prystupa

class OrderBook(side: Side, orderTypes: (Order => OrderType)) {

  private var marketBook: List[Order] = Nil
  private var limitBook: List[(Double, List[Order])] = Nil
  private val priceOrdering = if (side == Sell) Ordering[Double] else Ordering[Double].reverse

  def add(order: Order) {

    orderTypes(order).price match {

prystupa

  Scenario Outline: Decrease top outstanding order partially and then fill it completely
    When the following orders are added to the "<Side>" book:
      | Broker | Qty | Price |
      | A      | 100 | 10.5  |
      | B      | 100 | 10.5  |
    Then the "<Side>" order book looks like:
      | Broker | Qty | Price |
      | A      | 100 | 10.5  |
      | B      | 100 | 10.5  |
    When the top order of the "<Side>" book is filled by "20"

prystupa

Feature: Core matching logic for limit orders

  Background: Submit initial non-crossing orders to work with
    Given the following orders are submitted in this order:
      | Broker | Side | Qty | Price |
      | A      | Buy  | 100 | 10.4  |
      | B      | Buy  | 200 | 10.3  |
      | C      | Sell | 100 | 10.7  |
      | D      | Sell | 200 | 10.8  |
    Then no trades are generated

prystupa

Feature: Core Market Order Functionality for Price and Time Priority

  Scenario Outline: Price and time priority of market orders over limit orders
    When the following orders are added to the "<Side>" book:
      | Broker | Qty | Price |
      | A      | 100 | 10.5  |
    Then the "<Side>" order book looks like:
      | Broker | Qty | Price |
      | A      | 100 | 10.5  |
    When the following orders are added to the "<Side>" book:

prystupa

Feature: Core matching logic for market orders

  Scenario: Matching a large Buy market order against multiple limit orders
  The order is large enough to fill the entire opposite book
  The remainder of the market order is expected to rest in its book
    When the following orders are submitted in this order:
      | Broker | Side | Qty | Price |
      | A      | Buy  | 100 | 10.7  |
      | B      | Buy  | 200 | 10.6  |
      | C      | Buy  | 300 | 10.5  |

prystupa

Feature: Maintaining best limit in the order book

  Scenario Outline: Various life cycles of the order book best limit
  # When are no orders in the book, the best limit is not defined
    Then the best limit for "<Side>" order book is "None"
  # If a market order enters the book, the best limit is still undefined
    When the following orders are added to the "<Side>" book:
      | Broker | Qty | Price |
      | A      | 100 | MO    |
    Then the "<Side>" order book looks like:

prystupa

  Scenario: Matching incoming Buy limit order against a single outstanding Sell market order
    When the following orders are submitted in this order:
      | Broker | Side | Qty | Price |
      | A      | Sell | 100 | MO    |
      | B      | Buy  | 120 | 10.5  |
    Then the following trades are generated:
      | Buying broker | Selling broker | Qty | Price |
      | B             | A              | 100 | 10.5  |
    And market order book looks like:
      | Broker | Qty | Price | Price | Qty | Broker |

prystupa

class StronglyConnectedComponentsAlgo {

  type GraphAdjList = Vector[Set[Int]]
  type SubGraphAdjList = Map[Int, Set[Int]]

  def compute(adjacencyList: GraphAdjList): Vector[SubGraphAdjList] = {

    def strongConnect(v: Int, state: State): State = {

      if (!state.visited(v).isDefined) {

prystupa

Feature: Computing strongly connected components of a graph using Tarjan's algorithm

  Scenario: Simple chain with no loops
    Given the following edges of a graph with "3" vertices:
      | Start | End |
      | 1     | 2   |
      | 2     | 3   |
    When I compute strongly connected components of this graph using Tarjan's algorithm
    Then there is a connected component of the graph:
      | Node | Successors |

prystupa

  Scenario: Matching incoming Buy market order against Sell market order when another - limit - Sell order present
    Given the following orders are submitted in this order:
      | Broker | Side | Qty | Price |
      | A      | Sell | 100 | MO    |
      | B      | Sell | 100 | 10.5  |
    Then market order book looks like:
      | Broker | Qty | Price | Price | Qty | Broker |
      |        |     |       | MO    | 100 | A      |
      |        |     |       | 10.5  | 100 | B      |
    When the following orders are submitted in this order: