import functools
import logging
import re
import sys
import types
from abc import ABC, abstractmethod
from typing import Union, List, Dict, Any, Sequence, Iterable, Optional, Mapping, Callable
reCommaWhitespacePotentiallyBreaks = re.compile(r",\s+")
log = logging.getLogger(__name__)
[docs]class StringConverter(ABC):
"""
Abstraction for a string conversion mechanism
"""
[docs] @abstractmethod
def to_string(self, x) -> str:
pass
[docs]def dict_string(d: Mapping, brackets: Optional[str] = None, converter: StringConverter = None):
"""
Converts a dictionary to a string of the form "<key>=<value>, <key>=<value>, ...", optionally enclosed
by brackets
:param d: the dictionary
:param brackets: a two-character string containing the opening and closing bracket to use, e.g. ``"{}"``;
if None, do not use enclosing brackets
:param converter: the string converter to use for values
:return: the string representation
"""
s = ', '.join([f'{k}={to_string(v, converter=converter, context=k)}' for k, v in d.items()])
if brackets is not None:
return brackets[:1] + s + brackets[-1:]
else:
return s
[docs]def list_string(l: Iterable[Any], brackets="[]", quote: Optional[str] = None, converter: StringConverter = None):
"""
Converts a list or any other iterable to a string of the form "[<value>, <value>, ...]", optionally enclosed
by different brackets or with the values quoted.
:param l: the list
:param brackets: a two-character string containing the opening and closing bracket to use, e.g. ``"[]"``;
if None, do not use enclosing brackets
:param quote: a 1-character string defining the quote to use around each value, e.g. ``"'"``.
:param converter: the string converter to use for values
:return: the string representation
"""
def item(x):
x = to_string(x, converter=converter, context="list")
if quote is not None:
return quote + x + quote
else:
return x
s = ", ".join((item(x) for x in l))
if brackets is not None:
return brackets[:1] + s + brackets[-1:]
else:
return s
[docs]def to_string(x, converter: StringConverter = None, apply_converter_to_non_complex_objects=True, context=None):
"""
Converts the given object to a string, with proper handling of lists, tuples and dictionaries, optionally using a converter.
The conversion also removes unwanted line breaks (as present, in particular, in sklearn's string representations).
:param x: the object to convert
:param converter: the converter with which to convert objects to strings
:param apply_converter_to_non_complex_objects: whether to apply/pass on the converter (if any) not only when converting complex objects
but also non-complex, primitive objects; use of this flag enables converters to implement their conversion functionality using this
function for complex objects without causing an infinite recursion.
:param context: context in which the object is being converted (e.g. dictionary key for case where x is the corresponding
dictionary value), only for debugging purposes (will be reported in log messages upon recursion exception)
:return: the string representation
"""
try:
if type(x) == list:
return list_string(x, converter=converter)
elif type(x) == tuple:
return list_string(x, brackets="()", converter=converter)
elif type(x) == dict:
return dict_string(x, brackets="{}", converter=converter)
elif type(x) == types.MethodType:
# could be bound method of a ToStringMixin instance (which would print the repr of the instance, which can potentially cause
# an infinite recursion)
return f"Method[{x.__name__}]"
else:
if converter and apply_converter_to_non_complex_objects:
s = converter.to_string(x)
else:
s = str(x)
# remove any unwanted line breaks and indentation after commas (as generated, for example, by sklearn objects)
s = reCommaWhitespacePotentiallyBreaks.sub(", ", s)
return s
except RecursionError as e:
log.error(f"Recursion in string conversion detected; context={context}")
raise
[docs]def object_repr(obj, member_names_or_dict: Union[List[str], Dict[str, Any]]):
if type(member_names_or_dict) == dict:
members_dict = member_names_or_dict
else:
members_dict = {m: to_string(getattr(obj, m)) for m in member_names_or_dict}
return f"{obj.__class__.__name__}[{dict_string(members_dict)}]"
[docs]def or_regex_group(allowed_names: Sequence[str]):
"""
:param allowed_names: strings to include as literals in the regex
:return: a regular expression string of the form (<name1>| ...|<nameN>), which any of the given names
"""
allowed_names = [re.escape(name) for name in allowed_names]
return r"(%s)" % "|".join(allowed_names)
[docs]def function_name(x: Callable) -> str:
if isinstance(x, functools.partial):
return function_name(x.func)
elif hasattr(x, "__name__"):
return x.__name__
else:
return str(x)
[docs]class ToStringMixin:
"""
Provides implementations for ``__str__`` and ``__repr__`` which are based on the format ``"<class name>[<object info>]"`` and
``"<class name>[id=<object id>, <object info>]"`` respectively, where ``<object info>`` is usually a list of entries of the
form ``"<name>=<value>, ..."``.
