FIR/LC: restructure light identifiers

* introduced KtLightIdentifierBase so that both FIR LC and ULC share
  basic implementations

* detach PsiCompiledElement as per KTIJ-21412,
  while introducing KtLightIdentifierWithOrigin so that
  UastLightIdentifier can still inherit origin computation logic

^KTIJ-21412 In Progress

analysis/symbol-light-classes/src/org/jetbrains/kotlin/light/classes/symbol/FirLightIdentifier.kt

@@ -5,26 +5,17 @@
 
 package org.jetbrains.kotlin.light.classes.symbol
 
-import com.intellij.openapi.util.TextRange
 import com.intellij.psi.PsiElement
-import com.intellij.psi.PsiFile
-import com.intellij.psi.impl.light.LightIdentifier
-import org.jetbrains.kotlin.asJava.elements.PsiElementWithOrigin
 import org.jetbrains.kotlin.analysis.api.symbols.KtSymbol
 import org.jetbrains.kotlin.analysis.api.symbols.markers.KtNamedSymbol
-import org.jetbrains.kotlin.psi.KtNamedDeclaration
+import org.jetbrains.kotlin.asJava.elements.KtLightIdentifierBase
-import org.jetbrains.kotlin.psi.KtPrimaryConstructor
+import org.jetbrains.kotlin.psi.*
-import org.jetbrains.kotlin.psi.KtPropertyAccessor
-import org.jetbrains.kotlin.psi.KtSecondaryConstructor
 import org.jetbrains.kotlin.psi.psiUtil.containingClassOrObject
 
 internal class FirLightIdentifier(
-    private val lightOwner: PsiElement,
+    lightOwner: PsiElement,
     private val firSymbol: KtSymbol?
-) : LightIdentifier(
+) : KtLightIdentifierBase(lightOwner, (firSymbol as? KtNamedSymbol)?.name?.identifierOrNullIfSpecial) {
-    lightOwner.manager,
-    (firSymbol as? KtNamedSymbol)?.name?.identifierOrNullIfSpecial
-), PsiElementWithOrigin<PsiElement> {
 
     override val origin: PsiElement?
         get() = when (val ktDeclaration = firSymbol?.psi) {
@@ -36,10 +27,4 @@ internal class FirLightIdentifier(
             is KtNamedDeclaration -> ktDeclaration.nameIdentifier
             else -> null
         }
-
-    override fun isPhysical(): Boolean = true
-    override fun getParent(): PsiElement = lightOwner
-    override fun getContainingFile(): PsiFile = lightOwner.containingFile
-    override fun getTextRange(): TextRange = origin?.textRange ?: TextRange.EMPTY_RANGE
-    override fun getTextOffset(): Int = origin?.textOffset ?: -1
 }

compiler/light-classes/src/org/jetbrains/kotlin/asJava/elements/KtLightIdentifier.kt

@@ -24,11 +24,21 @@ import com.intellij.psi.impl.light.LightIdentifier
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.psiUtil.containingClassOrObject
 
-open class KtLightIdentifier(
+abstract class KtLightIdentifierBase(
     private val lightOwner: PsiElement,
+    text: String?
+) : LightIdentifier(lightOwner.manager, text), PsiElementWithOrigin<PsiElement> {
+    override fun isPhysical() = true
+    override fun getParent() = lightOwner
+    override fun getContainingFile() = lightOwner.containingFile
+    override fun getTextRange() = origin?.textRange ?: TextRange.EMPTY_RANGE
+    override fun getTextOffset(): Int = origin?.textOffset ?: -1
+}
+
+open class KtLightIdentifierWithOrigin(
+    lightOwner: PsiElement,
     private val ktDeclaration: KtDeclaration?
-) : LightIdentifier(lightOwner.manager, ktDeclaration?.name ?: ""), PsiCompiledElement,
+) : KtLightIdentifierBase(lightOwner, ktDeclaration?.name) {
-    PsiElementWithOrigin<PsiElement> {
     override val origin: PsiElement?
         get() = when (ktDeclaration) {
             is KtSecondaryConstructor -> ktDeclaration.getConstructorKeyword()
@@ -39,12 +49,12 @@ open class KtLightIdentifier(
             is KtNamedDeclaration -> ktDeclaration.nameIdentifier
             else -> null
         }
+}
+
+class KtLightIdentifier(
+    private val lightOwner: PsiElement,
+    ktDeclaration: KtDeclaration?
+) : KtLightIdentifierWithOrigin(lightOwner, ktDeclaration), PsiCompiledElement {
 
     override fun getMirror() = ((lightOwner as? KtLightElement<*, *>)?.clsDelegate as? PsiNameIdentifierOwner)?.nameIdentifier
-
-    override fun isPhysical() = true
-    override fun getParent() = lightOwner
-    override fun getContainingFile() = lightOwner.containingFile
-    override fun getTextRange() = origin?.textRange ?: TextRange.EMPTY_RANGE
-    override fun getTextOffset(): Int = origin?.textOffset ?: -1
 }