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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 "sync"
// Stack is a simple LIFO stack that is safe for concurrent use.
type Stack[T any] struct {
items []T
zero T
mu sync.RWMutex
}
func NewStack[T any]() *Stack[T] {
return &Stack[T]{}
}
func (s *Stack[T]) Push(item T) {
s.mu.Lock()
defer s.mu.Unlock()
s.items = append(s.items, item)
}
func (s *Stack[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 *Stack[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 *Stack[T]) Len() int {
s.mu.RLock()
defer s.mu.RUnlock()
return len(s.items)
}
func (s *Stack[T]) Drain() []T {
s.mu.Lock()
defer s.mu.Unlock()
items := s.items
s.items = nil
return items
}
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