Examples with RecognitionException org.antlr.v4.runtime.RecognitionException used on opensource projects

Example 1 with RecognitionException

use of org.antlr.v4.runtime.RecognitionException in project antlr4 by antlr.

the class ParseTreePatternMatcher method compile.

/**
	 * For repeated use of a tree pattern, compile it to a
	 * {@link ParseTreePattern} using this method.
	 */
public ParseTreePattern compile(String pattern, int patternRuleIndex) {
    List<? extends Token> tokenList = tokenize(pattern);
    ListTokenSource tokenSrc = new ListTokenSource(tokenList);
    CommonTokenStream tokens = new CommonTokenStream(tokenSrc);
    ParserInterpreter parserInterp = new ParserInterpreter(parser.getGrammarFileName(), parser.getVocabulary(), Arrays.asList(parser.getRuleNames()), parser.getATNWithBypassAlts(), tokens);
    ParseTree tree = null;
    try {
        parserInterp.setErrorHandler(new BailErrorStrategy());
        tree = parserInterp.parse(patternRuleIndex);
    //			System.out.println("pattern tree = "+tree.toStringTree(parserInterp));
    } catch (ParseCancellationException e) {
        throw (RecognitionException) e.getCause();
    } catch (RecognitionException re) {
        throw re;
    } catch (Exception e) {
        throw new CannotInvokeStartRule(e);
    }
    // Make sure tree pattern compilation checks for a complete parse
    if (tokens.LA(1) != Token.EOF) {
        throw new StartRuleDoesNotConsumeFullPattern();
    }
    return new ParseTreePattern(this, pattern, patternRuleIndex, tree);
}

Example 2 with RecognitionException

use of org.antlr.v4.runtime.RecognitionException in project antlr4 by antlr.

the class DefaultErrorStrategy method recover.

/**
	 * {@inheritDoc}
	 *
	 * <p>The default implementation resynchronizes the parser by consuming tokens
	 * until we find one in the resynchronization set--loosely the set of tokens
	 * that can follow the current rule.</p>
	 */
@Override
public void recover(Parser recognizer, RecognitionException e) {
    //						   ", states="+lastErrorStates);
    if (lastErrorIndex == recognizer.getInputStream().index() && lastErrorStates != null && lastErrorStates.contains(recognizer.getState())) {
        // uh oh, another error at same token index and previously-visited
        // state in ATN; must be a case where LT(1) is in the recovery
        // token set so nothing got consumed. Consume a single token
        // at least to prevent an infinite loop; this is a failsafe.
        //			System.err.println("seen error condition before index="+
        //							   lastErrorIndex+", states="+lastErrorStates);
        //			System.err.println("FAILSAFE consumes "+recognizer.getTokenNames()[recognizer.getInputStream().LA(1)]);
        recognizer.consume();
    }
    lastErrorIndex = recognizer.getInputStream().index();
    if (lastErrorStates == null)
        lastErrorStates = new IntervalSet();
    lastErrorStates.add(recognizer.getState());
    IntervalSet followSet = getErrorRecoverySet(recognizer);
    consumeUntil(recognizer, followSet);
}

Example 3 with RecognitionException

use of org.antlr.v4.runtime.RecognitionException in project antlr4 by antlr.

the class DefaultErrorStrategy method sync.

