diff options
Diffstat (limited to 'vendor/github.com/dolthub/maphash/hasher.go')
-rw-r--r-- | vendor/github.com/dolthub/maphash/hasher.go | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/vendor/github.com/dolthub/maphash/hasher.go b/vendor/github.com/dolthub/maphash/hasher.go new file mode 100644 index 000000000..ef53596a2 --- /dev/null +++ b/vendor/github.com/dolthub/maphash/hasher.go @@ -0,0 +1,48 @@ +// Copyright 2022 Dolthub, Inc. +// +// Licensed under the Apache License, Version 2.0 (the "License"); +// you may not use this file except in compliance with the License. +// You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, software +// distributed under the License is distributed on an "AS IS" BASIS, +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +// See the License for the specific language governing permissions and +// limitations under the License. + +package maphash + +import "unsafe" + +// Hasher hashes values of type K. +// Uses runtime AES-based hashing. +type Hasher[K comparable] struct { + hash hashfn + seed uintptr +} + +// NewHasher creates a new Hasher[K] with a random seed. +func NewHasher[K comparable]() Hasher[K] { + return Hasher[K]{ + hash: getRuntimeHasher[K](), + seed: newHashSeed(), + } +} + +// NewSeed returns a copy of |h| with a new hash seed. +func NewSeed[K comparable](h Hasher[K]) Hasher[K] { + return Hasher[K]{ + hash: h.hash, + seed: newHashSeed(), + } +} + +// Hash hashes |key|. +func (h Hasher[K]) Hash(key K) uint64 { + // promise to the compiler that pointer + // |p| does not escape the stack. + p := noescape(unsafe.Pointer(&key)) + return uint64(h.hash(p, h.seed)) +} |