@aeternity/aepp-calldata/src/DataFactory/VariantDataFactory.js

Aeternity data serialization library

import FateVariant from '../types/FateVariant.js'
import FateTypeError from '../Errors/FateTypeError.js'
import BaseDataFactory from './BaseDataFactory.js'

const TYPES = [
    'variant',
    'Chain.ttl',
    'AENS.pointee',
    'AENSv2.pointee',
    'AENS.name',
    'AENSv2.name'
]

class VariantDataFactory extends BaseDataFactory {
    supports({ name, _valueTypes }) {
        return TYPES.includes(name)
    }

    create(type, value) {
        if (!this.isValid(value)) {
            throw new FateTypeError(
                type.name,
                `Variant should be an object mapping constructor to array of values, got "${value}" instead`
            )
        }

        const [variantCtor, variantArgs] = Object.entries(value)[0]

        const arities = type.variants.map(e => {
            const [[, args]] = Object.entries(e)
            return args.length
        })

        const tag = type.variants.findIndex(e => {
            const [[key, _]] = Object.entries(e)
            return key === variantCtor
        })

        if (tag === -1) {
            throw new FateTypeError(
                type.name,
                `Unknown variant constructor: ${variantCtor}`
            )
        }

        const [[, variantTypes]] = Object.entries(type.variants[tag])

        if (variantArgs.length !== variantTypes.length) {
            throw new FateTypeError(
                type.name,
                `"${variantCtor}" variant constructor expects ${variantTypes.length} argument(s) but got ${variantArgs.length} instead`
            )
        }

        const variantValue = this.valueFactory.createMultiple(variantTypes, variantArgs)

        return new FateVariant(arities, tag, variantValue, variantTypes, type.variants)
    }

    isValid(value) {
        return typeof value === 'object'
            && value !== null
            && Object.entries(value).length === 1
            && Array.isArray(Object.values(value)[0])
    }
}

export default VariantDataFactory