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// Copyright 2024 The Hugo Authors. All rights reserved.
//
// 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 collections
import (
"iter"
"slices"
"sync"
"github.com/gohugoio/hugo/common/hiter"
)
// StackThreadSafe is a simple LIFO stack that is safe for concurrent use.
type StackThreadSafe[T any] struct {
items []T
zero T
mu sync.RWMutex
}
func NewStackThreadSafe[T any]() *StackThreadSafe[T] {
return &StackThreadSafe[T]{}
}
func (s *StackThreadSafe[T]) Push(item T) {
s.mu.Lock()
defer s.mu.Unlock()
s.items = append(s.items, item)
}
func (s *StackThreadSafe[T]) Pop() (T, bool) {
s.mu.Lock()
defer s.mu.Unlock()
if len(s.items) == 0 {
return s.zero, false
}
item := s.items[len(s.items)-1]
s.items = s.items[:len(s.items)-1]
return item, true
}
func (s *StackThreadSafe[T]) Peek() (T, bool) {
s.mu.RLock()
defer s.mu.RUnlock()
if len(s.items) == 0 {
return s.zero, false
}
return s.items[len(s.items)-1], true
}
func (s *StackThreadSafe[T]) Len() int {
s.mu.RLock()
defer s.mu.RUnlock()
return len(s.items)
}
// All returns all items in the stack, from bottom to top.
func (s *StackThreadSafe[T]) All() iter.Seq2[int, T] {
return hiter.Lock2(slices.All(s.items), s.mu.RLock, s.mu.RUnlock)
}
func (s *StackThreadSafe[T]) Drain() []T {
s.mu.Lock()
defer s.mu.Unlock()
items := s.items
s.items = nil
return items
}
func (s *StackThreadSafe[T]) DrainMatching(predicate func(T) bool) []T {
s.mu.Lock()
defer s.mu.Unlock()
var items []T
for i := len(s.items) - 1; i >= 0; i-- {
if predicate(s.items[i]) {
items = append(items, s.items[i])
s.items = slices.Delete(s.items, i, i+1)
}
}
return items
}
// Stack is a simple LIFO stack that is not safe for concurrent use.
type Stack[T any] struct {
items []T
zero T
}
func NewStack[T any]() *Stack[T] {
return &Stack[T]{}
}
func (s *Stack[T]) Push(item T) {
s.items = append(s.items, item)
}
func (s *Stack[T]) Pop() (T, bool) {
if len(s.items) == 0 {
return s.zero, false
}
item := s.items[len(s.items)-1]
s.items = s.items[:len(s.items)-1]
return item, true
}
func (s *Stack[T]) Peek() (T, bool) {
if len(s.items) == 0 {
return s.zero, false
}
return s.items[len(s.items)-1], true
}
func (s *Stack[T]) Len() int {
return len(s.items)
}
func (s *Stack[T]) All() iter.Seq2[int, T] {
return slices.All(s.items)
}
func (s *Stack[T]) Drain() []T {
items := s.items
s.items = nil
return items
}
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