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pindent.py
#! /usr/bin/env python3
# Via: https://github.com/python/cpython/blob/main/Tools/scripts/pindent.py
# See also: https://stackoverflow.com/a/118744/454773
# This file contains a class and a main program that perform three
# related (though complimentary) formatting operations on Python
# programs. When called as "pindent -c", it takes a valid Python
# program as input and outputs a version augmented with block-closing
# comments. When called as "pindent -d", it assumes its input is a
# Python program with block-closing comments and outputs a commentless
# version. When called as "pindent -r" it assumes its input is a
# Python program with block-closing comments but with its indentation
# messed up, and outputs a properly indented version.
# A "block-closing comment" is a comment of the form '# end <keyword>'
# where <keyword> is the keyword that opened the block. If the
# opening keyword is 'def' or 'class', the function or class name may
# be repeated in the block-closing comment as well. Here is an
# example of a program fully augmented with block-closing comments:
# def foobar(a, b):
# if a == b:
# a = a+1
# elif a < b:
# b = b-1
# if b > a: a = a-1
# # end if
# else:
# print 'oops!'
# # end if
# # end def foobar
# Note that only the last part of an if...elif...else... block needs a
# block-closing comment; the same is true for other compound
# statements (e.g. try...except). Also note that "short-form" blocks
# like the second 'if' in the example must be closed as well;
# otherwise the 'else' in the example would be ambiguous (remember
# that indentation is not significant when interpreting block-closing
# comments).
# The operations are idempotent (i.e. applied to their own output
# they yield an identical result). Running first "pindent -c" and
# then "pindent -r" on a valid Python program produces a program that
# is semantically identical to the input (though its indentation may
# be different). Running "pindent -e" on that output produces a
# program that only differs from the original in indentation.
# Other options:
# -s stepsize: set the indentation step size (default 8)
# -t tabsize : set the number of spaces a tab character is worth (default 8)
# -e : expand TABs into spaces
# file ... : input file(s) (default standard input)
# The results always go to standard output
# Caveats:
# - comments ending in a backslash will be mistaken for continued lines
# - continuations using backslash are always left unchanged
# - continuations inside parentheses are not extra indented by -r
# but must be indented for -c to work correctly (this breaks
# idempotency!)
# - continued lines inside triple-quoted strings are totally garbled
# Secret feature:
# - On input, a block may also be closed with an "end statement" --
# this is a block-closing comment without the '#' sign.
# Possible improvements:
# - check syntax based on transitions in 'next' table
# - better error reporting
# - better error recovery
# - check identifier after class/def
# The following wishes need a more complete tokenization of the source:
# - Don't get fooled by comments ending in backslash
# - reindent continuation lines indicated by backslash
# - handle continuation lines inside parentheses/braces/brackets
# - handle triple quoted strings spanning lines
# - realign comments
# - optionally do much more thorough reformatting, a la C indent
# Defaults
STEPSIZE = 8
TABSIZE = 8
EXPANDTABS = False
import io
import re
import sys
next = {}
next['if'] = next['elif'] = 'elif', 'else', 'end'
next['while'] = next['for'] = 'else', 'end'
next['try'] = 'except', 'finally'
next['except'] = 'except', 'else', 'finally', 'end'
next['else'] = next['finally'] = next['with'] = \
next['def'] = next['class'] = 'end'
next['end'] = ()
start = 'if', 'while', 'for', 'try', 'with', 'def', 'class'
class PythonIndenter:
def __init__(self, fpi = sys.stdin, fpo = sys.stdout,
indentsize = STEPSIZE, tabsize = TABSIZE, expandtabs = EXPANDTABS):
self.fpi = fpi
self.fpo = fpo
self.indentsize = indentsize
self.tabsize = tabsize
self.lineno = 0
self.expandtabs = expandtabs
self._write = fpo.write
self.kwprog = re.compile(
r'^(?:\s|\\\n)*(?P<kw>[a-z]+)'
r'((?:\s|\\\n)+(?P<id>[a-zA-Z_]\w*))?'
r'[^\w]')
self.endprog = re.compile(
r'^(?:\s|\\\n)*#?\s*end\s+(?P<kw>[a-z]+)'
r'(\s+(?P<id>[a-zA-Z_]\w*))?'
