Added Inline Type Alias refactoring

CHANGELOG.md

@@ -1,3 +1,4 @@
+- Added Inline Type Alias refactoring: place the caret on a Kotlin `typealias` declaration or one of its type uses, press **Ctrl+Alt+N** or choose **Refactor → Inline...**, then expand every supported Kotlin occurrence or only the selected use and optionally retain the alias declaration; generic arguments, imports, and parenthesisation use the IntelliJ IDEA K2 engine, while **Undo Last Refactoring** restores all changed Kotlin files.
 - Added Change Kotlin Package refactoring: use **Refactor → Change Kotlin Package...** for the active Kotlin file or a folder's recursive Kotlin descendants to update package directives in place; nested files retain their relative package hierarchy, supported Kotlin code references and direct imports update, and **Undo Last Refactoring** restores the original contents.
 - Added Move Kotlin File and Directory refactoring: move the active `.kt` file from **Refactor → Move Kotlin File...**, or right-click a folder and choose **Move Kotlin Directory...** to recursively move its Kotlin files while retaining the selected directory and nested structure below a selected source root/package; matching package directives and supported Kotlin code references are updated, and **Undo Last Refactoring** restores the original locations and contents.
 - Improved Kotlin Inline Variable: local `var` declarations with one initializer and no subsequent writes can now be inlined from either a declaration or selected usage; assignments and increment/decrement writes are rejected before changing the source with the conflicting expression identified.

CoreImpl/pom.xml

@@ -5,7 +5,7 @@
   <parent>
     <groupId>io.github.nbplugins</groupId>
     <artifactId>netbeans-plugin-kotlin</artifactId>
-    <version>0.11.249-SNAPSHOT</version>
+    <version>0.11.250-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
   <artifactId>netbeans-plugin-kotlin-core-impl</artifactId>

KotlinCompilerCliBase/pom.xml

@@ -5,7 +5,7 @@
   <parent>
     <groupId>io.github.nbplugins</groupId>
     <artifactId>netbeans-plugin-kotlin</artifactId>
-    <version>0.11.249-SNAPSHOT</version>
+    <version>0.11.250-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
   <artifactId>netbeans-plugin-kotlin-compiler-cli-base</artifactId>

KotlinFixesImpl/pom.xml

@@ -5,7 +5,7 @@
   <parent>
     <groupId>io.github.nbplugins</groupId>
     <artifactId>netbeans-plugin-kotlin</artifactId>
-    <version>0.11.249-SNAPSHOT</version>
+    <version>0.11.250-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
   <artifactId>netbeans-plugin-kotlin-fixes-impl</artifactId>

KotlinFormatter/pom.xml

@@ -5,7 +5,7 @@
   <parent>
     <groupId>io.github.nbplugins</groupId>
     <artifactId>netbeans-plugin-kotlin</artifactId>
-    <version>0.11.249-SNAPSHOT</version>
+    <version>0.11.250-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
   <artifactId>netbeans-plugin-kotlin-formatter</artifactId>

KotlinHighlighting/pom.xml

@@ -5,7 +5,7 @@
   <parent>
     <groupId>io.github.nbplugins</groupId>
     <artifactId>netbeans-plugin-kotlin</artifactId>
-    <version>0.11.249-SNAPSHOT</version>
+    <version>0.11.250-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
   <artifactId>netbeans-plugin-kotlin-highlighting</artifactId>

KotlinIcons/pom.xml

@@ -5,7 +5,7 @@
   <parent>
     <groupId>io.github.nbplugins</groupId>
     <artifactId>netbeans-plugin-kotlin</artifactId>
-    <version>0.11.249-SNAPSHOT</version>
+    <version>0.11.250-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
   <artifactId>netbeans-plugin-kotlin-icons</artifactId>

KotlinIntentionUtils/pom.xml

@@ -5,7 +5,7 @@
   <parent>
     <groupId>io.github.nbplugins</groupId>
     <artifactId>netbeans-plugin-kotlin</artifactId>
-    <version>0.11.249-SNAPSHOT</version>
+    <version>0.11.250-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
   <artifactId>netbeans-plugin-kotlin-intention-utils</artifactId>

KotlinRefactoring/pom.xml

@@ -5,7 +5,7 @@
   <parent>
     <groupId>io.github.nbplugins</groupId>
     <artifactId>netbeans-plugin-kotlin</artifactId>
-    <version>0.11.249-SNAPSHOT</version>
+    <version>0.11.250-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
   <artifactId>netbeans-plugin-kotlin-refactoring</artifactId>
@@ -279,6 +279,7 @@
                   <includes>
                     <include>org/jetbrains/kotlin/idea/k2/refactoring/inline/KotlinInlinePropertyProcessor.kt</include>
                     <include>org/jetbrains/kotlin/idea/k2/refactoring/inline/KotlinInlineFunctionProcessor.kt</include>
+                    <include>org/jetbrains/kotlin/idea/k2/refactoring/inline/KotlinInlineTypeAliasProcessor.kt</include>
                     <include>org/jetbrains/kotlin/idea/k2/refactoring/inline/KotlinInlineAnonymousFunctionProcessor.kt</include>
                     <include>org/jetbrains/kotlin/idea/k2/refactoring/inline/codeInliner/**</include>
                     <include>org/jetbrains/kotlin/idea/k2/refactoring/util/**</include>

KotlinRefactoring/src/main/kotlin/io/github/nbplugins/kotlin/refactoring/KaInlineTypeAliasComputer.kt

