/Demo/scripts/eqfix.py

  1#! /usr/bin/env python
  2
  3# Fix Python source files to use the new equality test operator, i.e.,
  4#       if x = y: ...
  5# is changed to
  6#       if x == y: ...
  7# The script correctly tokenizes the Python program to reliably
  8# distinguish between assignments and equality tests.
  9#
 10# Command line arguments are files or directories to be processed.
 11# Directories are searched recursively for files whose name looks
 12# like a python module.
 13# Symbolic links are always ignored (except as explicit directory
 14# arguments).  Of course, the original file is kept as a back-up
 15# (with a "~" attached to its name).
 16# It complains about binaries (files containing null bytes)
 17# and about files that are ostensibly not Python files: if the first
 18# line starts with '#!' and does not contain the string 'python'.
 19#
 20# Changes made are reported to stdout in a diff-like format.
 21#
 22# Undoubtedly you can do this using find and sed or perl, but this is
 23# a nice example of Python code that recurses down a directory tree
 24# and uses regular expressions.  Also note several subtleties like
 25# preserving the file's mode and avoiding to even write a temp file
 26# when no changes are needed for a file.
 27#
 28# NB: by changing only the function fixline() you can turn this
 29# into a program for a different change to Python programs...
 30
 31import sys
 32import re
 33import os
 34from stat import *
 35import string
 36
 37err = sys.stderr.write
 38dbg = err
 39rep = sys.stdout.write
 40
 41def main():
 42    bad = 0
 43    if not sys.argv[1:]: # No arguments
 44        err('usage: ' + sys.argv[0] + ' file-or-directory ...\n')
 45        sys.exit(2)
 46    for arg in sys.argv[1:]:
 47        if os.path.isdir(arg):
 48            if recursedown(arg): bad = 1
 49        elif os.path.islink(arg):
 50            err(arg + ': will not process symbolic links\n')
 51            bad = 1
 52        else:
 53            if fix(arg): bad = 1
 54    sys.exit(bad)
 55
 56ispythonprog = re.compile('^[a-zA-Z0-9_]+\.py$')
 57def ispython(name):
 58    return ispythonprog.match(name) >= 0
 59
 60def recursedown(dirname):
 61    dbg('recursedown(%r)\n' % (dirname,))
 62    bad = 0
 63    try:
 64        names = os.listdir(dirname)
 65    except os.error, msg:
 66        err('%s: cannot list directory: %r\n' % (dirname, msg))
 67        return 1
 68    names.sort()
 69    subdirs = []
 70    for name in names:
 71        if name in (os.curdir, os.pardir): continue
 72        fullname = os.path.join(dirname, name)
 73        if os.path.islink(fullname): pass
 74        elif os.path.isdir(fullname):
 75            subdirs.append(fullname)
 76        elif ispython(name):
 77            if fix(fullname): bad = 1
 78    for fullname in subdirs:
 79        if recursedown(fullname): bad = 1
 80    return bad
 81
 82def fix(filename):
 83##      dbg('fix(%r)\n' % (dirname,))
 84    try:
 85        f = open(filename, 'r')
 86    except IOError, msg:
 87        err('%s: cannot open: %r\n' % (filename, msg))
 88        return 1
 89    head, tail = os.path.split(filename)
 90    tempname = os.path.join(head, '@' + tail)
 91    g = None
 92    # If we find a match, we rewind the file and start over but
 93    # now copy everything to a temp file.
 94    lineno = 0
 95    while 1:
 96        line = f.readline()
 97        if not line: break
 98        lineno = lineno + 1
 99        if g is None and '\0' in line:
100            # Check for binary files
101            err(filename + ': contains null bytes; not fixed\n')
102            f.close()
103            return 1
104        if lineno == 1 and g is None and line[:2] == '#!':
105            # Check for non-Python scripts
106            words = string.split(line[2:])
107            if words and re.search('[pP]ython', words[0]) < 0:
108                msg = filename + ': ' + words[0]
109                msg = msg + ' script; not fixed\n'
110                err(msg)
111                f.close()
112                return 1
113        while line[-2:] == '\\\n':
114            nextline = f.readline()
115            if not nextline: break
116            line = line + nextline
117            lineno = lineno + 1
118        newline = fixline(line)
119        if newline != line:
120            if g is None:
121                try:
122                    g = open(tempname, 'w')
123                except IOError, msg:
124                    f.close()
125                    err('%s: cannot create: %r\n' % (tempname, msg))
126                    return 1
127                f.seek(0)
128                lineno = 0
129                rep(filename + ':\n')
130                continue # restart from the beginning
131            rep(repr(lineno) + '\n')
132            rep('< ' + line)
133            rep('> ' + newline)
134        if g is not None:
135            g.write(newline)
136
137    # End of file
138    f.close()
139    if not g: return 0 # No changes
140
141    # Finishing touch -- move files
142
143    # First copy the file's mode to the temp file
144    try:
145        statbuf = os.stat(filename)
146        os.chmod(tempname, statbuf[ST_MODE] & 07777)
147    except os.error, msg:
148        err('%s: warning: chmod failed (%r)\n' % (tempname, msg))
149    # Then make a backup of the original file as filename~
150    try:
151        os.rename(filename, filename + '~')
152    except os.error, msg:
153        err('%s: warning: backup failed (%r)\n' % (filename, msg))
154    # Now move the temp file to the original file
155    try:
156        os.rename(tempname, filename)
157    except os.error, msg:
158        err('%s: rename failed (%r)\n' % (filename, msg))
159        return 1
160    # Return succes
161    return 0
162
163
164from tokenize import tokenprog
165
166match = {'if':':', 'elif':':', 'while':':', 'return':'\n', \
167         '(':')', '[':']', '{':'}', '`':'`'}
168
169def fixline(line):
170    # Quick check for easy case
171    if '=' not in line: return line
172
173    i, n = 0, len(line)
174    stack = []
175    while i < n:
176        j = tokenprog.match(line, i)
177        if j < 0:
178            # A bad token; forget about the rest of this line
179            print '(Syntax error:)'
180            print line,
181            return line
182        a, b = tokenprog.regs[3] # Location of the token proper
183        token = line[a:b]
184        i = i+j
185        if stack and token == stack[-1]:
186            del stack[-1]
187        elif match.has_key(token):
188            stack.append(match[token])
189        elif token == '=' and stack:
190            line = line[:a] + '==' + line[b:]
191            i, n = a + len('=='), len(line)
192        elif token == '==' and not stack:
193            print '(Warning: \'==\' at top level:)'
194            print line,
195    return line
196
197if __name__ == "__main__":
198    main()