# -*- coding: utf-8 -*-
import asyncio
from .assertions import isiter
from .reduce import reduce
from .decorator import overload
from .assertions import assert_corofunction, assert_iter
@overload
@asyncio.coroutine
[docs]def flat_map(coro, iterable, limit=0, loop=None, timeout=None,
return_exceptions=False, initializer=None, *args, **kw):
"""
Concurrently iterates values yielded from an iterable, passing them to
an asynchronous coroutine.
This function is the flatten version of to ``paco.map()``.
Mapped values will be returned as an ordered list.
Items order is preserved based on origin iterable order.
Concurrency level can be configurable via ``limit`` param.
All coroutines will be executed in the same loop.
This function is a coroutine.
This function can be composed in a pipeline chain with ``|`` operator.
Arguments:
coro (coroutinefunction): coroutine iterator function that accepts
iterable values.
iterable (iterable|asynchronousiterable): an iterable collection
yielding coroutines functions.
limit (int): max iteration concurrency limit. Use ``0`` for no limit.
collect (bool): return yielded values from coroutines. Default False.
loop (asyncio.BaseEventLoop): optional event loop to use.
return_exceptions (bool): enable/disable returning exceptions in case
of error. `collect` param must be True.
timeout (int|float): timeout can be used to control the maximum number
of seconds to wait before returning. timeout can be an int or
float. If timeout is not specified or None, there is no limit to
the wait time.
*args (mixed): optional variadic arguments to pass to the
coroutine iterable function.
Returns:
results (list): ordered list of values yielded by coroutines
Raises:
TypeError: in case of invalid input arguments.
Usage::
async def mul_2(num):
return num * 2
await paco.flat_map(mul_2, [1, [2], [3, [4]], [(5,)]])
# => [2, 4, 6, 8, 10]
# Pipeline style
await [1, [2], [3, [4]], [(5,)]] | paco.flat_map(mul_2)
# => [2, 4, 6, 8, 10]
"""
assert_corofunction(coro=coro)
assert_iter(iterable=iterable)
# By default do not collect yielded values from coroutines
results = initializer if isiter(initializer) else []
@asyncio.coroutine
def reducer(buf, value):
if isiter(value):
yield from _reduce(value)
else:
buf.append((yield from coro(value)))
return buf
def _reduce(iterable):
return reduce(reducer, iterable,
initializer=results, limit=limit, loop=loop)
# Returns list of mapped reduced results
return (yield from _reduce(iterable))