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Diffstat (limited to 'PdfFileTransformer/PyPDF2/pagerange.py')
| -rw-r--r-- | PdfFileTransformer/PyPDF2/pagerange.py | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/PdfFileTransformer/PyPDF2/pagerange.py b/PdfFileTransformer/PyPDF2/pagerange.py new file mode 100644 index 0000000..ce96ec5 --- /dev/null +++ b/PdfFileTransformer/PyPDF2/pagerange.py @@ -0,0 +1,152 @@ +#!/usr/bin/env python +""" +Representation and utils for ranges of PDF file pages. + +Copyright (c) 2014, Steve Witham <switham_github@mac-guyver.com>. +All rights reserved. This software is available under a BSD license; +see https://github.com/mstamy2/PyPDF2/blob/master/LICENSE +""" + +import re +from .utils import isString + +_INT_RE = r"(0|-?[1-9]\d*)" # A decimal int, don't allow "-0". +PAGE_RANGE_RE = "^({int}|({int}?(:{int}?(:{int}?)?)))$".format(int=_INT_RE) +# groups: 12 34 5 6 7 8 + + +class ParseError(Exception): + pass + + +PAGE_RANGE_HELP = """Remember, page indices start with zero. + Page range expression examples: + : all pages. -1 last page. + 22 just the 23rd page. :-1 all but the last page. + 0:3 the first three pages. -2 second-to-last page. + :3 the first three pages. -2: last two pages. + 5: from the sixth page onward. -3:-1 third & second to last. + The third, "stride" or "step" number is also recognized. + ::2 0 2 4 ... to the end. 3:0:-1 3 2 1 but not 0. + 1:10:2 1 3 5 7 9 2::-1 2 1 0. + ::-1 all pages in reverse order. +""" + + +class PageRange(object): + """ + A slice-like representation of a range of page indices, + i.e. page numbers, only starting at zero. + The syntax is like what you would put between brackets [ ]. + The slice is one of the few Python types that can't be subclassed, + but this class converts to and from slices, and allows similar use. + o PageRange(str) parses a string representing a page range. + o PageRange(slice) directly "imports" a slice. + o to_slice() gives the equivalent slice. + o str() and repr() allow printing. + o indices(n) is like slice.indices(n). + """ + + def __init__(self, arg): + """ + Initialize with either a slice -- giving the equivalent page range, + or a PageRange object -- making a copy, + or a string like + "int", "[int]:[int]" or "[int]:[int]:[int]", + where the brackets indicate optional ints. + {page_range_help} + Note the difference between this notation and arguments to slice(): + slice(3) means the first three pages; + PageRange("3") means the range of only the fourth page. + However PageRange(slice(3)) means the first three pages. + """ + if isinstance(arg, slice): + self._slice = arg + return + + if isinstance(arg, PageRange): + self._slice = arg.to_slice() + return + + m = isString(arg) and re.match(PAGE_RANGE_RE, arg) + if not m: + raise ParseError(arg) + elif m.group(2): + # Special case: just an int means a range of one page. + start = int(m.group(2)) + stop = start + 1 if start != -1 else None + self._slice = slice(start, stop) + else: + self._slice = slice(*[int(g) if g else None + for g in m.group(4, 6, 8)]) + + # Just formatting this when there is __doc__ for __init__ + if __init__.__doc__: + __init__.__doc__ = __init__.__doc__.format(page_range_help=PAGE_RANGE_HELP) + + @staticmethod + def valid(input): + """ True if input is a valid initializer for a PageRange. """ + return isinstance(input, slice) or \ + isinstance(input, PageRange) or \ + (isString(input) + and bool(re.match(PAGE_RANGE_RE, input))) + + def to_slice(self): + """ Return the slice equivalent of this page range. """ + return self._slice + + def __str__(self): + """ A string like "1:2:3". """ + s = self._slice + if s.step == None: + if s.start != None and s.stop == s.start + 1: + return str(s.start) + + indices = s.start, s.stop + else: + indices = s.start, s.stop, s.step + return ':'.join("" if i == None else str(i) for i in indices) + + def __repr__(self): + """ A string like "PageRange('1:2:3')". """ + return "PageRange(" + repr(str(self)) + ")" + + def indices(self, n): + """ + n is the length of the list of pages to choose from. + Returns arguments for range(). See help(slice.indices). + """ + return self._slice.indices(n) + + +PAGE_RANGE_ALL = PageRange(":") # The range of all pages. + + +def parse_filename_page_ranges(args): + """ + Given a list of filenames and page ranges, return a list of + (filename, page_range) pairs. + First arg must be a filename; other ags are filenames, page-range + expressions, slice objects, or PageRange objects. + A filename not followed by a page range indicates all pages of the file. + """ + pairs = [] + pdf_filename = None + did_page_range = False + for arg in args + [None]: + if PageRange.valid(arg): + if not pdf_filename: + raise ValueError("The first argument must be a filename, " \ + "not a page range.") + + pairs.append( (pdf_filename, PageRange(arg)) ) + did_page_range = True + else: + # New filename or end of list--do all of the previous file? + if pdf_filename and not did_page_range: + pairs.append( (pdf_filename, PAGE_RANGE_ALL) ) + + pdf_filename = arg + did_page_range = False + return pairs |