57 lines
941 B
Go
57 lines
941 B
Go
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package collections
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import "sync"
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type (
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stack struct {
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top *node
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length int
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lock *sync.RWMutex
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}
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node struct {
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value interface{}
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prev *node
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}
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)
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// NewStack Create a new stack
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func NewStack() *stack {
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return &stack{nil, 0, &sync.RWMutex{}}
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}
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// Len Return the number of items in the stack
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func (this *stack) Len() int {
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return this.length
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}
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// Peek View the top item on the stack
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func (this *stack) Peek() interface{} {
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if this.length == 0 {
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return nil
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}
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return this.top.value
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}
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// Pop the top item of the stack and return it
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func (this *stack) Pop() interface{} {
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this.lock.Lock()
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defer this.lock.Unlock()
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if this.length == 0 {
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return nil
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}
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n := this.top
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this.top = n.prev
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this.length--
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return n.value
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}
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// Push a value onto the top of the stack
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func (this *stack) Push(value interface{}) {
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this.lock.Lock()
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defer this.lock.Unlock()
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n := &node{value, this.top}
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this.top = n
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this.length++
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}
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