/*
* 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
*
* http://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 com.facebook.presto.sql.planner.plan;
import java.util.List;
import static com.facebook.presto.sql.planner.plan.ChildReplacer.replaceChildren;
import static com.google.common.base.Verify.verify;
import static com.google.common.collect.ImmutableList.toImmutableList;
public abstract class SimplePlanRewriter<C>
extends PlanVisitor<SimplePlanRewriter.RewriteContext<C>, PlanNode>
{
public static <C> PlanNode rewriteWith(SimplePlanRewriter<C> rewriter, PlanNode node)
{
return node.accept(rewriter, new RewriteContext<>(rewriter, null));
}
public static <C> PlanNode rewriteWith(SimplePlanRewriter<C> rewriter, PlanNode node, C context)
{
return node.accept(rewriter, new RewriteContext<>(rewriter, context));
}
@Override
protected PlanNode visitPlan(PlanNode node, RewriteContext<C> context)
{
return context.defaultRewrite(node, context.get());
}
public static class RewriteContext<C>
{
private final C userContext;
private final SimplePlanRewriter<C> nodeRewriter;
private RewriteContext(SimplePlanRewriter<C> nodeRewriter, C userContext)
{
this.nodeRewriter = nodeRewriter;
this.userContext = userContext;
}
public C get()
{
return userContext;
}
/**
* Invoke the rewrite logic recursively on children of the given node and swap it
* out with an identical copy with the rewritten children
*/
public PlanNode defaultRewrite(PlanNode node)
{
return defaultRewrite(node, null);
}
/**
* Invoke the rewrite logic recursively on children of the given node and swap it
* out with an identical copy with the rewritten children
*/
public PlanNode defaultRewrite(PlanNode node, C context)
{
List<PlanNode> children = node.getSources().stream()
.map(child -> rewrite(child, context))
.collect(toImmutableList());
return replaceChildren(node, children);
}
/**
* This method is meant for invoking the rewrite logic on children while processing a node
*/
public PlanNode rewrite(PlanNode node, C userContext)
{
PlanNode result = node.accept(nodeRewriter, new RewriteContext<>(nodeRewriter, userContext));
verify(result != null, "nodeRewriter returned null for %s", node.getClass().getName());
return result;
}
/**
* This method is meant for invoking the rewrite logic on children while processing a node
*/
public PlanNode rewrite(PlanNode node)
{
return rewrite(node, null);
}
}
}