From c7c33b133002b8adacdcfd10a9df196ea2b648a8 Mon Sep 17 00:00:00 2001
From: Googler <jcater@google.com>
Date: Thu, 9 May 2024 10:25:49 -0700
Subject: [PATCH] Add visitor pattern for transition factories.

Part of #22248.

PiperOrigin-RevId: 632193752
Change-Id: Ic41afbc4ec508ad08615a8861278d5593bb73849
---
 .../config/transitions/ComposingTransitionFactory.java |  6 ++++++
 .../analysis/config/transitions/TransitionFactory.java | 10 ++++++++++
 2 files changed, 16 insertions(+)

diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/transitions/ComposingTransitionFactory.java b/src/main/java/com/google/devtools/build/lib/analysis/config/transitions/ComposingTransitionFactory.java
index 74c9cf100320f5..055ea54c5b1b21 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/transitions/ComposingTransitionFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/transitions/ComposingTransitionFactory.java
@@ -100,4 +100,10 @@ public boolean isTool() {
   public boolean isSplit() {
     return transitionFactory1().isSplit() || transitionFactory2().isSplit();
   }
+
+  @Override
+  public void visit(Visitor<T> visitor) {
+    this.transitionFactory1().visit(visitor);
+    this.transitionFactory2().visit(visitor);
+  }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/transitions/TransitionFactory.java b/src/main/java/com/google/devtools/build/lib/analysis/config/transitions/TransitionFactory.java
index 726dd44931e70a..0d15a9a09c0fd1 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/transitions/TransitionFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/transitions/TransitionFactory.java
@@ -76,4 +76,14 @@ default boolean isTool() {
   default boolean isSplit() {
     return false;
   }
+
+  /** Visit this trnsition factory with the given visitor. */
+  default void visit(Visitor<T> visitor) {
+    visitor.visit(this);
+  }
+
+  /** Interface used to progressively visit transitions. */
+  interface Visitor<T extends TransitionFactory.Data> {
+    void visit(TransitionFactory<T> factory);
+  }
 }