| import re |
| import string |
| from typing import Any, Dict, Tuple, Union |
|
|
| from .util import escape_url |
|
|
| PREVENT_BACKSLASH = r"(?<!\\)(?:\\\\)*" |
| PUNCTUATION = r"[" + re.escape(string.punctuation) + r"]" |
|
|
| LINK_LABEL = r"(?:[^\\\[\]]|\\.){0,500}" |
|
|
| LINK_BRACKET_START = re.compile(r"[ \t]*\n?[ \t]*<") |
| LINK_BRACKET_RE = re.compile(r"<([^<>\n\\\x00]*)>") |
| LINK_HREF_BLOCK_RE = re.compile(r"[ \t]*\n?[ \t]*([^\s]+)(?:\s|$)") |
| LINK_HREF_INLINE_RE = re.compile( |
| r"[ \t]*\n?[ \t]*([^ \t\n]*?)(?:[ \t\n]|" |
| r"(?:" + PREVENT_BACKSLASH + r"\)))" |
| ) |
|
|
| LINK_TITLE_RE = re.compile( |
| r"[ \t\n]+(" |
| r'"(?:\\' + PUNCTUATION + r'|[^"\x00])*"|' |
| r"'(?:\\" + PUNCTUATION + r"|[^'\x00])*'" |
| r")" |
| ) |
| PAREN_END_RE = re.compile(r"\s*\)") |
|
|
| HTML_TAGNAME = r"[A-Za-z][A-Za-z0-9-]*" |
| HTML_ATTRIBUTES = ( |
| r"(?:\s+[A-Za-z_:][A-Za-z0-9_.:-]*" |
| r'(?:\s*=\s*(?:[^ !"\'=<>`]+|\'[^\']*?\'|"[^\"]*?"))?)*' |
| ) |
|
|
| BLOCK_TAGS = ( |
| "address", |
| "article", |
| "aside", |
| "base", |
| "basefont", |
| "blockquote", |
| "body", |
| "caption", |
| "center", |
| "col", |
| "colgroup", |
| "dd", |
| "details", |
| "dialog", |
| "dir", |
| "div", |
| "dl", |
| "dt", |
| "fieldset", |
| "figcaption", |
| "figure", |
| "footer", |
| "form", |
| "frame", |
| "frameset", |
| "h1", |
| "h2", |
| "h3", |
| "h4", |
| "h5", |
| "h6", |
| "head", |
| "header", |
| "hr", |
| "html", |
| "iframe", |
| "legend", |
| "li", |
| "link", |
| "main", |
| "menu", |
| "menuitem", |
| "meta", |
| "nav", |
| "noframes", |
| "ol", |
| "optgroup", |
| "option", |
| "p", |
| "param", |
| "section", |
| "source", |
| "summary", |
| "table", |
| "tbody", |
| "td", |
| "tfoot", |
| "th", |
| "thead", |
| "title", |
| "tr", |
| "track", |
| "ul", |
| ) |
| PRE_TAGS = ("pre", "script", "style", "textarea") |
|
|
| _INLINE_LINK_LABEL_RE = re.compile(LINK_LABEL + r"\]") |
| _INLINE_SQUARE_BRACKET_RE = re.compile(PREVENT_BACKSLASH + r"[\[\]]") |
| _ESCAPE_CHAR_RE = re.compile(r"\\(" + PUNCTUATION + r")") |
|
|
|
|
| def unescape_char(text: str) -> str: |
| return _ESCAPE_CHAR_RE.sub(r"\1", text) |
|
|
|
|
| def parse_link_text(src: str, pos: int) -> Union[Tuple[str, int], Tuple[None, None]]: |
| level = 1 |
| found = False |
| start_pos = pos |
|
|
| while pos < len(src): |
| m = _INLINE_SQUARE_BRACKET_RE.search(src, pos) |
| if not m: |
| break |
|
|
| pos = m.end() |
| marker = m.group(0) |
| if marker == "]": |
| level -= 1 |
| if level == 0: |
| found = True |
| break |
| else: |
| level += 1 |
|
|
| if found: |
| text = src[start_pos : pos - 1] |
| return text, pos |
| return None, None |
|
|
|
|
| def parse_link_label(src: str, start_pos: int) -> Union[Tuple[str, int], Tuple[None, None]]: |
| m = _INLINE_LINK_LABEL_RE.match(src, start_pos) |
| if m: |
| label = m.group(0)[:-1] |
| return label, m.end() |
| return None, None |
|
|
|
|
| def parse_link_href(src: str, start_pos: int, block: bool = False) -> Union[Tuple[str, int], Tuple[None, None]]: |
| m = LINK_BRACKET_START.match(src, start_pos) |
| if m: |
| start_pos = m.end() - 1 |
| m = LINK_BRACKET_RE.match(src, start_pos) |
| if m: |
| return m.group(1), m.end() |
| return None, None |
|
|
| if block: |
| m = LINK_HREF_BLOCK_RE.match(src, start_pos) |
| else: |
| m = LINK_HREF_INLINE_RE.match(src, start_pos) |
|
|
| if not m: |
| return None, None |
|
|
| end_pos = m.end() |
| href = m.group(1) |
|
|
| if block and src[end_pos - 1] == href[-1]: |
| return href, end_pos |
| return href, end_pos - 1 |
|
|
|
|
| def parse_link_title(src: str, start_pos: int, max_pos: int) -> Union[Tuple[str, int], Tuple[None, None]]: |
| m = LINK_TITLE_RE.match(src, start_pos, max_pos) |
| if m: |
| title = m.group(1)[1:-1] |
| title = unescape_char(title) |
| return title, m.end() |
| return None, None |
|
|
|
|
| def parse_link(src: str, pos: int) -> Union[Tuple[Dict[str, Any], int], Tuple[None, None]]: |
| href, href_pos = parse_link_href(src, pos) |
| if href is None: |
| return None, None |
| assert href_pos is not None |
| title, title_pos = parse_link_title(src, href_pos, len(src)) |
| next_pos = title_pos or href_pos |
| m = PAREN_END_RE.match(src, next_pos) |
| if not m: |
| return None, None |
|
|
| href = unescape_char(href) |
| attrs = {"url": escape_url(href)} |
| if title: |
| attrs["title"] = title |
| return attrs, m.end() |
|
|
