Method parseDataType

pkg/sql/parser/expressions.go:289–349

parseDataType parses a SQL data type for CAST or :: expressions Handles: simple types (INTEGER, TEXT), parameterized types (VARCHAR(100), NUMERIC(10,2))

()

// parseDataType parses a SQL data type for CAST or :: expressions
// Handles: simple types (INTEGER, TEXT), parameterized types (VARCHAR(100), NUMERIC(10,2))
func (p *Parser) parseDataType() (string, error) {
	// Data type can be an identifier or a keyword like INT, VARCHAR, etc.
	if !p.isIdentifier() && !p.isDataTypeKeyword() {
		return "", p.expectedError("data type")
	}

	// Use strings.Builder for efficient string concatenation
	var sb strings.Builder
	sb.WriteString(p.currentToken.Token.Value)
	p.advance() // Consume type name

	// Check for type parameters (e.g., VARCHAR(100), DECIMAL(10,2))
	if p.isType(models.TokenTypeLParen) {
		p.advance() // Consume (
		sb.WriteByte('(')

		paramCount := 0
		for !p.isType(models.TokenTypeRParen) {
			if paramCount > 0 {
				if !p.isType(models.TokenTypeComma) {
					return "", p.expectedError(", or )")
				}
				sb.WriteString(p.currentToken.Token.Value)
				p.advance() // Consume comma
			}

			// Parse parameter (should be a number or identifier)
			// Use token type constants for consistency
			if !p.isType(models.TokenTypeNumber) && !p.isType(models.TokenTypeIdentifier) && !p.isNumericLiteral() {
				return "", goerrors.InvalidSyntaxError(
					fmt.Sprintf("expected numeric type parameter, got '%s'", p.currentToken.Token.Value),
					p.currentLocation(),
					"Use TYPE(precision[, scale]) syntax",
				)
			}

			sb.WriteString(p.currentToken.Token.Value)
			p.advance()
			paramCount++
		}

		sb.WriteByte(')')

		if !p.isType(models.TokenTypeRParen) {
			return "", p.expectedError(")")
		}
		p.advance() // Consume )
	}

	// Check for array type suffix (e.g., INTEGER[], TEXT[])
	if p.isType(models.TokenTypeLBracket) {
		p.advance() // Consume [
		if !p.isType(models.TokenTypeRBracket) {
			return "", p.expectedError("]")
		}
		p.advance() // Consume ]
		sb.WriteString("[]")
	}