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Refactor to remove Head and Tail address #129

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Refactor to remove Head and Tail address #129

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a20867d
fix: remove head and tail
Tristan22400 May 3, 2023
b3cd26f
fix: prevent from removing address(0) account
Tristan22400 May 3, 2023
e01fa6b
fix: change insertSorted func
Tristan22400 May 4, 2023
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29 changes: 13 additions & 16 deletions src/DoubleLinkedList.sol
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Original file line number Diff line number Diff line change
Expand Up @@ -16,8 +16,6 @@ library DoubleLinkedList {

struct List {
mapping(address => Account) accounts;
address head;
address tail;
}

/* ERRORS */
Expand Down Expand Up @@ -48,14 +46,14 @@ library DoubleLinkedList {
/// @param list The list to get the head.
/// @return The address of the head.
function getHead(List storage list) internal view returns (address) {
return list.head;
return list.accounts[address(0)].next;
}

/// @notice Returns the address at the tail of the `list`.
/// @param list The list to get the tail.
/// @return The address of the tail.
function getTail(List storage list) internal view returns (address) {
return list.tail;
return list.accounts[address(0)].prev;
}

/// @notice Returns the next id address from the current `id`.
Expand All @@ -79,12 +77,11 @@ library DoubleLinkedList {
/// @param id The address of the account.
function remove(List storage list, address id) internal {
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@makcandrov makcandrov May 9, 2023 •
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this function can be optimized:

function remove(List storage list, address id) internal {
    Account storage account = list.accounts[id];
    if (id == address(0)) revert AddressIsZero();
    if (account.value == 0) revert AccountDoesNotExist();

    address prevId = account.prev;
    address nextId = account.next;
    list.accounts[prevId].next = nextId;
    list.accounts[nextId].prev = prevId;

    account.prev = address(0);
    account.next = address(0);
    account.value = 0;
}
gas diff

The line if (id == address(0)) revert AddressIsZero(); can be removed, but the error thrown would no longer be accurate in the case of a null address.

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I will implement but not sure we will merge the PR as mentioned above

Account memory account = list.accounts[id];
if (id == address(0)) revert AddressIsZero();
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if (account.value == 0) revert AccountDoesNotExist();

if (account.prev != address(0)) list.accounts[account.prev].next = account.next;
else list.head = account.next;
if (account.next != address(0)) list.accounts[account.next].prev = account.prev;
else list.tail = account.prev;
list.accounts[account.prev].next = account.next;
list.accounts[account.next].prev = account.prev;

delete list.accounts[id];
}
Expand All @@ -100,7 +97,7 @@ library DoubleLinkedList {
if (list.accounts[id].value != 0) revert AccountAlreadyInserted();

uint256 numberOfIterations;
address next = list.head; // If not added at the end of the list `id` will be inserted before `next`.
address next = list.accounts[address(0)].next; // If not added at the end of the list `id` will be inserted before `next`.

while (numberOfIterations < maxIterations && next != address(0) && list.accounts[next].value >= value) {
next = list.accounts[next].next;
Expand All @@ -112,9 +109,9 @@ library DoubleLinkedList {
// Account is not the new tail.
if (numberOfIterations < maxIterations && next != address(0)) {
// Account is the new head.
if (next == list.head) {
if (next == list.accounts[address(0)].next) {
list.accounts[id] = Account({prev: address(0), next: next, value: value});
list.head = id;
list.accounts[address(0)].next = id;
list.accounts[next].prev = id;
}
// Account is not the new head.
Expand All @@ -128,17 +125,17 @@ library DoubleLinkedList {
// Account is the new tail.
else {
// Account is the new head.
if (list.head == address(0)) {
if (list.accounts[address(0)].next == address(0)) {
list.accounts[id] = Account({prev: address(0), next: address(0), value: value});
list.head = id;
list.tail = id;
list.accounts[address(0)].next = id;
list.accounts[address(0)].prev = id;
}
// Account is not the new head.
else {
address tail = list.tail;
address tail = list.accounts[address(0)].prev;
list.accounts[id] = Account({prev: tail, next: address(0), value: value});
list.accounts[tail].next = id;
list.tail = id;
list.accounts[address(0)].prev = id;
}
}
}
Expand Down
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