What's the big IDEA? Writing IntelliJ plugins for Kotlin

Given with Egor Andreevich

With Kotlin having full interop with Java, mixed codebases have become common and effective - but have made writing developer tools more challenging. How do you support multiple languages with a single tool? How do you convert existing plugins from Java to Kotlin and is there a way to avoid having to?

This talk will cover UAST (Universal Abstract Syntax Tree), an API for working with languages generically. With UAST you can write a single tool that will work for both Java and Kotlin - no special casing needed. We will talk about how to setup a plugin to use UAST and walk through a sample that works on mixed codebases.

The talk will also dive into the types of problems you can solve by writing an IntelliJ plugin, as well as other applications for UAST outside of IntelliJ IDEA.

Video to follow

Transcript

1. What’s the big IDEA? @strongolopolis @egorand | Writing IntelliJ plugins for Kotlin
2. Life without IDEs
3. Writing Code • Autocompletion • Error highlighting • Autoimports • Refactoring tools
4. • Switching to a different window • Memorizing the commands • Error reporting Running Code
5. Debugging? Profiling?
7. Plugins
9. Gradle
10. Gradle
11. Gradle
12. Plugins • Developer experience • Simplify how you interact with code • Problems you can’t solve with code • Demystifying confusing parts • e.g. concurrency
13. Plugins that we use (and love)
14. SQLDelight
15. Android
16. Plugins that we want
17. Wire
18. Dagger (for Kotlin)
19. Writing one
20. import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } }
21. import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } Imports
22. import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } Imports Classes
23. import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } Imports Classes • Fields
24. import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } Imports Classes • Fields
 • Annotations
25. import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } Imports Classes • Fields
 • Annotations Types
26. import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } Imports Classes • Fields
 • Annotations Types Expressions
27. import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.printlnd(); } } Imports Classes • Fields
 • Annotations Types Expressions Identifiers
28. import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } Imports Classes • Fields
 • Annotations Types Expressions Identifiers Tokens
29. import javax.inject.Inject; class SomeClass {A @Inject String injectedString; private void someMethod() {A System.out.println(injectedString); }A }A Imports Classes • Fields
 • Annotations Types Expressions Identifiers Tokens Psi Psi Psi Psi Psi Psi Psi Psi
30. import javax.inject.Inject; class SomeClass {A @Inject String injectedString; private void someMethod() {A System.out.println(injectedString); }A }A PsiImports PsiClasses PsiFields
 PsiAnnotations PsiTypes PsiExpressions PsiIdentifiers PsiTokens
31. import javax.inject.Inject; class SomeClass {A @Inject String injectedString; private void someMethod() {A System.out.println(injectedString); }A }A PsiJavaToken
32. PsiJavaToken : PsiElement import javax.inject.Inject; class SomeClass {A @Inject String injectedString; private void someMethod() {A System.out.println(injectedString); }A }A
33. import javax.inject.Inject; class SomeClass {A @Inject String injectedString; private void someMethod() {A System.out.println(injectedString); }A }A PsiWhitespace : PsiElement
34. import javax.inject.Inject; class SomeClass {A @Inject String injectedString; private void someMethod() {A System.out.println(injectedString); }A }A PsiType
35. PsiElementType : PsiElement import javax.inject.Inject; class SomeClass {A @Inject String injectedString; private void someMethod() {A System.out.println(injectedString); }A }A import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } }
36. import javax.inject.Inject; class SomeClass {A @Inject String injectedString; private void someMethod() {A System.out.println(injectedString); }A }A import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } val typeElement: PsiTypeElement val type: PsiType = typeElement.type
37. import javax.inject.Inject; class SomeClass {A @Inject String injectedString; private void someMethod() {A System.out.println(injectedString); }A }A import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } val typeElement: PsiTypeElement val type: PsiJavaCodeReferenceElement? = typeElement.innermostComponentReferenceElement
