/*
* [The "BSD license"]
* Copyright (c) 2013 Terence Parr
* Copyright (c) 2013 Sam Harwell
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.antlr.v4.runtime;
import org.antlr.v4.runtime.atn.ATN;
import org.antlr.v4.runtime.atn.ATNState;
import org.antlr.v4.runtime.atn.ActionTransition;
import org.antlr.v4.runtime.atn.AtomTransition;
import org.antlr.v4.runtime.atn.DecisionState;
import org.antlr.v4.runtime.atn.LoopEndState;
import org.antlr.v4.runtime.atn.ParserATNSimulator;
import org.antlr.v4.runtime.atn.PrecedencePredicateTransition;
import org.antlr.v4.runtime.atn.PredicateTransition;
import org.antlr.v4.runtime.atn.PredictionContextCache;
import org.antlr.v4.runtime.atn.RuleStartState;
import org.antlr.v4.runtime.atn.RuleTransition;
import org.antlr.v4.runtime.atn.StarLoopEntryState;
import org.antlr.v4.runtime.atn.Transition;
import org.antlr.v4.runtime.dfa.DFA;
import org.antlr.v4.runtime.misc.Pair;
import java.util.ArrayDeque;
import java.util.BitSet;
import java.util.Collection;
import java.util.Deque;
/** A parser simulator that mimics what ANTLR's generated
* parser code does. A ParserATNSimulator is used to make
* predictions via adaptivePredict but this class moves a pointer through the
* ATN to simulate parsing. ParserATNSimulator just
* makes us efficient rather than having to backtrack, for example.
*
* This properly creates parse trees even for left recursive rules.
*
* We rely on the left recursive rule invocation and special predicate
* transitions to make left recursive rules work.
*
* See TestParserInterpreter for examples.
*/
public class ParserInterpreter extends Parser {
protected final String grammarFileName;
protected final ATN atn;
protected final BitSet pushRecursionContextStates;
protected final DFA[] decisionToDFA; // not shared like it is for generated parsers
protected final PredictionContextCache sharedContextCache =
new PredictionContextCache();
protected final String[] tokenNames;
protected final String[] ruleNames;
protected final Deque<Pair<ParserRuleContext, Integer>> _parentContextStack = new ArrayDeque<Pair<ParserRuleContext, Integer>>();
public ParserInterpreter(String grammarFileName, Collection<String> tokenNames,
Collection<String> ruleNames, ATN atn, TokenStream input)
{
super(input);
this.grammarFileName = grammarFileName;
this.atn = atn;
this.tokenNames = tokenNames.toArray(new String[tokenNames.size()]);
this.ruleNames = ruleNames.toArray(new String[ruleNames.size()]);
this.decisionToDFA = new DFA[atn.getNumberOfDecisions()];
for (int i = 0; i < decisionToDFA.length; i++) {
decisionToDFA[i] = new DFA(atn.getDecisionState(i), i);
}
// identify the ATN states where pushNewRecursionContext must be called
this.pushRecursionContextStates = new BitSet(atn.states.size());
for (ATNState state : atn.states) {
if (!(state instanceof StarLoopEntryState)) {
continue;
}
if (((StarLoopEntryState)state).precedenceRuleDecision) {
this.pushRecursionContextStates.set(state.stateNumber);
}
}
// get atn simulator that knows how to do predictions
setInterpreter(new ParserATNSimulator(this, atn,
decisionToDFA,
sharedContextCache));
}
@Override
public ATN getATN() {
return atn;
}
@Override
public String[] getTokenNames() {
return tokenNames;
}
@Override
public String[] getRuleNames() {
return ruleNames;
}
@Override
public String getGrammarFileName() {
return grammarFileName;
}
/** Begin parsing at startRuleIndex */
public ParserRuleContext parse(int startRuleIndex) {
RuleStartState startRuleStartState = atn.ruleToStartState[startRuleIndex];
InterpreterRuleContext rootContext = new InterpreterRuleContext(null, ATNState.INVALID_STATE_NUMBER, startRuleIndex);
if (startRuleStartState.isPrecedenceRule) {
enterRecursionRule(rootContext, startRuleStartState.stateNumber, startRuleIndex, 0);
}
else {
