A file view provider (see the FileViewProvider class) was introduced in IntelliJ IDEA 6.0. Its main purpose is to manage access to multiple PSI trees within a single file.
For example, a JSPX page has a separate PSI tree for the Java code in it (PsiJavaFile), a separate tree for the XML code (XmlFile), and a separate tree for JSP as a whole JspFile).
Each of the PSI trees covers the entire contents of the file, and contains special "outer language elements" in the places where contents in a different language can be found.
A FileViewProvider instance corresponds to a single VirtualFile, a single Document, and can be used to retrieve multiple PsiFile instances.
How do I get an FVP?
- From a VirtualFile:
PsiManager.getInstance(project).findViewProvider() - From a PSI file:
psiFile.getViewProvider()
What can I do with an FVP?
- To get the list of all languages for which PSI trees exist in a file:
fileViewProvider.getLanguages() - To get the PSI tree for a particular language:
fileViewProvider.getPsi(language), where thelanguageparameter can take values of the Language type defined in StdLanguages class. For example, to get the PSI tree for XML, usefileViewProvider.getPsi(StdLanguages.XML). - To find an element of a particular language at the specified offset in the file:
fileViewProvider.findElementAt(offset,language)
How do I extend the FileViewProvider?
To create a file type that has multiple interspersing trees for different languages, your plugin must contain an extension to the fileType.fileViewProviderFactory extension point available in the IntelliJ Platform core.
This extension point is declared using the FileTypeExtensionPoint bean class.
To access this extension point, create a Java class that implements the FileViewProviderFactory interface, and in this class, override the createFileViewProvider method.
To declare the extension to the fileType.fileViewProviderFactory extension point, to the <extensions> section of the plugin.xml file, add the following syntax:
<extensions>
<fileType.fileViewProviderFactory filetype="%file_type%" implementationClass="%class_name%" />
</extensions>
Where %file_type% refers to the type of the file being created (for example, "JFS"), and the %class_name% refers to the name of your Java class that implements the FileViewProviderFactory interface.