Method parseWindowSpec

pkg/sql/parser/window.go:359–468

parseWindowSpec parses a window specification (PARTITION BY, ORDER BY, frame clause). Supports both inline specs OVER (...) and named window references OVER w (SQL:2003 §7.11).

()

// parseWindowSpec parses a window specification (PARTITION BY, ORDER BY, frame clause).
// Supports both inline specs OVER (...) and named window references OVER w (SQL:2003 §7.11).
func (p *Parser) parseWindowSpec() (*ast.WindowSpec, error) {
	// Named window reference: OVER w - bare identifier, no parentheses.
	// This must be checked before the '(' path so that e.g. OVER w is not
	// mistakenly rejected.
	if p.isIdentifier() {
		spec := &ast.WindowSpec{Name: p.currentToken.Token.Value}
		p.advance()
		return spec, nil
	}

	// Expect opening parenthesis
	if !p.isType(models.TokenTypeLParen) {
		return nil, p.expectedError("(")
	}
	p.advance() // Consume (

	windowSpec := &ast.WindowSpec{}

	// Parse PARTITION BY clause
	if p.isType(models.TokenTypePartition) {
		p.advance() // Consume PARTITION
		if !p.isType(models.TokenTypeBy) {
			return nil, p.expectedError("BY after PARTITION")
		}
		p.advance() // Consume BY

		// Parse partition expressions
		for {
			expr, err := p.parseExpression()
			if err != nil {
				return nil, err
			}
			windowSpec.PartitionBy = append(windowSpec.PartitionBy, expr)

			if p.isType(models.TokenTypeComma) {
				p.advance() // Consume comma
			} else {
				break
			}
		}
	}

	// Parse ORDER BY clause
	if p.isType(models.TokenTypeOrder) {
		p.advance() // Consume ORDER
		if !p.isType(models.TokenTypeBy) {
			return nil, p.expectedError("BY after ORDER")
		}
		p.advance() // Consume BY

		// Parse order expressions
		for {
			expr, err := p.parseExpression()
			if err != nil {
				return nil, err
			}

			// Create OrderByExpression with defaults