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Update psi_files.md

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Obfuskator 2015-06-15 19:29:00 +02:00
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basics/architectural_overview/psi_files.md
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@ -15,7 +15,7 @@ class represents an XML file.
Unlike ```VirtualFile``` and ```Document```, which have application scope (even if multiple projects are open, each file is represented by the same ```VirtualFile``` instance), PSI has project scope (the same file is represented by multiple PsiFile instances if the file belongs to multiple projects open at the same time).
## How do I get one?
## How do I get a PSI file?
* From an action: ```e.getData(LangDataKeys.PSI_FILE)```.
* From a VirtualFile: ```PsiManager.getInstance(project).findFile()```
@ -23,25 +23,25 @@ Unlike ```VirtualFile``` and ```Document```, which have application scope (even
* From an element inside the file: ```psiElement.getContainingFile()```
* To find files with a specific name anywhere in the project, use ```FilenameIndex.getFilesByName(project, name, scope)```
## What can I do with one?
## 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 it come from?
## Where does it a PSI file come from?
As the PSI is language-dependent, PSI files are created through the
As PSI is language-dependent, PSI files are created through the
[Language](https://github.com/JetBrains/intellij-community/tree/master/platform/core-api/src/com/intellij/lang/Language.java)
object, using the ```LanguageParserDefinitions.INSTANCE.forLanguage(language).createFile(fileViewProvider)``` method.
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.
## How long does it live?
## How long do PSI files persist?
Again, like documents, PSI files are weakly referenced from the corresponding ```VirtualFile``` instances and can be garbage collected if not referenced by anyone.
Like documents, PSI files are weakly referenced from the corresponding ```VirtualFile``` instances and can be garbage-collected if not referenced by anyone.
## How do I create one?
## How do I create a PSI file?
The
[PsiFileFactory](https://github.com/JetBrains/intellij-community/tree/master/platform/core-api/src/com/intellij/psi/PsiFileFactory.java).
@ -50,18 +50,17 @@ To save the PSI file to disk, use the
[PsiDirectory](https://github.com/JetBrains/intellij-community/tree/master/platform/core-api/src/com/intellij/psi/PsiDirectory.java).
```add()``` method.
## How do I get notified when it changes?
## How do I get notified when PSI files change?
```PsiManager.getInstance(project).addPsiTreeChangeListener()``` allows you to receive notifications about all changes to the PSI tree of a project.
## How do I extend it?
## How do I extend PSI?
The PSI can be extended to support additional languages through custom language plugins.
Developing such plugins is documented in
PSI can be extended to support additional languages through custom language plugins. For more details on developing custom language plugins, see the
[Custom Language Support](reference_guide/custom_language_support.html)
reference guide.
## What are the rules for working with it?
## 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.