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

Example 76 with Parser

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

the class ParserATNSimulator method getTokenName.

public String getTokenName(int t) {
    if (t == Token.EOF) {
        return "EOF";
    }
    Vocabulary vocabulary = parser != null ? parser.getVocabulary() : VocabularyImpl.EMPTY_VOCABULARY;
    String displayName = vocabulary.getDisplayName(t);
    if (displayName.equals(Integer.toString(t))) {
        return displayName;
    }
    return displayName + "<" + t + ">";
}

Example 77 with Parser

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

the class ParserATNSimulator method reportAttemptingFullContext.

protected void reportAttemptingFullContext(DFA dfa, BitSet conflictingAlts, ATNConfigSet configs, int startIndex, int stopIndex) {
    if (debug || retry_debug) {
        Interval interval = Interval.of(startIndex, stopIndex);
        System.out.println("reportAttemptingFullContext decision=" + dfa.decision + ":" + configs + ", input=" + parser.getTokenStream().getText(interval));
    }
    if (parser != null)
        parser.getErrorListenerDispatch().reportAttemptingFullContext(parser, dfa, startIndex, stopIndex, conflictingAlts, configs);
}

Example 78 with Parser

use of org.antlr.v4.runtime.Parser 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 79 with Parser

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

the class GrammarParserInterpreter method getLookaheadParseTrees.

/** Return a list of parse trees, one for each alternative in a decision
	 *  given the same input.
	 *
	 *  Very similar to {@link #getAllPossibleParseTrees} except
	 *  that it re-parses the input for every alternative in a decision,
	 *  not just the ambiguous ones (there is no alts parameter here).
	 *  This method also tries to reduce the size of the parse trees
	 *  by stripping away children of the tree that are completely out of range
	 *  of startIndex..stopIndex. Also, because errors are expected, we
	 *  use a specialized error handler that more or less bails out
	 *  but that also consumes the first erroneous token at least. This
	 *  ensures that an error node will be in the parse tree for display.
	 *
	 *  NOTES:
    // we must parse the entire input now with decision overrides
	// we cannot parse a subset because it could be that a decision
	// above our decision of interest needs to read way past
	// lookaheadInfo.stopIndex. It seems like there is no escaping
	// the use of a full and complete token stream if we are
	// resetting to token index 0 and re-parsing from the start symbol.
	// It's not easy to restart parsing somewhere in the middle like a
	// continuation because our call stack does not match the
	// tree stack because of left recursive rule rewriting. grrrr!
	 *
	 * @since 4.5.1
	 */
public static List<ParserRuleContext> getLookaheadParseTrees(Grammar g, ParserInterpreter originalParser, TokenStream tokens, int startRuleIndex, int decision, int startIndex, int stopIndex) {
    List<ParserRuleContext> trees = new ArrayList<ParserRuleContext>();
    // Create a new parser interpreter to parse the ambiguous subphrase
    ParserInterpreter parser = deriveTempParserInterpreter(g, originalParser, tokens);
    DecisionState decisionState = originalParser.getATN().decisionToState.get(decision);
    for (int alt = 1; alt <= decisionState.getTransitions().length; alt++) {
        // 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.)
        GrammarParserInterpreter.BailButConsumeErrorStrategy errorHandler = new GrammarParserInterpreter.BailButConsumeErrorStrategy();
        parser.setErrorHandler(errorHandler);
        parser.reset();
        parser.addDecisionOverride(decision, startIndex, alt);
        ParserRuleContext tt = parser.parse(startRuleIndex);
        int stopTreeAt = stopIndex;
        if (errorHandler.firstErrorTokenIndex >= 0) {
            // cut off rest at first error
            stopTreeAt = errorHandler.firstErrorTokenIndex;
        }
        Interval overallRange = tt.getSourceInterval();
        if (stopTreeAt > overallRange.b) {
            // If we try to look beyond range of tree, stopTreeAt must be EOF
            // for which there is no EOF ref in grammar. That means tree
            // will not have node for stopTreeAt; limit to overallRange.b
            stopTreeAt = overallRange.b;
        }
        ParserRuleContext subtree = Trees.getRootOfSubtreeEnclosingRegion(tt, startIndex, stopTreeAt);
        // Use higher of overridden decision tree or tree enclosing all tokens
        if (Trees.isAncestorOf(parser.getOverrideDecisionRoot(), subtree)) {
            subtree = parser.getOverrideDecisionRoot();
        }
        Trees.stripChildrenOutOfRange(subtree, parser.getOverrideDecisionRoot(), startIndex, stopTreeAt);
        trees.add(subtree);
    }
    return trees;
}

Example 80 with Parser

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

the class GrammarParserInterpreter method deriveTempParserInterpreter.

/** Derive a new parser from an old one that has knowledge of the grammar.
	 *  The Grammar object is used to correctly compute outer alternative
	 *  numbers for parse tree nodes. A parser of the same type is created
	 *  for subclasses of {@link ParserInterpreter}.
	 */
public static ParserInterpreter deriveTempParserInterpreter(Grammar g, Parser originalParser, TokenStream tokens) {
    ParserInterpreter parser;
    if (originalParser instanceof ParserInterpreter) {
        Class<? extends ParserInterpreter> c = originalParser.getClass().asSubclass(ParserInterpreter.class);
        try {
            Constructor<? extends ParserInterpreter> ctor = c.getConstructor(Grammar.class, ATN.class, TokenStream.class);
            parser = ctor.newInstance(g, originalParser.getATN(), originalParser.getTokenStream());
        } catch (Exception e) {
            throw new IllegalArgumentException("can't create parser to match incoming " + originalParser.getClass().getSimpleName(), e);
        }
    } else {
        // must've been a generated parser
        char[] serializedAtn = ATNSerializer.getSerializedAsChars(originalParser.getATN());
        ATN deserialized = new ATNDeserializer().deserialize(serializedAtn);
        parser = new ParserInterpreter(originalParser.getGrammarFileName(), originalParser.getVocabulary(), Arrays.asList(originalParser.getRuleNames()), deserialized, tokens);
    }
    parser.setInputStream(tokens);
    // Make sure that we don't get any error messages from using this temporary parser
    parser.setErrorHandler(new BailErrorStrategy());
    parser.removeErrorListeners();
    parser.removeParseListeners();
    parser.getInterpreter().setPredictionMode(PredictionMode.LL_EXACT_AMBIG_DETECTION);
    return parser;
}