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