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get_range

async def get_range(name: str, *, start:int, stop: int = None) -> list:

Get items using the range: [start, stop).

If stop is None, returns all remaining.

start and stop can be negative, similar to Python slicing:

  • -1 is the tail
  • -2 is the node before the tail

Either or both start and stop can be negative/positive, but they must represent indices such that start < stop.

Returns

A list of node values. The list will be empty if:

  • the range is invalid
  • start == stop

Examples

await list.create('list', type='str')
await list.add_head('list', ['A', 'B', 'C', 'D', 'E'])

print(await list.get_range('list', start=0))
print(await list.get_range('list', start=2))
print(await list.get_range('list', start=-2))
print(await list.get_range('list', start=1, stop=-2))
print(await list.get_range('list', start=-4, stop=-1))

# invalid: [3,1)
print(await list.get_range('list', start=-2, stop=1))
# invalid: [3,2)
print(await list.get_range('list', start=3, stop=-3))
Output
['A', 'B', 'C', 'D', 'E']
['C', 'D', 'E']
['D', 'E']
['B', 'C']
['B', 'C', 'D']
[]
[]

Notes

The API performs simple checks on the ranges to spot problems before sending the query, but it's not always possible without knowing the list's size.

Consider the example above, this range is invalid:

print(await list.get_range('list', start=3, stop=-3))

But add two items and try again:

await list.add_tail('list', ['F','G'])
# now [3,4)
print(await list.get_range('list', start=3, stop=-3))
Output
['D']