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# Copyright (c) 2016-2023 European Synchrotron Radiation Facility
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"""URL module"""
from __future__ import annotations
__authors__ = ["V. Valls"]
__license__ = "MIT"
__date__ = "29/01/2018"
import logging
from collections.abc import Iterable
from typing import Union
import urllib.parse
from pathlib import Path
_logger = logging.getLogger(__name__)
SliceLike = Union[slice, int, type(Ellipsis)]
def _slice_to_string(s: SliceLike) -> str:
"""Convert a Python slice into a string"""
if s == Ellipsis:
return "..."
elif isinstance(s, slice):
result = ""
if s.start is None:
result += ":"
else:
result += f"{s.start}:"
if s.stop is not None:
result += f"{s.stop}"
if s.step is not None:
result += f":{s.step}"
return result
elif isinstance(s, int):
return str(s)
else:
raise TypeError("Unexpected slicing type. Found %s" % type(s))
[docs]
def slice_sequence_to_string(data_slice: Iterable[SliceLike] | SliceLike) -> str:
"""Convert a Python slice sequence or a slice into a string"""
if isinstance(data_slice, Iterable):
return ",".join([_slice_to_string(s) for s in data_slice])
else:
return _slice_to_string(data_slice)
[docs]
class DataUrl(object):
"""Non-mutable object to parse a string representing a resource data
locator.
It supports:
- path to file and path inside file to the data
- data slicing
- fabio or silx access to the data
- absolute and relative file access
>>> # fabio access using absolute path
>>> DataUrl("fabio:///data/image.edf?slice=2")
>>> DataUrl("fabio:///C:/data/image.edf?slice=2")
>>> # silx access using absolute path
>>> DataUrl("silx:///data/image.h5?path=/data/dataset&slice=1,5")
>>> DataUrl("silx:///data/image.edf?path=/scan_0/detector/data")
>>> DataUrl("silx:///C:/data/image.edf?path=/scan_0/detector/data")
>>> # `path=` can be omitted if there are no other query keys
>>> DataUrl("silx:///data/image.h5?/data/dataset")
>>> # is the same as
>>> DataUrl("silx:///data/image.h5?path=/data/dataset")
>>> # `::` can be used instead of `?` which can be useful with shell in
>>> # command lines
>>> DataUrl("silx:///data/image.h5::/data/dataset")
>>> # is the same as
>>> DataUrl("silx:///data/image.h5?/data/dataset")
>>> # Relative path access
>>> DataUrl("silx:./image.h5")
>>> DataUrl("fabio:./image.edf")
>>> DataUrl("silx:image.h5")
>>> DataUrl("fabio:image.edf")
>>> # It also supports parsing of file access for convenience
>>> DataUrl("./foo/bar/image.edf")
>>> DataUrl("C:/data/")
:param path: Path representing a link to a data. If specified, other
arguments must not be provided.
:param file_path: Link to the file containing the the data.
None if there is no data selection.
:param data_path: Data selection applied to the data file selected.
None if there is no data selection.
:param data_slice: Slicing applied of the selected
data. None if no slicing applied.
:param scheme: Scheme of the URL. "silx", "fabio"
is supported. Other strings can be provided, but :meth:`is_valid` will
be false.
"""
def __init__(
self,
path: str | Path | None = None,
file_path: str | Path | None = None,
data_path: str | None = None,
data_slice: tuple[SliceLike, ...] | None = None,
scheme: str | None = None,
):
self.__is_valid = False
if path is not None:
assert file_path is None
assert data_path is None
assert data_slice is None
assert scheme is None
self.__parse_from_path(str(path))
else:
if file_path is not None:
file_path = str(file_path)
self.__file_path = file_path
self.__data_path = data_path
self.__data_slice = data_slice
self.__scheme = scheme
self.__path = None
self.__check_validity()
def __eq__(self, other):
if not isinstance(other, DataUrl):
return False
if self.is_valid() != other.is_valid():
return False
if self.is_valid():
if self.__scheme != other.scheme():
return False
if self.__file_path != other.file_path():
return False
if self.__data_path != other.data_path():
return False
if self.__data_slice != other.data_slice():
return False
return True
else:
return self.__path == other.path()
def __ne__(self, other):
return not (self == other)
def __repr__(self):
return str(self)
def __str__(self):
if self.is_valid() or self.__path is None:
def quote_string(string):
if isinstance(string, str):
return "'%s'" % string
else:
return string
template = "DataUrl(valid=%s, scheme=%s, file_path=%s, data_path=%s, data_slice=%s)"
return template % (
self.__is_valid,
quote_string(self.__scheme),
quote_string(self.__file_path),
quote_string(self.__data_path),
self.__data_slice,
)
else:
template = "DataUrl(valid=%s, string=%s)"
return template % (self.__is_valid, self.__path)
def __check_validity(self):
"""Check the validity of the attributes."""
if self.__file_path in [None, ""]:
self.__is_valid = False
return
if self.__scheme is None:
self.__is_valid = True
elif self.__scheme == "fabio":
self.__is_valid = self.__data_path is None
elif self.__scheme == "silx":
# If there is a slice you must have a data path
# But you can have a data path without slice
slice_implies_data = (
self.__data_path is None and self.__data_slice is None
) or self.__data_path is not None
self.__is_valid = slice_implies_data
else:
self.__is_valid = False
@staticmethod
def _parse_slice(slice_string: str) -> tuple[SliceLike, ...]:
"""Parse a slicing sequence and return an associated tuple.
