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import { getStr } from "./wasm.ts";import { Status, Types, Values } from "./constants.ts";import SqliteError from "./error.ts";import { RowObjects } from "./row_objects.ts";
export interface ColumnName {  name: string;  originName: string;  tableName: string;}
export class Rows {  private _db: any;  private _stmt: number;  private _done: boolean;
  /**   * Rows   *   * Rows represent a set of results from a query.   * They are iterable and yield arrays with   * the data from the selected columns.   *   * This class is not exported from the module   * and the only correct way to obtain a `Rows`   * object is by making a database query.   */  constructor(db: any, stmt: number) {    this._db = db;    this._stmt = stmt;    this._done = false;
    if (!this._db) {      this._done = true;    }  }
  /**   * Rows.return   *   * Implements the closing iterator   * protocol. See also:   * https://exploringjs.com/es6/ch_iteration.html#sec_closing-iterators   */  return(): IteratorResult<any> {    if (this._done) {      return { done: true, value: undefined };    }    // Release transaction slot    this._db._wasm.finalize(this._stmt);    this._db._transactions.delete(this);    this._done = true;    return { done: true, value: undefined };  }
  /**   * Rows.done   *   * Deprecated, prefer `Rows.return`.   */  done() {    this.return();  }
  /**   * Rows.next   *   * Implements the iterator protocol.   */  next(): IteratorResult<any[]> {    if (this._done) return { value: undefined, done: true };    // Load row data and advance statement    const row = this._get();    const status = this._db._wasm.step(this._stmt);    switch (status) {      case Status.SqliteRow:        // NO OP        break;      case Status.SqliteDone:        this.return();        break;      default:        this.return();        throw this._db._error(status);        break;    }    return { value: row, done: false };  }
  /**   * Rows.columns   *   * Call this if you need column names from the result of a select query.   *   * This method returns an array of objects, where each object has the following properties:   *   * | Property     | Value                                      |   * |--------------|--------------------------------------------|   * | `name`       | the result of `sqlite3_column_name`        |   * | `originName` | the result of `sqlite3_column_origin_name` |   * | `tableName`  | the result of `sqlite3_column_table_name`  |   */  columns(): ColumnName[] {    if (this._done) {      throw new SqliteError(        "Unable to retrieve column names as transaction is finalized.",      );    }
    const columnCount = this._db._wasm.column_count(this._stmt);    const columns: ColumnName[] = [];    for (let i = 0; i < columnCount; i++) {      const name = getStr(        this._db._wasm,        this._db._wasm.column_name(this._stmt, i),      );      const originName = getStr(        this._db._wasm,        this._db._wasm.column_origin_name(this._stmt, i),      );      const tableName = getStr(        this._db._wasm,        this._db._wasm.column_table_name(this._stmt, i),      );      columns.push({ name, originName, tableName });    }    return columns;  }
  /**   * Rows.asObjects   *    * Call this if you need to ouput the rows as objects.   *    *     const rows = [...db.query("SELECT name FROM users;").asObjects()];   */  asObjects<T extends any = Record<string, any>>(): RowObjects<T> {    return new RowObjects<T>(this);  }
  [Symbol.iterator]() {    return this;  }
  private _get(): any[] {    // Get results from row    const row = [];    // return row;    for (      let i = 0, c = this._db._wasm.column_count(this._stmt);      i < c;      i++    ) {      switch (this._db._wasm.column_type(this._stmt, i)) {        case Types.Integer:          row.push(this._db._wasm.column_int(this._stmt, i));          break;        case Types.Float:          row.push(this._db._wasm.column_double(this._stmt, i));          break;        case Types.Text:          row.push(            getStr(              this._db._wasm,              this._db._wasm.column_text(this._stmt, i),            ),          );          break;        case Types.Blob: {          const ptr = this._db._wasm.column_blob(this._stmt, i);          if (ptr === 0) {            // Zero pointer results in null            row.push(null);          } else {            const length = this._db._wasm.column_bytes(this._stmt, i);            // Slice should copy the bytes, as it makes a shallow copy            row.push(              new Uint8Array(this._db._wasm.memory.buffer, ptr, length).slice(),            );          }          break;        }        case Types.BigInteger: {          const ptr = this._db._wasm.column_text(this._stmt, i);          row.push(BigInt(getStr(this._db._wasm, ptr)));          break;        }        default:          // TODO: Differentiate between NULL and not-recognized?          row.push(null);          break;      }    }    return row;  }}
/** * Empty * * A special constant. This is a `Rows` object * which has no results. It is still iterable, * however it won't yield any results. * * `Empty` is returned from queries which return * no data. */export const Empty = new Rows(null, Values.Null);