rename(filename, backup)
except os.error, err:
self.log_message("Can't rename %s to %s", filename, backup)
try:
f = open(filename, "w")
except os.error, err:
self.log_error("Can't create %s: %s", filename, err)
return
try:
try:
f.write(new_text)
except os.error, err:
self.log_error("Can't write %s: %s", filename, err)
finally:
f.close()
if self.options.verbose:
self.log_message("Wrote changes to %s", filename)
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(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, err:
if self.options.verbose:
for line in block:
self.log_message("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(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.options.write:
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.
"""
return self.driver.parse_tokens(self.wrap_toks(block, lineno, indent))
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 ""
def diff_texts(a, b, filename):
"""Prints a unified diff of two strings."""
a = a.splitlines()
b = b.splitlines()
for line in difflib.unified_diff(a, b, filename, filename,
"(original)", "(refactored)",
lineterm=""):
print line
if __name__ == "__main__":
sys.exit(main())