commonMain.implementations.immutableList.Utils.kt Maven / Gradle / Ivy

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Kotlin Immutable Collections multiplatform library

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/*
 * Copyright 2016-2019 JetBrains s.r.o.
 * Use of this source code is governed by the Apache 2.0 License that can be found in the LICENSE.txt file.
 */

package kotlinx.collections.immutable.implementations.immutableList

import kotlinx.collections.immutable.PersistentList

internal const val MAX_BUFFER_SIZE = 32
internal const val LOG_MAX_BUFFER_SIZE = 5
internal const val MAX_BUFFER_SIZE_MINUS_ONE = MAX_BUFFER_SIZE - 1
internal const val MUTABLE_BUFFER_SIZE = MAX_BUFFER_SIZE + 1

internal class ObjectRef(var value: Any?)

internal fun  persistentVectorOf(): PersistentList {
    return SmallPersistentVector.EMPTY
}


/** Creates new buffer of [MAX_BUFFER_SIZE] capacity having first element initialized with the specified [element]. */
internal fun presizedBufferWith(element: Any?): Array {
    val buffer = arrayOfNulls(MAX_BUFFER_SIZE)
    buffer[0] = element
    return buffer
}

/**
 * Gets trie index segment of the specified [index] at the level specified by [shift].
 *
 * `shift` equal to zero corresponds to the bottommost (leaf) level.
 * For each upper level `shift` increments by [LOG_MAX_BUFFER_SIZE].
 */
internal fun indexSegment(index: Int, shift: Int): Int =
        (index shr shift) and MAX_BUFFER_SIZE_MINUS_ONE

/**
 * Returns the size of trie part of a persistent vector of the specified [vectorSize].
 */
internal fun rootSize(vectorSize: Int) =
        (vectorSize - 1) and MAX_BUFFER_SIZE_MINUS_ONE.inv()