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import base64
import io
from typing import Optional
from urllib.parse import unquote
from fsspec import AbstractFileSystem
class DataFileSystem(AbstractFileSystem):
"""A handy decoder for data-URLs
Example
-------
>>> with fsspec.open("data:,Hello%2C%20World%21") as f:
... print(f.read())
b"Hello, World!"
See https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URLs
"""
protocol = "data"
def __init__(self, **kwargs):
"""No parameters for this filesystem"""
super().__init__(**kwargs)
def cat_file(self, path, start=None, end=None, **kwargs):
pref, data = path.split(",", 1)
if pref.endswith("base64"):
return base64.b64decode(data)[start:end]
return unquote(data).encode()[start:end]
def info(self, path, **kwargs):
pref, name = path.split(",", 1)
data = self.cat_file(path)
mime = pref.split(":", 1)[1].split(";", 1)[0]
return {"name": name, "size": len(data), "type": "file", "mimetype": mime}
def _open(
self,
path,
mode="rb",
block_size=None,
autocommit=True,
cache_options=None,
**kwargs,
):
if "r" not in mode:
raise ValueError("Read only filesystem")
return io.BytesIO(self.cat_file(path))
@staticmethod
def encode(data: bytes, mime: Optional[str] = None):
"""Format the given data into data-URL syntax
This version always base64 encodes, even when the data is ascii/url-safe.
"""
return f"data:{mime or ''};base64,{base64.b64encode(data).decode()}"