r'[^\w]')
self.wsprog = re.compile(r'^[ \t]*')
# end def __init__
def write(self, line):
if self.expandtabs:
self._write(line.expandtabs(self.tabsize))
else:
self._write(line)
# end if
# end def write
def readline(self):
line = self.fpi.readline()
if line: self.lineno += 1
# end if
return line
# end def readline
def error(self, fmt, *args):
if args: fmt = fmt % args
# end if
sys.stderr.write('Error at line %d: %s\n' % (self.lineno, fmt))
self.write('### %s ###\n' % fmt)
# end def error
def getline(self):
line = self.readline()
while line[-2:] == '\\\n':
line2 = self.readline()
if not line2: break
# end if
line += line2
# end while
return line
# end def getline
def putline(self, line, indent):
tabs, spaces = divmod(indent*self.indentsize, self.tabsize)
i = self.wsprog.match(line).end()
line = line[i:]
if line[:1] not in ('\n', '\r', ''):
line = '\t'*tabs + ' '*spaces + line
# end if
self.write(line)
# end def putline
def reformat(self):
stack = []
while True:
line = self.getline()
if not line: break # EOF
# end if
m = self.endprog.match(line)
if m:
kw = 'end'
kw2 = m.group('kw')
if not stack:
self.error('unexpected end')
elif stack.pop()[0] != kw2:
self.error('unmatched end')
# end if
self.putline(line, len(stack))
continue
# end if
m = self.kwprog.match(line)
if m:
kw = m.group('kw')
if kw in start:
self.putline(line, len(stack))
stack.append((kw, kw))
continue
# end if
if kw in next and stack:
self.putline(line, len(stack)-1)
kwa, kwb = stack[-1]
stack[-1] = kwa, kw
continue
# end if
# end if
self.putline(line, len(stack))
# end while
if stack:
self.error('unterminated keywords')
for kwa, kwb in stack:
self.write('\t%s\n' % kwa)
# end for
# end if
# end def reformat
def delete(self):
begin_counter = 0
end_counter = 0
while True:
line = self.getline()
if not line: break # EOF
# end if
m = self.endprog.match(line)
if m:
end_counter += 1
continue
# end if
m = self.kwprog.match(line)
if m:
kw = m.group('kw')
if kw in start:
begin_counter += 1
# end if
# end if
self.write(line)
# end while
if begin_counter - end_counter < 0:
sys.stderr.write('Warning: input contained more end tags than expected\n')
elif begin_counter - end_counter > 0:
sys.stderr.write('Warning: input contained less end tags than expected\n')
# end if
# end def delete
def complete(self):
stack = []
todo = []
currentws = thisid = firstkw = lastkw = topid = ''
while True:
line = self.getline()
i = self.wsprog.match(line).end()
m = self.endprog.match(line)
if m:
thiskw = 'end'
endkw = m.group('kw')
thisid = m.group('id')
else:
m = self.kwprog.match(line)
if m:
thiskw = m.group('kw')
if thiskw not in next:
thiskw = ''
# end if
if thiskw in ('def', 'class'):
thisid = m.group('id')
else:
thisid = ''
# end if
elif line[i:i+1] in ('\n', '#'):
todo.append(line)
continue
else:
thiskw = ''
# end if
# end if
indentws = line[:i]
indent = len(indentws.expandtabs(self.tabsize))
current = len(currentws.expandtabs(self.tabsize))
while indent < current:
if firstkw:
if topid:
s = '# end %s %s\n' % (
firstkw, topid)
else:
s = '# end %s\n' % firstkw
# end if
self.write(currentws + s)
firstkw = lastkw = ''
# end if
currentws, firstkw, lastkw, topid = stack.pop()
current = len(currentws.expandtabs(self.tabsize))
# end while
if indent == current and firstkw:
if thiskw == 'end':
if endkw != firstkw:
self.error('mismatched end')
# end if
firstkw = lastkw = ''
elif not thiskw or thiskw in start:
if topid:
s = '# end %s %s\n' % (
firstkw, topid)
else:
s = '# end %s\n' % firstkw
# end if
self.write(currentws + s)
firstkw = lastkw = topid = ''
# end if
# end if
if indent > current:
stack.append((currentws, firstkw, lastkw, topid))
if thiskw and thiskw not in start:
# error
thiskw = ''
# end if
currentws, firstkw, lastkw, topid = \
indentws, thiskw, thiskw, thisid
# end if
if thiskw:
if thiskw in start:
firstkw = lastkw = thiskw
topid = thisid
else:
lastkw = thiskw
# end if
# end if
for l in todo: self.write(l)
# end for
todo = []
if not line: break
# end if
self.write(line)
# end while
# end def complete
# end class PythonIndenter
# Simplified user interface
# - xxx_filter(input, output): read and write file objects
# - xxx_string(s): take and return string object
# - xxx_file(filename): process file in place, return true iff changed
def complete_filter(input = sys.stdin, output = sys.stdout,
stepsize = STEPSIZE, tabsize = TABSIZE, expandtabs = EXPANDTABS):
pi = PythonIndenter(input, output, stepsize, tabsize, expandtabs)
pi.complete()
# end def complete_filter
def delete_filter(input= sys.stdin, output = sys.stdout,
stepsize = STEPSIZE, tabsize = TABSIZE, expandtabs = EXPANDTABS):
