From d0a82236c68300d38ef8c0267fa723db96b761f6 Mon Sep 17 00:00:00 2001
From: Jens Schauder <jschauder@vmware.com>
Date: Mon, 28 Nov 2022 10:57:11 +0100
Subject: [PATCH] Dedicate visitor

---
 .../data/relational/core/sql/Subselect.java   |  3 ++
 .../core/sql/render/FromTableVisitor.java     | 14 +----
 .../core/sql/render/SubselectVisitor.java     | 53 +++++++++++++++++++
 3 files changed, 57 insertions(+), 13 deletions(-)
 create mode 100644 spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/render/SubselectVisitor.java

diff --git a/spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/Subselect.java b/spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/Subselect.java
index ab880b8b..31b3eeed 100644
--- a/spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/Subselect.java
+++ b/spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/Subselect.java
@@ -27,6 +27,9 @@ public abstract class Subselect extends AbstractSegment {
 	private final Select select;
 
 	protected Subselect(Select select) {
+
+		super(select);
+
 		this.select = select;
 	}
 
diff --git a/spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/render/FromTableVisitor.java b/spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/render/FromTableVisitor.java
index e8915dd6..b3bf925c 100644
--- a/spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/render/FromTableVisitor.java
+++ b/spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/render/FromTableVisitor.java
@@ -35,7 +35,6 @@ class FromTableVisitor extends TypedSubtreeVisitor<TableLike> {
 
 	private final RenderContext context;
 	private final RenderTarget parent;
-	@Nullable private SelectStatementVisitor delegate;
 	@Nullable private StringBuilder builder = null;
 
 	FromTableVisitor(RenderContext context, RenderTarget parent) {
@@ -50,10 +49,7 @@ class FromTableVisitor extends TypedSubtreeVisitor<TableLike> {
 		builder = new StringBuilder();
 
 		if (segment instanceof InlineQuery) {
-
-			builder.append("(");
-			delegate = new SelectStatementVisitor(context);
-			return Delegation.delegateTo(delegate);
+			return Delegation.delegateTo(new SubselectVisitor(context, builder::append));
 		}
 
 		return super.enterMatched(segment);
@@ -64,14 +60,6 @@ class FromTableVisitor extends TypedSubtreeVisitor<TableLike> {
 
 		Assert.state(builder != null, "Builder must not be null in leaveMatched");
 
-		if (delegate != null) {
-
-			builder.append(delegate.getRenderedPart());
-			builder.append(") ");
-
-			delegate = null;
-		}
-
 		builder.append(NameRenderer.render(context, segment));
 		if (segment instanceof Aliased) {
 			builder.append(" ").append(NameRenderer.render(context, (Aliased) segment));
diff --git a/spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/render/SubselectVisitor.java b/spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/render/SubselectVisitor.java
new file mode 100644
index 00000000..fac89b97
--- /dev/null
+++ b/spring-data-relational/src/main/java/org/springframework/data/relational/core/sql/render/SubselectVisitor.java
@@ -0,0 +1,53 @@
+/*
+ * Copyright 2022 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.relational.core.sql.render;
+
+import org.springframework.data.relational.core.sql.Subselect;
+import org.springframework.lang.Nullable;
+
+public class SubselectVisitor extends TypedSubtreeVisitor<Subselect> {
+
+	private final RenderContext context;
+	private final RenderTarget parent;
+
+	private final SelectStatementVisitor delegate;
+	private final StringBuilder builder = new StringBuilder("(");
+
+	public SubselectVisitor(RenderContext context, RenderTarget parent) {
+
+		this.context = context;
+		this.parent = parent;
+
+		this.delegate = new SelectStatementVisitor(context);
+	}
+
+	@Override
+	Delegation enterMatched(Subselect segment) {
+		return Delegation.delegateTo(delegate);
+	}
+
+	@Override
+	Delegation leaveMatched(Subselect segment) {
+
+		builder.append(delegate.getRenderedPart());
+		builder.append(") ");
+
+		parent.onRendered(builder);
+
+		return super.leaveMatched(segment);
+	}
+
+}