CircularBuffer

*A fixed-size buffer for keeping bytes32 items in storage. This data structure allows for pushing elements to it, and when its length exceeds the specified fixed size, new items take the place of the oldest element in the buffer, keeping at most N elements in the structure. Elements can't be removed but the data structure can be cleared. See clear. Complexity:

insertion ({push}): O(1)
lookup ({last}): O(1)
inclusion ({includes}): O(N) (worst case)
reset ({clear}): O(1) The struct is called Bytes32CircularBuffer. Other types can be cast to and from bytes32. This data structure can only be used in storage, and not in memory. Example usage:

contract Example {
// Add the library methods
using CircularBuffer for CircularBuffer.Bytes32CircularBuffer;
// Declare a buffer storage variable
CircularBuffer.Bytes32CircularBuffer private myBuffer;
}

Available since v5.1.*

Functions

setup

Initialize a new CircularBuffer of a given size. If the CircularBuffer was already setup and used, calling that function again will reset it to a blank state. NOTE: The size of the buffer will affect the execution of includes function, as it has a complexity of O(N). Consider a large buffer size may render the function unusable.

function setup(Bytes32CircularBuffer storage self, uint256 size) internal;

clear

Clear all data in the buffer without resetting memory, keeping the existing size.

function clear(Bytes32CircularBuffer storage self) internal;

push

Push a new value to the buffer. If the buffer is already full, the new value replaces the oldest value in the buffer.

function push(Bytes32CircularBuffer storage self, bytes32 value) internal;

count

Number of values currently in the buffer. This value is 0 for an empty buffer, and cannot exceed the size of the buffer.

function count(Bytes32CircularBuffer storage self) internal view returns (uint256);

length

Length of the buffer. This is the maximum number of elements kept in the buffer.

function length(Bytes32CircularBuffer storage self) internal view returns (uint256);

last

Getter for the i-th value in the buffer, from the end. Reverts with {Panic-ARRAY_OUT_OF_BOUNDS} if trying to access an element that was not pushed, or that was dropped to make room for newer elements.

function last(Bytes32CircularBuffer storage self, uint256 i) internal view returns (bytes32);

includes

Check if a given value is in the buffer.

function includes(Bytes32CircularBuffer storage self, bytes32 value) internal view returns (bool);

Errors

InvalidBufferSize

Error emitted when trying to setup a buffer with a size of 0.

error InvalidBufferSize();

Structs

Bytes32CircularBuffer

*Counts the number of items that have been pushed to the buffer. The residuo modulo _data.length indicates where the next value should be stored. Struct members have an underscore prefix indicating that they are "private" and should not be read or written to directly. Use the functions provided below instead. Modifying the struct manually may violate assumptions and lead to unexpected behavior. In a full buffer:

The most recently pushed item (last) is at data[(index - 1) % data.length]
The oldest item (first) is at data[index % data.length]*

struct Bytes32CircularBuffer {
    uint256 _count;
    bytes32[] _data;
}

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