163 lines
2.8 KiB
JavaScript
163 lines
2.8 KiB
JavaScript
/*!
|
|
* range-parser
|
|
* Copyright(c) 2012-2014 TJ Holowaychuk
|
|
* Copyright(c) 2015-2016 Douglas Christopher Wilson
|
|
* MIT Licensed
|
|
*/
|
|
|
|
'use strict'
|
|
|
|
/**
|
|
* Module exports.
|
|
* @public
|
|
*/
|
|
|
|
module.exports = rangeParser
|
|
|
|
/**
|
|
* Parse "Range" header `str` relative to the given file `size`.
|
|
*
|
|
* @param {Number} size
|
|
* @param {String} str
|
|
* @param {Object} [options]
|
|
* @return {Array}
|
|
* @public
|
|
*/
|
|
|
|
function rangeParser (size, str, options) {
|
|
if (typeof str !== 'string') {
|
|
throw new TypeError('argument str must be a string')
|
|
}
|
|
|
|
var index = str.indexOf('=')
|
|
|
|
if (index === -1) {
|
|
return -2
|
|
}
|
|
|
|
// split the range string
|
|
var arr = str.slice(index + 1).split(',')
|
|
var ranges = []
|
|
|
|
// add ranges type
|
|
ranges.type = str.slice(0, index)
|
|
|
|
// parse all ranges
|
|
for (var i = 0; i < arr.length; i++) {
|
|
var range = arr[i].split('-')
|
|
var start = parseInt(range[0], 10)
|
|
var end = parseInt(range[1], 10)
|
|
|
|
// -nnn
|
|
if (isNaN(start)) {
|
|
start = size - end
|
|
end = size - 1
|
|
// nnn-
|
|
} else if (isNaN(end)) {
|
|
end = size - 1
|
|
}
|
|
|
|
// limit last-byte-pos to current length
|
|
if (end > size - 1) {
|
|
end = size - 1
|
|
}
|
|
|
|
// invalid or unsatisifiable
|
|
if (isNaN(start) || isNaN(end) || start > end || start < 0) {
|
|
continue
|
|
}
|
|
|
|
// add range
|
|
ranges.push({
|
|
start: start,
|
|
end: end
|
|
})
|
|
}
|
|
|
|
if (ranges.length < 1) {
|
|
// unsatisifiable
|
|
return -1
|
|
}
|
|
|
|
return options && options.combine
|
|
? combineRanges(ranges)
|
|
: ranges
|
|
}
|
|
|
|
/**
|
|
* Combine overlapping & adjacent ranges.
|
|
* @private
|
|
*/
|
|
|
|
function combineRanges (ranges) {
|
|
var ordered = ranges.map(mapWithIndex).sort(sortByRangeStart)
|
|
|
|
for (var j = 0, i = 1; i < ordered.length; i++) {
|
|
var range = ordered[i]
|
|
var current = ordered[j]
|
|
|
|
if (range.start > current.end + 1) {
|
|
// next range
|
|
ordered[++j] = range
|
|
} else if (range.end > current.end) {
|
|
// extend range
|
|
current.end = range.end
|
|
current.index = Math.min(current.index, range.index)
|
|
}
|
|
}
|
|
|
|
// trim ordered array
|
|
ordered.length = j + 1
|
|
|
|
// generate combined range
|
|
var combined = ordered.sort(sortByRangeIndex).map(mapWithoutIndex)
|
|
|
|
// copy ranges type
|
|
combined.type = ranges.type
|
|
|
|
return combined
|
|
}
|
|
|
|
/**
|
|
* Map function to add index value to ranges.
|
|
* @private
|
|
*/
|
|
|
|
function mapWithIndex (range, index) {
|
|
return {
|
|
start: range.start,
|
|
end: range.end,
|
|
index: index
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Map function to remove index value from ranges.
|
|
* @private
|
|
*/
|
|
|
|
function mapWithoutIndex (range) {
|
|
return {
|
|
start: range.start,
|
|
end: range.end
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Sort function to sort ranges by index.
|
|
* @private
|
|
*/
|
|
|
|
function sortByRangeIndex (a, b) {
|
|
return a.index - b.index
|
|
}
|
|
|
|
/**
|
|
* Sort function to sort ranges by start position.
|
|
* @private
|
|
*/
|
|
|
|
function sortByRangeStart (a, b) {
|
|
return a.start - b.start
|
|
}
|