Structure

Hasher

The universal hash function used by Set and Dictionary.

Declaration

@frozen struct Hasher

Overview

Hasher can be used to map an arbitrary sequence of bytes to an integer hash value. You can feed data to the hasher using a series of calls to mutating combine methods. When you’ve finished feeding the hasher, the hash value can be retrieved by calling finalize():

var hasher = Hasher()
hasher.combine(23)
hasher.combine("Hello")
let hashValue = hasher.finalize()

Within the execution of a Swift program, Hasher guarantees that finalizing it will always produce the same hash value as long as it is fed the exact same sequence of bytes. However, the underlying hash algorithm is designed to exhibit avalanche effects: slight changes to the seed or the input byte sequence will typically produce drastic changes in the generated hash value.

Topics

Creating a Hasher

init()

Creates a new hasher.

Adding Values

func combine<H>(H)

Adds the given value to this hasher, mixing its essential parts into the hasher state.

func combine(bytes: UnsafeRawBufferPointer)

Adds the contents of the given buffer to this hasher, mixing it into the hasher state.

Finalizing a Hasher

func finalize() -> Int

Finalizes the hasher state and returns the hash value.