forked from s3lph/matemat
324 lines
12 KiB
Python
324 lines
12 KiB
Python
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from typing import Dict, Iterator, List, Tuple, Union
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class RequestArguments(object):
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"""
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Container for HTTP Request arguments.
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Usage:
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# Create empty instance
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ra = RequestArguments()
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# Add an entry for the key 'foo' with the value 'bar' and Content-Type 'text/plain'
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ra['foo'].append('text/plain', 'bar')
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# Retrieve the value for the key 'foo', as a string...
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foo = str(ra.foo)
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# ... or as raw bytes
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foo = bytes(ra.foo)
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"""
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def __init__(self) -> None:
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"""
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Create an empty container instance.
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"""
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self.__container: Dict[str, RequestArgument] = dict()
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def __getitem__(self, key: str) -> 'RequestArgument':
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"""
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Retrieve the argument for the given name, creating it on the fly, if it doesn't exist.
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:param key: Name of the argument to retrieve.
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:return: A RequestArgument instance.
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:raises TypeError: If key is not a string.
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"""
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if not isinstance(key, str):
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raise TypeError('key must be a str')
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# Create empty argument, if it doesn't exist
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if key not in self.__container:
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self.__container[key] = RequestArgument(key)
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# Return the argument for the name
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return self.__container[key]
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def __getattr__(self, key: str) -> 'RequestArgument':
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"""
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Syntactic sugar for accessing values with a name that can be used in Python attributes. The value will be
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returned as an immutable view.
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:param key: Name of the argument to retrieve.
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:return: An immutable view of the RequestArgument instance.
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"""
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return _View.of(self.__container[key])
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def __iter__(self) -> Iterator['RequestArgument']:
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"""
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Returns an iterator over the values in this instance. Values are represented as immutable views.
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:return: An iterator that yields immutable views of the values.
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"""
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for ra in self.__container.values():
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# Yield an immutable scalar view for each value
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yield _View.of(ra)
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def __contains__(self, key: str) -> bool:
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"""
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Checks whether an argument with a given name exists in the RequestArguments instance.
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:param key: The name to check whether it exists.
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:return: True, if present, False otherwise.
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"""
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return key in self.__container
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def __len__(self) -> int:
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"""
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:return: The number of arguments in this instance.
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"""
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return len(self.__container)
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class RequestArgument(object):
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"""
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Container class for HTTP request arguments that simplifies dealing with
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- scalar and array arguments:
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Automatically converts between single values and arrays where necessary: Arrays with one element can be
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accessed as scalars, and scalars can be iterated, yielding themselves as a single item.
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- UTF-8 strings and binary data (e.g. file uploads):
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All data can be retrieved both as a str (if utf-8 decoding is possible) and a bytes object.
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The objects returned from iteration or indexing are immutable views of (parts of) this object.
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Usage example:
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qsargs = urllib.parse.parse_qs(qs, strict_parsing=True, keep_blank_values=True, errors='strict')
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args: RequestArguments
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for k, vs in qsargs:
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args[k].clear()
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for v in vs:
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# text/plain usually is a sensible choice for values decoded from urlencoded strings
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# IF ALREADY IN STRING FORM (which parse_qs does)!
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args[k].append('text/plain', v)
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if 'username' in args and args.username.is_scalar:
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username = str(args.username)
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"""
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def __init__(self,
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name: str,
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value: Union[Tuple[str, Union[bytes, str]], List[Tuple[str, Union[bytes, str]]]] = None) -> None:
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"""
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Create a new RequestArgument with a name and optionally an initial value.
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:param name: The name for this argument, as provided via GET or POST.
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:param value: The initial value, if any. Optional, initializes with empty array if omitted.
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"""
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# Assign name
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self.__name: str = name
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# Initialize value
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self.__value: List[Tuple[str, Union[bytes, str]]] = []
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# Default to empty array
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if value is None:
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self.__value = []
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else:
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if isinstance(value, list):
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# Store the array
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self.__value = value
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else:
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# Turn scalar into an array before storing
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self.__value = [value]
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@property
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def is_array(self) -> bool:
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"""
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:return: True, if the value is a (possibly empty) array, False otherwise.
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"""
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return len(self.__value) != 1
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@property
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def is_scalar(self) -> bool:
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"""
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:return: True, if the value is a single scalar value, False otherwise.
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"""
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return len(self.__value) == 1
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@property
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def is_view(self) -> bool:
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"""
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:return: True, if this instance is an immutable view, False otherwise.
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"""
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return False
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@property
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def name(self) -> str:
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"""
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:return: The name of this argument.
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"""
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return self.__name
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def get_str(self, index: int = 0) -> str:
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"""
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Attempts to return a value as a string. The index defaults to 0.
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:param index: The index of the value to retrieve. Default: 0.
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:return: An UTF-8 string representation of the requested value.
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:raises UnicodeDecodeError: If the value cannot be decoded into an UTF-8 string.
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:raises IndexError: If the index is out of bounds.
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:raises TypeError: If the index is not an int.
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:raises TypeError: If the requested value is neither a str nor a bytes object.
