def compose(first, second):
name = '{0} | {1}'.format(get_name(first), get_name(second))
def composite(*args, **kwargs):
with pipe_exception_handler('pipe | ' + name):
return second(first(*args, **kwargs))
return set_name(name, composite)
def compose(first, second):
name = lambda: '{0} ?| {1}'.format(get_name(first), get_name(second))
def composite(*args, **kwargs):
result = first(*args, **kwargs)
return None if result is None else second(result)
return set_name(name, composite)
def unless(exception_class_or_tuple, func, *args, **kwargs):
"""
When `exception_class_or_tuple` occurs while executing `func`, it will
be caught and ``None`` will be returned.
>>> f = where(X > 10) | list | unless(IndexError, X[0])
>>> f([5, 8, 12, 4])
12
>>> f([1, 2, 3])
None
"""
@pipe_util
@auto_string_formatter
@data_structure_builder
def construct_unless(function):
# a wrapper so we can re-use the decorators
def _unless(*args, **kwargs):
try:
return function(*args, **kwargs)
except exception_class_or_tuple:
pass
return _unless
name = 'unless(%s, %s)' % (exception_class_or_tuple, ', '.join(
filter(None, (get_name(func), repr_args(*args, **kwargs)))))
return set_name(name, construct_unless(func, *args, **kwargs))
def compose(first, second):
name = lambda: '{0} | {1}'.format(get_name(first), get_name(second))
def composite(*args, **kwargs):
return second(first(*args, **kwargs))
return set_name(name, composite)
def compose(first, second):
name = lambda: '{0} ?| {1}'.format(get_name(first), get_name(second))
def composite(*args, **kwargs):
result = first(*args, **kwargs)
return None if result is None else second(result)
return set_name(name, composite)
def unless(exception_class_or_tuple, func, *args, **kwargs):
"""
When `exception_class_or_tuple` occurs while executing `func`, it will
be caught and ``None`` will be returned.
>>> f = where(X > 10) | list | unless(IndexError, X[0])
>>> f([5, 8, 12, 4])
12
>>> f([1, 2, 3])
None
"""
@pipe_util
@auto_string_formatter
@data_structure_builder
def construct_unless(function):
# a wrapper so we can re-use the decorators
def _unless(*args, **kwargs):
try:
return function(*args, **kwargs)
except exception_class_or_tuple:
pass
return _unless
name = lambda: 'unless(%s, %s)' % (exception_class_or_tuple, ', '.join(
filter(None, (get_name(func), repr_args(*args, **kwargs)))))
return set_name(name, construct_unless(func, *args, **kwargs))
def compose(first, second):
name = '{0} | {1}'.format(get_name(first), get_name(second))
def composite(*args, **kwargs):
with pipe_exception_handler('pipe | ' + name):
return second(first(*args, **kwargs))
return set_name(name, composite)
def compose(first, second):
name = '{0} ?| {1}'.format(get_name(first), get_name(second))
def composite(*args, **kwargs):
with pipe_exception_handler('maybe ?| ' + name):
result = first(*args, **kwargs)
return None if result is None else second(result)
return set_name(name, composite)
def compose(first, second):
name = '{0} ?| {1}'.format(get_name(first), get_name(second))
def composite(*args, **kwargs):
with pipe_exception_handler('maybe ?| ' + name):
result = first(*args, **kwargs)
return None if result is None else second(result)
return set_name(name, composite)
def take_first(count):
"""
Assumes an iterable on the input, returns an iterable with first `count`
items from the input (or possibly less, if there isn't that many).
>>> xrange(9000) > where(X % 100 == 0) | take_first(5) | tuple
(0, 100, 200, 300, 400)
"""
def _take_first(iterable):
return islice(iterable, count)
return pipe | set_name('take_first(%s)' % count, _take_first)
def drop_first(count):
"""
Assumes an iterable on the input, returns an iterable with identical items
except for the first `count`.
>>> xrange(10) > drop_first(5) | tuple
(5, 6, 7, 8, 9)
"""
def _drop_first(iterable):
g = (x for x in xrange(1, count + 1))
return dropwhile(lambda i: unless(StopIteration, g.next)(), iterable)
return pipe | set_name('drop_first(%s)' % count, _drop_first)
def StringFormatter(template):
f = text_type(template).format
def format(content):
if isinstance(content, dict):
return f(**content)
if _iterable(content):
return f(*content)
return f(content)
return set_name(lambda: "format('%s')" % template[:20], format)
def StringFormatter(template):
f = text_type(template).format
def format(content):
if isinstance(content, dict):
return f(**content)
if _iterable(content):
return f(*content)
return f(content)
return set_name(lambda: "format('%s')" % template[:20], format)
def drop_first(count):
"""
Assumes an iterable on the input, returns an iterable with identical items
except for the first `count`.
>>> xrange(10) > drop_first(5) | tuple
(5, 6, 7, 8, 9)
"""
def _drop_first(iterable):
g = (x for x in xrange(1, count + 1))
return dropwhile(lambda i: unless(StopIteration, g.next)(), iterable)
return pipe | set_name('drop_first(%s)' % count, _drop_first)
def pipe_util_wrapper(function, *args, **kwargs):
if isinstance(function, XObject):
function = ~function
function_name = get_name(function)
if args or kwargs:
function = xcurry(function, *args, **kwargs)
name = '%s(%s)' % (func.__name__, ', '.join(
filter(None, (function_name, repr_args(*args, **kwargs)))))
return pipe | set_name(name, func(function))
def take_first(count):
"""
Assumes an iterable on the input, returns an iterable with first `count`
items from the input (or possibly less, if there isn't that many).
