/*!
* 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
}