This repository contains utilities to generate C# code from EXPRESS schema definitions. Resulting code depends on Xbim.Common which contains common interfaces and abstract classes designed for work with generated schema implementations.

This project contains an implementation of part of SDAI which describes structure of EXPRESS language. Parser generated with GPPG/GPLEX is used to load EXPRESS schema into object model. This is a separate project and can be used on its own to perform other tasks based on the instantiated EXPRESS schema. We use this only to feed T4 templates to generate C# code. But it could equally be used for late bingind applications as well as various analyses of the schema.

Generator is not able to process any arbitrary EXPRESS definition but was implemented to the level where it can generate implementation of IFC schemas. It can generate any schema which uses the same constrains and design patterns. EXPRESS language allows for multiple instance inheritance for example which doesn't suit our implementation patterns.

Also validation rules are not implemented. Saying so, it is poossible to use the generator to create stubs for implementation of validation routines. Simple derived attributes are supported but for more complicated cases only a stub is generated with TODO comment and NotImplementedException. So, make sure you check all TODO tasks after the generation.

White generated code will always override existing files, there are special blocs generated in the code which will survive regeneration. At the same time, all classes are generated as partial, so it is possible to define additional functionality in partial files sitting somewhere else in the project.

To access the data using generated schema you can either implement your own IModel and related interfaces or you can use Xbim.IO which can load STEP21 physical representation of the schema into the generated implementation of the schema. You can than use specific implementation of IModel to access, create of change the data. It is also possible to save and load data in XML but that uses configuration and settings specific to IFC and is different for IFC2x3 and IFC4.