org.ballerinalang.util.parser.BallerinaParserErrorStrategy.java Source code

Introduction

Here is the source code for org.ballerinalang.util.parser.BallerinaParserErrorStrategy.java

Source

/*
 * Copyright (c) 2016, WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
 *
 * WSO2 Inc. licenses this file to you under the Apache License,
 * Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License.
 * You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.ballerinalang.util.parser;

import org.antlr.v4.runtime.DefaultErrorStrategy;
import org.antlr.v4.runtime.FailedPredicateException;
import org.antlr.v4.runtime.InputMismatchException;
import org.antlr.v4.runtime.NoViableAltException;
import org.antlr.v4.runtime.Parser;
import org.antlr.v4.runtime.ParserRuleContext;
import org.antlr.v4.runtime.RecognitionException;
import org.antlr.v4.runtime.Token;
import org.antlr.v4.runtime.misc.IntervalSet;
import org.antlr.v4.runtime.misc.ParseCancellationException;

/**
 * Error Handling strategy for {@link BallerinaParser}.
 */
public class BallerinaParserErrorStrategy extends DefaultErrorStrategy {

    @Override
    public void recover(Parser parser, RecognitionException e) {
        Token missingSymbol = parser.getCurrentToken();
        int line = missingSymbol.getLine();
        int position = missingSymbol.getCharPositionInLine();
        String mismatchedToken = getTokenErrorDisplay(missingSymbol);
        String msg = getSourceLocation(parser, line, position) + "invalid token " + mismatchedToken + ". "
                + e.getMessage();
        setContextException(parser);
        throw new ParseCancellationException(msg);
    }

    @Override
    public void reportInputMismatch(Parser parser, InputMismatchException e) {
        int line = getMissingSymbol(parser).getLine();
        int position = getMissingSymbol(parser).getCharPositionInLine();
        String mismatchedToken = getTokenErrorDisplay(e.getOffendingToken());
        String expectedToken = e.getExpectedTokens().toString(parser.getVocabulary());
        String msg = getSourceLocation(parser, line, position) + "mismatched input " + mismatchedToken
                + ". Expecting one of " + expectedToken;
        setContextException(parser);
        throw new ParseCancellationException(msg);
    }

    @Override
    public void reportMissingToken(Parser parser) {
        Token token = parser.getCurrentToken();
        IntervalSet expecting = getExpectedTokens(parser);
        int line = getMissingSymbol(parser).getLine();
        int position = getMissingSymbol(parser).getCharPositionInLine();
        String missingToken = expecting.toString(parser.getVocabulary());
        String msg = getSourceLocation(parser, line, position) + "missing " + missingToken + " before "
                + getTokenErrorDisplay(token);
        setContextException(parser);
        throw new ParseCancellationException(msg);
    }

    @Override
    public void reportNoViableAlternative(Parser parser, NoViableAltException e) {
        Token token = parser.getCurrentToken();
        int line = getMissingSymbol(parser).getLine();
        int position = getMissingSymbol(parser).getCharPositionInLine();
        String msg = getSourceLocation(parser, line, position) + "invalid identifier "
                + getTokenErrorDisplay(token);
        setContextException(parser);
        throw new ParseCancellationException(msg);
    }

    @Override
    public void reportUnwantedToken(Parser parser) {
        Token token = parser.getCurrentToken();
        int line = getMissingSymbol(parser).getLine();
        int position = getMissingSymbol(parser).getCharPositionInLine();
        String msg = getSourceLocation(parser, line, position) + "unwanted token " + getTokenErrorDisplay(token);
        setContextException(parser);
        throw new ParseCancellationException(msg);
    }

    @Override
    public void reportFailedPredicate(Parser parser, FailedPredicateException e) {
        int line = getMissingSymbol(parser).getLine();
        int position = getMissingSymbol(parser).getCharPositionInLine();
        setContextException(parser);
        throw new ParseCancellationException(getSourceLocation(parser, line, position) + e.getMessage());
    }

    public void reportError(Parser parser, RecognitionException e) {
        if (e instanceof NoViableAltException) {
            reportNoViableAlternative(parser, (NoViableAltException) e);
        } else if (e instanceof InputMismatchException) {
            reportInputMismatch(parser, (InputMismatchException) e);
        } else if (e instanceof FailedPredicateException) {
            reportFailedPredicate(parser, (FailedPredicateException) e);
        } else {
            int line = getMissingSymbol(parser).getLine();
            int position = getMissingSymbol(parser).getCharPositionInLine();
            setContextException(parser);
            throw new ParseCancellationException(getSourceLocation(parser, line, position) + e.getMessage());
        }
    }

    /**
     * Set an exception in the parser context. This is later used at {@link BLangAntlr4Listener} level
     * to determine whether the parse exception has occured and is in error state.
     * 
     * @param parser    Current parser
     */
    private void setContextException(Parser parser) {
        // Here the type of the exception is not important. 
        InputMismatchException e = new InputMismatchException(parser);
        for (ParserRuleContext context = parser.getContext(); context != null; context = context.getParent()) {
            context.exception = e;
        }
    }

    private String getSourceLocation(Parser parser, int line, int position) {
        return parser.getSourceName() + ":" + line + ":" + position + ": ";
    }

}