Symbols

A symbol is a semantic element in some model, e.g., language 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. This API allows implementing the same functionalities as in the References and Resolve mechanism, but it is a more abstract concept not limited to connecting only PSI elements. 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 database elements might be shared between projects.

See also Web Symbols.