/*
 * 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;

import org.antlr.v4.runtime.misc.Interval;
import org.antlr.v4.runtime.tree.ErrorNode;
import org.antlr.v4.runtime.tree.ErrorNodeImpl;
import org.antlr.v4.runtime.tree.ParseTree;
import org.antlr.v4.runtime.tree.ParseTreeListener;
import org.antlr.v4.runtime.tree.TerminalNode;
import org.antlr.v4.runtime.tree.TerminalNodeImpl;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

A rule invocation record for parsing.
 Contains all of the information about the current rule not stored in the
 RuleContext. It handles parse tree children list, Any ATN state
 tracing, and the default values available for rule invocations:
 start, stop, rule index, current alt number.
 Subclasses made for each rule and grammar track the parameters,
 return values, locals, and labels specific to that rule. These
 are the objects that are returned from rules.
 Note text is not an actual field of a rule return value; it is computed
 from start and stop using the input stream's toString() method.  I
 could add a ctor to this so that we can pass in and store the input
 stream, but I'm not sure we want to do that.  It would seem to be undefined
 to get the .text property anyway if the rule matches tokens from multiple
 input streams.
 I do not use getters for fields of objects that are used simply to
 group values such as this aggregate.  The getters/setters are there to
 satisfy the superclass interface.
/** A rule invocation record for parsing.
 *
 *  Contains all of the information about the current rule not stored in the
 *  RuleContext. It handles parse tree children list, Any ATN state
 *  tracing, and the default values available for rule invocations:
 *  start, stop, rule index, current alt number.
 *
 *  Subclasses made for each rule and grammar track the parameters,
 *  return values, locals, and labels specific to that rule. These
 *  are the objects that are returned from rules.
 *
 *  Note text is not an actual field of a rule return value; it is computed
 *  from start and stop using the input stream's toString() method.  I
 *  could add a ctor to this so that we can pass in and store the input
 *  stream, but I'm not sure we want to do that.  It would seem to be undefined
 *  to get the .text property anyway if the rule matches tokens from multiple
 *  input streams.
 *
 *  I do not use getters for fields of objects that are used simply to
 *  group values such as this aggregate.  The getters/setters are there to
 *  satisfy the superclass interface.
 */
public class ParserRuleContext extends RuleContext {
	
If we are debugging or building a parse tree for a visitor,
 we need to track all of the tokens and rule invocations associated
 with this rule's context. This is empty for parsing w/o tree constr.
 operation because we don't the need to track the details about
 how we parse this rule.
/** If we are debugging or building a parse tree for a visitor,
	 *  we need to track all of the tokens and rule invocations associated
	 *  with this rule's context. This is empty for parsing w/o tree constr.
	 *  operation because we don't the need to track the details about
	 *  how we parse this rule.
	 */
	public List<ParseTree> children;

	
For debugging/tracing purposes, we want to track all of the nodes in
 the ATN traversed by the parser for a particular rule.
 This list indicates the sequence of ATN nodes used to match
 the elements of the children list. This list does not include
 ATN nodes and other rules used to match rule invocations. It
 traces the rule invocation node itself but nothing inside that
 other rule's ATN submachine.
 There is NOT a one-to-one correspondence between the children and
 states list. There are typically many nodes in the ATN traversed
 for each element in the children list. For example, for a rule
 invocation there is the invoking state and the following state.
 The parser setState() method updates field s and adds it to this list
 if we are debugging/tracing.
 This does not trace states visited during prediction.
/** For debugging/tracing purposes, we want to track all of the nodes in
	 *  the ATN traversed by the parser for a particular rule.
	 *  This list indicates the sequence of ATN nodes used to match
	 *  the elements of the children list. This list does not include
	 *  ATN nodes and other rules used to match rule invocations. It
	 *  traces the rule invocation node itself but nothing inside that
	 *  other rule's ATN submachine.
	 *
	 *  There is NOT a one-to-one correspondence between the children and
	 *  states list. There are typically many nodes in the ATN traversed
	 *  for each element in the children list. For example, for a rule
	 *  invocation there is the invoking state and the following state.
	 *
	 *  The parser setState() method updates field s and adds it to this list
	 *  if we are debugging/tracing.
	 *
	 *  This does not trace states visited during prediction.
	 */
//	public List<Integer> states;

	public Token start, stop;

