49 lines
972 B
JavaScript
49 lines
972 B
JavaScript
const FixedFIFO = require('./fixed-size')
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module.exports = class FastFIFO {
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constructor (hwm) {
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this.hwm = hwm || 16
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this.head = new FixedFIFO(this.hwm)
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this.tail = this.head
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this.length = 0
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}
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clear () {
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this.head = this.tail
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this.head.clear()
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this.length = 0
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}
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push (val) {
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this.length++
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if (!this.head.push(val)) {
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const prev = this.head
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this.head = prev.next = new FixedFIFO(2 * this.head.buffer.length)
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this.head.push(val)
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}
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}
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shift () {
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if (this.length !== 0) this.length--
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const val = this.tail.shift()
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if (val === undefined && this.tail.next) {
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const next = this.tail.next
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this.tail.next = null
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this.tail = next
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return this.tail.shift()
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}
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return val
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}
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peek () {
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const val = this.tail.peek()
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if (val === undefined && this.tail.next) return this.tail.next.peek()
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return val
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}
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isEmpty () {
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return this.length === 0
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}
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}
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