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// Copyright ©2015 The Gonum Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package linear
import (
"gonum.org/v1/gonum/graph"
)
// NodeStack implements a LIFO stack of graph.Node.
type NodeStack []graph.Node
// Len returns the number of graph.Nodes on the stack.
func (s *NodeStack) Len() int { return len(*s) }
// Pop returns the last graph.Node on the stack and removes it
// from the stack.
func (s *NodeStack) Pop() graph.Node {
v := *s
v, n := v[:len(v)-1], v[len(v)-1]
*s = v
return n
}
// Push adds the node n to the stack at the last position.
func (s *NodeStack) Push(n graph.Node) { *s = append(*s, n) }
// NodeQueue implements a FIFO queue.
type NodeQueue struct {
head int
data []graph.Node
}
// Len returns the number of graph.Nodes in the queue.
func (q *NodeQueue) Len() int { return len(q.data) - q.head }
// Enqueue adds the node n to the back of the queue.
func (q *NodeQueue) Enqueue(n graph.Node) {
if len(q.data) == cap(q.data) && q.head > 0 {
l := q.Len()
copy(q.data, q.data[q.head:])
q.head = 0
q.data = append(q.data[:l], n)
} else {
q.data = append(q.data, n)
}
}
// Dequeue returns the graph.Node at the front of the queue and
// removes it from the queue.
func (q *NodeQueue) Dequeue() graph.Node {
if q.Len() == 0 {
panic("queue: empty queue")
}
var n graph.Node
n, q.data[q.head] = q.data[q.head], nil
q.head++
if q.Len() == 0 {
q.head = 0
q.data = q.data[:0]
}
return n
}
// Reset clears the queue for reuse.
func (q *NodeQueue) Reset() {
q.head = 0
q.data = q.data[:0]
}
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