By default, ``<class name>`` will be the qualified name of the class, and ``<object info>`` will include all properties
of the class, including private ones starting with an underscore (though the underscore will be dropped in the string
representation).
* To exclude private properties, override :meth:`_tostring_exclude_private` to return True. If there are exceptions
(and some private properties shall be retained), additionally override :meth:`_tostring_exclude_exceptions`.
* To exclude a particular set of properties, override :meth:`_tostring_excludes`.
* To include only select properties (introducing inclusion semantics), override :meth:`_tostring_includes`.
* To add values to the properties list that aren't actually properties of the object (i.e. derived properties),
override :meth:`_tostring_additional_entries`.
* To define a fully custom representation for ``<object info>`` which is not based on the above principles, override
:meth:`_tostring_object_info`.
For well-defined string conversions within a class hierarchy, it can be a good practice to define additional
inclusions/exclusions by overriding the respective method once more and basing the return value on an extended
version of the value returned by superclass.
In some cases, the requirements of a subclass can be at odds with the definitions in the superclass: The superclass
may make use of exclusion semantics, but the subclass may want to use inclusion semantics (and include
only some of the many properties it adds). In this case, if the subclass used :meth:`_tostring_includes`, the exclusion semantics
of the superclass would be void and none of its properties would actually be included.
In such cases, override :meth:`_tostring_includes_forced` to add inclusions regardless of the semantics otherwise used along
the class hierarchy.
.. document private functions
.. automethod:: _tostring_class_name
.. automethod:: _tostring_object_info
.. automethod:: _tostring_excludes
.. automethod:: _tostring_exclude_exceptions
.. automethod:: _tostring_includes
.. automethod:: _tostring_includes_forced
.. automethod:: _tostring_additional_entries
.. automethod:: _tostring_exclude_private
"""
_TOSTRING_INCLUDE_ALL = "__all__"
[docs] def _tostring_class_name(self):
"""
:return: the string use for <class name> in the string representation ``"<class name>[<object info]"``
"""
return type(self).__qualname__
def _tostring_properties(self,
exclude: Optional[Union[str, Iterable[str]]] = None,
include: Optional[Union[str, Iterable[str]]] = None,
exclude_exceptions: Optional[List[str]] = None,
include_forced: Optional[List[str]] = None,
additional_entries: Dict[str, Any] = None,
converter: StringConverter = None) -> str:
"""
Creates a string of the class attributes, with optional exclusions/inclusions/additions.
Exclusions take precedence over inclusions.
:param exclude: attributes to be excluded
:param include: attributes to be included; if non-empty, only the specified attributes will be printed (bar the ones
excluded by ``exclude``)
:param include_forced: additional attributes to be included
:param additional_entries: additional key-value entries to be added
:param converter: the string converter to use; if None, use default (which avoids infinite recursions)
:return: a string containing entry/property names and values
"""
def mklist(x):
if x is None:
return []
if type(x) == str:
return [x]
return x
exclude = mklist(exclude)
include = mklist(include)
include_forced = mklist(include_forced)
exclude_exceptions = mklist(exclude_exceptions)
def is_excluded(k):
if k in include_forced or k in exclude_exceptions:
return False
if k in exclude:
return True
if self._tostring_exclude_private():
is_private = k.startswith("_")
return is_private
else:
return False
# determine relevant attribute dictionary
if len(include) == 1 and include[0] == self._TOSTRING_INCLUDE_ALL: # exclude semantics (include everything by default)
attribute_dict = self.__dict__
else: # include semantics (include only inclusions)
attribute_dict = {k: getattr(self, k) for k in set(include + include_forced)
if hasattr(self, k) and k != self._TOSTRING_INCLUDE_ALL}
# apply exclusions and remove underscores from attribute names
d = {k.strip("_"): v for k, v in attribute_dict.items() if not is_excluded(k)}
if additional_entries is not None:
d.update(additional_entries)
if converter is None:
converter = self._StringConverterAvoidToStringMixinRecursion(self)
return dict_string(d, converter=converter)
[docs] def _tostring_object_info(self) -> str:
"""
Override this method to use a fully custom definition of the ``<object info>`` part in the full string
representation ``"<class name>[<object info>]"`` to be generated.
