Class WhereBuilder

packages/filter/src/query.ts:281–524

 * ```
 */
export class WhereBuilder<MT extends object = AnyObject> {
  where: Where<MT>;

  constructor(w?: Where<MT>) {
    this.where = w ?? {};
  }

  private add(w: Where<MT>): this {
    for (const k of Object.keys(w)) {
      if (k in this.where) {
        // Found conflicting keys, create an `and` operator to join the existing
        // conditions with the new one
        const where = {and: [this.where, w]};
        this.where = where;
        return this;
      }
    }
    // Merge the where items
    this.where = Object.assign(this.where, w);
    return this;
  }

  /**
   * @deprecated
   * Starting from TypeScript 3.2, we don't have to cast any more. This method
   * should be considered as `deprecated`.
   *
   * Cast an `and`, `or`, or condition clause to Where
   * @param clause - And/Or/Condition clause
   */
  cast(clause: AndClause<MT> | OrClause<MT> | Condition<MT>): Where<MT> {
    return clause;
  }

  /**
   * Add an `and` clause.
   * @param w - One or more where objects
   */
  and(...w: (Where<MT> | Where<MT>[])[]): this {
    let clauses: Where<MT>[] = [];
    w.forEach(where => {
      clauses = clauses.concat(Array.isArray(where) ? where : [where]);
    });
    return this.add({and: clauses});
  }

  /**
   * Add an `or` clause.
   * @param w - One or more where objects
   */
  or(...w: (Where<MT> | Where<MT>[])[]): this {
    let clauses: Where<MT>[] = [];
    w.forEach(where => {
      clauses = clauses.concat(Array.isArray(where) ? where : [where]);
    });
    return this.add({or: clauses});
  }