38. PsiJavaCodeReferenceElement : PsiElement, PsiReference import javax.inject.Inject; class SomeClass {A @Inject String injectedString; private void someMethod() {A System.out.println(injectedString); }A }A String
39. public interface PsiReference { /** * Returns the underlying (referencing) element of the reference. * * @return the underlying element of the reference. */ @NotNull PsiElement getElement(); }
40. import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } PsiJavaCodeReferenceElement : PsiElement, PsiReference
41. import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); }A }A
42. import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } PsiFile : PsiElement import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); }A }A
43. import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); }A }A PsiViewer
44. import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } PsiJavaFile : PsiElement import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); }A }A
45. import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } } import javax.inject.Inject; class SomeClass {A @Inject String injectedString; private void someMethod() {A System.out.println(injectedString); }A }A val element: PsiElement val file: PsiFile = element.containingFile
46. import javax.inject.Inject; class SomeClass {A @Inject String injectedString; private void someMethod() {A System.out.println(injectedString); }A }A val file: PsiJavaFile
47. import javax.inject.Inject; class SomeClass {A @Inject String injectedString; private void someMethod() {A System.out.println(injectedString); }A }A import javax.inject.Inject; class SomeClass {A @Inject String injectedString; private void someMethod() {A System.out.println(injectedString); }A }A val file: PsiJavaFile val classes: Array<PsiClass> = file.classes
48. import javax.inject.Inject; class SomeClass {A @Inject String injectedString; private void someMethod() {A System.out.println(injectedString); }A }A import javax.inject.Inject; class SomeClass {A @Inject String injectedString; private void someMethod() {A System.out.println(injectedString); }A }A val file: PsiJavaFile val classes: Array<PsiClass> = file.classes val fields: List<PsiField> = classes.flatMap { it.fields.asList() }
49. import javax.inject.Inject; class SomeClass {A @Inject String injectedString; private void someMethod() {A System.out.println(injectedString); }A }A import javax.inject.Inject; class SomeClass {A @Inject String injectedString; private void someMethod() {A System.out.println(injectedString); }A }A val file: PsiJavaFile val classes: Array<PsiClass> = file.classes val fields: List<PsiField> = classes.flatMap { it.fields.asList() } val injectedFields = fields .filter { it.hasAnnotation(“javax.inject.Inject") }
50. import javax.inject.Inject; class SomeClass {A @Inject String injectedString; private void someMethod() {A System.out.println(injectedString); }A }A val file: PsiJavaFile val classes = Array<PsiClass> = file.classes val fields: List<PsiField> = classes.flatMap { it.fields.asList() } val injectedFields = fields .filter { it.hasAnnotation(“javax.inject.Inject") } val file: PsiJavaFile
51. Application
52. Project
53. Module
54. VirtualFile
55. Document
56. Editor
57. Editor Document val editor: Editor val document: Document = editor.document
58. Document val document: Document val virtualFile: VirtualFile = FileDocumentManager.getInstance().getFile(document) VirtualFile
59. VirtualFile val virtualFile: VirtualFile val document: Document = FileDocumentManager.getInstance().getDocument(virtualFile) Document
60. VirtualFile val virtualFile: VirtualFile val cachedDocument: Document = FileDocumentManager.getInstance().getCachedDocument(virtualFile) Document
61. java.io.File val file: File val virtualFile: VirtualFile = LocalFileSystem.getInstance().findFileByIoFile(file) VirtualFile
62. VirtualFile val virtualFile: VirtualFile val psiFile: PsiFile = PsiManager.getInstance(project).findFile(virtualFile) PsiFile
63. val virtualFile: VirtualFile val psiFile: PsiFile = PsiManager.getInstance(project).findFile(virtualFile) VirtualFile val virtualFile: VirtualFile val psiFile: PsiFile = PsiManager.getInstance(project).findFile(virtualFile) PsiFile
64. plugin.xml
65. <idea-plugin version="2"> <id>com.squareup.ideaplugin.dagger</id> <name>Dagger Plugin</name> <version>2.0.0</version> <vendor email="support@squareup.com" url="http:// square.github.io">Square, Inc.</vendor> <depends>org.jetbrains.kotlin</depends> <project-components...> <extensions defaultExtensionNs="com.intellij"...> </idea-plugin>
66. <idea-plugin version="2"> <id>com.squareup.ideaplugin.dagger</id> <name>Dagger Plugin</name> <version>2.0.0</version> <vendor email="support@squareup.com" url="http:// square.github.io">Square, Inc.</vendor> <depends>org.jetbrains.kotlin</depends> <project-components...> <extensions defaultExtensionNs="com.intellij"...> </idea-plugin> <idea-plugin version="2"> <id>com.squareup.ideaplugin.dagger</id> <name>Dagger Plugin</name> <version>2.0.0</version> <vendor email="support@squareup.com" url="http:// square.github.io">Square, Inc.</vendor> <depends>org.jetbrains.kotlin</depends> <project-components...> <extensions defaultExtensionNs="com.intellij"...> </idea-plugin>
67. <idea-plugin version="2"> <id>com.squareup.ideaplugin.dagger</id> <name>Dagger Plugin</name> <version>2.0.0</version> <vendor email="support@squareup.com" url="http:// square.github.io">Square, Inc.</vendor> <depends>org.jetbrains.kotlin</depends> <project-components...> <extensions defaultExtensionNs="com.intellij"...> </idea-plugin> <project-components...>
68. <idea-plugin version="2"> <id>com.squareup.ideaplugin.dagger</id> <name>Dagger Plugin</name> <version>2.0.0</version> <vendor email="support@squareup.com" url="http:// square.github.io">Square, Inc.</vendor> <depends>org.jetbrains.kotlin</depends> <extensions defaultExtensionNs="com.intellij"...> </idea-plugin> <idea-plugin version=“2”> <id...> <project-components> <component> <implementation-class> com.squareup.idea.dagger.DaggerProjectComponent </implementation-class> </component> </project-components> <extensions defaultExtensionNs="com.intellij"...> </idea-plugin> <project-components> <component> <implementation-class> com.squareup.idea.dagger.DaggerProjectComponent </implementation-class> </component> </project-components>
69. class DaggerProjectComponent : ProjectComponent {A override fun projectOpened() {A println("Hello World!") }A override fun projectClosed() {A println("Goodbye!") }A }A
70. class DaggerProjectComponent( private val project: Project ) : ProjectComponent {A override fun projectOpened() {A println("Hello World!") }A override fun projectClosed() {A println("Goodbye!") }A }A
71. <idea-plugin version=“2”> <id...> <project-components> <component> <implementation-class> com.squareup.idea.dagger.DaggerProjectComponent </implementation-class> </component> </project-components> <extensions defaultExtensionNs="com.intellij"...> </idea-plugin> <extensions defaultExtensionNs="com.intellij"...> </idea-plugin>
72. <idea-plugin version=“2”> <id...> <project-components...> <extensions defaultExtensionNs="com.intellij"> <codeInsight.lineMarkerProvider language="JAVA" implementationClass= “com.squareup.idea.dagger.InjectionLineMarkerProvider" /> </extensions> </idea-plugin> <idea-plugin version=“2”> <id...> <project-components> <component> <implementation-class> com.squareup.idea.dagger.DaggerProjectComponent </implementation-class> </component> </project-components> </idea-plugin> <extensions defaultExtensionNs="com.intellij"> <codeInsight.lineMarkerProvider language="JAVA" implementationClass= “com.squareup.idea.dagger.InjectionLineMarkerProvider" /> </extensions>
73. class InjectionLineMarkerProvider : LineMarkerProvider { override fun getLineMarkerInfo( element: PsiElement ): LineMarkerInfo<*>? { ... } }
74. PSI in mixed codebases
75. import javax.inject.Inject; class SomeClass { @Inject String injectedString; private void someMethod() { System.out.println(injectedString); } }
76. import javax.inject.Inject class SomeClass { @Inject var injectedString: String? = null private fun someMethod() { println(injectedString) } }
78. public class InjectionLineMarkerProvider implements LineMarkerProvider { public LineMarkerInfo getLineMarkerInfo(PsiElement element) { … } else if (element instanceof PsiField) { // Field injection. PsiField fieldElement = (PsiField) element; PsiTypeElement typeElement = fieldElement.getTypeElement(); … } return null; }
80. public class InjectionLineMarkerProvider implements LineMarkerProvider { public LineMarkerInfo getLineMarkerInfo(PsiElement element) { … } else if (element instanceof PsiField) { // Field injection. PsiField fieldElement = (PsiField) element; PsiTypeElement typeElement = fieldElement.getTypeElement(); … } return null; }
