Initial revision

Demo/scripts/eqfix.py

+#! /ufs/guido/bin/sgi/python
+#! /usr/local/python
+
+# Fix Python source files to use the new equality test operator,
+# i.e.,
+#	if x == y: ...
+# instead of
+#	if x = y: ...
+#
+# Command line arguments are files or directories to be processed.
+# Directories are searched recursively for files whose name looks
+# like a python module.
+# Symbolic links are always ignored (except as explicit directory
+# arguments).  Of course, the original file is kept as a back-up
+# (with a "~" attached to its name).
+#
+# Changes made are reported to stdout in a diff-like format.
+#
+# Undoubtedly you can do this using find and sed or perl, but this is
+# a nice example of Python code that recurses down a directory tree
+# and uses regular expressions.  Also note several subtleties like
+# preserving the file's mode and avoiding to even write a temp file
+# when no changes are needed for a file.
+#
+# NB: by changing only the function fixline() you can turn this
+# into a program for a different change to Python programs...
+
+import sys
+import regex
+import posix
+import path
+from stat import *
+
+err = sys.stderr.write
+dbg = err
+rep = sys.stdout.write
+
+def main():
+	bad = 0
+	if not sys.argv[1:]: # No arguments
+		err('usage: ' + argv[0] + ' file-or-directory ...\n')
+		sys.exit(2)
+	for arg in sys.argv[1:]:
+		if path.isdir(arg):
+			if recursedown(arg): bad = 1
+		elif path.islink(arg):
+			err(arg + ': will not process symbolic links\n')
+			bad = 1
+		else:
+			if fix(arg): bad = 1
+	sys.exit(bad)
+
+ispythonprog = regex.compile('^[a-zA-Z0-9_]+\.py$')
+def ispython(name):
+	return ispythonprog.match(name) >= 0
+
+def recursedown(dirname):
+	dbg('recursedown(' + `dirname` + ')\n')
+	bad = 0
+	try:
+		names = posix.listdir(dirname)
+	except posix.error, msg:
+		err(dirname + ': cannot list directory: ' + `msg` + '\n')
+		return 1
+	names.sort()
+	subdirs = []
+	for name in names:
+		if name in ('.', '..'): continue
+		fullname = path.join(dirname, name)
+		if path.islink(fullname): pass
+		elif path.isdir(fullname):
+			subdirs.append(fullname)
+		elif ispython(name):
+			if fix(fullname): bad = 1
+	for fullname in subdirs:
+		if recursedown(fullname): bad = 1
+	return bad
+
+def fix(filename):
+	dbg('fix(' + `filename` + ')\n')
+	try:
+		f = open(filename, 'r')
+	except IOError, msg:
+		err(filename + ': cannot open: ' + `msg` + '\n')
+		return 1
+	head, tail = path.split(filename)
+	tempname = path.join(head, '@' + tail)
+	g = None
+	# If we find a match, we rewind the file and start over but
+	# now copy everything to a temp file.
+	lineno = 0
+	while 1:
+		line = f.readline()
+		if not line: break
+		lineno = lineno + 1
+		while line[-2:] == '\\\n':
+			nextline = f.readline()
+			if not nextline: break
+			line = line + nextline
+			lineno = lineno + 1
+		newline = fixline(line)
+		if newline != line:
+			if g is None:
+				try:
+					g = open(tempname, 'w')
+				except IOError, msg:
+					f.close()
+					err(tempname+': cannot create: '+\
+					    `msg`+'\n')
+					return 1
+				f.seek(0)
+				lineno = 0
+				rep(filename + ':\n')
+				continue # restart from the beginning
+			rep(`lineno` + '\n')
+			rep('< ' + line)
+			rep('> ' + newline)
+		if g is not None:
+			g.write(newline)
+
+	# End of file
+	f.close()
+	if not g: return 0 # No changes
+	
+	# Finishing touch -- move files
+
+	# First copy the file's mode to the temp file
+	try:
+		statbuf = posix.stat(filename)
+		posix.chmod(tempname, statbuf[ST_MODE] & 07777)
+	except posix.error, msg:
+		err(tempname + ': warning: chmod failed (' + `msg` + ')\n')
+	# Then make a backup of the original file as filename~
+	try:
+		posix.rename(filename, filename + '~')
+	except posix.error, msg:
+		err(filename + ': warning: backup failed (' + `msg` + ')\n')
+	# Now move the temp file to the original file
+	try:
+		posix.rename(tempname, filename)
+	except posix.error, msg:
+		err(filename + ': rename failed (' + `msg` + ')\n')
+		return 1
+	# Return succes
+	return 0
+
+PAT1 = '\<\(if\|elif\|while\)\>[\0-\377]*[^<>!=]\(=\)[^=][\0-\377]*[^[]:[^]]'
+#         \2                                    \3
+PAT2 = '\<return\>[\0-\377]*[^<>!=]\(=\)[^=]'
+#                                  \4
+PAT = '^[ \t]*\(' + PAT1 + '\|' + PAT2 + '\)'
+#             \1
+prog = regex.compile(PAT)
+
+def fixline(line):
+	while prog.match(line) >= 0:
+		regs = prog.regs
+		if regs[3] == (-1, -1):
+			a, b = regs[4]
+		else:
+			a, b = regs[3]
+		if not 0 < a < b < len(line):
+			dbg('Weird: ' + line)
+			break
+		line = line[:a] + '==' + line[b:]
+	return line
+
+main()