Jan Dubsky
57 lines
938 B
Go
57 lines
938 B
Go
package circ
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type Queue[T any] struct {
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arr []T
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begin int
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len int
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}
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func NewQueue[T any](capacity int) *Queue[T] {
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return &Queue[T]{
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// TODO: Do not preallocate whole capacity of Go upstream
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// accepts this: https://github.com/golang/go/issues/55978
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arr: make([]T, capacity),
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}
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}
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func (q *Queue[T]) Cap() int { return len(q.arr) }
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func (q *Queue[T]) Len() int { return q.len }
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func (q *Queue[T]) end() int {
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e := q.begin + q.len
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if l := len(q.arr); e >= l {
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e -= l
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}
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return e
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}
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func (q *Queue[T]) Enqueue(elem T) {
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if q.len == len(q.arr) {
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panic("enqueue: queue is full")
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}
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q.arr[q.end()] = elem
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q.len++
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}
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func (q *Queue[T]) Dequeue() T {
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if q.len < 1 {
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panic("dequeue: queue is empty")
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}
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elem := q.arr[q.begin]
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// Avoid memory leaks if T is pointer or contains pointers.
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var zeroVal T
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q.arr[q.begin] = zeroVal
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q.len--
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q.begin++
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if q.begin == len(q.arr) {
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q.begin = 0
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}
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return elem
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}
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