PSI file

The Program Structure Interface, 通常被称为是PSI，在IntelliJ平台上，负责解析文件，创建句法和语义编码模型，PSI集合了平台的许多特性。

A PSI (Program Structure Interface) file is the root of a structure representing the contents of a file as a hierarchy of elements in a particular programming language.

PsiFile 类 是所有PSI文件的共同基类，例如 PsiJavaFile 类 是Java PSI文件的基类

How do I get a PSI file

• From an action: e.getData(LangDataKeys.PSI_FILE).

• From a VirtualFile: PsiManager.getInstance(project).findFile()

• From a Document: PsiDocumentManager.getInstance(project).getPsiFile()

• From an element inside the file: psiElement.getContainingFile()

• 用指定的name在项目project中查找: FilenameIndex.getFilesByName(project, name, scope)

What can I do with a PSI file

Most interesting modification operations are performed on the level of individual PSI elements, not files as a whole.

To iterate over the elements in a file, use psiFile.accept(new PsiRecursiveElementWalkingVisitor()...);

Where does a PSI file come from

As PSI is language-dependent, PSI files are created through the Language object, by using the LanguageParserDefinitions.INSTANCE.forLanguage(language).createFile(fileViewProvider) method.

Like documents, PSI files are created on demand when the PSI is accessed for a particular file.

如何创建PSI file

The PsiFileFactory.getInstance(project).createFileFromText() method creates an in-memory PSI file with the specified contents.

To save the PSI file to disk, use the PsiDirectory.add() method.

What are the rules for working with PSI

Any changes done to the content of PSI files are reflected in documents, so all rules for working with documents (read/write actions, commands, read-only status handling) are in effect。