The set of IntelliJ IDEA features which are supported for custom languages includes:
In addition, IDEA provides a powerful framework on which additional intelligence features, like refactorings and code analysis, can be implemented.
If you have any questions or comments related to the Language API or any other aspects of IntelliJ IDEA plugin development, feel free to ask them in the jetbrains.intellij.openapi newsgroup on the news.jetbrains.com news server, or in the corresponding Web forum. The newsgroup is monitored by JetBrains developers who will be able to help you with the development.
The information in this document has been updated to cover the API changes and new features of IntelliJ IDEA 8.0.
The first step in developing a custom language plugin is registering a file type the language will be associated with. IDEA determines the type of a file by looking at its file name. Thus, a custom language can only be associated with specific file names or extensions - it is not currently possible to create a language which will be applied to files with specific content, like, for example, a specific XML root namespace.
A custom language file type is a class derived from LanguageFileType, which passes a Language implementation class to its base class constructor. To register a file type, the plugin developer provides an implementation of the FileTypeFactory interface, which is registered via the com.intellij.fileTypeFactory extension point.