from __future__ import annotations
import csv
import logging
from io import StringIO
from typing import TYPE_CHECKING, Any, Literal, cast, overload
from warnings import warn
from lxml import etree
from scrapy.exceptions import ScrapyDeprecationWarning
from scrapy.http import Response, TextResponse
from scrapy.selector import Selector
if TYPE_CHECKING:
from collections.abc import Callable, Iterator
logger = logging.getLogger(__name__)
[docs]
def xmliter_lxml(
obj: Response | str | bytes,
nodename: str,
namespace: str | None = None,
prefix: str = "x",
) -> Iterator[Selector]:
reader = _StreamReader(obj)
tag = f"{{{namespace}}}{nodename}" if namespace else nodename
iterable = etree.iterparse(
reader,
encoding=reader.encoding,
events=("end", "start-ns"),
resolve_entities=False,
huge_tree=True,
)
selxpath = "//" + (f"{prefix}:{nodename}" if namespace else nodename)
needs_namespace_resolution = not namespace and ":" in nodename
if needs_namespace_resolution:
prefix, nodename = nodename.split(":", maxsplit=1)
for event, data in iterable:
if event == "start-ns":
assert isinstance(data, tuple)
if needs_namespace_resolution:
_prefix, _namespace = data
if _prefix != prefix:
continue
namespace = _namespace
needs_namespace_resolution = False
selxpath = f"//{prefix}:{nodename}"
tag = f"{{{namespace}}}{nodename}"
continue
assert isinstance(data, etree._Element)
node = data
if node.tag != tag:
continue
nodetext = etree.tostring(node, encoding="unicode")
node.clear()
xs = Selector(text=nodetext, type="xml")
if namespace:
xs.register_namespace(prefix, namespace)
yield xs.xpath(selxpath)[0]
class _StreamReader:
def __init__(self, obj: Response | str | bytes):
self._ptr: int = 0
self._text: str | bytes
if isinstance(obj, TextResponse):
self._text, self.encoding = obj.body, obj.encoding
elif isinstance(obj, Response):
self._text, self.encoding = obj.body, "utf-8"
else:
self._text, self.encoding = obj, "utf-8"
self._is_unicode: bool = isinstance(self._text, str)
self._is_first_read: bool = True
def read(self, n: int = 65535) -> bytes:
method: Callable[[int], bytes] = (
self._read_unicode if self._is_unicode else self._read_string
)
result = method(n)
if self._is_first_read:
self._is_first_read = False
result = result.lstrip()
return result
def _read_string(self, n: int = 65535) -> bytes:
s, e = self._ptr, self._ptr + n
self._ptr = e
return cast("bytes", self._text)[s:e]
def _read_unicode(self, n: int = 65535) -> bytes:
s, e = self._ptr, self._ptr + n
self._ptr = e
return cast("str", self._text)[s:e].encode("utf-8")
[docs]
def csviter(
obj: Response | str | bytes,
delimiter: str | None = None,
headers: list[str] | None = None,
encoding: str | None = None,
quotechar: str | None = None,
) -> Iterator[dict[str, str]]:
"""Returns an iterator of dictionaries from the given csv object
obj can be:
- a Response object
- a unicode string
- a string encoded as utf-8
delimiter is the character used to separate fields on the given obj.
headers is an iterable that when provided offers the keys
for the returned dictionaries, if not the first row is used.
quotechar is the character used to enclosure fields on the given obj.
"""
if encoding is not None: # pragma: no cover
warn(
"The encoding argument of csviter() is ignored and will be removed"
" in a future Scrapy version.",
category=ScrapyDeprecationWarning,
stacklevel=2,
)
lines = StringIO(_body_or_str(obj, unicode=True))
kwargs: dict[str, Any] = {}
if delimiter:
kwargs["delimiter"] = delimiter
if quotechar:
kwargs["quotechar"] = quotechar
csv_r = csv.reader(lines, **kwargs)
if not headers:
try:
headers = next(csv_r)
except StopIteration:
return
for row in csv_r:
if len(row) != len(headers):
logger.warning(
"ignoring row %(csvlnum)d (length: %(csvrow)d, "
"should be: %(csvheader)d)",
{
"csvlnum": csv_r.line_num,
"csvrow": len(row),
"csvheader": len(headers),
},
)
continue
yield dict(zip(headers, row, strict=False))
@overload
def _body_or_str(obj: Response | str | bytes) -> str: ...
@overload
def _body_or_str(obj: Response | str | bytes, unicode: Literal[True]) -> str: ...
@overload
def _body_or_str(obj: Response | str | bytes, unicode: Literal[False]) -> bytes: ...
def _body_or_str(obj: Response | str | bytes, unicode: bool = True) -> str | bytes:
expected_types = (Response, str, bytes)
if not isinstance(obj, expected_types):
expected_types_str = " or ".join(t.__name__ for t in expected_types)
raise TypeError(
f"Object {obj!r} must be {expected_types_str}, not {type(obj).__name__}"
)
if isinstance(obj, Response):
if not unicode:
return obj.body
if isinstance(obj, TextResponse):
return obj.text
return obj.body.decode("utf-8")
if isinstance(obj, str):
return obj if unicode else obj.encode("utf-8")
return obj.decode("utf-8") if unicode else obj