Postfix Templates
The IntelliJ Platform allows plugins to provide custom postfix templates specific to the supported languages, frameworks, or libraries.
To provide custom postfix templates for an existing or custom language, register an implementation of PostfixTemplateProvider in the com.intellij.codeInsight.template.postfixTemplateProvider extension point (EP).
The PostfixTemplateProvider extension contains the list of templates that extend the PostfixTemplate class. During the code completion mechanism, all postfix template providers registered for the current language are queried for their templates. All templates enabled and applicable in the current context will be added to the completion popup items set.
Examples:
JavaPostfixTemplateProviderproviding Java postfix templatesPyPostfixTemplateProviderproviding Python postfix templates
Postfix Templates Implementation
The simplest way to create a postfix template is by extending the PostfixTemplate class and implementing the key methods:
boolean isApplicable()determining whether the template can be used in the context described by parametersvoid expand()inserting the template content in the editor
Examples:
InstanceofExpressionPostfixTemplatesurrounding an expression with the instanceof checkTryWithResourcesPostfixTemplatewrapping a selected expression in try-with-resources block
Postfix Template Description
All postfix templates must provide descriptions and examples showing the code before and after a template is expanded. The files describing the template must be placed in the plugin's resources in the postfixTemplates/$TEMPLATE_NAME$ where the $TEMPLATE_NAME$ directory must match the simple name of the template class, e.g., for a template implemented in com.example.IntroduceVariablePostfixTemplate class, the directory name should be named as IntroduceVariablePostfixTemplate.
Providing the description explaining the template purpose and context details is achieved by creating the description.html file.
Providing the code snippets showing the template in "before" and "after" expanding states is achieved via the before.$EXTENSION$.template and after.$EXTENSION$.template files accordingly. The $EXTENSION$ placeholder should be replaced with the extension of the template language, e.g., before.kt.template for a Kotlin template.
The code snippets included in the example files can use the <spot> marker, which should surround the most important code parts, e.g., expression to expand and position of the caret after expanding. Marked parts will be highlighted in the settings page, making it easier for users to understand how a template is expanded, e.g.:
before.java.template:
<spot>cart.getProducts()</spot>.varafter.java.template:
List<Product> products = cart.getProducts();<spot></spot>
Template example files can also use the $key placeholder which is replaced with the actual template key in the preview UI, e.g., consider a template with the var key:
The gutter icons for a postfix template class allow navigating to the corresponding description and before/after files in plugin resources.
Example: TryWithResourcesPostfixTemplate directory containing description files for TryWithResourcesPostfixTemplate template.