Hosting Your Own Language in Eclipse
- Apr 22, 2005
- FAQ 319: What is eScript?
- FAQ 320: Language integration phase 1: How do I compile and build programs?
- FAQ 321: How do I load source files edited outside Eclipse?
- FAQ 322: How do I run an external builder on my source files?
- FAQ 323: How do I implement a compiler that runs inside Eclipse?
- FAQ 324: How do I react to changes in source files?
- FAQ 325: How do I implement an Eclipse builder?
- FAQ 326: Where are project build specifications stored?
- FAQ 327: How do I add a builder to a given project?
- FAQ 328: How do I implement an incremental project builder?
- FAQ 329: How do I handle setup problems for a given builder?
- FAQ 330: How do I make my compiler incremental?
- FAQ 331: Language integration phase 2: How do I implement a DOM?
- FAQ 332: How do I implement a DOM for my language?
- FAQ 333: How can I ensure that my model is scalable?
- FAQ 334: Language integration phase 3: How do I edit programs?
- FAQ 335: How do I write an editor for my own language?
- FAQ 336: How do I add Content Assist to my language editor?
- FAQ 337: How do I add hover support to my text editor?
- FAQ 338: How do I create problem markers for my compiler?
- FAQ 339: How do I implement Quick Fixes for my own language?
- FAQ 340: How do I support refactoring for my own language?
- FAQ 341: How do I create an Outline view for my own language editor?
- FAQ 342: Language integration phase 4: What are the finishing touches?
- FAQ 343: What wizards do I define for my own language?
- FAQ 344: When does my language need its own nature?
- FAQ 345: When does my language need its own perspective?
- FAQ 346: How do I add documentation and help for my own language?
- FAQ 347: How do I support source-level debugging for my own language?
Through its JDT project, Eclipse has strong support for Java development, such as editing, refactoring, building, launching, and debugging. Likewise, the C development tools (CDT) project aims for similar support for writing C/C++ code. This chapter discusses some of the issues to address when you have your own language and want to host it in Eclipse for writing programs and plug-ins. We look at the various ways of integrating with Eclipse: from no integration to a fully integrated language development environment. To structure our discussion, we take a closer look at eScript, an experimental script language developed especially for this book. As is the case for all examples described in this book, you can find eScript on this book’s CD-ROM or Web site (http://eclipsefaq.org). For more details on eScript, see FAQ 319.
Many questions have been addressed in other FAQs in this book and may be somewhat repetitive. However, if you are planning to implement support for your own programming language, this chapter might serve well as a comprehensive overview of how to approach this big task.
Any classification of integration of a new programming language with Eclipse is somewhat arbitrary. We have identified the following degrees of integration of a new programming language, such as eScript, with Eclipse:
Phase 1—Compiling code and building projects. To obtain full integration with Eclipse in the area of compilation of programs and build processes for your own language, follow the various steps outlined in FAQ 320.
Phase 2—Implementing a DOM. The DOM is an in-memory structural representation of the source code of a program written in your language. Using the structural information contained in the DOM, all kinds of analysis and refactoring tools can be built. For more details, see FAQ 331.
Phase 3—Editing programs. After writing a compiler, a builder, and a DOM, you are ready to consider all the individual steps to build the ultimate Eclipse editor for your language. The steps are outlined in FAQ 334.
Phase 4—Adding the finishing touches. To give your language IDE a professional look, follow the steps outlined in FAQ 342.
If you carefully observe these four phases, you will find that the visual aspects of your language IDE happen late in the process. You will have to do some legwork before you are able to get to the pretty parts. We recommend patience and restraint. Time spent in phases 1 and 2 will be well spent, and once you get to phase 3 and 4, you will be grateful that you followed all the steps we outlined.
FAQ 319: What is eScript?
We designed and implemented eScript to describe the various steps in adding support for a new programming language to Eclipse. Our eScript is not an official product but simply serves as an experiment for this book.
The idea behind eScript is that someone can implement an Eclipse plug-in by using a simple script language instead of using a sometimes complicated and confusing combination of XML and Java. Figure 19.1 is a sample eScript that declares an update site containing a feature that contains a plug-in that contributes to the org.eclipse.ui.actionSets extension point.
Figure 19.1 An eScript example
The eScript language uses as much inferencing as possible. It does not need import statements, type declarations, or even the declaration of a required interface (the example in Figure 19.1 implements IActionDelegate, but nowhere is this specified in the script). Whenever possible, types and identities are inferred from the environment.
Files containing eScript scripts are compiled into Java bytecodes with the eScript compiler. The compiler generates a plugin.xml file and a JAR containing autogenerated Java class files.
See the eScript Web site (http://eclipsefaq.org/escript)