Offers a port of fractional indexing functionality, allowing generation of ordered indices between existing ones, ensuring consistent output. Supports generating multiple fractional indices simultaneously.
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Based on Implementing Fractional Indexing by David Greenspan.
This port is based on the rocicorp/fractional-indexing repo and is meant to give the same output for any given input, but no guarantees are made that this port is 100% accurate to the original JavaScript source code it was ported from.
This is compatible with Kotlin Multiplatform as it makes use of only the Kotlin standard library (no JVM-specific code).
You can add this library as a dependency in Gradle in a Kotlin or Kotlin Multiplatform project:
dependencies {
// ...
implementation("com.davidarvelo:fractional-indexing:${latestVersion}")
}
rocicorp for the original code implemented in JavaScript, located at https://github.com/rocicorp/fractional-indexing, and ported to Kotlin in this repo.
class Usages {
fun generateFractionalIndexBetween() {
val first = FractionalIndexing.generateFractionalIndexBetween(null, null); // "a0"
// Insert after 1st
val second = FractionalIndexing.generateFractionalIndexBetween(first, null); // "a1"
// Insert after 2nd
val third = FractionalIndexing.generateFractionalIndexBetween(second, null); // "a2"
// Insert before 1st
val zeroth = FractionalIndexing.generateFractionalIndexBetween(null, first); // "Zz"
// Insert in between 2nd and 3rd (midpoint)
val secondAndHalf = FractionalIndexing.generateFractionalIndexBetween(second, third); // "a1V"
val beforeZeroth = FractionalIndexing.generateFractionalIndexBetween(null, zeroth)
println(first)
println(second)
println(third)
println(zeroth)
println(secondAndHalf)
println(beforeZeroth)
}
fun generateNFractionalIndicesBetween() {
val (first, second) = FractionalIndexing.generateNFractionalIndicesBetween(null, null, 2); // ['a0', 'a1']
// Insert after 2nd
val nextSet = FractionalIndexing.generateFractionalIndexBetween(second, null); // "a2"
// Insert two keys after 2nd
val (secondAgain, third) = FractionalIndexing.generateNFractionalIndicesBetween(second, null, 2); // ['a2', 'a3']
// Insert two keys before 1st
val twoMore = FractionalIndexing.generateNFractionalIndicesBetween(null, first, 2); // ['Zy', 'Zz']
// Insert two keys in between 1st and 2nd (midpoints)
val betweenKeys = FractionalIndexing.generateNFractionalIndicesBetween(first, second, 2); // ['a0G', 'a0V']
println("$first, $second")
println(nextSet)
println("$secondAgain, $third")
println(twoMore)
println(betweenKeys)
}
}
fun main() {
Usages().generateFractionalIndexBetween()
Usages().generateNFractionalIndicesBetween()
}