)

var (
	errInvalidASTNode    = errors.New("invalid AST Node")
	errExpectedBool      = errors.New("expected bool")
	errLikeNonStrArg     = errors.New("LIKE clause requires string arguments")
	errLikeInvalidEscape = errors.New("LIKE clause has invalid ESCAPE character")
	errNotImplemented    = errors.New("not implemented")
)

// AST Node Evaluation functions
//

	n := len(values[0])
	r := values[0][1 : n-1]

	// Translate doubled quotes
	*qi = QuotedIdentifier(strings.ReplaceAll(r, `""`, `"`))
	return nil
}

// Types representing AST of SQL statement. Only SELECT is supported.

// Select is the top level AST node type
type Select struct {
	Expression *SelectExpression `parser:"\"SELECT\" @@"`
	From       *TableExpression  `parser:"\"FROM\" @@"`

	default:
		// TODO: traverse arguments and call aggregateRow on
		// them if they could be an ancestor of an
		// aggregation.
	}
	return nil
}

// getAggregate() implementation for each AST node follows. This is
// called after calling aggregateRow() on each input row, to calculate
// the final aggregate result.

func (e *FuncExpr) getAggregate() (*Value, error) {
	switch e.getFunctionName() {