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"""
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if not isinstance(index, int):
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# Index must be an int
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raise TypeError('index must be an int')
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# Type hint; access array element
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v: Tuple[str, Union[bytes, str]] = self.__value[index]
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if isinstance(v[1], str):
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# The value already is a string, return
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return v[1]
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elif isinstance(v[1], bytes):
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# The value is a bytes object, attempt to decode
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return v[1].decode('utf-8')
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raise TypeError('Value is neither a str nor bytes')
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def __str__(self) -> str:
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"""
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Attempts to return the first value as a string.
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:return: An UTF-8 string representation of the first value.
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:raises UnicodeDecodeError: If the value cannot be decoded into an UTF-8 string.
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"""
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return self.get_str()
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def get_bytes(self, index: int = 0) -> bytes:
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"""
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Attempts to return a value as a bytes object. The index defaults to 0.
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:param index: The index of the value to retrieve. Default: 0.
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:return: A bytes object representation of the requested value. Strings will be encoded as UTF-8.
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:raises IndexError: If the index is out of bounds.
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:raises TypeError: If the index is not an int.
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:raises TypeError: If the requested value is neither a str nor a bytes object.
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"""
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if not isinstance(index, int):
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# Index must be a int
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raise TypeError('index must be an int')
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# Type hint; access array element
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v: Tuple[str, Union[bytes, str]] = self.__value[index]
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if isinstance(v[1], bytes):
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# The value already is a bytes object, return
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return v[1]
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elif isinstance(v[1], str):
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# The value is a string, encode first
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return v[1].encode('utf-8')
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raise TypeError('Value is neither a str nor bytes')
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def __bytes__(self) -> bytes:
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"""
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Attempts to return the first value as a bytes object.
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:return: A bytes string representation of the first value.
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"""
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return self.get_bytes()
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def get_content_type(self, index: int = 0) -> str:
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"""
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Attempts to retrieve a value's Content-Type. The index defaults to 0.
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:param index: The index of the value to retrieve. Default: 0.
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:return: The Content-Type of the requested value, as sent by the client. Not necessarily trustworthy.
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:raises IndexError: If the index is out of bounds.
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:raises TypeError: If the index is not an int.
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"""
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# instance is an array value
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if not isinstance(index, int):
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# Needs an index for array values
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raise TypeError('index must be an int')
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# Type hint; access array element
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va: Tuple[str, Union[bytes, str]] = self.__value[index]
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# Return the content type of the requested value
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if not isinstance(va[0], str):
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raise TypeError('Content-Type is not a str')
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return va[0]
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def append(self, ctype: str, value: Union[str, bytes]) -> None:
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"""
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Append a value to this instance. Turns an empty argument into a scalar and a scalar into an array.
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:param ctype: The Content-Type, as provided in the request.
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:param value: The scalar value to append, either a string or bytes object.
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:raises TypeError: If called on an immutable view.
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"""
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if self.is_view:
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# This is an immutable view, raise exception
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raise TypeError('A RequestArgument view is immutable!')
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self.__value.append((ctype, value))
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def clear(self) -> None:
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"""
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Remove all values from this instance.
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:raises TypeError: If called on an immutable view.
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"""
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if self.is_view:
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# This is an immutable view, raise exception
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raise TypeError('A RequestArgument view is immutable!')
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self.__value.clear()
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def __len__(self) -> int:
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"""
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:return: Number of values for this argument.
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"""
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return len(self.__value)
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def __iter__(self) -> Iterator['RequestArgument']:
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"""
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Iterate the values of this argument. Each value is accessible as if it were a scalar RequestArgument in turn,
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although they are immutable.
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:return: An iterator that yields immutable views of the values.
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"""
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for v in self.__value:
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# Yield an immutable scalar view for each (ctype, value) element in the array
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yield _View(self.__name, v)
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def __getitem__(self, index: Union[int, slice]) -> 'RequestArgument':
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"""
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Index the argument with either an int or a slice. The returned values are represented as immutable
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RequestArgument views.
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:param index: The index or slice.
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:return: An immutable view of the indexed elements of this argument.
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"""
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# Pass the index or slice through to the array, packing the result in an immutable view
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return _View(self.__name, self.__value[index])
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class _View(RequestArgument):
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"""
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This class represents an immutable view of a (subset of a) RequestArgument object. Should not be instantiated
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directly.
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"""
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def __init__(self, name: str, value: Union[Tuple[str, Union[bytes, str]], List[Tuple[str, Union[bytes, str]]]])\
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-> None:
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"""
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Create a new immutable view of a (subset of a) RequestArgument.
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:param name: The name for this argument, same as in the original RequestArgument.
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:param value: The values to represent in this view, obtained by e.g. indexing or slicing.
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"""
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super().__init__(name, value)
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@staticmethod
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def of(argument: 'RequestArgument') ->'RequestArgument':
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"""
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Create an immutable, unsliced view of an RequestArgument instance.
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:param argument: The RequestArgument instance to create a view of.
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:return: An immutable view of the provided RequestArgument instance.
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"""
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return argument[:]
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@property
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def is_view(self) -> bool:
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"""
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:return: True, if this instance is an immutable view, False otherwise.
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"""
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return True
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