As soon as this method is overridden, any property-based exclusions, inclusions, etc. will have no effect
(unless the implementation is specifically designed to make use of them - as is the default
implementation).
NOTE: Overrides must not internally use super() because of a technical limitation in the proxy
object that is used for nested object structures.
:return: a string containing the string to use for ``<object info>``
"""
return self._tostring_properties(exclude=self._tostring_excludes(), include=self._tostring_includes(),
exclude_exceptions=self._tostring_exclude_exceptions(), include_forced=self._tostring_includes_forced(),
additional_entries=self._tostring_additional_entries())
[docs] def _tostring_excludes(self) -> List[str]:
"""
Makes the string representation exclude the returned attributes.
This method can be conveniently overridden by subclasses which can call super and extend the list returned.
This method will only have no effect if :meth:`_tostring_object_info` is overridden to not use its result.
:return: a list of attribute names
"""
return []
[docs] def _tostring_includes(self) -> List[str]:
"""
Makes the string representation include only the returned attributes (i.e. introduces inclusion semantics);
By default, the list contains only a marker element, which is interpreted as "all attributes included".
This method can be conveniently overridden by sub-classes which can call super and extend the list returned.
Note that it is not a problem for a list containing the aforementioned marker element (which stands for all attributes)
to be extended; the marker element will be ignored and only the user-added elements will be considered as included.
Note: To add an included attribute in a sub-class, regardless of any super-classes using exclusion or inclusion semantics,
use :meth:`_tostring_includes_forced` instead.
This method will have no effect if :meth:`_tostring_object_info` is overridden to not use its result.
:return: a list of attribute names to be included in the string representation
"""
return [self._TOSTRING_INCLUDE_ALL]
# noinspection PyMethodMayBeStatic
[docs] def _tostring_includes_forced(self) -> List[str]:
"""
Defines a list of attribute names that are required to be present in the string representation, regardless of the
instance using include semantics or exclude semantics, thus facilitating added inclusions in sub-classes.
This method will have no effect if :meth:`_tostring_object_info` is overridden to not use its result.
:return: a list of attribute names
"""
return []
[docs] def _tostring_additional_entries(self) -> Dict[str, Any]:
"""
:return: a dictionary of entries to be included in the ``<object info>`` part of the string representation
"""
return {}
[docs] def _tostring_exclude_private(self) -> bool:
"""
:return: whether to exclude properties that are private (start with an underscore); explicitly included attributes
will still be considered - as will properties exempt from the rule via :meth:`_tostring_exclude_exceptions`.
"""
return False
[docs] def _tostring_exclude_exceptions(self) -> List[str]:
"""
Defines attribute names which should not be excluded even though other rules (particularly the exclusion of private members
via :meth:`_tostring_exclude_private`) would otherwise exclude them.
:return: a list of attribute names
"""
return []
def __str__(self):
return f"{self._tostring_class_name()}[{self._tostring_object_info()}]"
def __repr__(self):
info = f"id={id(self)}"
property_info = self._tostring_object_info()
if len(property_info) > 0:
info += ", " + property_info
return f"{self._tostring_class_name()}[{info}]"
[docs] def pprint(self, file=sys.stdout):
"""
Prints a prettily formatted string representation of the object (with line breaks and indentations)
to ``stdout`` or the given file.
:param file: the file to print to
"""
print(self.pprints(), file=file)
[docs] def pprints(self) -> str:
"""
:return: a prettily formatted string representation with line breaks and indentations
"""
return pretty_string_repr(self)
class _StringConverterAvoidToStringMixinRecursion(StringConverter):
"""
Avoids recursions when converting objects implementing :class:`ToStringMixin` which may contain themselves to strings.
Use of this object prevents infinite recursions caused by a :class:`ToStringMixin` instance recursively containing itself in
either a property of another :class:`ToStringMixin`, a list or a tuple.
It handles all :class:`ToStringMixin` instances recursively encountered.
A previously handled instance is converted to a string of the form "<class name>[<<]".
