Mapper

A Mapper defines a function to map a value from a type to another type.

Kotlin

interface Mapper<in From, out To> {
   fun map(from: From): To
}

Swift

open class Mapper<From,To> {
    public init() { }
    open func map(_ from: From) throws -> To {
        fatalError("Undefined mapper. Class Mapper must be subclassed.")
    }
}

TypeScript

export interface Mapper<From, To> {
    map(from: From, toType?: new () => To): To;
}

PHP

interface Mapper
{
    /**
     * @param $from
     * @return mixed
     */
    public function map($from);
}

Mapping Arrays & Dictionaries

When the languages enables it, Mapper has extensions to map arrays and dictionaries. Otherwise, you will have to implement a custom mapper to map the values included in arrays and dictionaries.

Find below some of the supported extensions:

Kotlin

fun <From, To> Mapper<From, To>.map(values: List<From>): List<To> = values.map { ... }
fun <From, To, K> Mapper<From, To>.map(value: Map<K, From>): Map<K, To> { ... }

Swift

func map( _ array: [In]) throws -> [Out] { ... }
func map<K>(_ dictionary: [K:In]) throws -> [K:Out] where K:Hashable { ... }

Default implementations

Harmony has multiple pre-defined implementations of mapper.

• VoidMapper: Empty implementation that returns en error.
• CastMapper<In,Out>: Mapping by casting the object into the given types.
• ClosureMapper<In,Out>: Mapper that has a closure/lambda upon initialization specifiying the mapping action.

Important

Every Harmony library has its own set of pre-defined mappers. Before creating a new mapper, check always with the available mappers in your language.