Connect 4 Logic

This library provides APIs for manipulating and querying a standard (7x6) game of connect 4.

Installation

Using npm:

$ npm i --save @brajkowski/connect4-logic

Usage

Standard Behavior

The main class that should be used to manipulate and query the underlying game state is Logic.

To begin, instantiate an implementation of Logic (currently BitboardLogic is the only implementation):

const logic: Logic = new BitboardLogic();

From there, you may perform queries on the game state such as:

let column = 0;
let result: boolean = logic.canPlaceChip(column);

and place chips that belong to a player:

let landedOnRow = logic.placeChip(Player.One, column); // returns 0.
landedOnRow = logic.placeChip(Player.Two, column); // returns 1.

These operations prevent placing chips in non-existent columns (ie: out-of-bounds columns) as well as overflowing a column (ie: a column can only hold 6 chips).

A basic game loop may look like:

const logic: Logic = new BitboardLogic();
let activePlayer: Player = Player.One;
function gameLoop() {
  while (true) {
    let column = promptActivePlayerForMove();
    if (!logic.canPlaceChip(column)) {
      continue;
    }
    logic.placeChip(activePlayer, column);
    if (logic.didWin(activePlayer)) {
      break;
    }
    swapActivePlayer();
  }
}

Customized Behavior

The Logic class provides default connect 4 behavior (ie: chips fall to the bottom of a column and stack), but custom behavior can also be achieved by using the PlayerState class:

let row = 2;
let column = 3;
logic.getPlayerState(Player.One).occupyPosition(row, column);

The PlayerState operations allow for any chip placement, but are bounds-checked for valid row and column values and prevent duplicate chip placement (ie: trying to place another chip in a position that is already occupied).

Building from Source

Using npm:

$ npm run build

will produce the compiled library under /dist.

The test suite may also be executed with npm:

$ npm test

Future Plans

• Generalize the solution to fit arbitrary game board dimensions