commonMain.io.ktor.http.Ranges.kt Maven / Gradle / Ivy
The newest version!
/*
* Copyright 2014-2021 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
*/
package io.ktor.http
import io.ktor.util.*
import kotlin.math.*
/**
* Possible content range units: bytes and none
* @property unitToken Lower-case unit name
*/
public enum class RangeUnits(public val unitToken: String) {
/**
* Range unit `bytes`
*/
Bytes("bytes"),
/**
* Range unit `none`
*/
None("none")
}
/**
* Represents a `Range` header's particular range
*/
public sealed class ContentRange {
/**
* Represents a `Content-Range` bounded from both sides
* @property from index from which the content should begin
* @property to the last index the content should end at (inclusive)
*/
public data class Bounded(val from: Long, val to: Long) : ContentRange() {
override fun toString(): String = "$from-$to"
}
/**
* Represents a `Content-Range` bounded at the beginning (skip first bytes, show tail)
* @property from index from which the content should begin
*/
public data class TailFrom(val from: Long) : ContentRange() {
override fun toString(): String = "$from-"
}
/**
* Represents a `Content-Range` bounded by tail size
* @property lastCount number of tail bytes
*/
public data class Suffix(val lastCount: Long) : ContentRange() {
override fun toString(): String = "-$lastCount"
}
}
/**
* Parse `Range` header value
*/
public fun parseRangesSpecifier(rangeSpec: String): RangesSpecifier? {
try {
val (unit, allRangesString) = rangeSpec.chomp("=") { return null }
val allRanges = allRangesString.split(',').map {
if (it.startsWith("-")) {
ContentRange.Suffix(it.removePrefix("-").toLong())
} else {
val (from, to) = it.chomp("-") { "" to "" }
when {
to.isNotEmpty() -> ContentRange.Bounded(from.toLong(), to.toLong())
else -> ContentRange.TailFrom(from.toLong())
}
}
}
if (allRanges.isEmpty() || unit.isEmpty()) {
return null
}
val spec = RangesSpecifier(unit, allRanges)
return if (spec.isValid()) spec else null
} catch (e: Throwable) {
return null // according to the specification we should ignore syntactically incorrect headers
}
}
internal fun List.toLongRanges(contentLength: Long) = map {
when (it) {
is ContentRange.Bounded -> it.from..it.to.coerceAtMost(contentLength - 1)
is ContentRange.TailFrom -> it.from until contentLength
is ContentRange.Suffix -> (contentLength - it.lastCount).coerceAtLeast(0L) until contentLength
}
}.filterNot { it.isEmpty() }
// O (N^2 + N ln (N) + N)
internal fun List.mergeRangesKeepOrder(): List {
val sortedMerged = sortedBy { it.start }.fold(ArrayList(size)) { acc, range ->
when {
acc.isEmpty() -> acc.add(range)
acc.last().endInclusive < range.start - 1 -> acc.add(range)
else -> {
val last = acc.last()
acc[acc.lastIndex] = last.start..max(last.endInclusive, range.endInclusive)
}
}
acc
}
val result = arrayOfNulls(size)
for (range in sortedMerged) {
for (i in indices) {
if (this[i] in range) {
result[i] = range
break
}
}
}
return result.filterNotNull()
}