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intellij-sdk-code-samples/topics/basics/architectural_overview/psi_elements.md
Jakub Chrzanowski 4e802980f2
Webhelp migration (#347) 
* [webhelp] Fixes for TXP00152, TXP00002, test build 27 Jul 22:26

* [webhelp] Fixes for Part #4 TXP00010, EXCEPT decimal numbers in section titles

* [webhelp] Fixes for Part #5 TXP00017

* [webhelp] Fixes for Part #4 TXP00010 - removed numbers from page section titles in "Custom Language Support Tutorial" and "Testing a Custom Language Plugin".

* [webhelp] Removed numbers from page section titles in rest of project *.md files.

* [new webhelp] Build #44 changes

* [new webhelp] Maintenance merge from master

* [new webhelp] Add placeholder file for webhelp import.

* [webhelp] Correct redirects for file name changes

* [webhelp] TOC not needed in webhelp

* [format] {:toc} not needed for webhelp

* add {:disable-links} to ensure demo links are not interpreted as real links.

* Put all badges on the same line to simplify composition.

* formatter.md: fix upsource link

* fix some links

* api_changes_list.md: remove note

* migrate to webhelp - initial

* fix GH edit URL

* remove sdkdocs-template setup in VCS config

* remove recently_updated.md

* restore COC/CONTRIBUTING.md

* api_changes_list.md: remove note

* useful_links.md: IPE

Co-authored-by: JohnHake <john.hake@jetbrains.com>
Co-authored-by: Yann Cébron <yann.cebron@jetbrains.com>
2021-01-14 16:07:39 +01:00

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A PSI (Program Structure Interface) file represents a hierarchy of PSI elements (so-called PSI trees). A single PSI file (itself being a PSI element) may contain several PSI trees in specific programming languages. A PSI element, in its turn, can have child PSI elements.

PSI elements and operations at the level of individual PSI elements are used to explore the source code's internal structure as it is interpreted by the IntelliJ Platform. For example, you can use PSI elements to perform code analysis, such as code inspections or intention actions.

The PsiElement class is the common base class for PSI elements.

How do I get a PSI element?

  • From an action: e.getData(LangDataKeys.PSI_ELEMENT). Note: if an editor is currently open and the element under caret is a reference, this will return the result of resolving the reference. This may or may not be what you need.
  • From a file by offset: PsiFile.findElementAt(). Note: this returns the lowest level element ("leaf") at the specified offset, normally a lexer token. Most likely, you should use PsiTreeUtil.getParentOfType() to find the element you really need.
  • By iterating through a PSI file: using a PsiRecursiveElementWalkingVisitor.
  • By resolving a reference: PsiReference.resolve()

What can I do with PSI elements?

See PSI Cook Book