134 lines
2.7 KiB
JavaScript
134 lines
2.7 KiB
JavaScript
'use strict'
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/*!
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* Based on range-parser
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*
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* Copyright(c) 2012-2014 TJ Holowaychuk
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* Copyright(c) 2015-2016 Douglas Christopher Wilson
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* MIT Licensed
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*/
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/**
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* Parse "Range" header `str` relative to the given file `size`.
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*
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* @param {Number} size
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* @param {String} str
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* @return {Array}
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* @public
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*/
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function parseBytesRange (size, str) {
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// split the range string
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const values = str.slice(str.indexOf('=') + 1)
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const ranges = []
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const len = values.length
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let i = 0
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let il = 0
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let j = 0
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let start
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let end
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let commaIdx = values.indexOf(',')
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let dashIdx = values.indexOf('-')
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let prevIdx = -1
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// parse all ranges
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while (true) {
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commaIdx === -1 && (commaIdx = len)
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start = parseInt(values.slice(prevIdx + 1, dashIdx), 10)
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end = parseInt(values.slice(dashIdx + 1, commaIdx), 10)
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// -nnn
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// eslint-disable-next-line no-self-compare
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if (start !== start) { // fast path of isNaN(number)
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start = size - end
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end = size - 1
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// nnn-
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// eslint-disable-next-line no-self-compare
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} else if (end !== end) { // fast path of isNaN(number)
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end = size - 1
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// limit last-byte-pos to current length
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} else if (end > size - 1) {
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end = size - 1
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}
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// add range only on valid ranges
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if (
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// eslint-disable-next-line no-self-compare
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start === start && // fast path of isNaN(number)
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// eslint-disable-next-line no-self-compare
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end === end && // fast path of isNaN(number)
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start > -1 &&
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start <= end
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) {
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// add range
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ranges.push({
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start,
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end,
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index: j++
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})
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}
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if (commaIdx === len) {
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break
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}
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prevIdx = commaIdx++
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dashIdx = values.indexOf('-', commaIdx)
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commaIdx = values.indexOf(',', commaIdx)
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}
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// unsatisfiable
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if (
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j < 2
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) {
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return ranges
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}
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ranges.sort(sortByRangeStart)
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il = j
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j = 0
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i = 1
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while (i < il) {
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const range = ranges[i++]
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const current = ranges[j]
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if (range.start > current.end + 1) {
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// next range
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ranges[++j] = range
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} else if (range.end > current.end) {
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// extend range
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current.end = range.end
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current.index > range.index && (current.index = range.index)
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}
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}
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// trim ordered array
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ranges.length = j + 1
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// generate combined range
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ranges.sort(sortByRangeIndex)
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return ranges
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}
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/**
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* Sort function to sort ranges by index.
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* @private
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*/
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function sortByRangeIndex (a, b) {
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return a.index - b.index
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}
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/**
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* Sort function to sort ranges by start position.
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* @private
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*/
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function sortByRangeStart (a, b) {
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return a.start - b.start
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}
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module.exports.parseBytesRange = parseBytesRange
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