general-market-framework/contracts/xorll.se

# XOR Linked List
# For Trade Keys, points to hashmap for trade data

data xorll[](value, np)  # np = next xor previous


# traverse the list given either the head or the tail
def traverse(start):  # pointer to head or tail
    cur = start
    prev = start

    while self.xorll[cur].value:
        log(self.xorll[cur].value)

        if self.xorll[cur].np == cur:
            # finished
            break

        if cur == prev:
            cur = self.xorll[cur].np
        else:
            tmp = cur
            cur = prev xor self.xorll[cur].np
            prev = tmp


def insert(pointer, value, prev, cur):
    # if self.xorll[pointer].value != 0:
    #     stop

    self.xorll[pointer].value = value
    self.xorll[pointer].np = cur  # end node points to previous one

    if cur == 0:
        return pointer
        # end node, return
    elif prev == 0:
        # this is the second node (they point at each other)
        self.xorll[cur].np = pointer
        self.xorll[pointer].np = cur
    else:
        self.xorll[cur].np = prev xor pointer
    return pointer


def np(pointer):
    return self.xorll[pointer].np


def test():
    head = self.insert("head", 10, 0, 0)
    tail = head
    tail = self.insert("tail", 20, 0, tail)
    tail = self.insert("monkey", 30, self.np(tail), tail)
    tail = self.insert("finger", 40, self.np(tail), tail)
    self.traverse(tail)