@@ -0,0 +1,161 @@
+/*******************************************************************************
+ * Copyright 2000-2024 JetBrains s.r.o.
+ * Copyright 2026 nbplugins contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ *******************************************************************************/
+package io.github.nbplugins.kotlin.refactoring
+
+import com.intellij.psi.PsiElement
+import com.intellij.psi.util.PsiTreeUtil
+import org.jetbrains.kotlin.analysis.api.analyze
+import org.jetbrains.kotlin.idea.k2.refactoring.inline.codeInliner.TypeAliasUsageReplacementStrategy
+import org.jetbrains.kotlin.idea.references.mainReference
+import org.jetbrains.kotlin.psi.KtFile
+import org.jetbrains.kotlin.psi.KtNameReferenceExpression
+import org.jetbrains.kotlin.psi.KtReferenceExpression
+import org.jetbrains.kotlin.psi.KtTreeVisitorVoid
+import org.jetbrains.kotlin.psi.KtTypeAlias
+
+/**
+ * Prepared IDEA-engine data for a Kotlin **Inline Type Alias** refactoring.
+ *
+ * @param typeAlias declaration selected for expansion
+ * @param strategy actual IDEA K2 replacement strategy responsible for type substitution and shortening
+ * @param usages Kotlin references resolving to [typeAlias], grouped by their session-managed file
+ * @param triggerUsage reference at the invocation caret, when Inline was started from an alias use
+ * @param declarationName simple type-alias name for the UI
+ */
+data class KaInlineTypeAliasResult(
+    val typeAlias: KtTypeAlias,
+    val strategy: TypeAliasUsageReplacementStrategy,
+    val usages: Map<KtFile, List<KtReferenceExpression>>,
+    val triggerUsage: KtReferenceExpression?,
+    val declarationName: String,
+)
+
+/**
+ * User-facing validation failure returned by [KaInlineTypeAliasComputer].
+ *
+ * @param message explanation of why the selected alias cannot be inlined
+ * @param declarationName alias name, when available
+ */
+data class KaInlineTypeAliasError(
+    val message: String,
+    val declarationName: String,
+)
+
+/**
+ * Creates a standalone K2 plan for Kotlin **Inline Type Alias**.
+ *
+ * The computer uses IDEA's [TypeAliasUsageReplacementStrategy] rather than reconstructing an alias
+ * expansion as text. NetBeans owns the dialog, preview, persistence, and undo; the IDEA strategy owns
+ * K2 type substitution, parenthesisation, imports, and reference shortening.
+ *
+ * @param cursorKtFile session-managed Kotlin file containing the invocation caret
+ * @param offset caret offset within [cursorKtFile]
+ * @param projectKtFiles all Kotlin source files currently registered by the standalone session
+ */
+class KaInlineTypeAliasComputer(
+    private val cursorKtFile: KtFile,
+    private val offset: Int,
+    private val projectKtFiles: Collection<KtFile>,
+) {
+
+    /** Result of [compute]. */
+    sealed class Outcome {
+        /** The target alias and IDEA replacement plan are ready. */
+        data class Ready(val result: KaInlineTypeAliasResult) : Outcome()
+
+        /** A type alias was selected but lacks data required by IDEA's replacement engine. */
+        data class Error(val error: KaInlineTypeAliasError) : Outcome()
+
+        /** The caret is neither on a type alias declaration nor a reference to one. */
+        data object NotApplicable : Outcome()
+    }
+
+    /**
+     * Resolves the type alias at the caret and discovers portable Kotlin usages across the active session.
+     *
+     * @return [Outcome.Ready] with the IDEA strategy, [Outcome.Error] for an invalid alias, or
+     *         [Outcome.NotApplicable] when no type alias is selected
+     */
+    fun compute(): Outcome {
+        val element = cursorKtFile.findElementAt(offset) ?: return Outcome.NotApplicable
+        val triggerUsage = PsiTreeUtil.getParentOfType(element, KtReferenceExpression::class.java, false)
+        val typeAlias = resolveTypeAliasFromReference(element)
+            ?: PsiTreeUtil.getParentOfType(element, KtTypeAlias::class.java, false)
+            ?: return Outcome.NotApplicable
+        val declarationName = typeAlias.name ?: return Outcome.Error(
+            KaInlineTypeAliasError("Cannot inline type alias: it has no name.", ""),
+        )
+        if (typeAlias.getTypeReference() == null) {
+            return Outcome.Error(
+                KaInlineTypeAliasError(
+                    "Cannot inline type alias '$declarationName': it has no expanded type.",
+                    declarationName,
+                ),
+            )
+        }
+
+        return Outcome.Ready(
+            KaInlineTypeAliasResult(
+                typeAlias = typeAlias,
+                strategy = TypeAliasUsageReplacementStrategy(typeAlias),
+                usages = findUsages(typeAlias),
+                triggerUsage = triggerUsage?.takeIf { resolvesTo(it, typeAlias) },
+                declarationName = declarationName,
+            ),
+        )
+    }
+
+    /** Resolves a reference at the caret to its declared [KtTypeAlias], when applicable. */
+    private fun resolveTypeAliasFromReference(element: PsiElement): KtTypeAlias? {
+        val reference = PsiTreeUtil.getParentOfType(element, KtNameReferenceExpression::class.java, false)
+            ?: return null
+        return runCatching {
+            analyze(reference) {
+                reference.mainReference?.resolveToSymbol()?.psi as? KtTypeAlias
+            }
+        }.getOrNull()
+    }
+
+    /** Collects K2-resolved Kotlin references to [typeAlias] from every active source file. */
+    private fun findUsages(typeAlias: KtTypeAlias): Map<KtFile, List<KtReferenceExpression>> {
+        val usagesByFile = linkedMapOf<KtFile, MutableList<KtReferenceExpression>>()
+        for (file in projectKtFiles) {
+            val usages = mutableListOf<KtReferenceExpression>()
+            runCatching {
+                analyze(file) {
+                    file.accept(object : KtTreeVisitorVoid() {
+                        override fun visitReferenceExpression(expression: KtReferenceExpression) {
+                            super.visitReferenceExpression(expression)
+                            if (resolvesTo(expression, typeAlias)) usages += expression
+                        }
+                    })
+                }
+            }
+            if (usages.isNotEmpty()) usagesByFile[file] = usages
+        }
+        return usagesByFile
+    }
+
+    /** Checks K2 symbol identity rather than spelling so unrelated same-name aliases are excluded. */
+    private fun resolvesTo(reference: KtReferenceExpression, typeAlias: KtTypeAlias): Boolean =
+        runCatching {
+            analyze(reference) {
+                reference.mainReference?.resolveToSymbol()?.psi == typeAlias
+            }
+        }.getOrDefault(false)
+}

Nbm/pom.xml

@@ -5,7 +5,7 @@
   <parent>
     <groupId>io.github.nbplugins</groupId>
     <artifactId>netbeans-plugin-kotlin</artifactId>
-    <version>0.11.249-SNAPSHOT</version>
+    <version>0.11.250-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
   <artifactId>netbeans-plugin-kotlin-nbm</artifactId>