iddfs/src/Strategy.js

iterative deepening depth-first search (IDDFS) for JavaScript

// @flow

export type NodeId = number | string;

export type StrategyOptions<T> = {
  isVisited?: (T, Array<NodeId>) => ?number,
  isGoal: T => boolean,
  expand: T => Array<T>,
  extractId: T => NodeId,
  shouldContinue?: (T, number, number) => boolean,
  onVisit?: (T, number, Array<NodeId>) => Promise<void>
};

export default class Strategy<T> {
  customIsVisited: ?(T, Array<NodeId>) => ?number;
  isGoal: T => boolean;
  expand: T => Array<T>;
  extractId: T => NodeId;
  customShouldContinue: ?(T, number, number) => boolean;
  customOnVisit: ?(T, number, Array<NodeId>) => Promise<void>;

  constructor(options: StrategyOptions<T>) {
    this.isGoal = options.isGoal;
    this.expand = options.expand;
    this.extractId = options.extractId;
    this.customShouldContinue = options.shouldContinue || null;
    this.customIsVisited = options.isVisited || null;
    this.customOnVisit = options.onVisit || null;
  }

  shouldContinue(node: T, depth: number, depthLimit: number): boolean {
    if (this.customShouldContinue) {
      return this.customShouldContinue(node, depth, depthLimit);
    }

    return true;
  }

  isVisited(node: T, visited: Array<NodeId>): ?number {
    if (this.customIsVisited) {
      return this.customIsVisited(node, visited);
    }

    const index = visited.indexOf(this.extractId(node));
    return index < 0 ? null : index;
  }

  onVisit(node: T, depth: number, visited: Array<NodeId>): void {
    if (this.customOnVisit) {
      this.customOnVisit(node, depth, visited);
    }
  }
}