83. public class InjectionLineMarkerProvider implements LineMarkerProvider { public LineMarkerInfo getLineMarkerInfo(PsiElement element) { … } else if (element instanceof PsiField) { … } else if (element instanceof KtProperty) { … } return null; }
84. public class InjectionLineMarkerProvider implements LineMarkerProvider { public LineMarkerInfo getLineMarkerInfo(PsiElement element) { … } else if (element instanceof PsiField) { // Field injection. PsiField fieldElement = (PsiField) element; PsiTypeElement typeElement = fieldElement.getTypeElement(); … } else if (element instanceof KtProperty) { ??? } return null; }
85. UAST
86. Abstract Unified Syntax Tree
87. PsiElement PsiFile PsiClass PsiField PsiMethod UElement UFile UClass UField UMethod ⇨
88. val psiElement: PsiElement = ... val uElement: UElement = psiElement.toUElement() val uField: UField = psiElement.toUElementOfType<UField>()
89. class InjectionLineMarkerProvider : LineMarkerProvider { fun getLineMarkerInfo(element: PsiElement): LineMarkerInfo<*>? { val uElement = element.toUElement() if (uElement is UField) { // Field injection. val typeElement = uElement.typeElement … } return null }
91. val psiType = uElement.type
92. “The PsiElement obtained this way is ambiguous. If you need "physical" PsiElement please use UElementKt.getSourcePsiElement(), if you need PsiElement that "emulates" behaviour of Java-elements (PsiClass, PsiMethod, etc.) then please use UElementKt.getAsJavaPsiElement().”
93. interface UElement interface PsiElement interface PsiField interface UField
94. <extensions defaultExtensionNs="com.intellij"> <codeInsight.lineMarkerProvider language="JAVA" implementationClass=“com.squareup.idea.dagger.ILMP" /> </extensions>
95. <extensions defaultExtensionNs="com.intellij"> <codeInsight.lineMarkerProvider language="JAVA" implementationClass=“com.squareup.idea.dagger.ILMP" /> <codeInsight.lineMarkerProvider language="kotlin" implementationClass=“com.squareup.idea.dagger.ILMP" /> </extensions>
96. <extensions defaultExtensionNs="com.intellij"> <codeInsight.lineMarkerProvider language="JAVA" implementationClass=“com.squareup.idea.dagger.ILMP" /> <codeInsight.lineMarkerProvider language="kotlin" implementationClass=“com.squareup.idea.dagger.ILMP" /> </extensions> <extensions defaultExtensionNs="com.intellij"> <codeInsight.lineMarkerProvider language="JAVA" implementationClass=“com.squareup.idea.dagger.ILMP" /> <codeInsight.lineMarkerProvider language="kotlin" implementationClass=“com.squareup.idea.dagger.ILMP" /> </extensions>
97. <idea-plugin> <depends>org.jetbrains.kotlin</depends> <extensions defaultExtensionNs="com.intellij"> <codeInsight.lineMarkerProvider language="JAVA" implementationClass=“com.squareup.idea.dagger.ILMP" /> <codeInsight.lineMarkerProvider language="kotlin" implementationClass=“com.squareup.idea.dagger.ILMP" /> </extensions> </idea-plugin> <idea-plugin> <depends>org.jetbrains.kotlin</depends> <extensions defaultExtensionNs="com.intellij"> <codeInsight.lineMarkerProvider language="JAVA" implementationClass=“com.squareup.idea.dagger.ILMP" /> <codeInsight.lineMarkerProvider language="kotlin" implementationClass=“com.squareup.idea.dagger.ILMP" /> </extensions> </idea-plugin>
98. apply plugin: 'org.jetbrains.intellij'
99. apply plugin: 'org.jetbrains.intellij' intellij {A version “IC-2018.1" pluginName = 'SQLDelight' }A
100. apply plugin: 'org.jetbrains.intellij' intellij {A version “IC-2018.1" pluginName = 'SQLDelight' plugins = [A “org.jetbrains.kotlin:1.2.70-release-IJ2018.1-1” ]A }A
101. apply plugin: 'org.jetbrains.intellij' intellij {A version “IC-2018.1" pluginName = 'SQLDelight' plugins = [A “org.jetbrains.kotlin:1.2.70-release-IJ2018.1-1” ]A }A // Automatically adds tasks.create("runIde")
102. apply plugin: 'org.jetbrains.intellij' intellij { version “IC-2018.1" pluginName = 'SQLDelight' plugins = [ “org.jetbrains.kotlin:1.2.70-release-IJ2018.1-1” ] } // Automatically adds tasks.create("runIde") tasks.create("buildPlugin")
103. PSI UAST vs
104. PSI UAST • JVM language analysis • Language-agnostic types • Language-agnostic features • e.g. querying annotations • APIs that accept it • Language metadata • Text range
105. UAST use cases
106. • Language-agnostic Intellij plugins • Build tools • Lint • IDEA-based annotation processing • Headless IDEA environment UAST use cases
109. @strongolopolis @egorand | Thanks!