nimdeque/README.md

nimdeque

Various deque implementations in pure nim. A deque (short for "double-ended queue") is a data type that is optimized for access towards its ends. A deque's most interesting feauture is the ~O(1) time that it takes to pop/append at either ends (as opposed to regular lists where appending at the beginning is an O(n) operation).

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Examples

LinkedDeque

A LinkedDeque is a deque based on a doubly linked list

import nimdeque


queue = newLinkedDeque[int]()

# Appends at the end
queue.add(1)
queue.add(2)
queue.add(3)

# Prepends at the beginning
queue.addLeft(0)
queue.addLeft(-1)
queue.addLeft(-2)

# Pops the first element in O(1) time
queue.pop(0)

# Pops the last element in O(1) time
queue.pop(queue.high())  

# Supports iteration
for i, e in queue:
    echo i, " ", e

# Reversed iteration too!
for e in queue.reversed():
    echo e

echo queue.len()
echo 5 in queue  # false
echo 0 in queue  # true

# Item accessing works just like regular sequence types in Nim.
# Note that the further the item is from either end of the
# queue, the higher the time it takes to retrieve it. For
# fast random access, seqs should be used instead
assert queue[0] == -1
assert queue[^1] == queue[queue.high()]

Note: This is mostly a toy, there are no performance guarantees nor particular optimizations other than very obvious ones. With that said, the collections do work and are tested somewhat thoroughly (please report any bugs!)