chromium/third_party/angle/src/compiler/translator/IntermRebuild.h

//
// Copyright 2020 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//

#ifndef COMPILER_TRANSLATOR_INTERMREBUILD_H_
#define COMPILER_TRANSLATOR_INTERMREBUILD_H_

#include "compiler/translator/NodeType.h"
#include "compiler/translator/tree_util/IntermTraverse.h"

namespace sh
{

// Walks the tree to rebuild nodes.
// This class is intended to be derived with overridden visitXXX functions.
//
// Each visitXXX function that does not have a Visit parameter simply has the visitor called
// exactly once, regardless of (preVisit) or (postVisit) values.

// Each visitXXX function that has a Visit parameter behaves as follows:
//    * If (preVisit):
//      - The node is visited before children are traversed.
//      - The returned value is used to replace the visited node. The returned value may be the same
//        as the original node.
//      - If multiple nodes are returned, children and post visits of the returned nodes are not
//        preformed, even if it is a singleton collection.
//    * If (childVisit)
//      - If any new children are returned, the node is automatically rebuilt with the new children
//        before post visit.
//      - Depending on the type of the node, null children may be discarded.
//      - Ill-typed children cause rebuild errors. Ill-typed means the node to automatically rebuild
//        cannot accept a child of a certain type as input to its constructor.
//      - Only instances of TIntermAggregateBase can accept Multi results for any of its children.
//        If supplied, the nodes are spliced children at the spot of the original child.
//    * If (postVisit)
//      - The node is visited after any children are traversed.
//      - Only after such a rebuild (or lack thereof), the post-visit is performed.
//
// Nodes in visit functions are allowed to be modified in place, including TIntermAggregateBase
// child sequences.
//
// The default implementations of all the visitXXX functions support full pre and post traversal
// without modifying the visited nodes.
//
class TIntermRebuild : angle::NonCopyable
{ … };

}  // namespace sh

#endif  // COMPILER_TRANSLATOR_INTERMREBUILD_H_