	
The exception that forced this rule to return. If the rule successfully completed, this is null. /**
	 * The exception that forced this rule to return. If the rule successfully
	 * completed, this is {@code null}.
	 */
	public RecognitionException exception;

	public ParserRuleContext() { }

	
COPY a ctx (I'm deliberately not using copy constructor) to avoid
 confusion with creating node with parent. Does not copy children
 (except error leaves).
 This is used in the generated parser code to flip a generic XContext
 node for rule X to a YContext for alt label Y. In that sense, it is
 not really a generic copy function.
 If we do an error sync() at start of a rule, we might add error nodes
 to the generic XContext so this function must copy those nodes to
 the YContext as well else they are lost!
/** COPY a ctx (I'm deliberately not using copy constructor) to avoid
	 *  confusion with creating node with parent. Does not copy children
	 *  (except error leaves).
	 *
	 *  This is used in the generated parser code to flip a generic XContext
	 *  node for rule X to a YContext for alt label Y. In that sense, it is
	 *  not really a generic copy function.
	 *
	 *  If we do an error sync() at start of a rule, we might add error nodes
	 *  to the generic XContext so this function must copy those nodes to
	 *  the YContext as well else they are lost!
	 */
	public void copyFrom(ParserRuleContext ctx) {
		this.parent = ctx.parent;
		this.invokingState = ctx.invokingState;

		this.start = ctx.start;
		this.stop = ctx.stop;

		// copy any error nodes to alt label node
		if ( ctx.children!=null ) {
			this.children = new ArrayList<>();
			// reset parent pointer for any error nodes
			for (ParseTree child : ctx.children) {
				if ( child instanceof ErrorNode ) {
					addChild((ErrorNode)child);
				}
			}
		}
	}

	public ParserRuleContext(ParserRuleContext parent, int invokingStateNumber) {
		super(parent, invokingStateNumber);
	}

	// Double dispatch methods for listeners

	public void enterRule(ParseTreeListener listener) { }
	public void exitRule(ParseTreeListener listener) { }

	
Add a parse tree node to this as a child.  Works for
 internal and leaf nodes. Does not set parent link;
 other add methods must do that. Other addChild methods
 call this.
 We cannot set the parent pointer of the incoming node
 because the existing interfaces do not have a setParent()
 method and I don't want to break backward compatibility for this.
 @since 4.7
/** Add a parse tree node to this as a child.  Works for
	 *  internal and leaf nodes. Does not set parent link;
	 *  other add methods must do that. Other addChild methods
	 *  call this.
	 *
	 *  We cannot set the parent pointer of the incoming node
	 *  because the existing interfaces do not have a setParent()
	 *  method and I don't want to break backward compatibility for this.
	 *
	 *  @since 4.7
	 */
	public <T extends ParseTree> T addAnyChild(T t) {
		if ( children==null ) children = new ArrayList<>();
		children.add(t);
		return t;
	}

	public RuleContext addChild(RuleContext ruleInvocation) {
		return addAnyChild(ruleInvocation);
	}

	
Add a token leaf node child and force its parent to be this node. /** Add a token leaf node child and force its parent to be this node. */
	public TerminalNode addChild(TerminalNode t) {
		t.setParent(this);
		return addAnyChild(t);
	}

	
Add an error node child and force its parent to be this node.
Since:
4.7/** Add an error node child and force its parent to be this node.
	 *
	 * @since 4.7
	 */
	public ErrorNode addErrorNode(ErrorNode errorNode) {
		errorNode.setParent(this);
		return addAnyChild(errorNode);
	}

	
Add a child to this node based upon matchedToken. It creates a TerminalNodeImpl rather than using Parser.createTerminalNode(ParserRuleContext, Token). I'm leaving this in for compatibility but the parser doesn't use this anymore. /** Add a child to this node based upon matchedToken. It
	 *  creates a TerminalNodeImpl rather than using
	 *  {@link Parser#createTerminalNode(ParserRuleContext, Token)}. I'm leaving this
     *  in for compatibility but the parser doesn't use this anymore.
	 */
	@Deprecated
	public TerminalNode addChild(Token matchedToken) {
		TerminalNodeImpl t = new TerminalNodeImpl(matchedToken);
		addAnyChild(t);
		t.setParent(this);
		return t;
	}

	
Add a child to this node based upon badToken. It creates a ErrorNodeImpl rather than using Parser.createErrorNode(ParserRuleContext, Token). I'm leaving this in for compatibility but the parser doesn't use this anymore. /** Add a child to this node based upon badToken.  It
	 *  creates a ErrorNodeImpl rather than using
	 *  {@link Parser#createErrorNode(ParserRuleContext, Token)}. I'm leaving this
	 *  in for compatibility but the parser doesn't use this anymore.
	 */
	@Deprecated
	public ErrorNode addErrorNode(Token badToken) {
		ErrorNodeImpl t = new ErrorNodeImpl(badToken);
		addAnyChild(t);
		t.setParent(this);
		return t;
	}

//	public void trace(int s) {
//		if ( states==null ) states = new ArrayList<Integer>();
//		states.add(s);
//	}

