||Provides a file-like object that takes care of all the things you|
commonly want to do when processing a text file that has some
line-by-line syntax: strip comments (as long as "#" is your comment
character), skip blank lines, join adjacent lines by escaping the
newline (ie. backslash at end of line), strip leading and/or
trailing whitespace, and collapse internal whitespace. All of these
are optional and independently controllable.
Provides a 'warn()' method so you can generate warning messages that
report physical line number, even if the logical line in question
spans multiple physical lines. Also provides 'unreadline()' for
implementing line-at-a-time lookahead.
Constructor is called as:
TextFile (filename=None, file=None, **options)
It bombs (RuntimeError) if both 'filename' and 'file' are None;
'filename' should be a string, and 'file' a file object (or
something that provides 'readline()' and 'close()' methods). It is
recommended that you supply at least 'filename', so that TextFile
can include it in warning messages. If 'file' is not supplied,
TextFile creates its own using the 'open()' builtin.
The options are all boolean, and affect the value returned by
strip_comments [default: true]
strip from "#" to end-of-line, as well as any whitespace
leading up to the "#" -- unless it is escaped by a backslash
lstrip_ws [default: false]
strip leading whitespace from each line before returning it
rstrip_ws [default: true]
strip trailing whitespace (including line terminator!) from
each line before returning it
skip_blanks [default: true}
skip lines that are empty *after* stripping comments and
whitespace. (If both lstrip_ws and rstrip_ws are true,
then some lines may consist of solely whitespace: these will
*not* be skipped, even if 'skip_blanks' is true.)
join_lines [default: false]
if a backslash is the last non-newline character on a line
after stripping comments and whitespace, join the following line
to it to form one "logical line"; if N consecutive lines end
with a backslash, then N+1 physical lines will be joined to
form one logical line.
collapse_ws [default: false]
after stripping comments and whitespace and joining physical
lines into logical lines, all internal whitespace (strings of
whitespace surrounded by non-whitespace characters, and not at
the beginning or end of the logical line) will be collapsed
to a single space.
Note that since 'rstrip_ws' can strip the trailing newline, the
semantics of 'readline()' must differ from those of the builtin file
object's 'readline()' method! In particular, 'readline()' returns
None for end-of-/get.cgi/ an empty string might just be a blank line (or
an all-whitespace line), if 'rstrip_ws' is true but 'skip_blanks' is
- __init__(self, filename=None, file=None, **options)
- Construct a new TextFile object. At least one of 'filename'
(a string) and 'file' (a file-like object) must be supplied.
They keyword argument options are described above and affect
the values returned by 'readline()'.
- Close the current file and forget everything we know about it
(filename, current line number).
- open(self, filename)
- Open a new file named 'filename'. This overrides both the
'filename' and 'file' arguments to the constructor.
- Read and return a single logical line from the current file (or
from an internal buffer if lines have previously been "unread"
with 'unreadline()'). If the 'join_lines' option is true, this
may involve reading multiple physical lines concatenated into a
single string. Updates the current line number, so calling
'warn()' after 'readline()' emits a warning about the physical
line(s) just read. Returns None on end-of-file, since the empty
string can occur if 'rstrip_ws' is true but 'strip_blanks' is
- Read and return the list of all logical lines remaining in the
- unreadline(self, line)
- Push 'line' (a string) onto an internal buffer that will be
checked by future 'readline()' calls. Handy for implementing
a parser with line-at-a-time lookahead.
- warn(self, msg, line=None)
- Print (to stderr) a warning message tied to the current logical
line in the current file. If the current logical line in the
file spans multiple physical lines, the warning refers to the
whole range, eg. "lines 3-5". If 'line' supplied, it overrides
the current line number; it may be a list or tuple to indicate a
range of physical lines, or an integer for a single physical