Method parseSnowflakeVariantPath

pkg/sql/parser/expressions.go:405–453

parseSnowflakeVariantPath parses the tail of a Snowflake VARIANT path expression. The current token must be `:`. Returns a VariantPath with the given root and the parsed segments. Grammar: path := ':' step ( '.' field | '[' expr ']' )* step := field | '"' quoted '"' field := ident

(root ast.Expression)

//	step      := field | '"' quoted '"'
//	field     := identifier
func (p *Parser) parseSnowflakeVariantPath(root ast.Expression) (*ast.VariantPath, error) {
	pos := p.currentLocation()
	if !p.isType(models.TokenTypeColon) {
		return nil, p.expectedError(":")
	}
	p.advance() // Consume leading :

	vp := &ast.VariantPath{Root: root, Pos: pos}

	// First segment must be a field name (identifier or string literal).
	name, err := p.parseVariantFieldName()
	if err != nil {
		return nil, err
	}
	vp.Segments = append(vp.Segments, ast.VariantPathSegment{Name: name})

	// Subsequent segments: `.field` | `[expr]` | `:field` (rare).
	for {
		switch {
		case p.isType(models.TokenTypePeriod):
			p.advance()
			n, err := p.parseVariantFieldName()
			if err != nil {
				return nil, err
			}
			vp.Segments = append(vp.Segments, ast.VariantPathSegment{Name: n})
		case p.isType(models.TokenTypeColon):
			p.advance()
			n, err := p.parseVariantFieldName()
			if err != nil {
				return nil, err
			}
			vp.Segments = append(vp.Segments, ast.VariantPathSegment{Name: n})
		case p.isType(models.TokenTypeLBracket):
			p.advance() // Consume [
			idx, err := p.parseExpression()
			if err != nil {
				return nil, err
			}
			if !p.isType(models.TokenTypeRBracket) {
				return nil, p.expectedError("]")
			}
			p.advance() // Consume ]
			vp.Segments = append(vp.Segments, ast.VariantPathSegment{Index: idx})
		default:
			return vp, nil
		}
	}
}

// parseVariantFieldName consumes one VARIANT path field name, which may be
// a bare identifier or a double-quoted string. Returns the name and