سير العمل البرمجي · استخراج مقيد لكتل العلامات الخلفية

import re

def fenced_blocks(text):
    if type(text) is not str or len(text) > 4096:
        raise ValueError("fence.input")
    blocks, body, language = [], None, None
    for line in text.splitlines():
        if body is None:
            opening = re.fullmatch(r"```([A-Za-z0-9_-]*)", line)
            if opening:
                body, language = [], opening[1]
        elif line == "```":
            blocks.append((language, "\n".join(body)))
            body = None
        else:
            body.append(line)
    if body is not None:
        raise ValueError("fence.unclosed")
    return blocks