IDEA-359853 convert LanguageLevel#previewLevel and #nonPreviewLevel to functions

by Tagir's request

GitOrigin-RevId: 97b051c2dab03ac835a7cae3ebb3665141150d16

java/idea-ui/src/com/intellij/openapi/roots/ui/configuration/LanguageLevelCombo.kt

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+// Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.intellij.openapi.roots.ui.configuration
 
 import com.intellij.ide.JavaUiBundle
@@ -29,7 +29,7 @@ abstract class LanguageLevelCombo @JvmOverloads constructor(
     val items = mutableListOf<Any>()
     items.add(defaultItem ?: "")
 
-    val highestPreviewLevel = LanguageLevel.HIGHEST.previewLevel
+    val highestPreviewLevel = LanguageLevel.HIGHEST.getPreviewLevel()
     val highestWithPreview = highestPreviewLevel ?: LanguageLevel.HIGHEST
 
     fun MutableList<Any>.filterAndAdd(levels: Collection<LanguageLevel>) = levels.filter(levelFilter).also { addAll(it) }

java/java-syntax/src/com/intellij/pom/java/LanguageLevel.kt

@@ -106,25 +106,23 @@ enum class LanguageLevel {
   /**
    * @return corresponding preview level, or `null` if level has no paired preview level
    */
-  val previewLevel: LanguageLevel?
-    get() {
-      if (this.isPreview) return this
-      try {
-        return valueOf(name + "_PREVIEW")
-      }
-      catch (_: IllegalArgumentException) {
-        return null
-      }
+  fun getPreviewLevel(): LanguageLevel? {
+    if (isPreview) return this
+    try {
+      return valueOf(name + "_PREVIEW")
     }
+    catch (_: IllegalArgumentException) {
+      return null
+    }
+  }
 
   /**
    * @return corresponding non-preview level; this if this level is non-preview already
    */
-  val nonPreviewLevel: LanguageLevel
-    get() {
-      if (!this.isPreview) return this
-      return requireNotNull(ourStandardVersions[myVersion.feature])
-    }
+  fun getNonPreviewLevel(): LanguageLevel {
+    if (!isPreview) return this
+    return requireNotNull(ourStandardVersions[myVersion.feature])
+  }
 
   val presentableText: @Nls String
     get() = myPresentableText()

jvm/jvm-analysis-impl/src/com/intellij/codeInspection/JavaApiUsageInspection.kt

@@ -1,4 +1,4 @@
-// Copyright 2000-2023 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+// Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package com.intellij.codeInspection
 
 import com.intellij.analysis.JvmAnalysisBundle
@@ -170,7 +170,7 @@ class JavaApiUsageInspection : AbstractBaseUastLocalInspectionTool() {
       if (module != null) {
         languageLevel = getEffectiveLanguageLevel(module)
         if (languageLevel.isUnsupported) {
-          languageLevel = languageLevel.nonPreviewLevel
+          languageLevel = languageLevel.getNonPreviewLevel()
         }
       }
       else if (sourcePsi.containingFile.virtualFile is LightVirtualFile) {

plugins/maven/src/main/java/org/jetbrains/idea/maven/importing/MavenImportUtil.kt

@@ -1,4 +1,4 @@
-// Copyright 2000-2024 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+// Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 package org.jetbrains.idea.maven.importing
 
 import com.intellij.build.events.MessageEvent
@@ -310,14 +310,14 @@ object MavenImportUtil {
   private fun adjustPreviewLanguageLevel(mavenProject: MavenProject, level: LanguageLevel): LanguageLevel {
     val enablePreviewProperty = mavenProject.properties.getProperty("maven.compiler.enablePreview")
     if (enablePreviewProperty.toBoolean()) {
-      return level.previewLevel ?: level
+      return level.getPreviewLevel() ?: level
     }
 
     val compilerConfiguration = mavenProject.getPluginConfiguration(COMPILER_PLUGIN_GROUP_ID, COMPILER_PLUGIN_ARTIFACT_ID)
     if (compilerConfiguration != null) {
       val enablePreviewParameter = compilerConfiguration.getChildTextTrim("enablePreview")
       if (enablePreviewParameter.toBoolean()) {
-        return level.previewLevel ?: level
+        return level.getPreviewLevel() ?: level
       }
 
       val compilerArgs = compilerConfiguration.getChild("compilerArgs")
@@ -326,7 +326,7 @@ object MavenImportUtil {
             compilerArgs.getChildren("arg").any { isPreviewText(it) } ||
             compilerArgs.getChildren("compilerArg").any{ isPreviewText(it) }
         ) {
-          return level.previewLevel ?: level
+          return level.getPreviewLevel() ?: level
         }
       }
     }