[terminal] IJ-MR-158015 Refactor FusAwareTtyBasedDataStream

Use delegation instead of inheritance. Make the class private.

GitOrigin-RevId: 249caf3ac6ab166dd715e172692477f81949ebd5

plugins/terminal/backend/src/com/intellij/terminal/backend/TerminalSessionStart.kt

@@ -15,6 +15,7 @@ import com.jediterm.core.typeahead.TerminalTypeAheadManager
 import com.jediterm.core.util.TermSize
 import com.jediterm.terminal.TerminalExecutorServiceManager
 import com.jediterm.terminal.TerminalStarter
+import com.jediterm.terminal.TtyBasedArrayDataStream
 import com.jediterm.terminal.TtyConnector
 import com.jediterm.terminal.model.JediTermTypeAheadModel
 import com.jediterm.terminal.model.StyleState
@@ -23,7 +24,6 @@ import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.cancel
 import kotlinx.coroutines.flow.asSharedFlow
 import kotlinx.coroutines.launch
-import org.jetbrains.plugins.terminal.FusAwareTtyBasedDataStream
 import org.jetbrains.plugins.terminal.LocalBlockTerminalRunner
 import org.jetbrains.plugins.terminal.ShellStartupOptions
 import org.jetbrains.plugins.terminal.fus.BackendOutputActivity
@@ -115,7 +115,7 @@ private fun createJediTermServices(
   val terminalStarter = StopAwareTerminalStarter(
     controller,
     connector,
-    FusAwareTtyBasedDataStream(connector, fusActivity),
+    enableFus(TtyBasedArrayDataStream(connector), fusActivity),
     typeAheadManager,
     executorService,
     fusActivity

plugins/terminal/backend/src/com/intellij/terminal/backend/fus/BackendLatencyServiceImpl.kt

@@ -5,6 +5,8 @@ import com.intellij.platform.rpc.UID
 import com.intellij.terminal.session.TerminalContentUpdatedEvent
 import com.intellij.terminal.session.TerminalWriteBytesEvent
 import com.jediterm.core.util.TermSize
+import com.jediterm.terminal.TerminalDataStream
+import com.jediterm.terminal.TtyBasedArrayDataStream
 import com.jediterm.terminal.TtyConnector
 import fleet.multiplatform.shims.ConcurrentHashMap
 import org.jetbrains.plugins.terminal.fus.BackendLatencyService
@@ -38,6 +40,9 @@ internal class BackendLatencyServiceImpl : BackendLatencyService {
 internal fun enableFus(ttyConnector: TtyConnector, fusActivity: BackendOutputActivity): TtyConnector =
   FusAwareTtyConnector(ttyConnector, fusActivity)
 
+internal fun enableFus(stream: TerminalDataStream, fusActivity: BackendOutputActivity): TerminalDataStream =
+  FusAwareTtyBasedDataStream(stream, fusActivity)
+
 private val backendTypingActivityByByteArray = ConcurrentHashMap<ByteArray, BackendTypingActivityImpl>()
 
 private class BackendTypingActivityImpl(override val id: Int, private val bytes: ByteArray) : BackendTypingActivity {
@@ -334,6 +339,36 @@ private class IdentityWrapper<T : Any>(private val instance: T) {
   override fun hashCode(): Int = System.identityHashCode(instance)
 }
 
+private class FusAwareTtyBasedDataStream(
+  private val original: TerminalDataStream,
+  private val fusActivity: BackendOutputActivity,
+) : TerminalDataStream {
+  override fun getChar(): Char {
+    @Suppress("UsePropertyAccessSyntax")
+    val result = original.getChar()
+    fusActivity.charsProcessed(1)
+    return result
+  }
+
+  override fun pushChar(c: Char) {
+    fusActivity.charsProcessed(-1)
+    original.pushChar(c)
+  }
+
+  override fun readNonControlCharacters(maxChars: Int): String? {
+    val result = original.readNonControlCharacters(maxChars)
+    fusActivity.charsProcessed(result.length)
+    return result
+  }
+
+  override fun pushBackBuffer(bytes: CharArray, length: Int) {
+    fusActivity.charsProcessed(-length)
+    original.pushBackBuffer(bytes, length)
+  }
+
+  override fun isEmpty(): Boolean = original.isEmpty
+}
+
 private fun <T : Any> T.toIdentity(): IdentityWrapper<T> = IdentityWrapper(this)
 
 private val LOG = logger<BackendLatencyService>()

plugins/terminal/src/org/jetbrains/plugins/terminal/FusAwareTtyBasedDataStream.kt

@@ -1,36 +0,0 @@
-// 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.plugins.terminal
-
-import com.jediterm.terminal.TtyBasedArrayDataStream
-import com.jediterm.terminal.TtyConnector
-import org.jetbrains.annotations.ApiStatus
-import org.jetbrains.plugins.terminal.fus.BackendOutputActivity
-
-@ApiStatus.Internal
-class FusAwareTtyBasedDataStream(
-  connector: TtyConnector,
-  private val fusActivity: BackendOutputActivity,
-) : TtyBasedArrayDataStream(connector) {
-
-  override fun getChar(): Char {
-    val result = super.getChar()
-    fusActivity.charsProcessed(1)
-    return result
-  }
-
-  override fun readNonControlCharacters(maxChars: Int): String {
-    val result = super.readNonControlCharacters(maxChars)
-    fusActivity.charsProcessed(result.length)
-    return result
-  }
-
-  override fun pushChar(c: Char) {
-    fusActivity.charsProcessed(-1)
-    super.pushChar(c)
-  }
-
-  override fun pushBackBuffer(bytes: CharArray, length: Int) {
-    fusActivity.charsProcessed(-length)
-    super.pushBackBuffer(bytes, length)
-  }
-}