lib/rules/space-in-parens.js
function shouldOpenerHaveSpace( left, right ) {
      if ( sourceCode.isSpaceBetweenTokens( left, right ) ) {
        return false;
      }

      if ( ALWAYS ) {
        if ( astUtils.isClosingParenToken( right ) ) {
          return false;
        }
        return !isOpenerException( right );
      }
      return isOpenerException( right );
    }
function shouldOpenerHaveSpace( left, right ) {
      if ( sourceCode.isSpaceBetweenTokens( left, right ) ) {
        return false;
      }

      if ( ALWAYS ) {
        if ( astUtils.isClosingParenToken( right ) ) {
          return false;
        }
        return !isOpenerException( right );
      }
      return isOpenerException( right );
    }
Determines if an opener paren should have a missing space after it
@param {Object} left The paren token
@param {Object} right The token after it
@returns {boolean} True if the paren should have a space