>>> range(9000) > where(X % 100 == 0) | take_first(5) | tuple
(0, 100, 200, 300, 400)
"""
def _take_first(iterable):
return islice(iterable, count)
return pipe | set_name('take_first(%s)' % count, _take_first)
def xpartial(func, *xargs, **xkwargs):
"""
Like :func:`functools.partial`, but can take an :class:`XObject`
placeholder that will be replaced with the first positional argument
when the partially applied function is called.
Useful when the function's positional arguments' order doesn't fit your
situation, e.g.:
>>> reverse_range = xpartial(range, X, 0, -1)
>>> reverse_range(5)
[5, 4, 3, 2, 1]
It can also be used to transform the positional argument to a keyword
argument, which can come in handy inside a *pipe*::
xpartial(objects.get, id=X)
Also the XObjects are evaluated, which can be used for some sort of
destructuring of the argument::
xpartial(somefunc, name=X.name, number=X.contacts['number'])
Lastly, unlike :func:`functools.partial`, this creates a regular function
which will bind to classes (like the ``curry`` function from
``django.utils.functional``).
"""
any_x = any(
isinstance(a, XObject) for a in xargs + tuple(xkwargs.values()))
use = lambda x, value: (~x)(value) if isinstance(x, XObject) else x
@wraps(func, assigned=filter(partial(hasattr, func), WRAPPER_ASSIGNMENTS))
def xpartially_applied(*func_args, **func_kwargs):
if any_x:
if not func_args:
raise ValueError(
'Function "%s" partially applied with an '
'X placeholder but called with no positional arguments.' %
get_name(func))
first = func_args[0]
rest = func_args[1:]
args = tuple(use(x, first) for x in xargs) + rest
kwargs = dict((k, use(x, first)) for k, x in dict_items(xkwargs))
kwargs.update(func_kwargs)
else:
args = xargs + func_args
kwargs = dict(xkwargs, **func_kwargs)
return func(*args, **kwargs)
name = lambda: '%s(%s)' % (get_name(func), repr_args(*xargs, **xkwargs))
return set_name(name, xpartially_applied)
def xpartial(func, *xargs, **xkwargs):
"""
Like :func:`functools.partial`, but can take an :class:`XObject`
placeholder that will be replaced with the first positional argument
when the partially applied function is called.
Useful when the function's positional arguments' order doesn't fit your
situation, e.g.:
>>> reverse_range = xpartial(range, X, 0, -1)
>>> reverse_range(5)
[5, 4, 3, 2, 1]
It can also be used to transform the positional argument to a keyword
argument, which can come in handy inside a *pipe*::
xpartial(objects.get, id=X)
Also the XObjects are evaluated, which can be used for some sort of
destructuring of the argument::
xpartial(somefunc, name=X.name, number=X.contacts['number'])
Lastly, unlike :func:`functools.partial`, this creates a regular function
which will bind to classes (like the ``curry`` function from
``django.utils.functional``).
"""
any_x = any(isinstance(a, XObject) for a in xargs + tuple(xkwargs.values()))
use = lambda x, value: (~x)(value) if isinstance(x, XObject) else x
@wraps(func)
def xpartially_applied(*func_args, **func_kwargs):
if any_x:
if not func_args:
raise ValueError('Function "%s" partially applied with an '
'X placeholder but called with no positional arguments.'
% get_name(func))
first = func_args[0]
rest = func_args[1:]
args = tuple(use(x, first) for x in xargs) + rest
kwargs = dict((k, use(x, first)) for k, x in dict_items(xkwargs))
kwargs.update(func_kwargs)
else:
args = xargs + func_args
kwargs = dict(xkwargs, **func_kwargs)
return func(*args, **kwargs)
name = lambda: '%s(%s)' % (get_name(func), repr_args(*xargs, **xkwargs))
return set_name(name, xpartially_applied)
def pipe_util_wrapper(function, *args, **kwargs):
if isinstance(function, XObject):
function = ~function
original_function = function
if args or kwargs:
function = xpartial(function, *args, **kwargs)
name = lambda: '%s(%s)' % (get_name(func), ', '.join(
filter(None, (get_name(original_function), repr_args(*args, **kwargs)))))
f = func(function)
result = pipe | set_name(name, f)
# if the util defines an 'attrs' mapping, copy it as attributes
# to the result
attrs = getattr(f, 'attrs', {})
for k, v in dict_items(attrs):
setattr(result, k, v)
return result
def compose(first, second):
name = lambda: '{0} | {1}'.format(get_name(first), get_name(second))
def composite(*args, **kwargs):
return second(first(*args, **kwargs))
return set_name(name, composite)
def bind(self, name, func):
set_name(name, func)
return XObject((self._func | func) if self._func else (pipe | func))
def __invert__(self):
return self._func or set_name('X', lambda x: x)
def __init__(self, func=None):
self._func = func
set_name(lambda: get_name(func) if func else 'X', self)
def bind(self, name, func):
set_name(name, func)
return XObject((self._func | func) if self._func else (pipe | func))
def __invert__(self):
return self._func or set_name('X', lambda x: x)
def __init__(self, func=None):
self._func = func
set_name(lambda: get_name(func) if func else 'X', self)