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"""text_file
provides the TextFile class, which gives an interface to text files
that (optionally) takes care of stripping comments, ignoring blank
lines, and joining lines with backslashes."""
# created 1999/01/12, Greg Ward
__revision__ = "$Id$"
from types import *
import sys, os, string, re
class TextFile:
default_options = { 'strip_comments': 1,
'comment_re': re.compile (r'\s*#.*'),
'skip_blanks': 1,
'join_lines': 0,
'lstrip_ws': 0,
'rstrip_ws': 1,
'collapse_ws': 0,
}
def __init__ (self, filename=None, file=None, **options):
if filename is None and file is None:
raise RuntimeError, \
"you must supply either or both of 'filename' and 'file'"
# set values for all options -- either from client option hash
# or fallback to default_options
for opt in self.default_options.keys():
if options.has_key (opt):
if opt == 'comment_re' and type (options[opt]) is StringType:
self.comment_re = re.compile (options[opt])
else:
setattr (self, opt, options[opt])
else:
setattr (self, opt, self.default_options[opt])
# sanity check client option hash
for opt in options.keys():
if not self.default_options.has_key (opt):
raise KeyError, "invalid TextFile option '%s'" % opt
if file is None:
self.open (filename)
else:
self.filename = filename
self.file = file
self.current_line = 0 # assuming that file is at BOF!
# 'linestart' stores the file offset of the start of each logical
# line; it is used to back up the file pointer when the caller
# wants to "unread" a line
self.linestart = []
def open (self, filename):
self.filename = filename
self.file = open (self.filename, 'r')
self.current_line = 0
def close (self):
self.file.close ()
self.file = None
self.filename = None
self.current_line = None
def warn (self, msg):
sys.stderr.write (self.filename + ", ")
if type (self.current_line) is ListType:
sys.stderr.write ("lines %d-%d: " % tuple (self.current_line))
else:
sys.stderr.write ("line %d: " % self.current_line)
sys.stderr.write (msg + "\n")
def readline (self):
buildup_line = ''
while 1:
# record current file position; this will be appended to
# the linestart array *unless* we're accumulating a
# continued logical line
current_pos = self.file.tell()
# read the line, optionally strip comments
line = self.file.readline()
if self.strip_comments and line:
line = self.comment_re.sub ('', line)
# did previous line end with a backslash? then accumulate
if self.join_lines and buildup_line:
# oops: end of file
if not line:
self.warn ("continuation line immediately precedes "
"end-of-file")
return buildup_line
line = buildup_line + line
# careful: pay attention to line number when incrementing it
if type (self.current_line) is ListType:
self.current_line[1] = self.current_line[1] + 1
else:
self.current_line = [self.current_line, self.current_line+1]
# Forget current position: don't want to save it in the
# middle of a logical line
current_pos = None
# just an ordinary line, read it as usual
else:
if not line:
return None
# still have to be careful about incrementing the line number!
if type (self.current_line) is ListType:
self.current_line = self.current_line[1] + 1
else:
self.current_line = self.current_line + 1
# strip whitespace however the client wants (leading and
# trailing, or one or the other, or neither)
if self.lstrip_ws and self.rstrip_ws:
line = string.strip (line)
else:
if self.lstrip_ws:
line = string.lstrip (line)
if self.rstrip_ws:
line = string.rstrip (line)
# blank line (whether we rstrip'ed or not)? skip to next line
# if appropriate
if line == '' or line == '\n' and self.skip_blanks:
continue
# if we're still here and have kept the current position,
# then this physical line starts a logical line; record its
# starting offset
if current_pos is not None:
self.linestart.append (current_pos)
if self.join_lines:
if line[-1] == '\\':
buildup_line = line[:-1]
continue
if line[-2:] == '\\\n':
buildup_line = line[0:-2] + '\n'
continue
# collapse internal whitespace (*after* joining lines!)
if self.collapse_ws:
line = re.sub (r'(\S)\s+(\S)', r'\1 \2', line)
# well, I guess there's some actual content there: return it
return line
# end readline
def unreadline (self):
if not self.linestart:
raise IOError, "at beginning of file -- can't unreadline"
pos = self.linestart[-1]
del self.linestart[-1]
self.file.seek (pos)
def readlines (self):
lines = []
while 1:
line = self.readline()
if line is None:
return lines
lines.append (line)
if __name__ == "__main__":
test_data = """# test file
line 3 \\
continues on next line
"""
# result 1: no fancy options
result1 = map (lambda x: x + "\n", string.split (test_data, "\n")[0:-1])
# result 2: just strip comments
result2 = ["\n", "\n", "line 3 \\\n", "continues on next line\n"]
# result 3: just strip blank lines
result3 = ["# test file\n", "line 3 \\\n", "continues on next line\n"]
# result 4: default, strip comments, blank lines, and trailing whitespace
result4 = ["line 3 \\", "continues on next line"]
# result 5: full processing, strip comments and blanks, plus join lines
result5 = ["line 3 continues on next line"]
def test_input (count, description, file, expected_result):
result = file.readlines ()
# result = string.join (result, '')
if result == expected_result:
print "ok %d (%s)" % (count, description)
else:
print "not ok %d (%s):" % (count, description)
print "** expected:"
print expected_result
print "** received:"
print result
filename = "test.txt"
out_file = open (filename, "w")
out_file.write (test_data)
out_file.close ()
in_file = TextFile (filename, strip_comments=0, skip_blanks=0,
lstrip_ws=0, rstrip_ws=0)
test_input (1, "no processing", in_file, result1)
in_file = TextFile (filename, strip_comments=1, skip_blanks=0,
lstrip_ws=0, rstrip_ws=0)
test_input (2, "strip comments", in_file, result2)
in_file = TextFile (filename, strip_comments=0, skip_blanks=1,
lstrip_ws=0, rstrip_ws=0)
test_input (3, "strip blanks", in_file, result3)
in_file = TextFile (filename)
test_input (4, "default processing", in_file, result4)
in_file = TextFile (filename, strip_comments=1, skip_blanks=1,
join_lines=1, rstrip_ws=1)
test_input (5, "full processing", in_file, result5)
os.remove (filename)
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