mirror of
https://github.com/PiBrewing/craftbeerpi4.git
synced 2024-12-29 17:01:44 +01:00
287 lines
12 KiB
Python
287 lines
12 KiB
Python
|
"""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."""
|
||
|
|
|
||
|
|
import sys, io
|
||
|
|
|
||
|
|
|
||
|
|
class TextFile:
|
||
|
|
"""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. 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 'io.open()'.
|
||
|
|
|
||
|
|
The options are all boolean, and affect the value returned by
|
||
|
|
'readline()':
|
||
|
|
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 false,
|
||
|
|
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_join [default: false]
|
||
|
|
strip leading whitespace from lines that are joined to their
|
||
|
|
predecessor; only matters if (join_lines and not lstrip_ws)
|
||
|
|
errors [default: 'strict']
|
||
|
|
error handler used to decode the file content
|
||
|
|
|
||
|
|
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-file: an empty string might just be a blank line (or
|
||
|
|
an all-whitespace line), if 'rstrip_ws' is true but 'skip_blanks' is
|
||
|
|
not."""
|
||
|
|
|
||
|
|
default_options = { 'strip_comments': 1,
|
||
|
|
'skip_blanks': 1,
|
||
|
|
'lstrip_ws': 0,
|
||
|
|
'rstrip_ws': 1,
|
||
|
|
'join_lines': 0,
|
||
|
|
'collapse_join': 0,
|
||
|
|
'errors': 'strict',
|
||
|
|
}
|
||
|
|
|
||
|
|
def __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()'."""
|
||
|
|
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 opt in options:
|
||
|
|
setattr(self, opt, options[opt])
|
||
|
|
else:
|
||
|
|
setattr(self, opt, self.default_options[opt])
|
||
|
|
|
||
|
|
# sanity check client option hash
|
||
|
|
for opt in options.keys():
|
||
|
|
if opt not in self.default_options:
|
||
|
|
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!
|
||
|
|
|
||
|
|
# 'linebuf' is a stack of lines that will be emptied before we
|
||
|
|
# actually read from the file; it's only populated by an
|
||
|
|
# 'unreadline()' operation
|
||
|
|
self.linebuf = []
|
||
|
|
|
||
|
|
def open(self, filename):
|
||
|
|
"""Open a new file named 'filename'. This overrides both the
|
||
|
|
'filename' and 'file' arguments to the constructor."""
|
||
|
|
self.filename = filename
|
||
|
|
self.file = io.open(self.filename, 'r', errors=self.errors)
|
||
|
|
self.current_line = 0
|
||
|
|
|
||
|
|
def close(self):
|
||
|
|
"""Close the current file and forget everything we know about it
|
||
|
|
(filename, current line number)."""
|
||
|
|
file = self.file
|
||
|
|
self.file = None
|
||
|
|
self.filename = None
|
||
|
|
self.current_line = None
|
||
|
|
file.close()
|
||
|
|
|
||
|
|
def gen_error(self, msg, line=None):
|
||
|
|
outmsg = []
|
||
|
|
if line is None:
|
||
|
|
line = self.current_line
|
||
|
|
outmsg.append(self.filename + ", ")
|
||
|
|
if isinstance(line, (list, tuple)):
|
||
|
|
outmsg.append("lines %d-%d: " % tuple(line))
|
||
|
|
else:
|
||
|
|
outmsg.append("line %d: " % line)
|
||
|
|
outmsg.append(str(msg))
|
||
|
|
return "".join(outmsg)
|
||
|
|
|
||
|
|
def error(self, msg, line=None):
|
||
|
|
raise ValueError("error: " + self.gen_error(msg, line))
|
||
|
|
|
||
|
|
def 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
|
||
|
|
line."""
|
||
|
|
sys.stderr.write("warning: " + self.gen_error(msg, line) + "\n")
|
||
|
|
|
||
|
|
def readline(self):
|
||
|
|
"""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
|
||
|
|
not."""
