Method isStartOfRegex

packages/compiler/src/expression_parser/lexer.ts:657–690

()

  }

  private isStartOfRegex(): boolean {
    if (this.tokens.length === 0) {
      return true;
    }

    const prevToken = this.tokens[this.tokens.length - 1];

    // If a slash is preceded by a `!` operator, we need to distinguish whether it's a
    // negation or a non-null assertion. Regexes can only be precded by negations.
    if (prevToken.isOperator('!')) {
      const beforePrevToken = this.tokens.length > 1 ? this.tokens[this.tokens.length - 2] : null;
      const isNegation =
        beforePrevToken === null ||
        (beforePrevToken.type !== TokenType.Identifier &&
          !beforePrevToken.isCharacter(chars.$RPAREN) &&
          !beforePrevToken.isCharacter(chars.$RBRACKET));

      return isNegation;
    }

    // Only consider the slash a regex if it's preceded either by:
    // - Any operator, aside from `!` which is special-cased above.
    // - Opening paren (e.g. `(/a/)`).
    // - Opening bracket (e.g. `[/a/]`).
    // - A comma (e.g. `[1, /a/]`).
    // - A colon (e.g. `{foo: /a/}`).
    return (
      prevToken.type === TokenType.Operator ||
      prevToken.isCharacter(chars.$LPAREN) ||
      prevToken.isCharacter(chars.$LBRACKET) ||
      prevToken.isCharacter(chars.$COMMA) ||
      prevToken.isCharacter(chars.$COLON)
    );
  }

  private scanRegex(tokenStart: number): Token {
    this.advance();