Added: mems.lib.text_file: provides TextFile class for parsing text
files with (optional) comment stripping, blank line skipping, whitespace removal, and line joining with trailing backslashes.
This commit is contained in:
Greg Ward
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"""text_file
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provides the TextFile class, which gives an interface to text files
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that (optionally) takes care of stripping comments, ignoring blank
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lines, and joining lines with backslashes."""
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# created 1999/01/12, Greg Ward
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__revision__ = "$Id$"
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from types import *
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import os, string, re
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class TextFile:
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filename = None
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file = None
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current_line = None
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default_options = { 'strip_comments': 1,
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'comment_re': re.compile (r'\s*#.*'),
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'skip_blanks': 1,
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'join_lines': 0,
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'lstrip_ws': 0,
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'rstrip_ws': 1,
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}
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def __init__ (self, filename=None, **options):
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# set values for all options -- either from client option hash
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# or fallback to default_options
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for opt in self.default_options.keys():
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if options.has_key (opt):
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if opt == 'comment_re' and type (options[opt]) is StringType:
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self.comment_re = re.compile (options[opt])
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else:
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setattr (self, opt, options[opt])
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else:
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setattr (self, opt, self.default_options[opt])
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# sanity check client option hash
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for opt in options.keys():
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if not self.default_options.has_key (opt):
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raise KeyError, "invalid TextFile option '%s'" % opt
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self.filename = filename
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if self.filename:
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self.open ()
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def open (self, filename=None):
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if not self.filename:
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if not filename:
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raise RuntimeError, "must provide a filename somehow"
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self.filename = filename
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self.file = open (self.filename, 'r')
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self.current_line = 0
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def close (self):
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self.file.close ()
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self.file = None
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self.filename = None
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self.current_line = None
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def readline (self):
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buildup_line = ''
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while 1:
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# read the line, optionally strip comments
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line = self.file.readline()
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if self.strip_comments and line:
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line = self.comment_re.sub ('', line)
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# did previous line end with a backslash? then accumulate
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if self.join_lines and buildup_line:
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# oops: end of file
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if not line:
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self.warn ("continuation line immediately precedes "
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"end-of-file")
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return buildup_line
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line = buildup_line + line
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# careful: pay attention to line number when incrementing it
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if type (self.current_line) is ListType:
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self.current_line[1] = self.current_line[1] + 1
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else:
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self.current_line = [self.current_line, self.current_line+1]
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# just an ordinary line, read it as usual
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else:
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if not line:
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return None
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# still have to be careful about incrementing the line number!
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if type (self.current_line) is ListType:
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self.current_line = self.current_line[1] + 1
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else:
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self.current_line = self.current_line + 1
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# strip whitespace however the client wants (leading and
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# trailing, or one or the other, or neither)
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if self.lstrip_ws and self.rstrip_ws:
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line = string.strip (line)
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else:
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if self.lstrip_ws:
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line = string.lstrip (line)
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if self.rstrip_ws:
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line = string.rstrip (line)
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# blank line (whether we rstrip'ed or not)? skip to next line
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# if appropriate
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if line == '' or line == '\n' and self.skip_blanks:
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continue
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if self.join_lines:
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if line[-1] == '\\':
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buildup_line = line[:-1]
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continue
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if line[-2:] == '\\\n':
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buildup_line = line[0:-2] + '\n'
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continue
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# well, I guess there's some actual content there: return it
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return line
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# end readline
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def readlines (self):
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lines = []
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while 1:
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line = self.readline()
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if line is None:
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return lines
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lines.append (line)
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if __name__ == "__main__":
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test_data = """# test file
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line 3 \\
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continues on next line
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"""
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# result 1: no fancy options
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result1 = map (lambda x: x + "\n", string.split (test_data, "\n")[0:-1])
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# result 2: just strip comments
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result2 = ["\n", "\n", "line 3 \\\n", "continues on next line\n"]
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# result 3: just strip blank lines
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result3 = ["# test file\n", "line 3 \\\n", "continues on next line\n"]
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# result 4: default, strip comments, blank lines, and trailing whitespace
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result4 = ["line 3 \\", "continues on next line"]
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# result 5: full processing, strip comments and blanks, plus join lines
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result5 = ["line 3 continues on next line"]
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def test_input (count, description, file, expected_result):
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result = file.readlines ()
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# result = string.join (result, '')
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if result == expected_result:
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print "ok %d (%s)" % (count, description)
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else:
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print "not ok %d (%s):" % (count, description)
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print "** expected:"
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print expected_result
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print "** received:"
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print result
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filename = "test.txt"
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out_file = open (filename, "w")
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out_file.write (test_data)
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out_file.close ()
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in_file = TextFile (filename, strip_comments=0, skip_blanks=0,
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lstrip_ws=0, rstrip_ws=0)
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test_input (1, "no processing", in_file, result1)
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in_file = TextFile (filename, strip_comments=1, skip_blanks=0,
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lstrip_ws=0, rstrip_ws=0)
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test_input (2, "strip comments", in_file, result2)
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in_file = TextFile (filename, strip_comments=0, skip_blanks=1,
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lstrip_ws=0, rstrip_ws=0)
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test_input (3, "strip blanks", in_file, result3)
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in_file = TextFile (filename)
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test_input (4, "default processing", in_file, result4)
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in_file = TextFile (filename, strip_comments=1, skip_blanks=1,
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join_lines=1, rstrip_ws=1)
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test_input (5, "full processing", in_file, result5)
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os.remove (filename)
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