commonMain.io.ktor.util.Attributes.kt Maven / Gradle / Ivy

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/*
* 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.util

/**
 * Specifies a key for an attribute in [Attributes]
 * @param T is a type of the value stored in the attribute
 * @param name is a name of the attribute for diagnostic purposes. Can't be blank
 */
public class AttributeKey(public val name: String) {
    init {
        if (name.isEmpty()) {
            throw IllegalStateException("Name can't be blank")
        }
    }

    override fun toString(): String = "AttributeKey: $name"

    override fun equals(other: Any?): Boolean {
        if (this === other) return true
        if (other == null || this::class != other::class) return false

        other as AttributeKey<*>

        if (name != other.name) return false

        return true
    }

    override fun hashCode(): Int {
        return name.hashCode()
    }
}

/**
 * A version of [AttributeKey] that overrides [equals] and [hashCode] using [name]
 * @param T is a type of the value stored in the attribute
 * @param name is a name of the attribute
 */
@Suppress("DEPRECATION")
@Deprecated(
    "Please use `AttributeKey` class instead",
    replaceWith = ReplaceWith("AttributeKey")
)
public typealias EquatableAttributeKey = AttributeKey

/**
 * Creates an attributes instance suitable for the particular platform
 */
public expect fun Attributes(concurrent: Boolean = false): Attributes

/**
 * Map of attributes accessible by [AttributeKey] in a typed manner
 */
public interface Attributes {
    /**
     * Gets a value of the attribute for the specified [key], or throws an exception if an attribute doesn't exist
     */
    public operator fun  get(key: AttributeKey): T =
        getOrNull(key) ?: throw IllegalStateException("No instance for key $key")

    /**
     * Gets a value of the attribute for the specified [key], or return `null` if an attribute doesn't exist
     */
    public fun  getOrNull(key: AttributeKey): T?

    /**
     * Checks if an attribute with the specified [key] exists
     */
    public operator fun contains(key: AttributeKey<*>): Boolean

    /**
     * Creates or changes an attribute with the specified [key] using [value]
     */
    public fun  put(key: AttributeKey, value: T)

    /**
     * Removes an attribute with the specified [key]
     */
    public fun  remove(key: AttributeKey)

    /**
     * Removes an attribute with the specified [key] and returns its current value, throws an exception if an attribute doesn't exist
     */
    public fun  take(key: AttributeKey): T = get(key).also { remove(key) }

    /**
     * Removes an attribute with the specified [key] and returns its current value, returns `null` if an attribute doesn't exist
     */
    public fun  takeOrNull(key: AttributeKey): T? = getOrNull(key).also { remove(key) }

    /**
     * Gets a value of the attribute for the specified [key], or calls supplied [block] to compute its value
     */
    public fun  computeIfAbsent(key: AttributeKey, block: () -> T): T

    /**
     * Returns [List] of all [AttributeKey] instances in this map
     */
    public val allKeys: List>
}

/**
 * Adds all attributes from another collection, replacing original values if any.
 */
public fun Attributes.putAll(other: Attributes) {
    other.allKeys.forEach {
        @Suppress("UNCHECKED_CAST")
        put(it as AttributeKey, other[it])
    }
}