|
||
|
|
# If any "unread" lines waiting in 'linebuf', return the top
|
||
|
|
# one. (We don't actually buffer read-ahead data -- lines only
|
||
|
|
# get put in 'linebuf' if the client explicitly does an
|
||
|
|
# 'unreadline()'.
|
||
|
|
if self.linebuf:
|
||
|
|
line = self.linebuf[-1]
|
||
|
|
del self.linebuf[-1]
|
||
|
|
return line
|
||
|
|
|
||
|
|
buildup_line = ''
|
||
|
|
|
||
|
|
while True:
|
||
|
|
# read the line, make it None if EOF
|
||
|
|
line = self.file.readline()
|
||
|
|
if line == '':
|
||
|
|
line = None
|
||
|
|
|
||
|
|
if self.strip_comments and line:
|
||
|
|
|
||
|
|
# Look for the first "#" in the line. If none, never
|
||
|
|
# mind. If we find one and it's the first character, or
|
||
|
|
# is not preceded by "\", then it starts a comment --
|
||
|
|
# strip the comment, strip whitespace before it, and
|
||
|
|
# carry on. Otherwise, it's just an escaped "#", so
|
||
|
|
# unescape it (and any other escaped "#"'s that might be
|
||
|
|
# lurking in there) and otherwise leave the line alone.
|
||
|
|
|
||
|
|
pos = line.find("#")
|
||
|
|
if pos == -1: # no "#" -- no comments
|
||
|
|
pass
|
||
|
|
|
||
|
|
# It's definitely a comment -- either "#" is the first
|
||
|
|
# character, or it's elsewhere and unescaped.
|
||
|
|
elif pos == 0 or line[pos-1] != "\\":
|
||
|
|
# Have to preserve the trailing newline, because it's
|
||
|
|
# the job of a later step (rstrip_ws) to remove it --
|
||
|
|
# and if rstrip_ws is false, we'd better preserve it!
|
||
|
|
# (NB. this means that if the final line is all comment
|
||
|
|
# and has no trailing newline, we will think that it's
|
||
|
|
# EOF; I think that's OK.)
|
||
|
|
eol = (line[-1] == '\n') and '\n' or ''
|
||
|
|
line = line[0:pos] + eol
|
||
|
|
|
||
|
|
# If all that's left is whitespace, then skip line
|
||
|
|
# *now*, before we try to join it to 'buildup_line' --
|
||
|
|
# that way constructs like
|
||
|
|
# hello \\
|
||
|
|
# # comment that should be ignored
|
||
|
|
# there
|
||
|
|
# result in "hello there".
|
||
|
|
if line.strip() == "":
|
||
|
|
continue
|
||
|
|
else: # it's an escaped "#"
|
||
|
|
line = line.replace("\\#", "#")
|
||
|
|
|
||
|
|
# did previous line end with a backslash? then accumulate
|
||
|
|
if self.join_lines and buildup_line:
|
||
|
|
# oops: end of file
|
||
|
|
if line is None:
|
||
|
|
self.warn("continuation line immediately precedes "
|
||
|
|
"end-of-file")
|
||
|
|
return buildup_line
|
||
|
|
|
||
|
|
if self.collapse_join:
|
||
|
|
line = line.lstrip()
|
||
|
|
line = buildup_line + line
|
||
|
|
|
||
|
|
# careful: pay attention to line number when incrementing it
|
||
|
|
if isinstance(self.current_line, list):
|
||
|
|
self.current_line[1] = self.current_line[1] + 1
|
||
|
|
else:
|
||
|
|
self.current_line = [self.current_line,
|
||
|
|
self.current_line + 1]
|
||
|
|
# just an ordinary line, read it as usual
|
||
|
|
else:
|
||
|
|
if line is None: # eof
|
||
|
|
return None
|
||
|
|
|
||
|
|
# still have to be careful about incrementing the line number!
|
||
|
|
if isinstance(self.current_line, list):
|
||
|
|
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 = line.strip()
|
||
|
|
elif self.lstrip_ws:
|
||
|
|
line = line.lstrip()
|
||
|
|
elif self.rstrip_ws:
|
||
|
|
line = line.rstrip()
|
||
|
|
|
||
|
|
# 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 self.join_lines:
|
||
|
|
if line[-1] == '\\':
|
||
|
|
buildup_line = line[:-1]
|
||
|
|
continue
|
||
|
|
|
||
|
|
if line[-2:] == '\\\n':
|
||
|
|
buildup_line = line[0:-2] + '\n'
|
||
|
|
continue
|
||
|
|
|
||
|
|
# well, I guess there's some actual content there: return it
|
||
|
|
return line
|
||
|
|
|
||
|
|
def readlines(self):
|
||
|
|
"""Read and return the list of all logical lines remaining in the
|
||
|
|
current file."""
|
||
|
|
lines = []
|
||
|
|
while True:
|
||
|
|
line = self.readline()
|
||
|
|
if line is None:
|
||
|
|
return lines
|
||
|
|
lines.append(line)
|
||
|
|
|
||
|
|
def 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."""
|
||
|
|
self.linebuf.append(line)
|