SupportParserHelper.java

/*
 * *************************************************************************************
 *  Copyright (C) 2008 EsperTech, Inc. All rights reserved.                            *
 *  http://esper.codehaus.org                                                          *
 *  http://www.espertech.com                                                           *
 *  ---------------------------------------------------------------------------------- *
 *  The software in this package is published under the terms of the GPL license       *
 *  a copy of which has been included with this distribution in the license.txt file.  *
 * *************************************************************************************
 */

package com.espertech.esper.support.epl.parse;

import com.espertech.esper.antlr.NoCaseSensitiveStream;
import com.espertech.esper.antlr.ASTUtil;
import com.espertech.esper.collection.Pair;
import com.espertech.esper.epl.generated.EsperEPL2GrammarLexer;
import com.espertech.esper.epl.generated.EsperEPL2GrammarParser;
import com.espertech.esper.epl.parse.ParseRuleSelector;
import org.antlr.runtime.CharStream;
import org.antlr.runtime.CommonTokenStream;
import org.antlr.runtime.RecognitionException;
import org.antlr.runtime.tree.RewriteCardinalityException;
import org.antlr.runtime.tree.Tree;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.io.IOException;
import java.io.StringReader;

public class SupportParserHelper
{
    public static void displayAST(Tree ast) throws Exception
    {
        log.debug(".displayAST...");
        if (log.isDebugEnabled())
        {
            ASTUtil.dumpAST(ast);
        }
    }

    public static Pair<Tree, CommonTokenStream> parsePattern(String text) throws Exception
    {
        ParseRuleSelector startRuleSelector = new ParseRuleSelector()
        {
            public Tree invokeParseRule(EsperEPL2GrammarParser parser) throws RecognitionException
            {
                EsperEPL2GrammarParser.startPatternExpressionRule_return r = parser.startPatternExpressionRule();
                return (Tree) r.getTree();
            }
        };
        return parse(startRuleSelector, text);
    }

    public static Pair<Tree, CommonTokenStream> parseEPL(String text) throws Exception
    {
        ParseRuleSelector startRuleSelector = new ParseRuleSelector()
        {
            public Tree invokeParseRule(EsperEPL2GrammarParser parser) throws RecognitionException
            {
                EsperEPL2GrammarParser.startEPLExpressionRule_return r = parser.startEPLExpressionRule();
                return (Tree) r.getTree();
            }
        };
        return parse(startRuleSelector, text);
    }

    public static Pair<Tree, CommonTokenStream> parseEventProperty(String text) throws Exception
    {
        ParseRuleSelector startRuleSelector = new ParseRuleSelector()
        {
            public Tree invokeParseRule(EsperEPL2GrammarParser parser) throws RecognitionException
            {
                return (Tree) parser.startEventPropertyRule().getTree();
            }
        };
        return parse(startRuleSelector, text);
    }

    public static Pair<Tree, CommonTokenStream> parseJson(String text) throws Exception
    {
        ParseRuleSelector startRuleSelector = new ParseRuleSelector()
        {
            public Tree invokeParseRule(EsperEPL2GrammarParser parser) throws RecognitionException
            {
                EsperEPL2GrammarParser.startJsonValueRule_return r = parser.startJsonValueRule();
                return (Tree) r.getTree();
            }
        };
        return parse(startRuleSelector, text);
    }

    public static Pair<Tree, CommonTokenStream> parse(ParseRuleSelector parseRuleSelector, String text) throws Exception
    {
        CharStream input;
        try
        {
            input = new NoCaseSensitiveStream(new StringReader(text));
        }
        catch (IOException ex)
        {
            throw new RuntimeException("IOException parsing text '" + text + '\'', ex);
        }

        EsperEPL2GrammarLexer lex = new EsperEPL2GrammarLexer(input);
        CommonTokenStream tokens = new CommonTokenStream(lex);
        ASTUtil.printTokens(tokens);
        EsperEPL2GrammarParser g = new EsperEPL2GrammarParser(tokens);
        EsperEPL2GrammarParser.startEventPropertyRule_return r;

        Tree tree;
        try
        {
            tree = parseRuleSelector.invokeParseRule(g);
        }
        catch (RewriteCardinalityException ex)
        {
            log.error(ex.getMessage());
            throw ex;
        }
        return new Pair<Tree, CommonTokenStream>(tree, tokens);
    }

    private static Log log = LogFactory.getLog(SupportParserHelper.class);
}