mirror of
https://github.com/gohugoio/hugo.git
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115 lines
2.6 KiB
Go
115 lines
2.6 KiB
Go
// Copyright 2017-present The Hugo Authors. All rights reserved.
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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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// 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 types contains types shared between packages in Hugo.
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package types
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import (
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"slices"
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"sync"
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)
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// EvictingQueue is a queue which automatically evicts elements from the head of
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// the queue when attempting to add new elements onto the queue and it is full.
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// This queue orders elements LIFO (last-in-first-out). It throws away duplicates.
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type EvictingQueue[T comparable] struct {
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size int
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vals []T
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set map[T]bool
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mu sync.Mutex
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zero T
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}
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// NewEvictingQueue creates a new queue with the given size.
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func NewEvictingQueue[T comparable](size int) *EvictingQueue[T] {
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return &EvictingQueue[T]{size: size, set: make(map[T]bool)}
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}
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// Add adds a new string to the tail of the queue if it's not already there.
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func (q *EvictingQueue[T]) Add(v T) *EvictingQueue[T] {
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q.mu.Lock()
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if q.set[v] {
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q.mu.Unlock()
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return q
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}
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if len(q.set) == q.size {
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// Full
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delete(q.set, q.vals[0])
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q.vals = slices.Delete(q.vals, 0, 1)
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}
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q.set[v] = true
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q.vals = append(q.vals, v)
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q.mu.Unlock()
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return q
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}
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func (q *EvictingQueue[T]) Len() int {
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if q == nil {
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return 0
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}
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q.mu.Lock()
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defer q.mu.Unlock()
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return len(q.vals)
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}
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// Contains returns whether the queue contains v.
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func (q *EvictingQueue[T]) Contains(v T) bool {
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if q == nil {
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return false
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}
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q.mu.Lock()
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defer q.mu.Unlock()
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return q.set[v]
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}
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// Peek looks at the last element added to the queue.
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func (q *EvictingQueue[T]) Peek() T {
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q.mu.Lock()
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l := len(q.vals)
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if l == 0 {
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q.mu.Unlock()
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return q.zero
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}
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elem := q.vals[l-1]
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q.mu.Unlock()
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return elem
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}
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// PeekAll looks at all the elements in the queue, with the newest first.
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func (q *EvictingQueue[T]) PeekAll() []T {
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if q == nil {
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return nil
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}
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q.mu.Lock()
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vals := make([]T, len(q.vals))
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copy(vals, q.vals)
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q.mu.Unlock()
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for i, j := 0, len(vals)-1; i < j; i, j = i+1, j-1 {
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vals[i], vals[j] = vals[j], vals[i]
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}
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return vals
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}
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// PeekAllSet returns PeekAll as a set.
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func (q *EvictingQueue[T]) PeekAllSet() map[T]bool {
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all := q.PeekAll()
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set := make(map[T]bool)
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for _, v := range all {
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set[v] = true
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}
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return set
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}
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