amazon-route-53-dns-zone-file/src/parser/parser.ts

Makes DNS Zone File easy. Parses and validates BIND zone files and can be extended for custom features. Functionality is modular. Features are made open for extension and closed for runtime mutation. Written in TypeScript.

import { ParsedTypings } from '../shared/types_domain_specific';
import { ParserTypings } from './types_parser';
import { transformInputText } from './utils_parser';
import { visitors } from './visitors';
import { ParserNode } from './parser_node';

export class Parser implements ParserTypings.Parser {
  public zoneObj: ParserTypings.Parser['zoneObj'];
  public parsingMeta: ParserTypings.Parser['parsingMeta'] = new Map();
  public stack: ParserTypings.Parser['stack'] = [];
  public visitors: ParserTypings.Parser['visitors'] = visitors;
  public input: ParserTypings.Parser['input'] = {
    textInput: null as any,
    textInputFlattened: '',
    textInputSplitByLine: [],
  };

  constructor($originName: string = '') {
    this.zoneObj = { $ORIGIN: $originName } as ParsedTypings.Obj;
    this.input.$originName = $originName;
  }

  public setText(textInput: string): this {
    const [flattened, splitByLine] = transformInputText(textInput);
    this.input.textInput = textInput;
    this.input.textInputFlattened = flattened;
    this.input.textInputSplitByLine = splitByLine;
    return this;
  }

  /**
   * @perf can optimize this looping
   * @note sharing the node instance across iterations can save memory but also add confusion like React SyntheticEvent
   */
  public parse(): this {
    /* istanbul ignore next */
    if (process.env.NODE_ENV !== 'production' && this.input.textInput == null) {
      console.error(`[Parser] must setText(string) before calling parse()`);
    }

    const node = new ParserNode(this);
    const findVisitor = (x: ParserTypings.Visitor) => x.isSatisfied(node);

    for (const [
      index,
      lineContent,
    ] of this.input.textInputSplitByLine.entries()) {
      node.update(lineContent, index);
      this.visitors.find(findVisitor)?.visit(this, node);
    }

    return this;
  }
}