IntelliJ Platform Plugin SDK Help

Symbols

A symbol is a semantic element in some model, e.g., language model or framework model. The IntelliJ Platform uses Symbol to represent symbols, and Symbol serves as a link between Platform APIs, such as navigation, finding usages, or renaming. The platform obtains the target symbol from a declaration or by resolving a reference, and then uses it to perform an action. The PsiElement is considered as an element in the source tree (enhanced ASTNode ). Symbol decouples semantic actions from PSI.

A Symbol is not required to be backed by a PsiElement, and it is incorrect to try to obtain the PsiElement from a Symbol.
Symbol is not required to be bound to a Project as well, meaning the same instance might be shared between projects.

Examples:

  • Java local variable is a symbol in Java language model, it's backed by a PsiVariable element;

  • Compiled class is a symbol in JVM model, it's backed by JDK library stubs, and it's not bound to any project;

  • Spring Bean is a symbol in Spring framework model, it's defined on-the-fly by framework support (not backed by a PsiElement) and bound to a Project;

  • Database column is a symbol defined by data source (not backed by a PsiElement) and not bound to a Project since DB elements might be shared between projects.

Lifecycle

The Symbol instance is expected to stay valid within a single read action, which means it's safe to pass the instance to different APIs. A Symbol instance should not be referenced between read actions. One should create a pointer via Symbol.createPointer() in the current read action, and then call Pointer.dereference() to obtain a Symbol instance in the subsequent read action.

Last modified: 14 January 2021