Method parseRelationStatement

pkg/dsl/parser/parser.go:457–494

parseRelationStatement method parses a RELATION statement and returns a RelationStatement AST node

(entityName string)

// parseRelationStatement method parses a RELATION statement and returns a RelationStatement AST node
func (p *Parser) parseRelationStatement(entityName string) (*ast.RelationStatement, error) {
	// create a new RelationStatement object and set its Relation field to the currentToken
	stmt := &ast.RelationStatement{Relation: p.currentToken}

	// expect the next token to be an identifier token, and set the RelationStatement's Name field to the identifier's value
	if !p.expectAndNext(token.IDENT) {
		return nil, p.Error()
	}
	stmt.Name = p.currentToken
	relationName := stmt.Name.Literal

	// expect the next token to be a SIGN token, indicating the start of the relation type(s)
	if !p.expect(token.SIGN) {
		return nil, p.Error()
	}

	// loop through the relation types until no more SIGN tokens are encountered
	for p.peekTokenIs(token.SIGN) {
		// parse a RelationTypeStatement and append it to the RelationStatement's RelationTypes field
		relationStatement, err := p.parseRelationTypeStatement()
		if err != nil {
			return nil, p.Error()
		}
		stmt.RelationTypes = append(stmt.RelationTypes, *relationStatement)
	}

	key := utils.Key(entityName, relationName)

	// add the relation reference to the Parser's relationReferences and relationalReferences maps
	err := p.references.AddRelationReferences(key, stmt.RelationTypes)
	if err != nil {
		p.duplicationError(key) // Generate an error message indicating a duplication error
		return nil, p.Error()
	}

	// return the parsed RelationStatement and nil for the error value
	return stmt, nil
}

// parseRelationTypeStatement method parses a single relation type within a RELATION statement and returns a RelationTypeStatement AST node
func (p *Parser) parseRelationTypeStatement() (*ast.RelationTypeStatement, error) {