Method scanToken

packages/compiler/src/expression_parser/lexer.ts:260–365

()

  }

  private scanToken(): Token | null {
    const input = this.input;
    const length = this.length;
    let peek = this.peek;
    let index = this.index;

    // Skip whitespace.
    while (peek <= chars.$SPACE) {
      if (++index >= length) {
        peek = chars.$EOF;
        break;
      } else {
        peek = input.charCodeAt(index);
      }
    }

    this.peek = peek;
    this.index = index;

    if (index >= length) {
      return null;
    }

    // Handle identifiers and numbers.
    if (isIdentifierStart(peek)) {
      return this.scanIdentifier();
    }

    if (chars.isDigit(peek)) {
      return this.scanNumber(index);
    }

    const start: number = index;
    switch (peek) {
      case chars.$PERIOD:
        this.advance();

        if (chars.isDigit(this.peek)) {
          return this.scanNumber(start);
        }

        if (this.peek !== chars.$PERIOD) {
          return newCharacterToken(start, this.index, chars.$PERIOD);
        }

        this.advance();
        if (this.peek === chars.$PERIOD) {
          this.advance();
          return newOperatorToken(start, this.index, '...');
        }
        return this.error(`Unexpected character [${String.fromCharCode(peek)}]`, 0);
      case chars.$LPAREN:
      case chars.$RPAREN:
      case chars.$LBRACKET:
      case chars.$RBRACKET:
      case chars.$COMMA:
      case chars.$COLON:
      case chars.$SEMICOLON: