FirRenderer: extract separate printer & visitor

compiler/fir/semantics/src/org/jetbrains/kotlin/fir/resolve/dfa/cfg/CFGNodeRenderer.kt

@@ -50,12 +50,14 @@ fun CFGNode<*>.render(): String =
 
                 is ConstExpressionNode -> "Const: ${fir.render()}"
                 is VariableDeclarationNode ->
-                    "Variable declaration: ${buildString {
-                        FirRenderer(
-                            this,
-                            CfgRenderMode
-                        ).visitCallableDeclaration(fir)
-                    }}"
+                    "Variable declaration: ${
+                        buildString {
+                            FirRenderer(
+                                this,
+                                CfgRenderMode
+                            ).Visitor().visitCallableDeclaration(fir)
+                        }
+                    }"
 
                 is VariableAssignmentNode -> "Assignment: ${fir.lValue.render(CfgRenderMode)}"
                 is FunctionCallNode -> "Function call: ${fir.render(CfgRenderMode)}"

compiler/fir/tree/src/org/jetbrains/kotlin/fir/Utils.kt

@@ -83,8 +83,8 @@ val FirContextReceiver.labelName: Name? get() = customLabelName ?: labelNameFrom
 fun FirElement.renderWithType(mode: FirRenderer.RenderMode = FirRenderer.RenderMode.Normal): String = buildString {
     append(this@renderWithType)
     append(": ")
-    this@renderWithType.accept(FirRenderer(this, mode))
+    this@renderWithType.accept(FirRenderer(this, mode).Visitor())
 }
 
 fun FirElement.render(mode: FirRenderer.RenderMode = FirRenderer.RenderMode.Normal): String =
-    buildString { this@render.accept(FirRenderer(this, mode)) }
+    buildString { this@render.accept(FirRenderer(this, mode).Visitor()) }

compiler/fir/tree/src/org/jetbrains/kotlin/fir/renderer/FirPrinter.kt

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2010-2022 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.fir.renderer
+
+import org.jetbrains.kotlin.utils.Printer
+
+abstract class FirPrinter internal constructor(builder: StringBuilder) {
+    private val printer = Printer(builder)
+
+    private var lineBeginning = true
+
+    protected fun print(vararg objects: Any) {
+        if (lineBeginning) {
+            lineBeginning = false
+            printer.print(*objects)
+        } else {
+            printer.printWithNoIndent(*objects)
+        }
+    }
+
+    protected fun println(vararg objects: Any) {
+        print(*objects)
+        printer.printlnWithNoIndent()
+        lineBeginning = true
+    }
+
+    protected fun pushIndent() {
+        printer.pushIndent()
+    }
+
+    protected fun popIndent() {
+        printer.popIndent()
+    }
+
+    protected fun newLine() {
+        println()
+    }
+
+}

compiler/tests-common-new/tests/org/jetbrains/kotlin/test/frontend/fir/handlers/FirDumpHandler.kt

@@ -39,7 +39,7 @@ class FirDumpHandler(
 
         val renderer = FirRendererWithGeneratedDeclarations(info.session, builderForModule)
         allFiles.forEach {
-            it.accept(renderer)
+            it.accept(renderer.Visitor())
         }
     }