org.antlr.v4.runtime.ParserRuleContext Maven / Gradle / Ivy
/*
* Copyright (c) 2012-2016 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.
*/
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.
*/
public List 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.
*/
// public List states;
public Token start, stop;
/**
* 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.
*
* 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 ErrorNodeImpl ) {
this.children.add(child);
((ErrorNodeImpl) child).parent = this;
}
}
}
}
public ParserRuleContext(ParserRuleContext parent, int invokingStateNumber) {
super(parent, invokingStateNumber);
}
// Double dispatch methods for listeners
public void enterRule(ParseTreeListener listener) { }
public void exitRule(ParseTreeListener listener) { }
/** Does not set parent link; other add methods do that */
public TerminalNode addChild(TerminalNode t) {
if ( children==null ) children = new ArrayList();
children.add(t);
return t;
}
public RuleContext addChild(RuleContext ruleInvocation) {
if ( children==null ) children = new ArrayList();
children.add(ruleInvocation);
return ruleInvocation;
}
/** 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);
}
}
// public void trace(int s) {
// if ( states==null ) states = new ArrayList();
// states.add(s);
// }
public TerminalNode addChild(Token matchedToken) {
TerminalNodeImpl t = new TerminalNodeImpl(matchedToken);
addChild(t);
t.parent = this;
return t;
}
public ErrorNode addErrorNode(Token badToken) {
ErrorNodeImpl t = new ErrorNodeImpl(badToken);
addChild(t);
t.parent = this;
return t;
}
@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 T getChild(Class 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 getTokens(int ttype) {
if ( children==null ) {
return Collections.emptyList();
}
List 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();
}
tokens.add(tnode);
}
}
}
if ( tokens==null ) {
return Collections.emptyList();
}
return tokens;
}
public T getRuleContext(Class ctxType, int i) {
return getChild(ctxType, i);
}
public List getRuleContexts(Class ctxType) {
if ( children==null ) {
return Collections.emptyList();
}
List contexts = null;
for (ParseTree o : children) {
if ( ctxType.isInstance(o) ) {
if ( contexts==null ) {
contexts = new ArrayList();
}
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() rules = recognizer.getRuleInvocationStack(this);
Collections.reverse(rules);
return "ParserRuleContext"+rules+"{" +
"start=" + start +
", stop=" + stop +
'}';
}
}
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