"""
def __init__(self, *handled_objects: "ToStringMixin"):
"""
:param handled_objects: objects which are initially assumed to have been handled already
"""
self._handled_to_string_mixin_ids = set([id(o) for o in handled_objects])
def to_string(self, x) -> str:
if isinstance(x, ToStringMixin):
oid = id(x)
if oid in self._handled_to_string_mixin_ids:
return f"{x._tostring_class_name()}[<<]"
self._handled_to_string_mixin_ids.add(oid)
return str(self._ToStringMixinProxy(x, self))
else:
return to_string(x, converter=self, apply_converter_to_non_complex_objects=False, context=x.__class__)
class _ToStringMixinProxy:
"""
A proxy object which wraps a ToStringMixin to ensure that the converter is applied when creating the properties string.
The proxy is to achieve that all ToStringMixin methods that aren't explicitly overwritten are bound to this proxy
(rather than the original object), such that the transitive call to `_tostring_properties` will call the new
implementation.
"""
# methods where we assume that they could transitively call `_tostring_properties` (others are assumed not to)
TOSTRING_METHODS_TRANSITIVELY_CALLING_TOSTRINGPROPERTIES = {"_tostring_object_info"}
def __init__(self, x: "ToStringMixin", converter):
self.x = x
self.converter = converter
def _tostring_properties(self, *args, **kwargs):
return self.x._tostring_properties(*args, **kwargs, converter=self.converter)
def _tostring_class_name(self):
return self.x._tostring_class_name()
def __getattr__(self, attr: str):
if attr.startswith("_tostring"): # ToStringMixin method which we may bind to use this proxy to ensure correct transitive call
method = getattr(self.x.__class__, attr)
obj = self if attr in self.TOSTRING_METHODS_TRANSITIVELY_CALLING_TOSTRINGPROPERTIES else self.x
return lambda *args, **kwargs: method(obj, *args, **kwargs)
else:
return getattr(self.x, attr)
def __str__(self: "ToStringMixin"):
return ToStringMixin.__str__(self)
[docs]def pretty_string_repr(s: Any, initial_indentation_level=0, indentation_string=" "):
"""
Creates a pretty string representation (using indentations) from the given object/string representation (as generated, for example, via
ToStringMixin). An indentation level is added for every opening bracket.
:param s: an object or object string representation
:param initial_indentation_level: the initial indentation level
:param indentation_string: the string which corresponds to a single indentation level
:return: a reformatted version of the input string with added indentations and line breaks
"""
if type(s) != str:
s = str(s)
indent = initial_indentation_level
result = indentation_string * indent
i = 0
def nl():
nonlocal result
result += "\n" + (indentation_string * indent)
def take(cnt=1):
nonlocal result, i
result += s[i:i+cnt]
i += cnt
def find_matching(j):
start = j
op = s[j]
cl = {"[": "]", "(": ")", "'": "'"}[s[j]]
is_bracket = cl != s[j]
stack = 0
while j < len(s):
if s[j] == op and (is_bracket or j == start):
stack += 1
elif s[j] == cl:
stack -= 1
if stack == 0:
return j
j += 1
return None
brackets = "[("
quotes = "'"
while i < len(s):
is_bracket = s[i] in brackets
is_quote = s[i] in quotes
if is_bracket or is_quote:
i_match = find_matching(i)
take_full_match_without_break = False
if i_match is not None:
k = i_match + 1
full_match = s[i:k]
take_full_match_without_break = is_quote or not("=" in full_match and "," in full_match)
if take_full_match_without_break:
take(k-i)
if not take_full_match_without_break:
take(1)
indent += 1
nl()
elif s[i] in "])":
take(1)
indent -= 1
elif s[i:i+2] == ", ":
take(2)
nl()
else:
take(1)
return result
[docs]class TagBuilder:
"""
Assists in building strings made up of components that are joined via a glue string
"""
def __init__(self, *initial_components: str, glue="_"):
"""
:param initial_components: initial components to always include at the beginning
:param glue: the glue string which joins components
"""
self.glue = glue
self.components = list(initial_components)
[docs] def with_component(self, component: str):
self.components.append(component)
return self
[docs] def with_conditional(self, cond: bool, component: str):
"""
Conditionally adds the given component
:param cond: the condition
:param component: the component to add if the condition holds
:return: the builder
"""
if cond:
self.components.append(component)
return self
[docs] def with_alternative(self, cond: bool, true_component: str, false_component: str):
"""
Adds a component depending on a condition
:param cond: the condition
:param true_component: the component to add if the condition holds
:param false_component: the component to add if the condition does not hold
:return: the builder
"""
self.components.append(true_component if cond else false_component)
return self
[docs] def build(self):
"""
:return: the string (with all components joined)
"""
return self.glue.join(self.components)
