Spaces:
Runtime error
Runtime error
| """ | |
| Representation and utils for ranges of PDF file pages. | |
| Copyright (c) 2014, Steve Witham <[email protected]>. | |
| All rights reserved. This software is available under a BSD license; | |
| see https://github.com/py-pdf/PyPDF2/blob/main/LICENSE | |
| """ | |
| import re | |
| from typing import Any, List, Tuple, Union | |
| from .errors import ParseError | |
| _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 PageRange: | |
| """ | |
| A slice-like representation of a range of page indices. | |
| For example, 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. | |
| - PageRange(str) parses a string representing a page range. | |
| - PageRange(slice) directly "imports" a slice. | |
| - to_slice() gives the equivalent slice. | |
| - str() and repr() allow printing. | |
| - indices(n) is like slice.indices(n). | |
| """ | |
| def __init__(self, arg: Union[slice, "PageRange", str]) -> None: | |
| """ | |
| 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. | |
| 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. | |
| 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 = isinstance(arg, str) 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)]) | |
| def valid(input: Any) -> bool: | |
| """True if input is a valid initializer for a PageRange.""" | |
| return isinstance(input, (slice, PageRange)) or ( | |
| isinstance(input, str) and bool(re.match(PAGE_RANGE_RE, input)) | |
| ) | |
| def to_slice(self) -> slice: | |
| """Return the slice equivalent of this page range.""" | |
| return self._slice | |
| def __str__(self) -> str: | |
| """A string like "1:2:3".""" | |
| s = self._slice | |
| indices: Union[Tuple[int, int], Tuple[int, int, int]] | |
| if s.step is None: | |
| if s.start is not 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 is None else str(i) for i in indices) | |
| def __repr__(self) -> str: | |
| """A string like "PageRange('1:2:3')".""" | |
| return "PageRange(" + repr(str(self)) + ")" | |
| def indices(self, n: int) -> Tuple[int, int, int]: | |
| """ | |
| 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) | |
| def __eq__(self, other: Any) -> bool: | |
| if not isinstance(other, PageRange): | |
| return False | |
| return self._slice == other._slice | |
| def __add__(self, other: "PageRange") -> "PageRange": | |
| if not isinstance(other, PageRange): | |
| raise TypeError(f"Can't add PageRange and {type(other)}") | |
| if self._slice.step is not None or other._slice.step is not None: | |
| raise ValueError("Can't add PageRange with stride") | |
| a = self._slice.start, self._slice.stop | |
| b = other._slice.start, other._slice.stop | |
| if a[0] > b[0]: | |
| a, b = b, a | |
| # Now a[0] is the smallest | |
| if b[0] > a[1]: | |
| # There is a gap between a and b. | |
| raise ValueError("Can't add PageRanges with gap") | |
| return PageRange(slice(a[0], max(a[1], b[1]))) | |
| PAGE_RANGE_ALL = PageRange(":") # The range of all pages. | |
| def parse_filename_page_ranges( | |
| args: List[Union[str, PageRange, None]] | |
| ) -> List[Tuple[str, PageRange]]: | |
| """ | |
| 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: List[Tuple[str, PageRange]] = [] | |
| 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 | |
| PageRangeSpec = Union[str, PageRange, Tuple[int, int], Tuple[int, int, int], List[int]] | |