/**
	 * The default implementation of {@link ANTLRErrorStrategy#sync} makes sure
	 * that the current lookahead symbol is consistent with what were expecting
	 * at this point in the ATN. You can call this anytime but ANTLR only
	 * generates code to check before subrules/loops and each iteration.
	 *
	 * <p>Implements Jim Idle's magic sync mechanism in closures and optional
	 * subrules. E.g.,</p>
	 *
	 * <pre>
	 * a : sync ( stuff sync )* ;
	 * sync : {consume to what can follow sync} ;
	 * </pre>
	 *
	 * At the start of a sub rule upon error, {@link #sync} performs single
	 * token deletion, if possible. If it can't do that, it bails on the current
	 * rule and uses the default error recovery, which consumes until the
	 * resynchronization set of the current rule.
	 *
	 * <p>If the sub rule is optional ({@code (...)?}, {@code (...)*}, or block
	 * with an empty alternative), then the expected set includes what follows
	 * the subrule.</p>
	 *
	 * <p>During loop iteration, it consumes until it sees a token that can start a
	 * sub rule or what follows loop. Yes, that is pretty aggressive. We opt to
	 * stay in the loop as long as possible.</p>
	 *
	 * <p><strong>ORIGINS</strong></p>
	 *
	 * <p>Previous versions of ANTLR did a poor job of their recovery within loops.
	 * A single mismatch token or missing token would force the parser to bail
	 * out of the entire rules surrounding the loop. So, for rule</p>
	 *
	 * <pre>
	 * classDef : 'class' ID '{' member* '}'
	 * </pre>
	 *
	 * input with an extra token between members would force the parser to
	 * consume until it found the next class definition rather than the next
	 * member definition of the current class.
	 *
	 * <p>This functionality cost a little bit of effort because the parser has to
	 * compare token set at the start of the loop and at each iteration. If for
	 * some reason speed is suffering for you, you can turn off this
	 * functionality by simply overriding this method as a blank { }.</p>
	 */
@Override
public void sync(Parser recognizer) throws RecognitionException {
    ATNState s = recognizer.getInterpreter().atn.states.get(recognizer.getState());
    // If already recovering, don't try to sync
    if (inErrorRecoveryMode(recognizer)) {
        return;
    }
    TokenStream tokens = recognizer.getInputStream();
    int la = tokens.LA(1);
    // try cheaper subset first; might get lucky. seems to shave a wee bit off
    IntervalSet nextTokens = recognizer.getATN().nextTokens(s);
    if (nextTokens.contains(Token.EPSILON) || nextTokens.contains(la)) {
        return;
    }
    switch(s.getStateType()) {
        case ATNState.BLOCK_START:
        case ATNState.STAR_BLOCK_START:
        case ATNState.PLUS_BLOCK_START:
        case ATNState.STAR_LOOP_ENTRY:
            // report error and recover if possible
            if (singleTokenDeletion(recognizer) != null) {
                return;
            }
            throw new InputMismatchException(recognizer);
        case ATNState.PLUS_LOOP_BACK:
        case ATNState.STAR_LOOP_BACK:
            //			System.err.println("at loop back: "+s.getClass().getSimpleName());
            reportUnwantedToken(recognizer);
            IntervalSet expecting = recognizer.getExpectedTokens();
            IntervalSet whatFollowsLoopIterationOrRule = expecting.or(getErrorRecoverySet(recognizer));
            consumeUntil(recognizer, whatFollowsLoopIterationOrRule);
            break;
        default:
            // do nothing if we can't identify the exact kind of ATN state
            break;
    }
}

Example 4 with RecognitionException

use of org.antlr.v4.runtime.RecognitionException in project antlr4 by antlr.

the class GrammarParserInterpreter method getAllPossibleParseTrees.

