| 1 | # SPDX-License-Identifier: GPL-2.0-only |
| 2 | # |
| 3 | # Copyright (C) 2023 EfficiOS Inc. |
| 4 | # |
| 5 | # pyright: strict, reportTypeCommentUsage=false |
| 6 | |
| 7 | import re |
| 8 | from typing import TextIO |
| 9 | |
| 10 | |
| 11 | # One part of a moultipart document. |
| 12 | # |
| 13 | # For example, for this part of which the header is at line 37: |
| 14 | # |
| 15 | # --- Another Oscar Wilde quote |
| 16 | # I can resist everything except temptation. |
| 17 | # |
| 18 | # The corresponding `Part` object is: |
| 19 | # |
| 20 | # Part('Another Oscar Wilde quote', |
| 21 | # 'I can resist everything except temptation', |
| 22 | # 38) |
| 23 | class Part: |
| 24 | def __init__(self, header_info: str, content: str, first_content_line_no: int): |
| 25 | self._header_info = header_info |
| 26 | self._content = content |
| 27 | self._first_content_line_no = first_content_line_no |
| 28 | |
| 29 | @property |
| 30 | def header_info(self): |
| 31 | return self._header_info |
| 32 | |
| 33 | @property |
| 34 | def content(self): |
| 35 | return self._content |
| 36 | |
| 37 | # Number of the first line, relative to the beginning of the |
| 38 | # containing moultipart document, of the content of this part. |
| 39 | @property |
| 40 | def first_content_line_no(self): |
| 41 | return self._first_content_line_no |
| 42 | |
| 43 | def __repr__(self): |
| 44 | return "Part({}, {}, {})".format( |
| 45 | repr(self.header_info), repr(self.content), self.first_content_line_no |
| 46 | ) |
| 47 | |
| 48 | |
| 49 | def _try_parse_header(line: str): |
| 50 | m = re.match(r"---(\s*| .+)$", line) |
| 51 | |
| 52 | if m is None: |
| 53 | return |
| 54 | |
| 55 | return m.group(1).strip() |
| 56 | |
| 57 | |
| 58 | # Parses the moultipart document file `in_file` and returns its parts |
| 59 | # (list of `Part` objects). |
| 60 | # |
| 61 | # A moultipart document is a sequence of parts. |
| 62 | # |
| 63 | # A moutlipart part is: |
| 64 | # |
| 65 | # 1. A header line, that is, in this order: |
| 66 | # |
| 67 | # a) Exactly `---`. |
| 68 | # b) Zero or more spaces. |
| 69 | # c) Optional: custom information until the end of the line. |
| 70 | # |
| 71 | # 2. Zero or more lines of text which aren't header lines. |
| 72 | # |
| 73 | # For example, consider the following moultipart document: |
| 74 | # |
| 75 | # --- Victoria |
| 76 | # Parenteau |
| 77 | # --- |
| 78 | # Taillon |
| 79 | # --- This part is empty |
| 80 | # --- Josianne |
| 81 | # Gervais |
| 82 | # |
| 83 | # Then this function would return the following part objects: |
| 84 | # |
| 85 | # [ |
| 86 | # Part('Victoria', 'Parenteau\n', 2), |
| 87 | # Part('', 'Taillon\n', 4), |
| 88 | # Part('This part is empty', '', 6), |
| 89 | # Part('Josianne', 'Gervais\n', 7), |
| 90 | # ] |
| 91 | # |
| 92 | # Raises `RuntimeError` on any parsing error. |
| 93 | def parse(in_file: TextIO): |
| 94 | # Read the first header |
| 95 | cur_part_content = "" |
| 96 | cur_first_content_line_no = 2 |
| 97 | parts = [] # type: list[Part] |
| 98 | line_no = 1 |
| 99 | line = next(in_file) |
| 100 | cur_part_header_info = _try_parse_header(line) |
| 101 | |
| 102 | if cur_part_header_info is None: |
| 103 | raise RuntimeError( |
| 104 | "Expecting header line starting with `---`, got `{}`".format( |
| 105 | line.strip("\n") |
| 106 | ) |
| 107 | ) |
| 108 | |
| 109 | for line in in_file: |
| 110 | line_no += 1 |
| 111 | maybe_part_header_info = _try_parse_header(line) |
| 112 | |
| 113 | if maybe_part_header_info is not None: |
| 114 | # New header |
| 115 | parts.append( |
| 116 | Part( |
| 117 | cur_part_header_info, |
| 118 | cur_part_content, |
| 119 | cur_first_content_line_no, |
| 120 | ) |
| 121 | ) |
| 122 | cur_part_content = "" |
| 123 | cur_part_header_info = maybe_part_header_info |
| 124 | cur_first_content_line_no = line_no + 1 |
| 125 | continue |
| 126 | |
| 127 | # Accumulate content lines |
| 128 | cur_part_content += line |
| 129 | |
| 130 | # Last part (always exists) |
| 131 | parts.append( |
| 132 | Part( |
| 133 | cur_part_header_info, |
| 134 | cur_part_content, |
| 135 | cur_first_content_line_no, |
| 136 | ) |
| 137 | ) |
| 138 | |
| 139 | return parts |
| 140 | |
| 141 | |
| 142 | if __name__ == "__main__": |
| 143 | import sys |
| 144 | import pprint |
| 145 | |
| 146 | with open(sys.argv[1]) as f: |
| 147 | pprint.pprint(parse(f)) |