	
Used by enterOuterAlt to toss out a RuleContext previously added as
 we entered a rule. If we have # label, we will need to remove
 generic ruleContext object.
/** Used by enterOuterAlt to toss out a RuleContext previously added as
	 *  we entered a rule. If we have # label, we will need to remove
	 *  generic ruleContext object.
	 */
	public void removeLastChild() {
		if ( children!=null ) {
			children.remove(children.size()-1);
		}
	}

	@Override
	/** Override to make type more specific */
	public ParserRuleContext getParent() {
		return (ParserRuleContext)super.getParent();
	}

	@Override
	public ParseTree getChild(int i) {
		return children!=null && i>=0 && i<children.size() ? children.get(i) : null;
	}

	public <T extends ParseTree> T getChild(Class<? extends T> ctxType, int i) {
		if ( children==null || i < 0 || i >= children.size() ) {
			return null;
		}

		int j = -1; // what element have we found with ctxType?
		for (ParseTree o : children) {
			if ( ctxType.isInstance(o) ) {
				j++;
				if ( j == i ) {
					return ctxType.cast(o);
				}
			}
		}
		return null;
	}

	public TerminalNode getToken(int ttype, int i) {
		if ( children==null || i < 0 || i >= children.size() ) {
			return null;
		}

		int j = -1; // what token with ttype have we found?
		for (ParseTree o : children) {
			if ( o instanceof TerminalNode ) {
				TerminalNode tnode = (TerminalNode)o;
				Token symbol = tnode.getSymbol();
				if ( symbol.getType()==ttype ) {
					j++;
					if ( j == i ) {
						return tnode;
					}
				}
			}
		}

		return null;
	}

	public List<TerminalNode> getTokens(int ttype) {
		if ( children==null ) {
			return Collections.emptyList();
		}

		List<TerminalNode> tokens = null;
		for (ParseTree o : children) {
			if ( o instanceof TerminalNode ) {
				TerminalNode tnode = (TerminalNode)o;
				Token symbol = tnode.getSymbol();
				if ( symbol.getType()==ttype ) {
					if ( tokens==null ) {
						tokens = new ArrayList<TerminalNode>();
					}
					tokens.add(tnode);
				}
			}
		}

		if ( tokens==null ) {
			return Collections.emptyList();
		}

		return tokens;
	}

	public <T extends ParserRuleContext> T getRuleContext(Class<? extends T> ctxType, int i) {
		return getChild(ctxType, i);
	}

	public <T extends ParserRuleContext> List<T> getRuleContexts(Class<? extends T> ctxType) {
		if ( children==null ) {
			return Collections.emptyList();
		}

		List<T> contexts = null;
		for (ParseTree o : children) {
			if ( ctxType.isInstance(o) ) {
				if ( contexts==null ) {
					contexts = new ArrayList<T>();
				}

				contexts.add(ctxType.cast(o));
			}
		}

		if ( contexts==null ) {
			return Collections.emptyList();
		}

		return contexts;
	}

	@Override
	public int getChildCount() { return children!=null ? children.size() : 0; }

	@Override
	public Interval getSourceInterval() {
		if ( start == null ) {
			return Interval.INVALID;
		}
		if ( stop==null || stop.getTokenIndex()<start.getTokenIndex() ) {
			return Interval.of(start.getTokenIndex(), start.getTokenIndex()-1); // empty
		}
		return Interval.of(start.getTokenIndex(), stop.getTokenIndex());
	}

	
Get the initial token in this context.
Note that the range from start to stop is inclusive, so for rules that do not consume anything
(for example, zero length or error productions) this token may exceed stop.
/**
	 * Get the initial token in this context.
	 * Note that the range from start to stop is inclusive, so for rules that do not consume anything
	 * (for example, zero length or error productions) this token may exceed stop.
	 */
	public Token getStart() { return start; }
	
Get the final token in this context.
Note that the range from start to stop is inclusive, so for rules that do not consume anything
(for example, zero length or error productions) this token may precede start.
/**
	 * Get the final token in this context.
	 * Note that the range from start to stop is inclusive, so for rules that do not consume anything
	 * (for example, zero length or error productions) this token may precede start.
	 */
	public Token getStop() { return stop; }

	
Used for rule context info debugging during parse-time, not so much for ATN debugging /** Used for rule context info debugging during parse-time, not so much for ATN debugging */
	public String toInfoString(Parser recognizer) {
		List<String> rules = recognizer.getRuleInvocationStack(this);
		Collections.reverse(rules);
		return "ParserRuleContext"+rules+"{" +
			"start=" + start +
			", stop=" + stop +
			'}';
	}
}