pi = PythonIndenter(input, output, stepsize, tabsize, expandtabs)
pi.delete()
# end def delete_filter
def reformat_filter(input = sys.stdin, output = sys.stdout,
stepsize = STEPSIZE, tabsize = TABSIZE, expandtabs = EXPANDTABS):
pi = PythonIndenter(input, output, stepsize, tabsize, expandtabs)
pi.reformat()
# end def reformat_filter
def complete_string(source, stepsize = STEPSIZE, tabsize = TABSIZE, expandtabs = EXPANDTABS):
input = io.StringIO(source)
output = io.StringIO()
pi = PythonIndenter(input, output, stepsize, tabsize, expandtabs)
pi.complete()
return output.getvalue()
# end def complete_string
def delete_string(source, stepsize = STEPSIZE, tabsize = TABSIZE, expandtabs = EXPANDTABS):
input = io.StringIO(source)
output = io.StringIO()
pi = PythonIndenter(input, output, stepsize, tabsize, expandtabs)
pi.delete()
return output.getvalue()
# end def delete_string
def reformat_string(source, stepsize = STEPSIZE, tabsize = TABSIZE, expandtabs = EXPANDTABS):
input = io.StringIO(source)
output = io.StringIO()
pi = PythonIndenter(input, output, stepsize, tabsize, expandtabs)
pi.reformat()
return output.getvalue()
# end def reformat_string
def make_backup(filename):
import os, os.path
backup = filename + '~'
if os.path.lexists(backup):
try:
os.remove(backup)
except OSError:
print("Can't remove backup %r" % (backup,), file=sys.stderr)
# end try
# end if
try:
os.rename(filename, backup)
except OSError:
print("Can't rename %r to %r" % (filename, backup), file=sys.stderr)
# end try
# end def make_backup
def complete_file(filename, stepsize = STEPSIZE, tabsize = TABSIZE, expandtabs = EXPANDTABS):
with open(filename, 'r') as f:
source = f.read()
# end with
result = complete_string(source, stepsize, tabsize, expandtabs)
if source == result: return 0
# end if
make_backup(filename)
with open(filename, 'w') as f:
f.write(result)
# end with
return 1
# end def complete_file
def delete_file(filename, stepsize = STEPSIZE, tabsize = TABSIZE, expandtabs = EXPANDTABS):
with open(filename, 'r') as f:
source = f.read()
# end with
result = delete_string(source, stepsize, tabsize, expandtabs)
if source == result: return 0
# end if
make_backup(filename)
with open(filename, 'w') as f:
f.write(result)
# end with
return 1
# end def delete_file
def reformat_file(filename, stepsize = STEPSIZE, tabsize = TABSIZE, expandtabs = EXPANDTABS):
with open(filename, 'r') as f:
source = f.read()
# end with
result = reformat_string(source, stepsize, tabsize, expandtabs)
if source == result: return 0
# end if
make_backup(filename)
with open(filename, 'w') as f:
f.write(result)
# end with
return 1
# end def reformat_file
# Test program when called as a script
usage = """
usage: pindent (-c|-d|-r) [-s stepsize] [-t tabsize] [-e] [file] ...
-c : complete a correctly indented program (add #end directives)
-d : delete #end directives
-r : reformat a completed program (use #end directives)
-s stepsize: indentation step (default %(STEPSIZE)d)
-t tabsize : the worth in spaces of a tab (default %(TABSIZE)d)
-e : expand TABs into spaces (default OFF)
[file] ... : files are changed in place, with backups in file~
If no files are specified or a single - is given,
the program acts as a filter (reads stdin, writes stdout).
""" % vars()
def error_both(op1, op2):
sys.stderr.write('Error: You can not specify both '+op1+' and -'+op2[0]+' at the same time\n')
sys.stderr.write(usage)
sys.exit(2)
# end def error_both
def test():
import getopt
try:
opts, args = getopt.getopt(sys.argv[1:], 'cdrs:t:e')
except getopt.error as msg:
sys.stderr.write('Error: %s\n' % msg)
sys.stderr.write(usage)
sys.exit(2)
# end try
action = None
stepsize = STEPSIZE
tabsize = TABSIZE
expandtabs = EXPANDTABS
for o, a in opts:
if o == '-c':
if action: error_both(o, action)
# end if
action = 'complete'
elif o == '-d':
if action: error_both(o, action)
# end if
action = 'delete'
elif o == '-r':
if action: error_both(o, action)
# end if
action = 'reformat'
elif o == '-s':
stepsize = int(a)
elif o == '-t':
tabsize = int(a)
elif o == '-e':
expandtabs = True
# end if
# end for
if not action:
sys.stderr.write(
'You must specify -c(omplete), -d(elete) or -r(eformat)\n')
sys.stderr.write(usage)
sys.exit(2)
# end if
if not args or args == ['-']:
action = eval(action + '_filter')
action(sys.stdin, sys.stdout, stepsize, tabsize, expandtabs)
else:
action = eval(action + '_file')
for filename in args:
action(filename, stepsize, tabsize, expandtabs)
# end for
# end if
# end def test
if __name__ == '__main__':
test()
# end if
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