samples/store-cluster/domains/jane/shopping-cart.py

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# Shopping cart implementation
import uuid
import sys

# Convert a particular host and user email to a cart id
def cartid(host, email):
    return ("cart", host.eval(), email.eval())

# Get the shopping cart from the cache
# Return an empty cart if not found
def getcart(id, cache):
    cart = cache.get(id)
    if cart is None:
        return ()
    return cart

# Post a new item to the cart, create a new cart if necessary
def post(collection, item, cache, host, email):
    id = str(uuid.uuid1())
    cart = (("'entry", item[0][1], ("'id", id), item[0][3]),) + getcart(cartid(host, email), cache)
    cache.put(cartid(host, email), cart)
    return (id,)


# Find an item in the cart
def find(id, cart):
    if cart == ():
        return (("'entry", ("'title", "Item"), ("'id", 0)),)
    elif id == cart[0][2][1]:
        return (cart[0],)
    else:
        return find(id, cart[1:])

# Get items from the cart
def get(id, cache, host, email):
    if id == ():
        return ((("'feed", ("'title", "Your Cart"), ("'id", email.eval())) + getcart(cartid(host,email), cache)),)
    return find(id[0], getcart(cartid(host, email), cache))

# Delete items from the  cart
def delete(id, cache, host, email):
    if id == ():
        return cache.delete(cartid(host, email))
    return True

# Return the price of an item
def price(item):
    return float(filter(lambda x: x[0] == "'price", item[3][1][1:])[0][1])

# Sum the prices of a list of items
def sum(items):
    if items == ():
        return 0
    return price(items[0]) + sum(items[1:])

# Return the total price of the items in the cart
def total(cache, host, email):
    return sum(getcart(cartid(host, email), cache))