61 lines
1.2 KiB
Go
61 lines
1.2 KiB
Go
// Package circ implements a circular FIFO buffer.
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package circ
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// B is a circular FIFO buffer.
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type B[T any] struct {
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buf []T
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len int
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head int
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tail int
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}
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// Make creates a new circular buffer.
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func Make[T any](cap int) B[T] {
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buf := make([]T, cap)
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return B[T]{buf: buf}
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}
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// CanPush returns true if the buffer has space for new items.
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func (b *B[T]) CanPush() bool {
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return cap(b.buf)-b.len != 0
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}
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// CanPop returns true if the buffer has one or more items.
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func (b *B[T]) CanPop() bool {
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return b.len != 0
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}
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// PopFront returns the front-most item from the buffer.
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//
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// If the buffer is empty, it panics.
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func (b *B[T]) PopFront() T {
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if !b.CanPop() {
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panic("cannot pop from empty buffer")
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}
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var empty T
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item := b.buf[b.head]
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// clear buffer slot so that we don't hold on to garbage
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b.buf[b.head] = empty
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b.len--
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b.head++
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if b.head == cap(b.buf) {
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b.head = 0
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}
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return item
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}
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// PushBack adds an item to the end of the buffer.
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//
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// If the buffer is full, it panics.
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func (b *B[T]) PushBack(value T) {
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if !b.CanPush() {
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panic("cannot push back to full buffer")
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}
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b.buf[b.tail] = value
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b.len++
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b.tail++
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if b.tail == cap(b.buf) {
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b.tail = 0
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}
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}
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