enterRule(rootContext, startRuleStartState.stateNumber, startRuleIndex);
}
while ( true ) {
ATNState p = getATNState();
switch ( p.getStateType() ) {
case ATNState.RULE_STOP :
// pop; return from rule
if ( _ctx.isEmpty() ) {
if (startRuleStartState.isPrecedenceRule) {
ParserRuleContext result = _ctx;
Pair<ParserRuleContext, Integer> parentContext = _parentContextStack.pop();
unrollRecursionContexts(parentContext.a);
return result;
}
else {
exitRule();
return rootContext;
}
}
visitRuleStopState(p);
break;
default :
try {
visitState(p);
}
catch (RecognitionException e) {
setState(atn.ruleToStopState[p.ruleIndex].stateNumber);
getContext().exception = e;
getErrorHandler().reportError(this, e);
getErrorHandler().recover(this, e);
}
break;
}
}
}
@Override
public void enterRecursionRule(ParserRuleContext localctx, int state, int ruleIndex, int precedence) {
_parentContextStack.push(new Pair<ParserRuleContext, Integer>(_ctx, localctx.invokingState));
super.enterRecursionRule(localctx, state, ruleIndex, precedence);
}
protected ATNState getATNState() {
return atn.states.get(getState());
}
protected void visitState(ATNState p) {
int edge;
if (p.getNumberOfTransitions() > 1) {
getErrorHandler().sync(this);
edge = getInterpreter().adaptivePredict(_input, ((DecisionState)p).decision, _ctx);
}
else {
edge = 1;
}
Transition transition = p.transition(edge - 1);
switch (transition.getSerializationType()) {
case Transition.EPSILON:
if (pushRecursionContextStates.get(p.stateNumber) && !(transition.target instanceof LoopEndState)) {
InterpreterRuleContext ctx = new InterpreterRuleContext(_parentContextStack.peek().a, _parentContextStack.peek().b, _ctx.getRuleIndex());
pushNewRecursionContext(ctx, atn.ruleToStartState[p.ruleIndex].stateNumber, _ctx.getRuleIndex());
}
break;
case Transition.ATOM:
match(((AtomTransition)transition).label);
break;
case Transition.RANGE:
case Transition.SET:
case Transition.NOT_SET:
if (!transition.matches(_input.LA(1), Token.MIN_USER_TOKEN_TYPE, 65535)) {
_errHandler.recoverInline(this);
}
matchWildcard();
break;
case Transition.WILDCARD:
matchWildcard();
break;
case Transition.RULE:
RuleStartState ruleStartState = (RuleStartState)transition.target;
int ruleIndex = ruleStartState.ruleIndex;
InterpreterRuleContext ctx = new InterpreterRuleContext(_ctx, p.stateNumber, ruleIndex);
if (ruleStartState.isPrecedenceRule) {
enterRecursionRule(ctx, ruleStartState.stateNumber, ruleIndex, ((RuleTransition)transition).precedence);
}
else {
enterRule(ctx, transition.target.stateNumber, ruleIndex);
}
break;
case Transition.PREDICATE:
PredicateTransition predicateTransition = (PredicateTransition)transition;
if (!sempred(_ctx, predicateTransition.ruleIndex, predicateTransition.predIndex)) {
throw new FailedPredicateException(this);
}
break;
case Transition.ACTION:
ActionTransition actionTransition = (ActionTransition)transition;
action(_ctx, actionTransition.ruleIndex, actionTransition.actionIndex);
break;
case Transition.PRECEDENCE:
if (!precpred(_ctx, ((PrecedencePredicateTransition)transition).precedence)) {
throw new FailedPredicateException(this, String.format("precpred(_ctx, %d)", ((PrecedencePredicateTransition)transition).precedence));
}
break;
default:
throw new UnsupportedOperationException("Unrecognized ATN transition type.");
}
setState(transition.target.stateNumber);
}
protected void visitRuleStopState(ATNState p) {
RuleStartState ruleStartState = atn.ruleToStartState[p.ruleIndex];
if (ruleStartState.isPrecedenceRule) {
Pair<ParserRuleContext, Integer> parentContext = _parentContextStack.pop();
unrollRecursionContexts(parentContext.a);
setState(parentContext.b);
}
else {
exitRule();
}
RuleTransition ruleTransition = (RuleTransition)atn.states.get(getState()).transition(0);
setState(ruleTransition.followState.stateNumber);
}
}