IJPL-163132 Add KMP-compatible codePointAt and toCodePoint implementations to idea-flex-kotlin.skeleton

Also bumped to KFlex 1.10.13


Merge-request: IJ-MR-160215
Merged-by: Codrin Ogreanu <codrin.ogreanu@jetbrains.com>

GitOrigin-RevId: 5726f30797c1eb0341a5b0119cd82fdba9b5da2e

java/java-frontback-psi-impl/gen/com/intellij/lang/java/lexer/_JavaDocLexer.java

@@ -1,6 +1,6 @@
 // Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 
-// Generated by JFlex 1.10.11 http://jflex.de/  (tweaked for IntelliJ platform)
+// Generated by JFlex 1.10.13 http://jflex.de/  (tweaked for IntelliJ platform)
 // source: _JavaDocLexer.flex
 
   /* It's an automatically generated code. Do not modify it. */

java/java-frontback-psi-impl/gen/com/intellij/lang/java/lexer/_JavaLexer.java

@@ -1,6 +1,6 @@
 // Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 
-// Generated by JFlex 1.9.1 http://jflex.de/  (tweaked for IntelliJ platform)
+// Generated by JFlex 1.10.13 http://jflex.de/  (tweaked for IntelliJ platform)
 // source: _JavaLexer.flex
 
 package com.intellij.lang.java.lexer;

tools/lexer/idea-flex-kotlin.skeleton

@@ -153,6 +153,21 @@ companion object {
       return high.code
   }
 
+  /** Returns the character (Unicode code point) at the specified index. */
+  internal fun String.codePointAt(index: Int): Int {
+      val high = this[index]
+      if (high.isHighSurrogate() && index + 1 < this.length) {
+          val low = this[index + 1]
+          if (low.isLowSurrogate()) {
+              return Char.toCodePoint(high, low)
+          }
+      }
+      return high.code
+  }
+
+  internal fun Char.Companion.toCodePoint(high: Char, low: Char): Int =
+      (((high - MIN_HIGH_SURROGATE) shl 10) or (low - MIN_LOW_SURROGATE)) + 0x10000
+
   private fun charCount(codePoint: Int): Int = if (codePoint < 0x10000) 1 else 2