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3-js-structs.js
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67 lines (57 loc) · 1.65 KB
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'use strict';
// Elements to be visited
const product = (name, price) => {
const instance = { type: 'Product', name, price };
instance.accept = (visitor) => {
const inStock = true; // Just a stub
visitor(instance, inStock);
};
return instance;
};
const SUNDAY = 0;
const SATURDAY = 6;
const service = (name) => {
const instance = { type: 'Service', name };
instance.accept = (visitor) => {
const day = new Date().getDay();
const available = day > SUNDAY && day < SATURDAY;
visitor(instance, available);
};
return instance;
};
// Visitors to be acceped
const purchase = (items, delivery) => {
const instance = { items: [], delivery: null };
const visit = (item, available) => {
const status = `${available ? '' : 'not '}available`;
console.log(`${item.type} "${item.name}" is ${status}`);
if (item.type === 'Service') instance.delivery = item;
else instance.items.push(item);
};
for (const item of items) {
item.accept(visit);
}
delivery.accept(visit);
return instance;
};
const inspection = (items) => {
const products = [...items];
const visit = (item, available) => {
const status = `${available ? 'in' : 'aut of'} stock`;
console.log(`${item.type} "${item.name}" is ${status}`);
};
const check = () => {
for (const item of products) {
item.accept(visit);
}
};
return { items: products, check };
};
// Usage
const p1 = product('Laptop', 1500);
const p2 = product('Keyboard', 100);
const delivery = service('Delivery');
const electronics = purchase([p1, p2], delivery);
console.dir({ electronics });
const stockInspection = inspection([p1, p2]);
stockInspection.check();