Method parseFrameBound

pkg/sql/parser/window.go:513–554

parseFrameBound parses a window frame bound

()

// parseFrameBound parses a window frame bound
func (p *Parser) parseFrameBound() (*ast.WindowFrameBound, error) {
	bound := &ast.WindowFrameBound{}

	if p.isType(models.TokenTypeUnbounded) {
		p.advance() // Consume UNBOUNDED
		if p.isType(models.TokenTypePreceding) {
			bound.Type = "UNBOUNDED PRECEDING"
			p.advance() // Consume PRECEDING
		} else if p.isType(models.TokenTypeFollowing) {
			bound.Type = "UNBOUNDED FOLLOWING"
			p.advance() // Consume FOLLOWING
		} else {
			return nil, p.expectedError("PRECEDING or FOLLOWING after UNBOUNDED")
		}
	} else if p.isType(models.TokenTypeCurrent) {
		p.advance() // Consume CURRENT
		if !p.isType(models.TokenTypeRow) {
			return nil, p.expectedError("ROW after CURRENT")
		}
		bound.Type = "CURRENT ROW"
		p.advance() // Consume ROW
	} else {
		// Numeric bound
		expr, err := p.parseExpression()
		if err != nil {
			return nil, err
		}
		bound.Value = expr

		if p.isType(models.TokenTypePreceding) {
			bound.Type = "PRECEDING"
			p.advance() // Consume PRECEDING
		} else if p.isType(models.TokenTypeFollowing) {
			bound.Type = "FOLLOWING"
			p.advance() // Consume FOLLOWING
		} else {
			return nil, p.expectedError("PRECEDING or FOLLOWING after numeric value")
		}
	}

	return bound, nil
}

// parseNullsClause parses the optional NULLS FIRST/LAST clause in ORDER BY expressions.
// Returns a pointer to bool indicating null ordering: true for NULLS FIRST, false for NULLS LAST, nil if not specified.