/** Given an ambiguous parse information, return the list of ambiguous parse trees.
	 *  An ambiguity occurs when a specific token sequence can be recognized
	 *  in more than one way by the grammar. These ambiguities are detected only
	 *  at decision points.
	 *
	 *  The list of trees includes the actual interpretation (that for
	 *  the minimum alternative number) and all ambiguous alternatives.
	 *  The actual interpretation is always first.
	 *
	 *  This method reuses the same physical input token stream used to
	 *  detect the ambiguity by the original parser in the first place.
	 *  This method resets/seeks within but does not alter originalParser.
	 *
	 *  The trees are rooted at the node whose start..stop token indices
	 *  include the start and stop indices of this ambiguity event. That is,
	 *  the trees returned will always include the complete ambiguous subphrase
	 *  identified by the ambiguity event.  The subtrees returned will
	 *  also always contain the node associated with the overridden decision.
	 *
	 *  Be aware that this method does NOT notify error or parse listeners as
	 *  it would trigger duplicate or otherwise unwanted events.
	 *
	 *  This uses a temporary ParserATNSimulator and a ParserInterpreter
	 *  so we don't mess up any statistics, event lists, etc...
	 *  The parse tree constructed while identifying/making ambiguityInfo is
	 *  not affected by this method as it creates a new parser interp to
	 *  get the ambiguous interpretations.
	 *
	 *  Nodes in the returned ambig trees are independent of the original parse
	 *  tree (constructed while identifying/creating ambiguityInfo).
	 *
	 *  @since 4.5.1
	 *
	 *  @param g              From which grammar should we drive alternative
	 *                        numbers and alternative labels.
	 *
	 *  @param originalParser The parser used to create ambiguityInfo; it
	 *                        is not modified by this routine and can be either
	 *                        a generated or interpreted parser. It's token
	 *                        stream *is* reset/seek()'d.
	 *  @param tokens		  A stream of tokens to use with the temporary parser.
	 *                        This will often be just the token stream within the
	 *                        original parser but here it is for flexibility.
	 *
	 *  @param decision       Which decision to try different alternatives for.
	 *
	 *  @param alts           The set of alternatives to try while re-parsing.
	 *
	 *  @param startIndex	  The index of the first token of the ambiguous
	 *                        input or other input of interest.
	 *
	 *  @param stopIndex      The index of the last token of the ambiguous input.
	 *                        The start and stop indexes are used primarily to
	 *                        identify how much of the resulting parse tree
	 *                        to return.
	 *
	 *  @param startRuleIndex The start rule for the entire grammar, not
	 *                        the ambiguous decision. We re-parse the entire input
	 *                        and so we need the original start rule.
	 *
	 *  @return               The list of all possible interpretations of
	 *                        the input for the decision in ambiguityInfo.
	 *                        The actual interpretation chosen by the parser
	 *                        is always given first because this method
	 *                        retests the input in alternative order and
	 *                        ANTLR always resolves ambiguities by choosing
	 *                        the first alternative that matches the input.
	 *                        The subtree returned
	 *
	 *  @throws RecognitionException Throws upon syntax error while matching
	 *                               ambig input.
	 */
public static List<ParserRuleContext> getAllPossibleParseTrees(Grammar g, Parser originalParser, TokenStream tokens, int decision, BitSet alts, int startIndex, int stopIndex, int startRuleIndex) throws RecognitionException {
    List<ParserRuleContext> trees = new ArrayList<ParserRuleContext>();
    // Create a new parser interpreter to parse the ambiguous subphrase
    ParserInterpreter parser = deriveTempParserInterpreter(g, originalParser, tokens);
    if (stopIndex >= (tokens.size() - 1)) {
        // if we are pointing at EOF token
        // EOF is not in tree, so must be 1 less than last non-EOF token
        stopIndex = tokens.size() - 2;
    }
    // get ambig trees
    int alt = alts.nextSetBit(0);
    while (alt >= 0) {
        // re-parse entire input for all ambiguous alternatives
        // (don't have to do first as it's been parsed, but do again for simplicity
        //  using this temp parser.)
        parser.reset();
        parser.addDecisionOverride(decision, startIndex, alt);
        ParserRuleContext t = parser.parse(startRuleIndex);
        GrammarInterpreterRuleContext ambigSubTree = (GrammarInterpreterRuleContext) Trees.getRootOfSubtreeEnclosingRegion(t, startIndex, stopIndex);
        // Use higher of overridden decision tree or tree enclosing all tokens
        if (Trees.isAncestorOf(parser.getOverrideDecisionRoot(), ambigSubTree)) {
            ambigSubTree = (GrammarInterpreterRuleContext) parser.getOverrideDecisionRoot();
        }
        trees.add(ambigSubTree);
        alt = alts.nextSetBit(alt + 1);
    }
    return trees;
}

Example 5 with RecognitionException

use of org.antlr.v4.runtime.RecognitionException in project antlr4 by antlr.

the class TestCodeGeneration method getEvalInfoForString.

public List<String> getEvalInfoForString(String grammarString, String pattern) throws RecognitionException {
    ErrorQueue equeue = new ErrorQueue();
    Grammar g = new Grammar(grammarString);
    List<String> evals = new ArrayList<String>();
    if (g.ast != null && !g.ast.hasErrors) {
        SemanticPipeline sem = new SemanticPipeline(g);
        sem.process();
        ATNFactory factory = new ParserATNFactory(g);
        if (g.isLexer())
            factory = new LexerATNFactory((LexerGrammar) g);
        g.atn = factory.createATN();
        CodeGenerator gen = new CodeGenerator(g);
        ST outputFileST = gen.generateParser();
        //			STViz viz = outputFileST.inspect();
        //			try {
        //				viz.waitForClose();
        //			}
        //			catch (Exception e) {
        //				e.printStackTrace();
        //			}
        boolean debug = false;
        DebugInterpreter interp = new DebugInterpreter(outputFileST.groupThatCreatedThisInstance, outputFileST.impl.nativeGroup.errMgr, debug);
        InstanceScope scope = new InstanceScope(null, outputFileST);
        StringWriter sw = new StringWriter();
        AutoIndentWriter out = new AutoIndentWriter(sw);
        interp.exec(out, scope);
        for (String e : interp.evals) {
            if (e.contains(pattern)) {
                evals.add(e);
            }
        }
    }
    if (equeue.size() > 0) {
        System.err.println(equeue.toString());
    }
    return evals;
}