wehub-resource-sync
89 lines
1.8 KiB
Go
89 lines
1.8 KiB
Go
// Copyright 2024 Dolthub, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package circular
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type Buff[T any] struct {
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// The backing array.
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arr []T
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// Front() and Pop() refer to this element.
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front int
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// The number of elements in the buffer. [0, len(arr)).
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len int
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}
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func NewBuff[T any](initSz int) *Buff[T] {
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return &Buff[T]{
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arr: make([]T, initSz),
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}
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}
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// Returns the number of elements currently in Buff.
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func (b *Buff[T]) Len() int {
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return b.len
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}
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func (b *Buff[T]) Cap() int {
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return cap(b.arr)
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}
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func (b *Buff[T]) At(i int) T {
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return *b.at(i)
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}
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func (b *Buff[T]) at(i int) *T {
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if i >= b.Len() {
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panic("At on Buff too small")
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}
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j := (b.front + i) % len(b.arr)
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return &b.arr[j]
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}
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func (b *Buff[T]) Front() T {
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return b.At(0)
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}
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func (b *Buff[T]) Pop() {
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if b.Len() == 0 {
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panic("Pop empty Buff")
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}
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// Don't leak entries...
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var empty T
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*b.at(0) = empty
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b.front = (b.front + 1) % len(b.arr)
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b.len -= 1
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}
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func (b *Buff[T]) ins() int {
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return (b.front + b.len) % len(b.arr)
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}
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func (b *Buff[T]) Push(t T) {
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if b.Len() == len(b.arr) {
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newarr := make([]T, len(b.arr)+len(b.arr))
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i := b.ins()
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if i > b.front {
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copy(newarr, b.arr[b.front:i])
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} else {
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first := b.arr[b.front:]
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copy(newarr, first)
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copy(newarr[len(first):], b.arr[:i])
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}
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b.arr = newarr
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b.front = 0
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}
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b.arr[b.ins()] = t
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b.len += 1
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}
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