It supports a sequence of `...`, `:`, and integers separated by a coma.
"""
def string_to_slice(string: str) -> SliceLike:
"""Convert a string to a Python slice"""
if string == "...":
return Ellipsis
elif ":" in string:
if string == ":":
return slice(None)
else:
def get_value(my_str):
if my_str in ("", None):
return None
else:
return int(my_str)
sss = string.split(":")
start = get_value(sss[0])
stop = get_value(sss[1] if len(sss) > 1 else None)
step = get_value(sss[2] if len(sss) > 2 else None)
return slice(start, stop, step)
else:
return int(string)
if slice_string == "":
raise ValueError("An empty slice is not valid")
tokens = slice_string.split(",")
data_slice: list[SliceLike] = []
for t in tokens:
try:
data_slice.append(string_to_slice(t))
except ValueError:
raise ValueError("'%s' is not a valid slicing" % t)
return tuple(data_slice)
def __parse_from_path(self, path: str):
"""Parse the path and initialize attributes.
:param path: Path representing the URL.
"""
self.__path = path
# only replace if ? not here already. Otherwise can mess sith
# data_slice if == ::2 for example
if "?" not in path:
path = path.replace("::", "?", 1)
url = urllib.parse.urlparse(path)
is_valid = True
if len(url.scheme) <= 2:
# Windows driver
scheme = None
pos = self.__path.index(url.path)
file_path = self.__path[0:pos] + url.path
else:
scheme = url.scheme if url.scheme != "" else None
file_path = url.path
# Check absolute windows path
if len(file_path) > 2 and file_path[0] == "/":
if file_path[1] == ":" or file_path[2] == ":":
file_path = file_path[1:]
self.__scheme = scheme
self.__file_path = file_path
query = urllib.parse.parse_qsl(url.query, keep_blank_values=True)
if len(query) == 1 and query[0][1] == "":
# there is no query keys
data_path = query[0][0]
data_slice = None
else:
merged_query = {}
for name, value in query:
if name in query:
merged_query[name].append(value)
else:
merged_query[name] = [value]
def pop_single_value(merged_query, name):
if name in merged_query:
values = merged_query.pop(name)
if len(values) > 1:
_logger.warning(
"More than one query key named '%s'. The last one is used.",
name,
)
value = values[-1]
else:
value = None
return value
data_path = pop_single_value(merged_query, "path")
data_slice = pop_single_value(merged_query, "slice")
if data_slice is not None:
try:
data_slice = self._parse_slice(data_slice)
except ValueError:
is_valid = False
data_slice = None
for key in merged_query.keys():
_logger.warning("Query key %s unsupported. Key skipped.", key)
self.__data_path = data_path
self.__data_slice = data_slice
if is_valid:
self.__check_validity()
else:
self.__is_valid = False
[docs]
def is_valid(self) -> bool:
"""Returns true if the URL is valid. Else attributes can be None."""
return self.__is_valid
[docs]
def path(self) -> str:
"""Returns the string representing the URL."""
if self.__path is not None:
return self.__path
if self.__data_path is not None and self.__data_slice is None:
query = self.__data_path
else:
queries = []
if self.__data_path is not None:
queries.append("path=" + self.__data_path)
if self.__data_slice is not None:
data_slice = slice_sequence_to_string(self.__data_slice)
queries.append("slice=" + data_slice)
query = "&".join(queries)
path = ""
if self.__file_path is not None:
path += self.__file_path
if query != "":
path = path + "?" + query
if self.__scheme is not None:
if self.is_absolute():
if path.startswith("/"):
path = self.__scheme + "://" + path
else:
path = self.__scheme + ":///" + path
else:
path = self.__scheme + ":" + path
return path
[docs]
def is_absolute(self) -> bool:
"""Returns true if the file path is an absolute path."""
file_path = self.file_path()
if file_path is None:
return False
if len(file_path) > 0:
if file_path[0] == "/":
return True
if len(file_path) > 2:
# Windows
if file_path[1] == ":" or file_path[2] == ":":
return True
elif len(file_path) > 1:
# Windows
if file_path[1] == ":":
return True
return False
[docs]
def file_path(self) -> str:
"""Returns the path to the file containing the data."""
return self.__file_path
[docs]
def data_path(self) -> str | None:
"""Returns the path inside the file to the data."""
return self.__data_path
[docs]
def data_slice(self) -> tuple[SliceLike, ...] | None:
"""Returns the slicing applied to the data.
It is a tuple containing numbers, slice or ellipses.
"""
return self.__data_slice
[docs]
def scheme(self) -> str | None:
"""Returns the scheme. It can be None if no scheme is specified."""
return self.__scheme
