/*
 * 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.
 */

package org.antlr.v4.runtime.tree;

import org.antlr.v4.runtime.Parser;
import org.antlr.v4.runtime.RuleContext;
import org.antlr.v4.runtime.Token;

An interface to access the tree of RuleContext objects created during a parse that makes the data structure look like a simple parse tree. This node represents both internal nodes, rule invocations, and leaf nodes, token matches. 
The payload is either a Token or a RuleContext object.
/** An interface to access the tree of {@link RuleContext} objects created
 *  during a parse that makes the data structure look like a simple parse tree.
 *  This node represents both internal nodes, rule invocations,
 *  and leaf nodes, token matches.
 *
 *  <p>The payload is either a {@link Token} or a {@link RuleContext} object.</p>
 */
public interface ParseTree extends SyntaxTree {
	// the following methods narrow the return type; they are not additional methods
	@Override
	ParseTree getParent();
	@Override
	ParseTree getChild(int i);


	
Set the parent for this node.
 This is not backward compatible as it changes
 the interface but no one was able to create custom
 nodes anyway so I'm adding as it improves internal
 code quality.
 One could argue for a restructuring of
 the class/interface hierarchy so that
 setParent, addChild are moved up to Tree
 but that's a major change. So I'll do the
 minimal change, which is to add this method.
 @since 4.7
/** Set the parent for this node.
	 *
	 *  This is not backward compatible as it changes
	 *  the interface but no one was able to create custom
	 *  nodes anyway so I'm adding as it improves internal
	 *  code quality.
	 *
	 *  One could argue for a restructuring of
	 *  the class/interface hierarchy so that
	 *  setParent, addChild are moved up to Tree
	 *  but that's a major change. So I'll do the
	 *  minimal change, which is to add this method.
	 *
	 *  @since 4.7
	 */
	void setParent(RuleContext parent);

	
The ParseTreeVisitor needs a double dispatch method. /** The {@link ParseTreeVisitor} needs a double dispatch method. */
	<T> T accept(ParseTreeVisitor<? extends T> visitor);

	
Return the combined text of all leaf nodes. Does not get any
 off-channel tokens (if any) so won't return whitespace and
 comments if they are sent to parser on hidden channel.
/** Return the combined text of all leaf nodes. Does not get any
	 *  off-channel tokens (if any) so won't return whitespace and
	 *  comments if they are sent to parser on hidden channel.
	 */
	String getText();

	
Specialize toStringTree so that it can print out more information
	based upon the parser.
/** Specialize toStringTree so that it can print out more information
	 * 	based upon the parser.
	 */
	String toStringTree(Parser parser);
}