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/* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
* Use of this file is governed by the BSD 3-clause license that
* can be found in the LICENSE.txt file in the project root.
*/
#pragma once
#include "support/Any.h"
namespace antlr4 {
namespace tree {
/// <summary>
/// This interface defines the basic notion of a parse tree visitor. Generated
/// visitors implement this interface and the {@code XVisitor} interface for
/// grammar {@code X}.
/// </summary>
/// @param <T> The return type of the visit operation. Use <seealso cref="Void"/> for
/// operations with no return type. </param>
// ml: no template parameter here, to avoid the need for virtual template functions. Instead we have our Any class.
class ANTLR4CPP_PUBLIC ParseTreeVisitor {
public:
virtual ~ParseTreeVisitor();
/// <summary>
/// Visit a parse tree, and return a user-defined result of the operation.
/// </summary>
/// <param name="tree"> The <seealso cref="ParseTree"/> to visit. </param>
/// <returns> The result of visiting the parse tree. </returns>
virtual std::any visit(ParseTree *tree) = 0;
/// <summary>
/// Visit the children of a node, and return a user-defined result of the
/// operation.
/// </summary>
/// <param name="node"> The <seealso cref="ParseTree"/> whose children should be visited. </param>
/// <returns> The result of visiting the children of the node. </returns>
virtual std::any visitChildren(ParseTree *node) = 0;
/// <summary>
/// Visit a terminal node, and return a user-defined result of the operation.
/// </summary>
/// <param name="node"> The <seealso cref="TerminalNode"/> to visit. </param>
/// <returns> The result of visiting the node. </returns>
virtual std::any visitTerminal(TerminalNode *node) = 0;
/// <summary>
/// Visit an error node, and return a user-defined result of the operation.
/// </summary>
/// <param name="node"> The <seealso cref="ErrorNode"/> to visit. </param>
/// <returns> The result of visiting the node. </returns>
virtual std::any visitErrorNode(ErrorNode *node) = 0;
};
} // namespace tree
} // namespace antlr4